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THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA PRESENTED BY PROF. CHARLES A. KOFOID AND MRS. PRUDENCE W. KOFOID ESSAYS SPIRIT OF THE INDUCTIVE PHILOSOPHY, UNITYOF WORLDS, AND THE PHILOSOPHY OF CREATION. BY THE EEV. BADEN POWELL, M.A. F.R.S. F.E.A.S.TF^.S. SAVILIAN PROFESSOR OF GEOMETRY IN THE UNIVERSITY OF OXFORD. LONDON: LONGMAN, BROWN, GREEN, AND LONGMANS. 1855. LONDON : A. and G. A. SS-OTTISWOOOE, New-street- Square. qni PREFACE. THE three following essays, though somewhat connected in subject, are yet each distinct and com- plete in themselves, having been originally composed at different times and with separate objects. Hence there will probably be found in some parts repetitions : but on the whole it appeared preferable to allow these to remain, rather than by omissions and altera- tions to render less complete and continuous the argument of each essay in itself. And the few topics which belong to them in common will, in most cases, be found treated under somewhat different aspects, according as the particular argument in each instance required. The First Essay consists mainly of an amplification of a few paragraphs in m^ paper " on Necessary and Contingent Truth " in the Oxford Ashmolean Memoirs, 1849, in reference to which I felt it iv PREFACE. desirable to explain and illustrate some points there but imperfectly treated, as well as some other topics related to them, and which have of late years been the subject of considerable discussion; some of which were also considered in my work on "the Connexion of Natural and Divine Truth," 1838. More precisely, the subjects of the primary grounds of inductive reasoning, and the theory of Causation, have long since appeared to me to be commonly in- volved in much confusion of thought, which has, as I think, been rather increased than diminished by some recent discussions from which we might have hoped for greater enlightenment ; and which ap- pears to me to be the source of many unhappy difficulties and objections connected with the so- called doctrine of " final causes," and the evidences of natural theology generally. To the object of clearing up some of these diffi- culties, and inculcating better views, some parts of my former work last referred to were devoted : And to the argument there pursued (so far as I am aware) no substantial objections^ave been alleged. Yet the frequent reproduction of the same original confusion of language and thought, in otherwise able and PREFACE. valuable writings at the present day, renders it not useless to recall attention to some of those considera- tions by which, I believe, the whole subject is put on a more satisfactory and unobjectionable basis. Many of these topics, it will be evident at first sight, are coextensive with those so elaborately and profoundly treated in Dr. Whe well's Philosophy of the Inductive Sciences and in Mr. Mill's Logic. If I have made very few specific references to either of those treatises, it has arisen from no want of respect and consideration for either of the distinguished authors ; but rather from an opposite feeling of high general esteem for the ability with which they have treated the subject, I entertained an unwillingness to appear to enter into direct controversy, in some material questions on which I have been constrained to hold opinions somewhat differing from those of both writers. If the grounds on which I maintain my views shall be found sufficiently indicated and explained, I trust the candid reader will be as well prepared to come to an unbiassed opinion on the points in ques- tion as if they were urged with a greater degree of critical detail ; and the opinions which I controvert A 3 PREFACE. will be equally marked out, without more minute reference to the particular authors. The Second Essay was called forth by a perusal of the two able and interesting works on the question of the Plurality of Worlds, which have of late at- tracted such an unexpected degree of public atten- tion ; an interest which, even up to the moment of bringing out this volume, does not appear to have abated, if we may judge from the several other pub- lications since announced on the same question. With respect to the author of the " Essay on the Plurality of Worlds," while it would be absurd to pre- tend ignorance of his real eminence, I have through- out felt it would at the same time be improper to refer to his opinions, otherwise than as those sustained by the masked character under which, doubtless for the greater freedom of such discussion, he has thought fit to veil academical dignity. The controversy itself, as to the question of inha- bited worlds, appears to me of comparatively little moment : it is rather for the sake of more general considerations involved, that I have been led to enter into the discussion, and, in some measure, to hold the balance between the two disputants. Those PREFACE. vii broader principles are closely connected with the subject of the First Essay. The collateral questions introduced into the Second Essay have also an immediate bearing on the sub- ject of the Third. The inquiry into the present con- dition of planetary worlds is closely connected with that of their past state and probable origin; and this with the general question of the history of cre- ation, so far as it can be traced on physical grounds. But this subject, again, is one which has of late years extensively occupied the public attention ; especially from the extraordinary popularity attained by the " Vestiges of the Natural History of Creation," and the controversies to which that work has given rise. In those controversial discussions, it cannot but be matter of regret that so acrimonious a tone, little suited to eliciting the truth, should have been adopted by some of the writers. Hence it seemed to me that a more calm and philosophical analysis of the whole question was much needed; and in some mea- sure to supply such a review of the general principles and grounds on which all speculations of the kind should be conducted, as well as to examine dispassion- ately into the alleged religious bearings of any the- A 4 I'KtT U f. ories by >\ hich some part of the stops and processes cation might bo explained, has been the aim of the Third Kssay. It should perhaps be expressly observed that if, in those passages whore 1 have spoken of the evidences of natural theology, I have professedly rest net ed my remarks to the / ''::. s:\\:.' portion ot the argument.- it is not from at all disparaging or o\orlooking the moral and mftophysiral ixirtions, that 1 have not adverted to them, but solely beeanse they are not immediately eonnected with the more direet object of these Kssays, aln\uly extended, perhaps, to too great a length. A similar remark ought, also, to be made with respect to the very brief and inadequate mention made of some other points of deeper import to the belief in revelation ; to which 1 could willingly have doNoteu a more extended discussion than it was pos- sible within my present limits to give them. ANALYTICAL TABLE OF CONTENTS. Y L ON THK SPIRIT OF THE INDUCTIVE PHILOSOPHY. L THE IKDUCTIVE PRINCIPLE. Page Induction something beyond mere Observation 3 Belief in a peculiar inductive Principle - - - 7 fjssary : Analysis up to simpler Elements - - 13 Relations of inductive and deducthre Methods : no a priori Proofs of physical Truth : Examples - - 19 Conclusion : Harmony of Reason and Nature 35 H. THE TTxiTT OP SCIENCES. Tendency towards Unity of Principle in all Branches of nee ---------40 Distinctions of Sciences not essential, but provisional - 44 Alleged Exceptions unfounded - - - - .: j gy : Founded on uniformity of natural Causes in all Time 59 _' animation and Life- - - - - -63 The vital Principle, physical 66 CONTENTS. Page Physiology not founded on final Causes, but Unity of Com- position ---------73 Case of Man : no real Exception : his Superiority moral, not physical --------74 Conclusion : Unity of Science Reflexion of Unity of Nature 78 in THE UNIFORMITY OF NATURE. Hindrances to Science : false Analogies and Dogmas - 82 The Philosophy of Conjecture ----- 89 Broad Principles of Analogy ----- 94 Uniformity of Nature the Essence of Induction - - 98 No Limits to inductive Inquiry - - - - 106 Interruptions of Order apparent, not real - - - 107 Conclusion : Inference of Supreme Reason - - -112 iv. THE THEORY OF CAUSATION. The Desire to seek Causes : confused Ideas - - - 114 Hume's Doctrine : requires farther Distinction - 115 Physical and moral Causation - - - - -118 Necessary Connexion in Reason, not in Events - - 119 Cases of Cause and Effect co-existent and convertible - 121 Cases of higher Connexion, not so - - - -123 Relation to Induction : physical Causes : higher Generali- sations --------- 125 Objections- -------- 129 Conclusion: physical Causes and a Supreme Moral Cause 132 v. FINAL CAUSES AND NATURAL THEOLOGY. Ideas of "final Causes" require Enlargement - - 133 Not Utility, but Order, the Proof of Intelligence - - 135 Confused Ideas of the Argument 145 Supposed Limits of Nature 150 CONTENTS. xi Page Anomalies, if real, would be Interruptions of Evidence of Design --------- 155 Higher Views from improved Science - - - - 158 Limits of Natural Theology - - - - - 162 Objections : Design and a Designer : Analogy of Mind - 165 Pantheism ---------167 Conclusion : universal Order the Proof of Supreme Mind 168 ESSAY II. ON THE UNITY OR PLURALITY OF WORLDS. i. THE ARGUMENT CONSIDERED IN A PHYSICAL AND PHILOSOPHICAL POINT OF VIEW. Introductory Remarks - - - - - -171 Statement of the Question in Relation to the Progress of Science --------- 179 Connexion with the past History of the Universe : nebular Theory 184 Sidereal Nebulae : their probable Nature, Motions, and Distances - - 190 Bearing on Question of Inhabitants - 198 The fixed Stars : binary Systems 200 Nebulous Portions of Solar System - 203 Present Condition of Solar System : Sun, Moon, Planets, Comets 208 Probable Evolution of Life, past, present, or future - 229 ii THE ARGUMENT CONSIDERED IN A THEOLOGICAL POINT OP VIEW. Opposing Views as to inhabited Worlds : each taken up on theological Grounds 236 Paradoxes and retrograde Spirit of the exclusive View - 237 CONTENTS. Page Relation of the Question to Man 242 Appeal to final Causes 252 Bearing of the Argument on Natural Theology - - 265 Alleged religious Difficulties of Plurality of Worlds. From Insignificance of Man - - - - - 276 From supposed Exclusiveness of Revelation - - 277 From Doctrines of Man's Nature - - - - 284 From Nature of Redemption - - - - 286 Alleged Connexion with a future State ... 293 More general View of the Relations of Science and Faith - - - - 294 Connexion of Science with Natural Theology - - 299 with Revelation - - - - 301 Physical Difficulties of the Bible 304 Christianity essentially spiritual and independent of phy- sical Speculations ; ' ..". - - - - 308 ESSAY III. ON THE PHILOSOPHY OF CREATION. INTRODUCTION : Nature of the proposed Inquiry - - 315 . i THE EVIDENCE DERIVED FROM GEOLOGY. Question of Progression - - - - - - 321 Law of Succession of Forms not yet made out - - 331 Principle of Continuity 335 Apparent Breaks in the Series not real : Objections con- sidered - - - 339 View of the Evidence 348 Immutable Laws equally observed in organic and inorganic Changes 354 CONTENTS. xiii ii. THE EVIDENCE DERIVED FROM PHYSIOLOGY. Page Earlier and limited Views of comparative Physiology - 363 Higher Principle of Unity of Composition ... 365 Owen's Vertebral Theory - - - 370 Extension of Unity of Composition - - - - 37 1 Nature of Species ------- 374 Theory of Permanence of Species - 376 Ultimate Infinity and Coalescence of Species - 378 Permanence for limited Periods - - - - - 381 Races of Men -------- 381 Theories of Mutability of Species and Development - 386 Local Distribution and specific Centres do not affect the Question -------- 402 Alternative of Origin of new Species out of existing Forms or inorganic Elements ------ 407 ni. GENERAL CONSIDERATIONS ARISING OUT OP THE PRECEDING EVIDENCE. Argument for Permanence of Species from Permanence of Natural Laws, unfounded 412 Argument from " Want of Experience" of Transmutation fallacious 415 Physical Causes of Origination of Species - - - 422 Recapitulation : Transmutation not proved, but a probable Conjecture subordinate to more general Laws as yet unknown - -- - - " " 425 Opposite Views of sudden Production of Life irrational and inconsistent - - - -- - -429 Principle of orderly Evolution by some natural Causes - 434 An absolute Beginning beyond physical Argument CONTENTS. iv. THE BEARING OF THE PRECEDING ARGUMENTS ON THE THEOLOGICAL VIEW OP CREATION. Page Common Misconception on the Subject - 440 Influence of Bigotry and Prejudice - 442 Theological Tendency of physical Theories of creative Processes .- ------- 443 Bearing on Natural Theology : Nebular Theory accordant with Design ... 445 Subsequent Revolutions : Unity of Plan evinces Design - 446 Development, if established, would afford increasing Evi- dence of Supreme Intelligence - - _<.. - - - 453 Bearing on Revelation : Discrepancy with the Old Testament, not increased by Theories of Development ------ 457 Repeated Creations more at variance - - - - 462 References to Creation in the New Testament not affected by any Theories ------- 463 Objections from Origin and primeval State of Man - 464 No Objections affecting Christianity - ... 467 Argument from successive Creations to Miracles inappli- cable - - -'. - 472 Conclusion : real Evidence of Creation in Continuity not in Interruption * -'. - - - - - 477 Law and Order the Divine Archetypes ... 480 APPENDIX. I. Inductive Reasoning ..... 435 II. The vital Principle, Dr. Carpenter - - - 488 III. The Satellite of Neptune - - ib. CONTENTS. Page IV. Psychology : Sir B. Brodie - - - 489 V. Causation 490 VI. Professor Owen's Vertebral Theory - - ib. VII. Mr. Huxley on Unity of Composition - - 495 VIII. Professor E. Forbes on Specific .Centres - 498 IX. Fossil Human Remains 501 ERRATA. Page 70. line 2. from bottom, for " and end " read " an end." 77. 1. for "concerned" read " properly such." 1 23. (margin), for " no " read " a." 240. line 3. for " bind " read " bend."- ,, 295. 2. for " threatened to " read "impending on.' ESSAY I. ON THE SPIRIT OF THE INDUCTIVE PHILOSOPHY. I THE INDUCTIVE PRINCIPLE. GALILEO, 1590. " Opinionum commenta delet dies, Naturae judicia confirmat." Cic. THE characteristic nature, genius, and grounds of introduc- the inductive philosophy have been much discussed marks, of late years, and under considerable varieties of view, by different parties. Whilst some have carried out their view of its principles into metaphysical abstractions often hardly intelligible, others have sought to narrow them to the results of mere sen- B 2 4 INDUCTIVE PRINCIPLE. [ESSAY I. i. sible experience ; and whilst the one would connect its aims with a higher intellectual philosophy, even verging on the mystical, the other school would lower its objects to the mere empire over matter, and the attainment of utilitarian ends. Distinction More precisely, an inquiry into the essential of sensa- tions and grounds and principles of induction involves the more general question of what has been termed "'the fundamental antithesis"* of sensations and ideas, facts and theories; in a word, of two essentially distinct and independent sources of all knowledge, the external and the internal observation by the senses, and ideas originating in the mind itself; while it is only by the application of the latter to reduce to system the materials supplied by the former, that any real philosophical theory can be constructed, the crude results of observation be converted into an inductive theory, or sense elabo- rated into science. Thus ideal conceptions, the pure offspring of mind, the mere creatures of intellect, seem to exercise a sort of plastic power over the mass of * See Dr. \Vhewell' s two able memoirs " On the Fundamental An- tithesis of Philosophy." Cambridge Phil. Society Transactions, 1848. ESSAY !.!.] INDUCTIVE PRINCIPLE. 5 material results, giving them a fresh character and scientific significance ; and thus we are enabled to make that ascent from facts to laws, from laws to causes, which is the aim and boast of the in- ductive philosophy. Such views, carried out in some instances to speculations of a kind still more re- mote and hardly comprehensible, have been adopted by many at the present day : while, on the other hand, the " positive philosophy " is characterised by a tendency to the contrary extreme of discarding all reference to those higher intellectual principles, reducing all science to the naked results of obser- vation and calculation, and all idea of causation to that of mere invariable sequence of phenomena. In looking more precisely to the meaning of the Meaning of the terra term experience, if we understand it literally as the expe- rience." mere collection of facts, such as sense and observation directly furnish, and the rejection of everything which is not, in this restricted sense, properly learnt by it, then, indeed, there is an end put to all really scien- tific or philosophical investigation; and beyond the narrow circle of those facts we can never enlarge our conceptions or raise our contemplations. The slightest consideration, however, will show B 3 6 INDUCTIVE PRINCIPLE. [EssAT I. I. induction that the term experience, even in the simplest case, implies more than mus t be understood in a wider sense : whilst the sensible ex- perience, logical analysis* of induction exhibits a syllogism in which a large assumption is necessarily implied, beyond and independent of any accumulation of facts. Thus every induction is seen essentially to involve a certain amount of hypothesis, a certain assumption of more than the bare facts themselves seem strictly to warrant. We form intellectual conceptions of a nature more general than the mere enumeration of a number of instances, how- ever many ; and thus supply " the string on which" (as Dr. Whewell happily expresses it) " the pearls are hung ; " and perceive, according to the illus- tration of another able writer f, how " philosophy proceeds upon a system of credit, and that, if she never advanced beyond her tangible capital, her wealth would not be so enormous as it is." It is certainly not the mere number of instances which constitutes the strength of an inductive con- clusion; but it is the kind and quality of them, as * See Archbishop Whately's Logic, book iv. ch. i. 1. 2. t Outlines of the Laws of Thought (p. 312.\ by Rev. W. Thomson, M.A. : London, 1849. ESSAY !.!.] INDUCTIVE PRINCIPLE. 7 bearing on the manifestation of the existence of certain relations among them, connecting them together by analogy. If the individual facts be thus connected, or of the right sort) a comparatively small number of them will be convincing, when in other cases the most laborious accumulation will be fruitless and unsatisfactory, as wanting in a real connection of analogy. When, however, that essen- tial condition is secured, it then infallibly happens (as has been well said) that a " vague and local idea .... passes through the mint of a very few decisive experiments into the treasury of accepted truths."* In arriving at any general inductive conclusion, what it is which is then, something is clearly superadded to the mere superadded to sensible mass of facts ; the question is, what is it ? In the facts, simplest case, that of knowledge acquired by the senses, something more than mere sensation is implied: besides sensations conveyed to the mind, there must be corresponding ideas excited or formed in it. All observation which involves mind involves theory : the facts of sense must be idealised. Of * Rev. W. V. Harcourt's Letter, &c., Phil. Mag. 1846, p. 76. B 4 8 INDUCTIVE PRINCIPLE. [ESSAY I. I. the truth of this no reflecting person entertains a doubt : the sole question is, how it is effected, and whence these ideas are formed. Supposed According to one school, these phenomena are inherent faculty or referred to a peculiar principle, supposed to be principle. implanted in the mind, not to be further analysed : a special faculty, producing a distinct mode of conviction; a kind of assurance, prior to and in- dependent of external sense, and derived from the interior resources of reason; an inherent intel- lectual element, which warrants us in extending our conclusions beyond the mere limits of obser- vation, and in inferring intuitively and certainly the future or unknown from the past or known. Or, more precisely, certain fundamental concep- tions are supposed primarily and originally formed within the mind itself, derived somehow from its interior resources, without any reference to external sensation ; and the introduction of these conceptions (differently modified according to the nature of the respective subjects) impresses the proper form on the collected facts. And it is from the fundamental ideas thus entering into combination that the attri- butes of universality and necessity are acquired ESSAY I. i.] INDUCTIVE PRINCIPLE. 9 by our conclusions and belief, and a certainty attained on a priori grounds which no mere observation could furnish. Another school, discarding all reference to any Another view. intuitive or internally created ideas, analyses the Gradual process of intellectual process into its elements, and shows abstraction and gene- that through successive steps of abstraction, from raiisation. the simple collection of facts, we advance to theories, which are true just in proportion as we are guided by the right perception of analogy and the im- portant rule of correcting one generalisation by another, and thus, that all knowledge is ultimately derived from observation. The theory of intuitive or internal principles idea of in- tuitive undoubtedly appeals powerfully to the imagination, principles natural. Nothing seems more natural or plausible than to refer everything to ultimate principles originating in the mind : it saves the labour of further analysis, and supplies a specious explanation of intellectual phenomena, which seems to gratify at once the desire of penetrating the secrets of our nature and the love of the mysterious, in appealing to great but hidden causes within us : a species of occult philosophy, which seems eminently to harmonise 10 INDUCTIVE PRINCIPLE. [ESSAY I. I. with the mysticising tendencies of the age; but which, nevertheless, appears to be conceived in a spirit very opposite to that of the simple and positive character of the inductive method, and, though sanctioned by great names, seems rather to be a retrograde movement, and to evince a lingering attachment to the scholastic mysticism, or to be in some sense a revival of it. Ought to be That we are naturally prone to entertain such analysed up to simpler notions may be very true; yet it may happen in elements. this, as in many other instances of what we are prone to do, that we do wrong. But the more strict metaphysical inquirer will acknowledge that it is unphilosophical to imagine peculiar and unknown mental principles, if processes carried on through already acknowledged intellectual powers can be shown to suffice for explaining the facts. In the present instance, indeed, as in other in- quiries, it may be perfectly allowable in the first instance to set down any outstanding class of phe- nomena as provisionally something sui generis, and of an elementary character, just as in chemistry we may regard any new substance as elementary while it is as yet undecomposed ; but still it is the ESSAY !.!.] INDUCTIVE PRINCIPLE. 11 aim of the chemist to decompose it if he can. In the same way there may be a multitude of ideas, impressions, intellectual sensations, and the like, which may at first seem like elementary principles ; but which, nevertheless, it should be the aim of the metaphysical analyst to reduce into their com- ponent simpler elements if possible. In such cases the powers of imagination may be Power of imagina- appealed to ; and doubtless those powers are suffi- tion. ciently prolific in suggesting theories. The minds of the ancient philosophers teemed with speculative schemes of nature before any study of facts had furnished them with substantial materials. Hum- boldt has well observed, that " long before the dis- covery of the New World it was thought land could be seen in the west from the Canaries and the Azores. They were phantasms not produced by any extraordinary refraction of the rays of light, but merely by a longing for the distant, for that which lies beyond the present. The natural philosophy of the Greeks, and the physics of the middle ages and even of much later centuries, presented swarms of such fantastic forms to the imagination. The mental eye still essays to pass the horizon of limited know- 12 INDUCTIVE PRINCIPLE. [EssAY I. i. ledge even as the material eye endeavours to pierce the natural horizon from an island height or shore. Faith in the unusual and wonderful gives definite outlines to every product of imagination; and the realm of fancy, a strange land of cosmological, geognostial, and imaginative dreams, is incessantly blended with the world of reality."* Yet mere imagination, however powerful and prolific, will avail little for creating any theories which will stand the test of observation, or which have any real application in nature. Something But, from considering tlfe nature of our gene- more than tion gina " ralisations, it is argued, that we must necessarily obtain ideas from some other source than sense, or that the mind possesses a peculiar power or faculty of acquiring a higher degree of certainty from within than experience can give from without. Or, again, it is said, in such cases as mathematical theorems, the mind attains certainty quite inde- pendently of experience ; whilst in other cases, such as limited inductions in subjects little known, it has no certainty beyond the mere facts which are directly presented to it. Why, then, is the mind * Cosmos, p. 84., 1st trans. ESSAY I. i.] INDUCTIVE PRINCIPLE. 13 so confident in one case and so cautious in the other, unless there be a real difference in the faculties brought into play in the two respective cases ? When we analyse the process logically, it is Logical analysis of manifest that, in induction, what is superadded to induction. a mere collection of facts consists precisely in the assumption " that all phenomena of the kind in ques- tion are similar to the few actually examined" The question, then, is reduced to this, How does Origin of this as- the mind come to make this universal assumption, sumption, and to be so firmly convinced of its truth ? In the first place, I think it will be allowed, on Mental pro- cesses car- reflection, that general conceptions of this kind, ried on uncon- however apparently abstract in their nature, may sciousiy. be created in our minds by very simple causes, of whose operation we may yet be quite un- conscious. There is nothing of which we are less conscious than the acquisition of the commonest ideas by daily experience, and the successive and gradual generalisation of that experience by the pro- cess of abstraction ; and in this way we constantly obtain (without being aware of it) numberless pre- possessions and convictions far stronger than any systematic demonstrations can supply. 14 INDUCTIVE PRINCIPLE. [ESSAY I. I. Assumption The primary assumption involved in all in- of the uni- formity of duction is the presumed uniformity of phenomena, nature. or the conformity of other facts of the same class with that under examination to the same law or type. Idea of It 18, then, perfectly true that no inductive pro- generalisa- tion derived cess can advance without the assumption of this from gra- dual expe- generalising principle, which is, nevertheless, ante- ricnce. cedent to the particular class of experimental testi- monies IN THAT INSTANCE appealed to. But what I would particularly dwell upon is, that it is not antecedent to ALL experience ; it is some principle already established in the mind by previous abs- tractions, remotely derived from previous expe- rience, and specially extended by ANALOGY beyond the precise limits of actual observation in this in- stance. Proneness It is true that there exists in the human mind a to hasty generaiisa- strong natural propensity to draw hasty inferences, tion. to generalise too rapidly, and to deceive ourselves by erecting conclusions on very unsubstantial and insufficient data ; and this is closely associated with the fondness for tracing resemblances ; being pleased with uniformity and the contemplation of analogy, ESSAY I. i.] INDUCTIVE PRINCIPLE. 15 real or imagined, where there are often but slight indications of it, or even where the appearances of it are in reality altogether fallacious. These propensities are evinced more or less strongly in different minds in the earliest exercise of their powers : and though in matters of common life and every-day occurrence they are soon and effectually subjected to the corrective process of enlarging ex- perience and reflection, which the pressing necessities of daily existence force upon us ; yet in other sub- jects, such as those of abstract speculation or philo- sophical inquiry, it may be long before they receive so salutary a check, or at least before they come to be really well regulated by rational principles. Our FIRST inductions are ALWAYS IMPERFECT Generalisa- tions imper- AND INCONCLUSIVE ; we advance towards real evi- feet at first, corrected dence by successive approximations ; and accordingly by increas- ing ex- we find false generalisation the besetting error of perience. most first attempts at scientific research. The faculty to generalise accurately and philosophically requires large caution and long training ; and is not fully attained, especially in reference to more general views, even by some who may properly claim the title of very accurate scientific observers in a more 16 INDUCTIVE PRINCIPLE. [ESSAY I. i. Tendency evinced in different degrees. Feeble in earlier stages. limited field. It is an intellectual habit which acquires immense and accumulating force from the contemplation of wider analogies; and in any one case our conviction of inductive truth is largely built up on past trial of its soundness in other cases ; and from the perpetual multiplication of such cases it obtains a perpetually progressive character of greater certainty, increasing in a rapidly accelerated ratio as experience enlarges. By trial of theoretical suggestions in succession, and only after repeated failure, we learn their erro- neous nature. But thus by acquiring more caution and confidence and adopting better conjectures, we revise and amend our attempts, and learn to proceed on more sound principles, until we gain a habit of generalisation worthy the name of inductive power. Again, the tendency to make the primary induc- tive assumption, and the extent to which it reaches, admit of many degrees. It is found in its higher perfection in those comprehensive views which con- stitute the discoveries of the greatest philosophers, and in varied inferior degrees in other instances. In the order of time, also, it is always evinced with far less effect in the earlier stages of scientific ESSAY I. i.] INDUCTIVE PRINCIPLE. 17 development, and with more full and perfect force in its later progress ; whether in the infancy of science, or of the experience of an individual. But as the cultivation of inquiry advances, the Gains strength by inductive process by habitual exercise derives force advance of experience. so naturally and insensibly, that the mind is utterly unconscious of its acquirement ; and hence it is that we readily give way to the very natural, but mis- taken persuasion, that the generalised idea is some- thing inherent, or created out of the intrinsic powers of reason itself. And in any case even of the most limited indue- And from absence of tion, there is one argument on which, more than any contradic- tory cases. other, we always fall back with perfect confidence, and which really constitutes the main force of the evidence, viz. the assurance that if there be any fatal exception to the law or truth supposed to be esta- blished, it will soon be sure to manifest itself. The wow-occurrence of such an exception against a sup- posed law is a far stronger argument than the occurrence of hundreds of instances in its favour : and this consideration probably operates far more strongly with most minds than any abstract prin- ciple of conviction. c 18 INDUCTIVE PKINCIPLE. [ESSAY I. i. NO intui- If there be any force in what has been advanced, tive percep- tion of ex- then, instead of any primary or inherent principle, ternal truth. any original element of the mind, enabling it to see the outward world blindfold, any intuitive internal power to create external facts, any authority derived solely from the interior resources of pure reason to show us physical and material things without re- The case ference to the senses, or the like, the simple resolvable into the analysis of the case would lead us to the more power of abstraction, so ber belief that the source of inductive cer- tainty, that certainty beyond the mere limits of sense, that superstructure larger than any found- ation of facts, is accounted for by natural and ac- knowledged processes. It arises in the first instance out of the power of abstraction, acting with unconscious force and power- ful rapidity, by whose aid the mind creates what are indeed new conceptions, yet formed only out of materials already furnished, and this not by addition, but by subtraction of properties and particulars. Mainly Above all, the process derives its whole force from aided by perception the discovery and acceptance of sound and well- of analogy. framed analogies, or, as I have elsewhere said, THE ESSAY I. i.] INDUCTIVE PKINCIPLE. 19 SOUL OF INDUCTION is ANALOGY; and higher, more efficacious, and more enduring, as the analogies adopted are more strictly accordant with the real harmonies of nature. The application of a higher reasoning to the mere Application of mathe- facts of observation which essentially constitutes maticai reasoning. science throughout a large extent of physical re- search, is mainly effected by the application of those systems of abstract and necessary mathematical truth which have been independently deduced from ab- stractions respecting quantity in its several species (themselves derived not less originally from ex- periences of sensible extension, division, and nume- ration), whence spring quantitative laws and mathe- matical theories, which confer on the inductive results, whenever they can be applied, a character of increasing certainty and power arising from the higher capacity for generalisation. Thus the two systems react on each other, and we are often en- abled to carry on our views, and predict results to which no mere extension of observation could have conducted us. The process of inductive generalisation indeed C 2 20 INDUCTIVE PKINCIPLE. [ESSAY I. i. Corre- spondence of mathe- matical and physical truths. Asserted a priori evi- dence of physical truths, ex- amined in several in- stances. becomes infinitely more rapid, decisive, and well- founded, when pursued in connection with the de- ductive method. The application of mathematical formulas, if found to apply to the subject, not only leads with greater readiness to general laws, but carries with it a powerful presumption in many cases that it is really the exponent of some actual and higher natural analogy which we could never have collected from any mere observation of facts. Such instances are, indeed, constantly occurring in various degrees ; but, in some particularly striking cases, have evinced, to a singular extent, the cor- respondence between the real, but as yet unknown, laws of nature, and the abstract creations of mathe- matical conception : as in the well-known instances of the change in polarisation predicted by Fresnel from the mere interpretation of an algebraic symbol, and the fact of conical and cylindrical refraction anti- cipated from the mathematical theory by Sir William Hamilton. But this assertion of a priori evidence is some- times made with reference to the primary princi- ples of all natural philosophy the laws of motion and of equilibrium whether in solids or fluids. It ESSAY I. i.] INDUCTIVE PRINCIPLE. 21 is alleged, that what is announced as the first law of Laws of motion. motion, though it may be attested by constant ex- perience, has yet in itself evidence arising out of the nature of the case beyond all experience. Now, in the first place, I would observe, that the very notions of a body in uniform rectilinear motion, or of forces acting on it, are essentially ideas of experience, and certainly could have no application without reference to the real existence of matter and force. It may be maintained that the law of inertia that a body will retain motion communicated to it after the direct impulse has ceased is at least deducible as a consequence from higher first prin- ciples ; but still those principles are themselves no- thing else than mere simple facts, or properties of matter, derived from experience. It is sometimes alleged that, to assert that a body, left to itself, will go on in uniform rectilinear mo- tion for ever, is presumptuously to assert what no experience can ever justify ; and, therefore, if ad- mitted at all, can only be received as an intellectual truth derived from a priori principles. But such perplexity would be removed if we only put the c 3 22 INDUCTIVE PRINCIPLE. [EssAT I. I. proposition thus : a body in motion, &c., must EITHER go on for ever, on its motion must be changed or stopped; but whatever changes, stops, or retards it, is a new force acting upon it, and the question is then reduced to an examination of the action of that force. Equili- Again, it has been sometimes asserted, that the brium. first principle of equilibrium the foundation of the doctrine of the lever is axiomatic or self-evident. \ Yet, without going further, it is obvious that the very idea must imply at least the existence of matter, capable of being acted upon by such a force as gravity through the intervention of something material corresponding to the inflexible straight line of theory; ideas which can only have been ob- tained ultimately from experience. When some such principles have been adopted, we can then, and then only, by strict deductive reasoning from them, arrive at the theorem of the lever, which we find confirmed by experiment.* ?ure a of PreS " ^ n ^ke manner, it has been maintained that the fluids. * See my " Essay on the Laws of Motion," and " Essay on Necessary and Contingent Truth ; " Ashmolean Memoirs : Oxford, 1837, 1849. ESSAY I. i.] INDUCTIVE PRINCIPLE. 23 first principle of all hydrostatics, the equal pressure of fluids, is not derived from experience, but that the mind can pronounce on its a priori certainty. Undoubtedly the mind can infer deductively this great law of fluids, as a necessary consequence from certain other assumptions, that is, when certain, yet more elementary properties of fluids are known, and taken as the basis of the science, but not other- wise. The ulterior principles to which the nature of A conse-; quence fluids may be reduced, may have been differently from the J J J nature of viewed and traced upwards to more or less simple fluids -. elements by different philosophers, but all have adopted, and must adopt, at the outset, some primary physical fact or property to start from. The more simple and general the property referred to, the more satisfactory and complete is the reasoning; and it is the main point in such an enquiry to determine what are the fewest and simplest principles we can assume, in proving these first properties and laws. Still, the ultimate principle, however simple, and however far back it may be traced, can of necessity be nothing else than some physical fact the result of universal observation; such as must C 4 24 INDUCTIVE PRINCIPLE. [ESSAY I. I. be even the very existence of fluids, and without which no reasoning of the kind could be appli- cable. Abstract It is, indeed, quite conceivable that a reasoning theory may be con- being, who had never seen a fluid, might imagine ceived. and create theoretically the conception of such a substance, and might reason mathematically on its properties, such as would follow by strict deduction But physi- from the constitution thus assigned to it ; but this cal observ- ation ne- would not apply to anything in nature until it were cessary for application, shown by experience that these properties were really manifested in some substance to which the theoretical notion might be referred. Example of This is no imaginary case : it actually occurs in the undula- tory theory, the speculations pursued by so many philosophers on an imagined sethereal medium. From the assumed nature of such a purely hypothetical medium, a supposed assemblage of imaginary molecules, acted on by attractive and repulsive forces and liable to agitations from without, by mathematical reasoning the whole of the refined and complicated theory of undulations has been deduced ; which, so far, might for ever remain a barren but most beautiful mathe- matical creation. Independent observation gives us ESSAY I. i.] INDUCTIVE PRINCIPLE. 25 no evidence of the existence of such a medium, and the theory is in no way founded on experience. When, however, by the aid of the eye, the pheno- Unapplied till optical mena of optics present themselves, we find a vast facts are introduced. range of such phenomena which admit of a complete explanation on the assumption of this hypothesis: here, for the first time in the inquiry, a reference to anything experimental or sensible comes in. That it must come in somewhere is clear; yet it would be absurd and untrue to say that such theo- retical reasoning alone can give any a priori certainty to the optical facts or laws to which it is applied, which must after all have been first founded on some small basis of observation. Nevertheless, such applications of mathematics confer the highest pre- sumption, little or at all short of certainty, for generalising conclusions actually observed to be true only in one or two instances. To take, perhaps, the strongest instance which inverse square of has been adduced. The law of force or intensity the dis- tance, varying as the inverse square of the distances, it is alleged, and doubtless with truth, is a conception of pure reason (so far as any mathematical conception is so) from abstract geometrical considerations, which 26 INDUCTIVE PRINCIPLE. [ESSAY I. I. must hold good in any kind of supposed emanation, radiating equally in all directions from a centre, and undergoing no change of condition, excepting that due to distance only. But though these geometrical ideas throughout may be pure creations of the mind, yet the idea of any such emanation of actual force, however abs- tract, must have been derived from some ideas of experience, and certainly can apply to nothing in nature without reference to such sensible ideas. Equal areas Again : to take what is almost an equally striking proved abs- . tractediy. instance, the law ot equal areas. It is undeniably a pure result of reason that a me- taphysical point revolving about another metaphysical point by virtue of an impulse conspiring with a cen- tripetal force tending to that point, varying according to any law whatsoever, must describe areas propor- tional to the times. inappii- But how do we get the idea of a centripetal, or of cable with- out some an impulsive force, unless, at least in the first in- ideas from experience, stance, by abstraction from observed facts ? Where- ever these forces exist in nature, we reason deduc- tively to the conclusion of a description of equal areas, and we find it confirmed by observation. ESSAY I. 1.] INDUCTIVE PRINCIPLE. 27 But this is a very different thing from gaining independent a priori evidence for physical facts. From expressions sometimes used, it would even Paradoxes, seem that additional force is supposed to be given to the argument for abstract conception as the ground of physical truth, by the allegation, that some of those primary abstract physical principles to which we have referred are even opposed to what mere sense and experience would naturally expect, and must therefore be ascribed to a higher faculty of internal reason ; and this, it is also alleged, is prac- tically evinced by the circumstance that such truths are appropriately termed paradoxes; as, e. g., the primary property of fluids has led to what is called the " hydrostatic paradox." But this is not owing to anything in the abstract nature of the reasoning. What does a paradox really imply ? Any new All truths paradoxes truth, even a mere matter of observation, is a paradox to prepos- in popular estimation, if it contradict a received pre- judice. The existence of Jupiter's satellites, and the fall of unequal weights in the same time, were paradoxes when announced by Galileo* to the Ari- * Vignette at the beginning. 28 INDUCTIVE PRINCIPLE. [ESSAY I. I. stotelians of his day. Yet these were facts of ob- servation. The Aristotelians had held that motion can only be caused by something in contact with the body moved; hence the law of inertia was a paradox when first asserted ; and so, indeed, it continued to be long afterwards even to the Copernicans, as appears from the difficulty they felt in accounting for the continual keeping up of the planetary motions. The application of abstract reasoning in such cases tends, in fact, to remove and explain the paradox, not to create it. The startling nature of the assertion, therefore, is no proof of its being derived from any intuition superior to sense. Deductive The question between the inductive and the de- proof only from physi- ductive process is merely a question of degree : in cal princi- ples more some cases the abstract part of the process may be or less re- mote, longer, and its origin more remote from material facts in others less so. The very same conclusion may often be arrived at by several distinct trains of reasoning, setting out from principles of lower or of higher degrees of abstraction; but there must always be, somewhere in the process, a recurrence to sensible experience. ESSAY I. i.] INDUCTIVE PRINCIPLE. 29 For instance, without any knowledge of mathe- Example. Theory of matical theories, we might discover experimentally pendulum. and empirically the laws of the motion of the pen- dulum ; and so might regard them as mere facts of observation. But, again: if we knew in the first instance, by experimental trial, the law of falling bodies, we could deduce mathematically what must be the law of the pendulum, that is, it is a necessary consequence in reason from a simpler mechanical truth, provided that reason be first furnished with that simpler truth. But, once more : the law of falling bodies itself is a necessary consequence of still simpler principles : if we knew, experimentally, the nature of terrestrial gravitation, we might deduce, by pure reasoning, the law, that the spaces described under its influence by bodies falling near the surface of the earth must be proportional to the squares of the times; and thence deduce the laws of the pendulum. But even, still further : if we investigated, on pure theory, the effects of a constant force, we should deduce the same law for bodies moving from a state of rest under its influence, and this would apply directly to the deduction of the laws of a body 30 INDUCTIVE PRINCIPLE. [ESSAY I. I. constituted as a pendulum under its influence ; and hence the laws of the pendulum, as actually moving under the influence of terrestrial gravitation, might be said to be deduced from pure theory and the abstract idea of a constant force. But the real application of such reasoning essen- tially involves the actual existence in nature of such a force as that of gravity, which can only be derived from observation. Foucauit's If the deviation of Foucault's pendulum had been pendulum experiment, originally a mere matter of observation, it would have been long before experiment would have ar- rived at the solution. Many would have been the hypotheses of peculiar magnetic, electric, or other causes, for the observed deviation. FOUCAULT'S PENDULUM AND GYROSCOPE. ESSAY !.!.] INDUCTIVE PKINCIPLE. 31 It was only from a just mathematical conception of the resolution of the rotatory motion of any point of the earth's surface into two, one round that point) the other at right angles to the former, and which would not affect the plane of the pendulum's vibration, while the former would, that M. Foucault foresaw the result. But this was not a priori reasoning dis- closing a physical fact ; it was simply reasoning de- ductively from a known fact to a consequence ; when the reasoning being logical, that consequence could not but be true and be confirmed by observation. Yet more astonishingly paradoxical are the effects Paradoxes of the gy- exhibited by means of the gyroscope, which seem to roscope. subvert all the acknowledged principles of equili- brium. To mention one only : a wheel loaded round its circumference, in rapid rotation at one end of a horizontal axis, having the other end merely resting on a pivot, is supported on that pivot alone against gravity, the whole at the same time revolving round the pivot. Scarcely less remarkable is the application of this i instrument by M. Foucault to another manifestation of the earth's rotation : the wheel retaining its original plane of rotation, which therefore apparently deviates with the rotation of the earth. 32 INDUCTIVE PKINCIPLE. [ESSAY I. i. It is probable that any person, even of con- siderable mechanical and experimental knowledge, seeing the action of the gyroscope for the first time, would be much puzzled to account for it, as, in fact, several persons have been ; and if he set about investigating it experimentally and inductively, might be long before he traced any law or connected it with any principle, so as to reconcile it with the established doctrine of equilibrium. If, however, he set out with a mathematical know- ledge of the principle of the " composition of rotatory motion," and proceeded deductively, the explanation is easy, and its relation to a number of other im- portant cases readily manifest. Yet the application of this mathematical theory requires the idea of a material body in rotation, inclined The ancients, notwithstanding all their refined plane. geometry and spirit of abstract speculation, were unable to advance to the solution of the case of oblique equilibrium, or the inclined plane ; and this is clearly a case where, if anywhere, a priori prin- ciples would have availed. But it was not until Stevin reasoned, not upon any abstruse axioms, but on simple mechanical considerations, that the demon- stration was discovered. The solution was effected ESSAY !.!.] INDUCTIVE PRINCIPLE. 33 by reasoning deductively ; but it was deduction from principles obtained on a primary physical or experi- mental property of matter. A highly instructive instance of the application Discovery of magneto- of an abstract principle to physical discovery may be electricity, found in the way in which Faraday reasoned to the discovery of magneto-electricity, which I cannot de- scribe better or more briefly than in the words of Mr. Grove * : " The discovery of (Ersted, by which electricity was made a source of magnetism, soon led philo- sophers to seek a converse effect ; that is, to educe electricity from a permanent magnet. Had these experimentalists succeeded in their expectations of making a stationary magnet a means of electric cur- rents, they would have realised the ancient dreams of perpetual motion they would have converted statics into dynamics they would have produced power without expenditure ; in other words, they would have become creators. They failed, and Faraday saw their error : he proved that to obtain electricity from magnetism, it was necessary to super- * Lecture on Progress of Science ; London Institution, 1842, p. 20. D 34 INDUCTIVE PRINCIPLE. [ESSAY I. i- add to this latter, motion ; that magnets, while in motion, induced electricity in contiguous conductors ; and that the direction of such electric currents was tangential to the polar direction of the magnet that as dynamic electricity may be made the source of magnetism and motion, so magnetism conjoined with motion may be made the source of electricity. Hence originates the science of magneto-electricity, the true converse of electro-magnetism." The application of mathematical reasoning to physical inquiries may sometimes, at every step, ex- hibit something corresponding to an actual step in the mechanical process, and thus capable of a physical interpretation : such is often the case in the older geometrical investigations. But in the prevalent applications of the modern analysis there is no cor- respondence of this kind; the original conditions being once put into an equation, we resign ourselves to mere symbolical operations, which have individu- ally no reference to any physical ideas, till we find ourselves landed as it were on the platform of a conclusion which marvellously harmonises with ex- perimental results. Yet these and the like instances are not at all ESSAY I. i.] INDUCTIVE PRINCIPLE. 35 cases of an a priori discovery of physical truth ; they are instances of a train of logical reasoning proceed- ing from some first principle derived from remote physical abstractions till it arrives at a conclusion which coincides with some other observed law having no other perceptible connexion with the first prin- ciple; or leads the philosopher to expect such a result ; which, on trial, is found to be the fact. Thus a simple analysis of the actual train of argu- conclusion, ment tends to dispel the mystification and confu- No really sion which have sometimes arisen on the subject proof o7 of abstract reasoning applied to physical subjects, truth. Pure reason out of its own resources may, in- deed, create theories apart from all observation of nature ; but to make them applicable to anything in nature, such creations of the mind must necessarily and universally involve some small assumption of material properties or mechanical conditions ; which can only be in some form or another ultimately- derived from observation : what is borrowed may be very little, but it must be something ; and it is a point of interesting research to the philosopher to endea vour to ascend to the fewest and simplest possible of such first principles. D 2 36 INDUCTIVE PKINCIPLE. [EssAY I. I. Necessary A confusion of ideas is sometimes introduced by truths only necessary the use of the term " necessary" dependence or conse- quences. " mechanical necessity ;" as if it were a blind or fated necessity ; but what we mean is, a necessity of reason or logical sequence. It is evinced by the dependence of a series of ideas deductively followed out; which are also found to accord in their result with natural facts and more comprehensive laws. Speculative The subject here discussed, is beautifully illus- ideas of (Ersted. trated by the philosophical views broached in a posthumous work*, which has so fitly and honour- ably crowned the labours of the great (Ersted, and added a new claim to our admiration of his genius. In those essays he maintains repeatedly the propo- sition that (f the laws of nature are the same as the thoughts within us ; " " the laws of motion are such as are required by our understanding;"! "the law of the inverse square of the distance is a conception of reason;" and several like instances: all which I should fully admit, subject to the qualification above suggested and understood in the sense * " The Soul in Nature." translated by the Misses Homer. London, 1852. t See especially pp. 10. 36. 93. ESSAY Li.] INDUCTIVE PEINCIPLE. 37 which it implies that the connexion and depen- dence of the facts in nature accords with the con- nexion and dependence in our reason, provided we set out from some more or less simple principle originally derived from observation, whence we ad- vance by abstract reasoning to a conclusion, which, however remote from the physical point whence we started, is found to accord with natural facts, and to be a general law of nature. In this sense I have above considered some of the cases just referred to ; and others adduced by OErsted are more obviously of the same kind ; such as the lesser planetary and lunar perturbations, too small for observation alone to detect, yet indicated by theory ; the identity of lightning and electricity ; the discovery of the metal- lic bases of the earth : all anticipated by theory. To which might be added (Ersted's own grand dis- covery of ELECTRO-MAGNETISM, and that of the planet Neptune in our own day. But these cases are, after all, not precisely in point to the original question, since here the starting-point was obviously previous inductive knowledge. These distinctions are important to the funda- Accordance of reason mental analysis of our reasonings on which we ad- and nature. D 3 33 INDUCTIVE PRINCIPLE. [EssAY I. I. vance legitimately to those broader ulterior reflexions on which QErsted enlarges, and which are the same to which the whole of the present inquiry points. CErsted has well remarked that it is a common error to imagine matter something constant and invariable. But the permanence and invariability of nature are not found in its individual parts, which are all undergoing perpetual changes. The invari- able, he argues, is found only in the abstract nature of things : " nothing is invariable in nature but laws which may be called the thoughts of nature."* Natural combinations (OErsted observes) which appear accidental are not really so. "All effects obey natural laws; these laws stand in the same necessary connexion as one axiom in reason to another : that this combination is precisely a combi- nation of reason we learn from this, that by reason we are enabled to deduce one law of nature from the other, and by the known laws to discover new and unknown ones. Innumerable as are the effects de- termined by natural laws in every object in nature, however insignificant it may be, I deeply feel an * The Soul in Nature, p. 23. ESSAY I. i.] INDUCTIVE PRINCIPLE. 39 unfathomable reason within them, of which I can only comprehend by fragments an incalculably small part. In short, nature is to me the revelation of an endless living and acting reason." " If the laws of reason did not exist in nature, we should vainly attempt to force them upon her : if the laws of nature did not exist in our reason, we should not be able to comprehend them." * And on the whole, " we find an agreement between our reason and works which our reason did not pro- duce." . . . (e All existence is a dominion of reason." " The laws of nature are laws of reason," and " alto- gether form an endless unity of reason," ..." one and the same throughout the uni verse, "f * The Soul in Nature, p. 18. t Ib. 12. 16. 87. 92. 377. D 4 40 II. THE UNITY OF SCIENCES. Tendency ALL branches of inductive science continually tend of sciences towards more and more towards a grand unity of principle. common principles. We perceive this to a partial and limited extent in every lesser advance of discovery : in proportion as new facts accumulate and become embarrassing from their multiplicity, sooner or later some happy advance in generalisation is always found to occur by which they are simplified and reduced to some ESSAY I. ii.] UNITY OF SCIENCES. 41 single principle, connecting them at the same time with other classes of phenomena. In the science of the ancients (exact as it was in progress of some limited departments, each within itself) all eneralisa - tion and branches were isolated and disconnected : and all Uf ? lon ot sciences. physical principles and causes were supposed of separate and even conflicting kinds. All the first great modern advances were directed First ad- vances. towards combining and uniting branches hitherto distinct, and tended to evince a unity of idea and principle pervading them. The first discoveries pointed to the identification of the celestial motions with terrestrial ; of astronomy with mechanics ; of the fall of an apple with the motion of the moon ; of the horror of a vacuum with the laws of equili- brium : as later discoveries have identified mag- Later physical dis- netic and electric currents, and connected sound, coveriss. heat, and light with the mechanism of waves ; and, again, the resulting effects of heat with dynamical force. Of the tendency and progress of discovery towards Faraday's general isa- a coalition and combination of different trains of tlons - research, perhaps we can nowhere find more striking instances than in the multitudinous re- 42 UNITY OF SCIENCES. [ESSAY I. II. searches and every research terminates in a dis- covery of FARADAY. The peculiar character of high generalisation which results out of an ap- parently immensely complicated mass of small de- tails, is perhaps one of the most striking features of this wonderful series of investigations. It is impossible here to do more than select one or two instances. Magnetism Few generalisations of a more striking character and dia- magnetism. nave ever b ee n announced than that of the magnetic properties of all matter, evinced in the classification of all substances under two species, magnetic and diamagnetic, and these characterised respectively by the properties of attraction and repulsion. Action of But in this union of relation between magnetic magnetism on light. and all other matter, there was to be disclosed a yet more striking instance of bringing together re- motely separated kinds of physical action under a common law, in the action of magnetism on light. What could be a more singular and striking identification of properties in cases apparently the most remote from each other than the production of rotatory polarisation in light passing through quartz and some other substances, and in passing through ESSAY I. ii.] UNITY OF SCIENCES. 43 ordinary transparent media when placed in the line of intense magnetic force ? Or to go back to an earlier discovery : Grand indeed was the conception of the principle Definite electrolysis. of the relations of chemical to electric action, partially illustrated in theories of Fabroni and Wollaston, but first announced in all its generality by Davy : thus bringing into close relation and unity two such great modifications of physical power. Equally important, though apparently remote from either of the last was the principle of definite proportions in atomic combinations disclosed by Dalton. These two comprehensive generalisations, each equally wonderful in itself, yet seemingly uncon- nected, it was reserved for the penetrating genius of Faraday to place in intimate connection and to unite in a still higher bond of generality. No single discovery perhaps could be cited of higher intrinsic value than the disclosure of the great principle of DEFINITE ELECTROLYSIS : but the high philoso- phical character of this discovery is enhanced the more specially in that it combines in a principle of unity the mathematical law of definite proportions in chemical combinations with the preservation of the 44 UNITY OF SCIENCES. [ESSAY I. n. same identical numerical relations in electrolytic action : and thus uniting both in intimate relation with the fundamental conception of atomic composition. Systematic As we look to the larger divisions of the sciences, division of sciences. and the successive wider generalisations which they imply, the same tendency to unity is continually though more slowly manifested. And thus, even where it does not yet appear, we cannot doubt that this is the legitimate and ultimate direction and tendency, however remote, of all scientific progress. But in treating of the sciences systematically, it is necessary to adopt some principles of classification and arrangement. Here some division is rendered necessary for this particular object ; but it ought to be carefully borne in mind that it should in no way really interfere with the increasing conviction of a real unity of principle pervading all branches. Some views It is a reversal of the order of inductive advance tending to isolate to endeavour to isolate each department of science, sciences. and to place it on a separate base, by a theory which would assign to each branch certain real differences of principle and peculiar fundamental ideas essentially characterising it. If such a dis- tinction were made out, it could be but a tern- ESSAY I. ii.] UNITY OF SCIENCES. 45 porary and provisional ground of classification, in time to be superseded by a reduction to a higher common principle. It is no doubt true, that the highest, the most Mechanical perfect, and satisfactory assignment of physical causes is effected when the phenomena can be analysed into mechanical laws. But the reason of this lies in no mysterious connection of mechanics, as such, with the idea of causation, but merely in this, that the conditions of purely mechanical reason- ing are so perfectly elementary in their nature, and so entirely free from all admixture of ambiguous or doubtful conditions, that we can directly investigate them with a simplicity differing in nothing from that of primary geometry, and thus attain the most perfectly satisfactory explanation, when everything is reduced to simple consequences of mechanical equilibrium or the composition of forces. In other branches it is clear that just in proportion Progress of all sciences as we can succeed in reducing the phenomena from towards the idea of me- obscure and apparently mysterious modes of action force and to these simple and intelligible cases of force and motion - motion, in the same proportion we bring those branches into the domain of exact science, and break 46 UNITY OF SCIENCES. [ESSAY I. n. down the line of demarcation which hitherto seemed to separate them. Common rpj^ gc j ences o f statics and dynamics, of equilibrium grounds of * an( ^ m ti n j nave been represented by some writers as based on inherently distinct principles : but it is at once a more satisfactory, and as I believe a more true, view which connects them by the consideration that the simplest cases of equilibrium or rest cannot fully be demonstrated without an explicit or tacit reference to the idea of motion * : which thus far helps the more general consideration of the ultimate unity of all sciences. The explanation of the precession of equinoxes (the same in substance as that of Newton, more circuitously followed out) by the direct application of the composition of rotatory motion announced by Frisi, and imitated by the rotatory apparatus of Atkinson and Bonenberger, exhibits a peculiarly striking exemplification of unity of principle in passing from such phenomena, vast in their relations both to space and time, to the identical cases pre- * See my " Essay on Necessary and Contingent Truth, " Ashmolean Memoirs: Oxford, "1837. ESSAY I. n.] UNITY OF SCIENCES.' 47 sented in the deviations of rotatory projectiles*, the cases of spinning tops in stable and in unstable equilibrium, and the various paradoxical effects pro- duced by the gyroscope : all, however diverse, direct consequences of one simple law.f The idea of " polarity," to which such mysterious Polarity re- duced to importance has been attached, has been sometimes resolution of motion. imagined to involve some essential peculiarity sup- plying an appropriate characteristic conception to mark a distinct class of physical phenomena. But this once marvellous notion, in the instance of light, has been reduced to a simple case of resolution of motion; and there can be as little doubt that the progress of inductive generalisation, and the appli- cation of mathematical principles, will, sooner or later, reduce other instances, at present provisionally designated by the same name, to equally simple modes of action. And with respect to the phenomena of optics Dynamical theory of generally, how completely remote do they appear waves - * See a Memoir by Prof. Magnus, translated in Taylor's Foreign Mem., N.S. pt iii. p. '210. t The Vignette at the head of this Section represents the apparatus as constructed on a large scale for lecture illustration at the Koyal Polytechnic Institution. 48 UNITY OF SCIENCES. [ESSAY I. n- from all notions of mechanical force? yet, by the mathematical labours of Fresnel, Cauchy, and others, these seemingly remote appearances have been con- nected with a recondite theory of pure dynamics ; which, followed out through a complicated train of deduction, ends in reducing nearly all these pheno- mena to the results of certain minute motions, sub- sisting and excited among a system of molecules acted on by attractive and repulsive forces, and subject to external agitation. So, again, when electric and magnetic action were reduced to systems of currents by the researches of the numerous and distinguished co-operators, in fol- lowing out the great principle disclosed by CErsted, there was a direct approach to ideas of motions in definite directions, which supply the abstract in- dications of force ; and though the subject has even yet been but imperfectly followed out, we perceive the direction it is taking, and must eventually take, towards satisfactory explanation, in a reduction to simple dynamical principles. Supposed One of the most remarkable approaches (as yet case of in- % . terference quite in obscurity) which has been made towards in galvanic action. a connexion in principle between two branches of Electro- magnetic currents. ESSAY I. ii.] UNITY OF SCIENCES. 49 science apparently remote, is that of a peculiar action of a galvanic current exhibiting all the marks of a case of INTERFERENCE, in the experi- ments of Mr. Grove.* If this should be followed out by a more close analysis, so as to show a real action of the kind, the analogy of galvanic action with a system of vibrations of a fluid analogous to the luminiferous aether as its cause, would open the way to a generalisation of the highest and most valuable kind. And further, it may not be altogether incon- ceivable that two sets of such vibrations, which, by superposition, give rise to elliptic vibrations, may be connected with the formation of currents running round the wire, by which so many of the phenomena are represented. Again: to insist on an essential scientific dis- Molecular forces. tinction between molecular forces and those acting on matter in larger masses, as the characteristic basis of a peculiar science, tends to isolate this branch from ordinary dynamics, to which we should rather seek to assimilate it. In the same way the broader distinction between * Phil. Trans. 1852. Part I. E 50 UNITY OF SCIENCES. [ESSAY I. n. Chemical mechanical and chemical action tends equally to forces. break up the idea of that essential and fundamental unity which the philosopher is persuaded must really subsist between these invisible actions of atoms on atoms, and those only more obvious, because on a larger scale, of worlds on worlds. The distinction of molecular forces, there can be no doubt, marks merely a present line of de- marcation from ordinary mechanical forces, which will at some future time be effectually broken down, and the two classes reduced to one higher genus. Chemical action, again, we may be assured, differs from mechanical only in our existing state of ig- norance ; but they will doubtless at some period be assimilated by the discovery of a common principle of equilibrium and its disturbance. Even in the present state of our knowledge, molecular forces have been shown with great probability to be reducible to a common theoretical expression with that of gravi- tation in the speculations of Boscovich and Mossotti. Cosmicai Again, the mode of aggregation of many of the forces. stellar clusters, as described by recent observation, is regarded by some very eminent philosophers as evincing the action of forces of a peculiar kind ESSAY I. ii.] UNITY OF SCIENCES. 51 different from those of gravitation. Should this prove to be the case, it would in no way derogate from the universality of some law of aggregation of matter, that a different species of law may prevail in those vast distant portions of the universe, which, when it shall have been investigated, may prove a more comprehensive kind of force, of which gravi- tation is but one form or modification. But if any such apparently outstanding exceptional putstand- case were fully made out rightly to claim the title of tions " J J main for involving an entirely new principle, still the inductive anal y sis * method would only mark out that principle as a legitimate subject of future analysis ; and we might be assured that in the successful course of such analysis at some future period, either this new prin- ciple must fall under some already recognised prin- ciples, or those recognised principles must fall under it. There may no doubt be a practical convenience Distinc- tions tem- in retaining some distinctions of this kind to preserve porary and provisional. arrangement in our subjects; but to attempt to fix them as essential foundations of real philosophical distinctions, seems to be reversing the proper order of inductive inquiry. Provisional and temporary 52 UNITY OF SCIENCES. [EssAY I. n. distinctions for classification, indeed, AVC may with convenience and advantage often make between different branches of science in regard to the modes of reasoning and nature of the leading ideas appro- priate to them ; but it is essential to remember that these distinctions are only provisional. Alleged ex. But in contemplating the unity of sciences, an ception as to geology, exception has been alleged in reference to GEOLOGY. The entire relation in which it stands to other branches of inductive science, and even its inductive character altogether, has been sometimes disparaged. Comte has most unaccountably denied it any place whatever in the scheme of " positive philosophy," and possibly some hypotheses which have continued to be occasionally indulged in, in connection with that science, might not unnaturally have influenced him in entertaining a prejudice against it. Not real : Yet this science, when rightly pursued, is emi- geology an inductive nently inductive. From its very nature it combines science. the resources of a variety of other sciences ; dynami- cal, hydrostatical, chemical, and especially physio- logical, and being thus entirely dependent on these other branches of inductive philosophy, itself acquires a perfectly strict inductive character. ESSAY I. II.] UNITY OF SCIENCES. 53 When, at the present day, it exhibits to us, pre- served in their stony sepulchres, the successive varie- ties of organised structures, as they lived and moved in the same world, subject to the same immutable laws, mechanical, optical, and physical, uninterrupt- edly in operation through all the incalculably vast periods of past time, it is an entire departure from all just appreciation of the unity of science and of NO really different nature to imagine that any essentially different laws causes re- ferred to. of vitality then prevailed, or that the changes in organised life thus brought to light were governed by any totally different series of causes from those now in operation of a peculiar and mysterious kind. Yet some seem to have supposed that the reason- The evi- dence of ing of geology ought to rest on something distinct geology not different in from that of the experimental sciences, inasmuch nature from that of as it refers to events which have so long since passed ther sciences. away, and which we cannot recall for examination, while the very terms " pal&ozoic" and " pal&tiology" might seem to insinuate that we are concerned with an order of causes belonging to the past, different from those now in action, a distinction just as unphilosophical as that of the peripatetics, who drew a distinction between " natural and violent" motion, E 3 54 UNITY OP SCIENCES. [ESSAY I. n. and ascribed the terrestrial motions and the celestial to distinct causes. Induction has no reference to distinction of past or present; if phenomena have been locked up for ages, yet, when once thrown open to us, they become objects of the same kind of investigation as those occurring at the present day. The investigation and restoration of the remains of a Saurian imbedded millions of ages ago, is an operation of precisely the same kind as the post-mortem examination of the subject of yesterday. Uniformity The inductive philosopher is convinced that the of nature in time and universal subordination of causes must hold Ood space. equally in time as in space; that as there is no region, however distant, in which physical laws do not apply, or in which, if as yet unknown, we are not fully warranted in feeling an assurance that they must apply ; so in time there is no period, however remote, at which we can legitimately imagine the chain of physical causation to be broken, and to give place to disconnected influences of a wholly different kind. Geology ap- More recently, the investigations of Mr. Hopkins proximat- ing to an h ave tended to connect geology even with dynamics ESSAY I. IL] UNITY OF SCIENCES. 55 and mathematical laws, and thus to establish its exact science. relation, not merely to the inductive, but even to the exact sciences : not that that name implies any real difference in nature, but merely marks the degree of perfection to which any branch of science has attained. If, then, from the examination of pheno- mena actually existing) and going on around us, we turn to the past, the rules and principles of inductive investigation will apply with equal force and pro- priety to phenomena which teach us the successive and gradual changes which the crust of the globe has undergone, and lead us to trace them as far back as we can towards its origin. The great principle which forms the basis of all influence of time ad- inductive geology the analogy of existing causes mitted. in explaining past changes must, however, be dis- tinctly understood, and, in fact, is so interpreted by its best advocates, not merely as restricted literally to those identical natural operations which we see going on, AND COMPLETED, daily before our eyes within the limited moment of time to which our observation extends. It would not fully vindicate its own power, if it did not include in the general analogy the influence E 4 56 UNITY OF SCIENCES. [ESSAY I. u. of some elements incapable, from their nature, of direct verification from our own experience, such as are due to the INFLUENCE OF TIME, especially of un- niustration limited periods of time; and in illustration of this from form- ation of idea we are reminded of some changes even in more coal and diamond. limited periods, which, though in their nature and results simply chemical, are yet such as cannot be, or at least have not been, produced in our laboratories. We may take as instances the formation of coal and of diamond; while on a grander scale we are under the necessity of acknowledging the long series of changes which must have accompanied the gradual cooling of the earth, an unavoidable inference from the fact of existing central heat. Miseoncep- Real inductive principles thus tend to reduce to tion of past duration, order those phenomena which have appeared to some to present so much more strongly marked vicissi- tudes only because we are apt to crowd the events together in the long perspective, and measure them too much according to our confined ideas of dura- tion. tSmif ^ n s P ecu ^i ns on changes where, it is alleged, all applications of known causes fail, it has been the favourite resource with some to appeal to mys- ESSAY I. ii.] UNITY OF SCIENCES. 57 terious revolutions and occult operations of a kind ill-explained, and even supposed to be inscrutable to our faculties, but thus the better calculated to dazzle the many with their imposing pretensions. But in the spirit of true induction we have no ofanunin- ductive right to imagine that any of the events or changes character, of past epochs, however apparently inexplicable, can be rationally set down as events of a different kind and order from those now going on, or as in- terruptions of the settled order of natural causes. Difference of opinion indeed may subsist as to Uniformi- tarianism the greater or less frequency or intensity of volcanic and cata- strophism. action, of fractures and dislocations, of variations in climate, of changes of condition due to the cooling of the terrestrial nucleus, or the like, in past epochs. But these, while they are on all hands allowed to be fair and legitimate topics of philosophical debate and inductive inquiry, would be most unduly exaggerated if supposed to mark any such real or fundamental difference in principle as to constitute two really distinct geological schools. They are questions merely of degree, not of kind or of principle. Yet, in the language often used, the (f uniformi- 58 UNITY OF SCIENCES. [ESSAY I. n. tarian" view would seem to be represented as an hypothesis to be fairly weighed against another antagonistic " catastrophic" theory. If the terms are to be understood with any such difference of sense as that thus implied, I conceive it appears that the two theories respectively occupy totally different grounds. The " uniformity " principle would mean simply the proper extension of inductive analogy and the law of continuity, even if not yet sufficiently sub- stantiated in detail in each particular instance ; while the " catastrophic " hypothesis seems of an essentially uninductive nature, and appeals to ideas remote from true analogies, confessedly re- sorted to on the very plea of the failure of explana- tion by natural causes. But, in such cases, the evidence of a violation of the uniformity of nature is purely negative: with all analogy against the reality of the exceptions, they can be such only to our present ignorance : the apparent anomaly is but a part of a more com- prehensive law, ill understood; a modification of its continuous action in reality equally regular, though not as yet fully made out or reduced to ESSAY I. 11.] UNITY OF SCIENCES. 59 law. Geology thus kept pure from the introduction of fanciful and unphilosophical hypotheses eminently conforms to the type of unity which binds together the whole range of inductive science. The unity of sciences is not impaired, but insured Revolutions in science and promoted, by those mutations which any of its only pro- gressive. branches may seem to have undergone. All real science is in a state of perpetual change. These changes have now and then been fundamental and revolutionary, and similar fluctuations are perpetually going on in lesser details. But this in no way makes science itself unstable or fluctuating. The change is always of one character, and that no other than the very nature of the inductive philosophy requires : a change from anomaly to regularity, from hetero- geneity to analogy, from confusion to order, from interruption to continuity, from artificial dogmatism to the simplicity of nature. Every branch of science approaches perfection and Discoveries superseded stability as it more fully approaches to and realises only by greater im- the grand principle of unity. It is the test of the provements. real advance of discovery to exhibit a progressively increasing conformity to these great principles : an advance which will not require a retreat, the 60 UNITY OF SCIENCES. [ESSAY I. n. erection of a structure which will not require re- modelling. Every philosophic research or conclusion, at pre- sent of the highest importance, must expect to be reduced to a subordinate place : every method now most justly esteemed must look to be superseded by greater improvements : but nothing will deprive such really great discoveries of their place in the page of history their lustre will but be increased by the brilliancy of newer results, to which they were the necessary preliminaries. Such mutations are sometimes made a topic of reproach, but only by those who are hostile to science from entire ignorance of its principles ; they may learn to observe that these changes are all in one direction : they are all steps in advance towards a higher and more enduring system all future pro- gress must be in the same direction ; we shall never see a recession from the more natural towards the more mysterious ; from the recognition of regulated causes, law and order, in a retrograde course towards arbitrary or fortuitous influences. Advance Most sciences had their origin in the clouds of from mysti- cism to mysticism, and thus occasionally long retain some reason. ESSAY I. ii.] UNITY OF SCIENCES. 61 tincture of it. Astronomy arose out of astrology, chemistry out of alchemy, and geology out of a theological cosmogony. Geology, indeed, being the youngest of the inductive sciences, has naturally in the course of its rapid growth, within a brief period, exhibited more of those changes from mysti- cism towards rationalism than any other branch. It Applied to geology. is but a short time since the whole science consisted of little better than a few detached general facts, connected by arbitrary hypotheses, and conformed to the language of dogmatic belief. With an increasing recognition of true inductive principles, we have witnessed progressive improve- ments in the philosophic character of the theory and candid retractations of opinions once warmly upheld, chiefly on grounds alien from those of science. Yet these concessions perhaps were made more frbm the disclosure of a few contradictory facts in particular instances, than from any perception of broader philo- sophic principles as those which in the first instance ought to have formed the basis of the whole science ; and, perhaps, such principles are hardly yet uni- versally recognised in their full force and extent. Those who continue really to indulge in the visions 62 UNITY OF SCIENCES. [EsSAY I. II. En'iuenceof w hi cn misled geology in its infancy, the dreams of dogmas. fc> feJ J > universal' cataclysms, and sudden creations, of a kind wholly remote from physical analogies, and to which it would be wrong to seek to apply physical ex- planations, so far place themselves out of the pale of the inductive philosophy. But the influence of such artificial theories we may be assured will in time entirely disappear, and all true cultivators of science will come to regard such distinction of schools in no other sense than as we now speak of Ptolemaists and Copernicans, Cartesians and Newtonians : these anticipations, however, are far from being yet generally realised. Many who smile at the fancies of a Whiston or a Buffon are scarcely less under the dominion of ideas of very kindred origin. Those who disown dogmatic authority to teach the mode of formation of the earth's crust are yet often not exempt from prepos- sessions equally narrow in speculating on the pro- bable order of creation, the succession of species, or the relations of our globe to other planetary and stellar worlds. Tendency J5 U ^ ^ m i n ^ s ft u \y impressed with the great principles of unity. Q f ana l gy ^ l aw an( j order, all anomalous imaginations ESSAY I. ii.] UNITY OF SCIENCES. 63 derived from sources extraneous to science will dis- appear. The increasing tendency of all research towards harmony, simplicity, and unity of character, will be recognised as a pledge of its ultimate rea- lisation : and even conjectural hypotheses, confes- sedly a mere indulgence in philosophical romance, provided it be strictly philosophical, will be hailed with satisfaction as helping out the general con- ception and keeping alive the spirit of analogical inquiry. But a yet more serious question, of the same kind Second al- leged ex- as that referring to geology, has been raised with ception in the science respect to the sciences of organisation and life : which of organisa- tion and are sometimes supposed to involve altogether a new We. class and order of ideas of so peculiar a kind that they must stand out as entirely exceptional cases to the general unity of the sciences. Now it will on all hands be allowed that these Peculiar difficulties subjects are as yet but imperfectly understood, and of the sub- ject, a large range of inquiry connected with them still involved in obscurity. And if from external pheno- mena we seek to advance to their causes and princi- ples, it is of course most fully admitted that of the ultimate causes of organisation and life we cannot 64 UNITY OF SCIENCES. [ESSAY I. ir. at present attain to any satisfactory explanation, or even form any definite conception. But hence we find many in treating the subject commonly set it down as in its own nature something essentially mysterious and inscrutable : as referring to an order of causes altogether distinct, wholly dis- connected with those of any branch of physical in- vestigation; as involving functions and operations wholly sui generis : and not only that we cannot explain them on any merely physical principles, but that we ought not to attempt to do so : that they are of an order wholly transcending such inquiries ; beyond the power of our faculties to apprehend; and ought to be kept apart, as being indications of a special and mysterious principle which it would be presumptuous and immoral to attempt to inquire into. Not really Everything doubtless is mysterious till it is made mysterious orinscru- known, but the inductive inquirer will never al- table. low the apparent obscurity of a subject to oppose any barrier to the endeavour to make it clear. Nothing can be more mysterious than gravitation ; but that does not hinder the philosopher from in- vestigating its laws, or thence, as far as he can. ESSAY I. ii.] UNITY OF SCIENCES. 65 penetrating towards its principle. Electricity and magnetism, thunder and lightning, were perfect mysteries a century ago. Instead of allowing any such prepossessions to paralyse his researches, the inductive philosopher would simply seek in regular order, first to determine the external conditions and ' laws of life, themselves as yet far from being well understood. Until these are known, he might reject as premature, or at least regard as wholly conjectural, all attempts to speculate on their higher laws or physical causes: yet not less confidently would he be assured that these more interior causes will one day come to be known ; just as surely as the proximate laws will be accurately traced and reduced to that determinate order which undoubtedly in reality pervades them, but of which we have at present only the most imperfect glimpses, yet which, imperfect as they are, are the true openings to the ultimate inductive knowledge of causes and prin- ciples. There have not been wanting, indeed, attempts at Proposed hypotheses theorising on the subject : various hypotheses have of the vital principle been started as to the nature of the "vital principle," often falla - cious. 66 UNITY OF SCIENCES. [ESSAY I. n. and the question discussed whether life is the result of organisation, or organisation of life. Some have referred to more particular modes of action, such as electric currents flowing through the nervous system, or the like ; and have represented animated beings as in fact nothing more than walking galvanic batteries : all these, and many similar theories, may be utterly fallacious and erroneous; and the opponents may triumph and revel in the real or supposed refutation of them. But all this in no way affects the con- viction of the existence of some physical principle, the cause of the vital functions, as yet, indeed, unknown, but which nevertheless will, at some time, become as well determined as the principle of respiration or the circulation of the blood are at present. Again, though chemical analysis has reduced or- ganised products to determinate elements, yet it is made a matter of no small boast by some, that no chemistry can reproduce an organic substance, or invest that organised substance with life : and eager and loud was the triumph of those who conceived they had refuted the alleged results of Messrs. Crosse and Weekes, and bitter the abuse and ridi- ESSAY I. ii.] UNITY OF SCIENCES. 67 cule heaped upon them for believing that they had evolved insect-life by galvanism. All such experiments may indeed be fallacious and But some physical premature ; and we may be as far as possible from cause of at present penetrating the secret of vitality, or the precise mode of its connexion with the bodily struc- ture and the chemical changes elaborated by the various organs. But the truly inductive inquirer can never doubt that there really exists as complete and continuous a relation and connexion of some kind between the manifestations of life and the simplest mechanical or chemical laws evinced in the varied actions of the body in which it resides, as there is between the action of any machine and the laws of motion and equilibrium, the weaving of cloth by a power-loom and the principle of latent heat : and that this connexion and dependence is but one com- ponent portion of the vast chain of physical causa- tion whose essential strength lies in its universal continuity, which extends, without interruption, through the entire world of order, and in which a real disruption of one link would be the destruction of the whole. The principles of inductive science apply to all F 2 68 UNITY OF SCIENCES. [ESSAY I. n. All nature physical truth and the investigation of all physical subject to law and causes. The laws of order, uniformity, and con- order. tinuity belong to all parts of the material world: and in this order and continuity animal life is in- cluded. From the lowest mechanical or chemical influences on inorganic matter, there is an unbroken series to the first manifestation of organic changes ; and from these again from the lowest vegetable or zoophyte up to the highest mammalia there is entirely one continuous progression, its connexion from one term to another being carried on through absolutely insensible degrees and shades of diffe- rence. Humboldt observes, "All myths about impon- derable matters and special vital forces inherent in organised beings, only render views of nature per- plexed and indistinct." * It is the unbroken preser- vation of this continuity which assures us that the nature of the vital principle must be sought for by no occult or mysterious process, but only by the patient application of the same inductive processes by which other physical principles have been and * Cosmos, 69. transl. 1845. ESSAY I. ii.] UNITY OF SCIENCES. 69 always continue to be gradually cleared up and elicited ; and by the operation of which, we may be assured, this hidden spring of life will, at some time, be disclosed, and brought out to occupy its place in harmony with all the other great principles of the universal cosmos. But there is another plea on which the phy- physiology . , . , , . supposed siological sciences have been sometimes supposed distinct, as to stand apart from other branches. It is alleged final causes. they are characterised by involving the peculiar and distinctive idea of organisation, that is, an idea essen- tially involving the conception of design or intention, and have hence been referred to a separate principle called teleology. This, however, appears to me a distinction un- founded in itself, or rather founded on an incidental and not on an essential distinction, and referring rather to the narrower view of this class of investi- gations as followed by an older and less advanced school; whereas in their more modern extension, they imply a more enlarged principle, and one closely accordant with the extension of analogy and the unity of science. It is of course obvious that throughout these F 3 70 UNITY OF SCIENCES. [ESSAY I. u. The dis- sciences, perpetual instances of such adaptation of tinction not ten- structure to the ends and purposes of life are able. abundantly manifested ; and it is rio less evident that they force themselves on the mind with that peculiar, immediate, and irresistible kind of effect which is justly dwelt upon by most writers on the subject, and admitted by all inquirers in such mul- titudes of convincing examples. On these, however, it is not my object to enlarge here ; the present question is as to the precise philosophic analysis of the case with reference to the classification of sciences. So rapid is the mental operation by which the inference of design in these cases flashes upon us, and so immediate is the impression, that it may seem almost to precede, or at least to go hand in hand with observation, without waiting for formal deduction : so that we may not unnaturally deceive ourselves, and may sometimes mistake it for an intuitive notion, acquired antecedently to the actual examination of organised structures, and may even imagine (as some have even maintained on philosophical grounds) the idea of a purpose, and end and means, is an integral part of our very idea of an organised being. Yet ESSAY I. ii.] UNITY OF SCIENCES. 71 when we analyse our conceptions more strictly, it must be apparent that our very notion of the exist- ence of organised beings must be acquired in the first instance from observation including the observation of ourselves: and this constitutes so constant and universal a case of experience, that it may well seem an idea whose origin we may set down as con- temporary with our earliest exercise of consciousness and thought. It is, however, in strictness, not merely from Not essen- tial, but in- observation, but by a considerable exercise of in- cidentai. ference and deduction, that we can legitimately arrive at the notion that an animal "is intended to live ; " it is derived from the study of its organisation ; whence we are led to look to the subserviency of its parts to the purposes of life and enjoyment. The idea which we form in general of an organised body, no doubt practically involves that of parts mu- tually dependent and adapted to each other ; but this is an inference, and the relation which it establishes is one in no way essentially differing, in this respect, from that existing among the component portions of a moving machine, or even of a stationary arch; though certainly differing in the degree of compli- F 4 72 UNITY OF SCIENCES. [ESSAY I. ir. cation, as in the higher and more varied and multi- plied design and object evinced in their structure. There is no essential distinction in kind between our conception of the one or the other. It is true we soon come practically and habitually to include these effects in the complex current idea of an organised being, and are unconsciously and involuntarily led as it were to connect these conditions with the idea of plan and intention, and to assume the relation of these as that of ends and means. But we are here con- cerned only with the analysis of our ideas. More en- That a combination of arrangements, perhaps larged views , . , , . , necessary, even complicated ones, which answer a purpose whose practical importance is obvious, and where the relation of one to the other as end and means almost forces itself on the mind the moment we contemplate them, must produce a high conviction of design, is as indisputable as it is invaluable in the high argument of which it forms a part. But such instances arising in the contemplation of organised structures do not stand in any way peculiarly distinguished in their nature from other cases of the like adaptation of means to an end in the wider arrangements of un- organised matter. ESSAY I. ii.] UNITY OF SCIENCES. 73 It may readily be granted as the fact, that several Discoveries made by remarkable physiological discoveries have been help of final causes ; only made in consequence of the habit of looking at final as hints, causes in animal structures. But what does this prove ? Reduced to its proper place in the philoso- phical system, the case is simply this : most disco- veries in physical science are originally prompted and suggested by some previous conjecture. Nothing can be more fruitful in furnishing such conjectures than the habitual recourse to instances of adaptation to an end in organisation already known, whence the enlightened physiologist often receives the most valuable hints, and frames the most probable con- jectures as to those which are as yet unknown. The value and force of such conjectures in general depends on the happy preservation of analogy ; and that ana- logy is in these cases most likely to be traced in the connected series of means and ends. The object is not in this place to enter on the Unity of composition general argument of " final causes : " and in re- the true principle of ference to the present subject I will only remark, philosophi- cal physio- that the wider extension of physiology by the intro- lo sy- duction of the more enlarged and modern principle of " unity of composition," besides its proper claims 74 UNITY OF SCIENCES. [ESSAY I. n. as the basis of all great and scientific conceptions of such subjects is also remarkable in this respect, that it leads us more directly to recognise the proper place of physiology among the sciences as exhibiting it more clearly in its relations to that unity of prin- Hence ciple which pervades them all. There is nothing unity of physiology exclusive or peculiar in the study of organised with other sciences. bodies ; it involves no essentially characteristic idea distinct from other branches of physical investiga- tion, but, like them, tends to the grand conclusion of a reference to common and high principles of unity and harmony of plan and design throughout nature. Difficulty as But the most difficult, and at the same time the to including man in the m ost important question in anv theory of this kind, series of J has been raised on the ground of its relation to the nature o/*MAN. It will, however, hardly be denied that man, con- sidered in his animal nature alone, is very little supe- rior to brutes, and in some respects inferior. In the scale of mere animal organisation, the difference between the lowest human form and the highest monkey is not greater than between one class of monkey and another. Whatever difference of opi- nature. ESSAY I. 11.] UNITY OF SCIENCES. 75 nion may have arisen on this subject of a moral and metaphysical kind, yet it is on all hands allowed that man has to a certain extent a nature in common with brutes : and we may avoid all cavil if we simply assert that man, in so far as he partakes in a nature common to brutes, is along with them, in that respect, a part of the same scale and system of organised life. In so far as his animal nature, functions, and in- Distinction of man's stincts are concerned, they are linked in the same nature; animal and chain of continuity with the order of other material higher, existences. To what extent mind and volition, especially in their lower functions, in man are different from the corresponding manifestations in inferior animals, is doubtless a very important question of psychology. To draw the line may be difficult or impracticable. Without pretending to determine such a point, we may safely say that, in so far as they belong to the animal part of man's constitution, the question as to the nature of such manifestations of intelligence may be a question of degree, and may be philosophically treated as connected with other questions of man's physical development, as part of the great scale of natural existence, governed by natural laws as yet 76 UNITY OF SCIENCES. [ESSAY I. n. very imperfectly known, but fairly subjects of in- ductive inquiry. The question of an intellectual principle is of a peculiarly metaphysical kind, and in no way affects the continuity of man's physical nature with the rest of the material order of things. Man's But the more important question refers to the spiritual nature of a further assertion of a distinct moral and spiritual different order of nature or principle existing in man, and all the higher relations consequent upon it, which place the nature of man in this respect in a category altogether different from that of inferior animals. Now on this most important point I would only ob- serve one thing in reference to our present subject: the assertion in its very nature and essence refers wholly to a DIFFERENT ORDER OF THINGS, apart from, and transcending, any material ideas whatso- ever : hence it cannot be affected by any considerations or conclusions belonging to the laws of matter or nature. Man con- J n a W ord. man's nature and existence on earth is in nected in the natural nothing of a peculiar kind, and in no way violates the essential unity and continuity of natural causes : in regard to man's animal nature, because, so far as that extends, it wholly belongs to the physical order of things; in regard to man's spiritual nature, ESSAY I. 11.] UNITY OF SCIENCES. 77 because, so far as that is concerned, it is wholly inde- pendent of all material things, and is therefore re- lieved from all possibility of connexion, or collision, with any physical truths, or theories. As, then, the foregoing consideration refers to the similar distinction study of the existing relations of organised life and of as to the past. man's nature, so far as it belongs to animal existence, so the same principles equally apply to the investiga- tion of its past history and origin, so far as we can trace it. We need seek for no more peculiar or occult cause in the one case than in the other. If we admit that the earth, being still hot inter- nally, must have cooled at its surface, and that this cooling must, in its progress, have caused contortions, dislocations, upheavals of strata ; and again, that the waters charged with matter must have deposited it ; and that the various crystallised bodies and metallic veins must have been formed during certain stages of these formations, it is only by parity of reason Rudiments of all phy- affirmed that the rudiments of all organic as well as sicai things in the pri- inorganic products and structures must have been maevaimass. evolved in like manner, as they were alike included and contained in the once fused, and therefore once vaporised, or nebulous, mass. In that mass all kinds 78 UNITY OF SCIENCES. [ESSAY I. n. of physical agents, or the elements of them,, thermotic, electric, chemical, molecular, gravitational, luminife- rous, and by consequence not less all organic and vital forces, must have been included. Out of it in some way, by equally regular laws in the one case as in the other, must have been evolved all forms of inorganic and equally of organic existence, whether amorphous masses, crystals, cells, monads, plants, zoophytes, animals, or man, the animal man ; the spiritual man belonging to another order of things, a spiritual creation. Conclusion. From this brief discussion, which was rendered necessary in order to meet some apparent exceptions Unity of to the general view and assertion of the unity of sciences re- presents sciences, we may now return to the main conclusion, unity of nature. equally valuable in regard to the view it tends to open of the study of the sciences and their relation to each other, as in its bearing on higher inferences which are the crowning pinnacle of scientific truth. Sciences in All science then is emphatically one : in all its parts different stages of and branches, however apparently distinct, or sup- advance. posed to involve peculiar modes of thought appropriate to each, we find, on close examination, that all such distinctions are but temporary and provisional, and ESSAY I. IT.] UNITY OF SCIENCES. 79 that what appears peculiar is so only because the in- vestigation in different parts of science is in different stages of progress. In one it has arrived at no more than a description and classification of pheno- mena, or even of the materials whose phenomena we propose to study ; in another we have been able to reduce all phenomena to laws of high generality, and those laws to simple principles of force and motion of the most elementary simplicity and the highest generality ; and between these extremes there exist all varieties of intermediate stages. But all sciences approach perfection as they ap- AH sciences proach to a unity of first principles, differently towards showing the applied, indeed, according to the different nature of unity of nature, the material objects contemplated, but in all cases recurring to or tending towards certain high ele- mentary conceptions which are the representatives of the unity of the great archetypal ideas according to Avhich the whole system is arranged. Inductive conceptions, very partially and imperfectly realised and apprehended by human intellect, are the ex- ponents in our minds of these great principles in nature. The great inference of uniformity is corroborated 80 UNITY OF SCIENCES. [ESSAY I. n. not only by the successively more and more com- prehensive laws of nature, which science exhibits, but by the very possibility of the existence of such a thing as systematic science : not only by the ac- cumulative proofs existing in nature, but by the marvellous adaptation and harmonising disposition of the human mind for appreciating and discover- ing them: not only by the occurrence of natural events in invariable order, but also by the possi- bility of expressing them by laws conveyed in exact terms, and of advancing deductively to the prediction of other phenomena. Thus, even this preliminary condition of all inductive inquiry affords confirmation of the principle of unity of design, connecting the physical with the intellectual world ; and this in a still higher degree, as all sciences are seen to tend towards unity. Our con- The actual laws and profound principles which ceptions of natural regulate the mechanism of the universe are the order the reflection of originals, the conception and expression of them in the reality in the su- ^he m i n d of man only the copies. The vast assem- preme mind - blage of physical causes, the great principles, whether of cosmical force or of the minutest molecular affec- tions, as they exist in the heavens or in terrestrial ESSAY I. IT.] UNITY OF SCIENCES. 81 bodies, are the realities : the exposition and demon- stration of them in the mind of the philosopher only their images. All science is but the partial reflexion in the reason of man, of the great all-pervading reason of the universe. And thus the unity of science is the reflexion of the unity of nature, and of the unity of that supreme reason and intelligence which pervades and rules over nature, and from whence all reason and all science is derived. 82 III THE UNIFORMITY OF NATURE. " The harmony of creation is such, that small things constitute a faithful type of greater things." JEREMIAH HORROCKS, 1637. Hindrances As real physical analogies form the true ground of to science ,... i, 1,1 n i from false inductive speculation, and the power of a right ap- prehension of them confers that inductive foresight which leads to successful discovery, so there are many false views of analogy to be carefully guarded against, involving misconceptions of the relations of ESSAY I. in.] UNIFORMITY OF NATURE. 83 physical facts, and leading to mistaken theories and unphilosophical hypotheses, which retard instead of promoting science. In the earlier stages of induction, laws are as- Exceptions and ano- signed of a limited character, circumscribed by many maiies maintained reservations, and qualified by various exceptions and as real principles. anomalies, real or apparent, yet which must be at least temporarily and provisionally noted as such. Yet it has sometimes happened that such limited views have been converted into positive and general dogmas, from neglecting the obvious caution of always speaking of them as provisional. Thus sometimes, on the one hand, an unduly Authority of a name. limited and restricted view, cautiously entertained by a great philosophical leader, may have been caught up by his followers, misunderstood, and invested with a false character and importance; or, on the other hand, crude ideas may be sometimes hastily thrown out by a great master mind, as first tem- porary or tentative hypotheses, and then come to be treasured up as absolute dicta by their less discerning disciples, and so have acquired the stamp of per- manency, to the great and serious hindrance of scientific progress. G 2 84 UNIFORMITY OF NATURE. [ESSAY I. in. irration The once common use of the term " irrationality " ality of dis- persion of of the prismatic spectrum, implied the prevailing light. prepossession that it might be expected to be ee ra- tional/' or follow the same proportion in all media ; whereas, in fact, great difference of ratio prevails. This erroneous first conception long retarded dis- covery. It, however, shelters itself under the au- thority of Newton, who assumed it without question, perhaps even as a natural consequence, from the fact, that as spectra given by prisms of all substances are analyses of white light, and can be recompounded into the same white light, the ingredient tints must in all cases be in the same proportion. Coral reefs. Nothing could be more marvellous than the hy- potheses once universally in vogue as to the form- ation of coral reefs, rising up in so inexplicable a manner from the depths of the ocean ; until, by the application of a more correct knowledge of the na- tural history of the animals, and a simple reference to the common geological phenomena of subsidence, Darwin has divested the whole history of its mar- vellous character, and restored the equilibrium of inductive uniformity. When the asteroids were first discovered, an ESSAY I. in.] UNIFOKMITY OF NATUKE. 85 eminent astronomer maintained that a large planet Hypothesis . of asteroids once moving at their mean distance had exploded, of from the explosion of which they were the fragments. Strange as this a planet, hypothesis was, it was generally adopted by philo- sophers, and even calculations were entered into to assign the place at which this marvellous catastrophe took place, and the directions followed by the frag- ments. But if we simply asked what analogy have we for such an event, when has a planet ever been known to burst ? or, indeed, how could such an effect be produced? its unphilosophical nature is sufficiently apparent. On the other hand, condensation of cosmical matter is an hypothesis which has gained ground from many probable analogies ; and the supposition of a ring of such matter, out of which these minute bodies (probably existing in vast numbers) have been condensed, formerly thrown out in a public lecture*, has been sanctioned by the authority of Mr. Adams, in an address from the chair of the Astronomical Society, f To take another instance : the authority of New- * Royal Institution, April 7. 1848 : see Athenaeum, f Astr. Soc. Notices, 1853, vol. xiii. 143. G 3 86 UNIFORMITY OF NATURE. [ESSAY I. HI. Geometri- ton's name and example undoubtedly, for a long cal method. series of years after his death, powerfully influenced for the worse the tendencies of the mathematical spirit of England towards an exclusive preference for the geometrical method: or where necessity might com- pel the use of analytical processes, still an entire devotion to the letter of Newton's fluxional notation restricted their application, and long continued to make the great advances of the continental analysts a sealed book to the English student, and to retard the progress of investigation in this country. Unity of In a similar spirit, without any more disparage- composition in physi- ment to the great name of Cuvier than to that of ology. Newton, it has been a subject of complaint on the part of a large and increasing school of physiologists, that a too prevalent devotion to the teleological me- thods which he so peculiarly supported, and which derived so undue a preponderance from the authority of his name, has been a great hindrance to the pro- gress of the more extended views opened by the higher principle of ff unity of composition " advo- cated by the school of Greoffry de St. Hilaire, which Cuvier so strenuously opposed, and which the influ- ence of his name was long so potent unduly to repress. ESSAY I. m.] UNIFORMITY OF NATURE. 87 The prepossession arising from Newton's dictum, Change of refrangi- " To the same ray ever belongs the same refrangi- witty, bility," seems long to have operated as a bar to even imagining any theory which involved an opposite idea. And it was accordingly as a sort of paradox that Professor Stokes ventured to announce his im- portant discovery of a change of refrangibility, which affords the key to so wide a range of curious phe- nomena of light, including and generalising the singular results before obtained by Sir J. Herschel and others of Sir D. Brewster. The higher and wider extension of analogy and slow pro- gress of ge- generalisation is not effected at once and at first, neraiisa- tion. The earliest, and sometimes the most highly and justly valued labourers in particular departments and fields of research, as collectors of facts, are not al- ways those best able to perceive the broader con- nexion of grand principles ; and hence are the more apt to cling to such prepossessions as those just alluded to. Even when many classes of facts have been successfully made out, it requires time, and the appearance of some genius of more rare original power, to indicate at once a comprehensive theo- retical principle by striking out some general con- G 4 88 UNIFORMITY OF NATURE. [ESSAY I. in. ception, startling, perhaps, from its very simplicity, yet revolutionising the whole science. Great prin- And even when they are proposed, such more ciples re- luctantly elevated views are not at once appreciated or under- adopted. stood, not merely by the many, but even by the cul- tivators of science. When Galileo opened the path of all true astronomy by the simple maxim that the same laws of motion which hold good on the surface of the earth apply also throughout the celestial spaces, and when Lyell did the same thing for geology, by maintaining that the analogy of real and existing causes ought to be extended through all the immeasurable periods of past time ; neither was at first admitted without much difficulty and opposition, not so much arising from the mere ignorance of the many, as from the preconceptions of the few. Dislike of Some very eminent men of science have been theorising. prone to cherish an intellectual disposition too strongly opposed to all indulgence in hypothesis, and have evinced a very stringent determination to keep to what is regarded as the exactness of demonstra- tive science, with an especial abhorrence of any thing wearing the appearance of theorising ; which they would most carefully shun under the idea of ESSAY I. in.] UNIFORMITY OF NATURE. 89 its being metaphysical and visionary, and altogether at variance with the severity of all that is worthy the name of real science, or, at any rate, beyond their province to pursue ; which is surely as much a fault in the one extreme as the spirit of fanciful hypothesis is in the other. Yet, men of the most comprehensive minds are the most ready to admit the value of such speculative ideas if well formed. " Beside positive knowledge," says Humboldt, " stand conjecture and opinion a philosophical science of nature strives to rise beyond the limited requirements of a bare description of nature. It consists not ... in the barren accumulation of iso- lated facts. The curious, the inquiring spirit of man must be suffered to make excursions, . . . still to surmise what cannot be positively known."* We have already observed that all induction im- The philo- sophy of plies a primary adoption of a certain amount of hypo- conjecture. thesis ; and the secret of its success in any instance lies mainly in the happy selection of such hypotheti- cal grounds, and not in the mere accumulation of facts. It is by the peculiar capacity for seizing sound * Cosmos, p. 252., 1st trans. 90 UNIFORMITY OF NATURE. [ESSAY I. in. analogies in these first hypotheses that the highest philosophical genius is mainly characterised. Some persons speak as if all conjecture were alike delusive ; but wise and skilful conjectures are very different from hasty and crude guesses; and the com- parative probability of several hypotheses, all purely imaginary, admits of many degrees ; and to reduce it to something like fixed principles would constitute no unimportant branch of mental science, the logic of anticipation, the philosophy of the unknown. Belief from It was in fact nothing else than the firm persuasion analogy be- fore demon- O f the truth of great and high principles of philoso- phical analogy, and the inherent force of sound ideas of probability, which so powerfully influenced those who were the first assertors of the solar system of the planetary world, and even martyrs to its cause, before it had received any absolute proof from the application of mechanical principles ; and when the assertion might be called merely conjectural. Yet it was a conjecture of that highest class which is formed by genius in its loftiest moments of inspiration, de- rived from an enlarged contemplation of the har- mony of nature ; and, we may add, in like manner it is, that on the other hand the antecedent incredi- ESSAY I. in.] UNIFORMITY OF NATURE. 91 bility of an alleged phenomenon weighs more against it with a sound philosopher,, than many assertions in its favour. A beautiful example of this kind of anticipation is Example of Horrocks. found in the correspondence of the unfortunate but pre-eminently promising Jeremiah Horrocks ; when, after objecting to some theories of Kepler , to account for the planetary motions, he adds, " It appears to me, however, that I have fallen upon the true theory, and that it admits of being illustrated by means of natural movements on the surface of the earth, for nature everywhere acts according to a uniform plan, and the harmony of creation is such that small things constitute a faithful type of greater things"* It was to illustrate this "true theory," that he devised that beautiful experiment (the most instruc- tive which the lecturer can exhibit even at the pre- sent day f ) of the freely suspended ball revolving in an ellipse under the combined influence of the central and tangential forces ; and in addition showing the motion of the apsides. Mere conjectural hints at explanation of obscure * In a letter dated Nov. 23. 1637. See Grant's Hist, of Astron. p. 425. f See Vignette. 92 UNIFORMITY OF NATURE. [ESSAY I. m. Conjectural phenomena may in many cases be thrown out, which explana- tions only may seem to some fanciful and idle, and may be to show that pheno- easily turned into ridicule ; when the real object and mena are not in their meaning is only to show that the phenomena in nature in- explicable, question are not necessarily of such a nature as to be beyond the boundary of legitimate investigation, or possible explanation. In such instances, to show a bare possibility is all that the case requires ; the lan- guage sometimes employed is perhaps censured as fanciful and evasive, or as a mere disguise for igno- rance ; but the real purport of such suggestions is overlooked ; they are not put forth as pretending to be complete explanations ; the point that is aimed at is merely to show that the phenomena in question are not necessarily of a kind outstanding and setting at defiance all physical explanation : now an event cannot be set down as inexplicable to our faculties, so long as any possible or imaginable combination of physical conditions can be suggested as capable of furnishing a plausible explanation of it. Example. Thus, for example, the nebular hypothesis of the Nebular theory. origin of the planetary system was thrown out by Laplace as confessedly a mere conjecture : yet one which was founded on rational probability; and ESSAY I. m.] UNIFORMITY OF NATURE. 93 tended to show that the observed peculiarity of the motions of the planets being all in one direction, was not absolutely inexplicable on physical principles, and evinced a probability that on this, or some equivalent principle, the origin of those motions might reason- ably be expected to find a solution. Yet further : to this uniformity in the motions of Anomaly of satellites of the system there appears one striking exception in Uranus, the satellites of Uranus, which are at once retrograde and highly inclined ; as they would be if originally direct and then turned over beyond the perpendicular. Such a disturbance could not occur from the action of any existing planetary attraction : but, in the state of nebulosity, it is far from impossible to conceive some action of the kind among the multitude of conflicting forces then acting. No sound philosopher doubts that the effect was due to some regular cause : the nebular hypothesis may serve to suggest that the conception of such a cause is not wholly beyond the limits of physical analogy. The progress of physical discovery may, it is true, Difficulties , . , .., ......in research be sometimes slow, and the appearance of objections no t to stop and difficulties so formidable, as to damp the ardour of research, or even to give some colour to the 94 UNIFORMITY OF NATURE. [ESSAY I. in. insinuations of those who may be sceptical as to the pretensions of philosophical advance, or entertain jealous or hostile feelings towards such pursuits. But the inquirer, truly imbued with inductive prin- ciples, will not despond. Lesser diffi- There is one grand maxim of pre-eminent value cutties not to hinder in philosophic inquiry generally, and which finds a reception of great prin- peculiar application under such circumstances as ciples. those just referred to, viz., that having once grasped firmly a great principle, we should be satisfied to leave minor difficulties to await their solution, assured that in time the progress of discovery will clear them up as certainly as it has now cleared up difficulties once quite as formidable and paradoxes quite as inex- plicable. It has been by adherence to this rule that all great philosophical systems have made their way Example. and finally triumphed over error. The Newtonian Newtonian . . system and theory was beset by palpable contradictions in its lunar apsides. results till many years after Newton's death ; yet all sound philosophers embraced it. The motion of the apsides of the moon's orbit was, with singular honesty, confessed by Newton to be in fact nearly twice as great as calculation from theory made it: and this contradiction remained an outstanding palpable ob- ESSAY I. in.] UNIFORMITY OF NATTJEE. 95 jection, yet without occasioning any misgiving in the mind of sound philosophers as to the general truth of gravitation, till the error was explained, and the calculation rectified by Clairault.* Up to the present time, all the anomalies of the The tides, tides are by no means reduced under the dominion of theory : yet no sound philosopher doubts the truth of the principle that they are due to the solar and lunar attractions. The theory of gravitation, again, was really de- Motion of Uranus, fective up to the present day: the motions of the planet Uranus, as calculated by theory, were found to be every year becoming more and more discordant with observation, and theory was completely at fault : until the calculation of Adams and Le Yerrier showed that the anomalies could be explained by the supposition of the disturbance occasioned by an exterior planet moving in a certain orbit; and, at the time, at a certain point in that orbit; as was directly verified by the observations of Galle and other astronomers. So again, the undulatory theory of light now un- The wave theory of _ light. * Princip. bk. i. sect. ix. prop. 45. cor. 2. 96 UNIFORMITY OF NATURE. [ESSAY I. in. hesitatingly accepted by all mathematicians is still confessedly defective in its application to several phenomena, especially the more extreme cases of prismatic dispersion. Meiioni's The rays of the sun under ordinary circumstances anomaly in . ... the solar possess a heating power in proportion to their in- tensity. When analysed, though the heating power differs greatly for different primary rays, and is not proportional to their illuminating power, yet it nowhere exists without rays which may be rendered visible, nor is any visible ray destitute of such power : and for the same ray under the same conditions the heating is proportional to the illuminating intensity. To this general law one, and one only, outstand- ing exception occurs in an experiment recorded by Melloni, viz., that, with a certain green glass, the rays transmitted, when concentrated by a lens, are in- tensely bright, but totally destitute of heat. This is a solitary exception a breach of all analogy unsupported by any corroborative experiments : and as yet unexamined by any critical experimenter. It is then simply an anomaly provisionally. The anomaly that water is at its greatest density at about 40 F., and below that expands with de- ESSAY I. in.] UNIFORMITY OF NATURE. 97 crease of temperature, has been held by some to be Maximum density oi a marvellous and peculiar outstanding fact, setting water. all theory at defiance. Yet no truly inductive philosopher for a moment doubts that it is really a part and consequence of some higher law of which the ordinary law of ex- pansion is a part. Indeed, Berthollet has speculated on the subject, so far, at least, as to maintain that the cause, whatever it be, which produces crystallisation, is in operation in expanding the water before the crystals of ice are actually formed, and which are specifically much lighter than the water.* He even states it as a general law that "the causes which determine the changes of constitution of bodies exercise an action, the effects of which are evident before the changes of constitution have taken place." And this property in water is not altogether an anomaly as compared with what takes place in antimony, iron, and bismuth. Instances also occur in certain substances in a fluid state which instantly solidify on the application of an extraneous body proving that the particles * Dr. Pereira's Lectures on Light, p. 168. 2nd ed. 1854. H 98 UNIFORMITY OF NATURE. [ESSAY I. ill. are already in a state of strain, and require only some extraneous agency to bring about that change in their arrangement. Other suggestions of a theoretical kind have also been made : but, at any rate, we see enough to show that the phenomenon is not one of necessity out- standing all explanation, and that it very probably will ere long be brought under the dominion of theory. Principle of The system of inductive reasoning in its full ex- uniformity throughout tent essentially involves the conviction of the universal nature the essence of and permanent uniformity of nature. This, as was ob- tion. served at first, has been emphatically and truly called " the inductive principle. " It is this which points to the great archetype of UNITY ; to which all our sub sequent conclusions minister increasing confirmation ; and from the influence of such a first principle in our inquiries arises all that distinguishes true science from mere empiricism, and an elevated philosophy from the grovelling and mechanical accumulation of mere millions of facts. Not an in- And we may remark that this idea, in its proper tuitive or natural be- extent, is by no means one of popular acceptance or lief. natural growth. Just so far as the daily experience ESSAY I. m.] UNIFOKMITY OF NATURE. 99 of every one goes, so far indeed he comes to em- brace a certain persuasion of this kind, but merely to this limited extent, that what is going on around him at present, in his own narrow sphere of observa- tion, will go on in like manner in future. The peasant believes that the sun which rose to-day will rise again to-morrow; that the seed put into the ground will be followed in due time by the harvest this year as it was last year, and the like ; but has no notion of such inferences in subjects beyond his immediate observation. And it should be observed that each class of per- commonly doubted or sons, in admitting this belief within the limited range denied be- yond nar- of his own experience, though he doubt or deny it in row limits. everything beyond, is, in fact, bearing unconscious testimony to its universal truth. Nor, again, is it only among the most ignorant that this limitation is put upon the truth. There is a very general pro- pensity to believe that everything beyond com- mon experience, or expressly ascertained laws of nature, is left to the dominion of chance or fate or arbitrary intervention; and even to object to any attempted explanation by physical causes, if conjee- 100 UNIFORMITY OF NATURE. [ESSAY I. m. Acquired only by philosophi- cal study. Increasing conviction by more extended research. turally thrown out for an apparently unaccountable phenomenon. The precise doctrine of the generalisation of this idea of the uniformity of nature, so far from being obvious, natural, or intuitive, is utterly beyond the attainment of the many. In all the extent of its uni- versality it is characteristic of the philosopher. It is clearly the result of philosophic cultivation and train- ing, and by no means the spontaneous offspring of any primary principle naturally inherent in the mind, as some seem to believe. It is no mere vague per- suasion taken up without examination as a common prepossession to which we are always accustomed; on the contrary, all common prejudices and associations are against it. It is pre-eminently an acquired idea. It is not attained without deep study and reflection. The best-informed philosopher is the man who most firmly believes it, even in opposition to received notions : its acceptance depends on the extent and profoundness of his inductive studies. Throughout the range which science opens to us we find the several classes and orders of phenomena defined by laws of increasing generality, and thus intimately connected and bound together, so that ESSAY I. m.] UNIFORMITY OF NATURE. 101 every part is essential to the coherence and unity of the whole. But when we have arrived at the highest of such generalisations to which science has yet attained, those most comprehensive laws, in the existing state of our knowledge, seem diverse, disunited, and not as yet connected by any common higher principle; yet we cannot for a moment suppose this to be anything else than the result of our ignorance ; they must each be really sub- ordinate members of some greater group. Future research will undoubtedly connect them together by a common principle, of which at present we can form no more conception than the predecessors of Newton did of universal gravitation, or than he did of elec- tro-magnetism, or geological epochs. Discoveries are being made every day ; and the very next impor- tant physical discovery will as assuredly effect an union between some two or more classes of pheno- mena at present not so connected, as the last dis- covery has done. New phenomena are being con- tinually detected. Not more surely does this happen than it is sooner or later followed by the disclosure of more comprehensive laws. The progress of discovery is as certain as the extent of nature is K 3 102 UNIFORMITY OF NATURE. [EssAY I. in. unlimited ; and the subordination of species of pheno- mena to genera ; of these genera, again, to classes or higher genera, and so on, must be as unbounded as the succession of phenomena, idea of The universality of law and order is the dis- chance. tinguishing conviction of the inductive philosopher; by this, in fact, science is elevated into philosophy. One main test of its force and extent is the exclusion, in consequence of its admission, of the very notion of chance, or of the possibility of any events in the universe really happening at random. In fact, the very term chance implies a theory ; and if we would examine its meaning, and employ it in a strict sense, we should find that what we really mean can never properly amount to more than a confession of our ignorance of the mode or order in which certain events have taken place. If we take any portion of the natural world, or any class of pheno- mena of which we know least, and which appear most fortuitous, can we correctly say more than that we are ignorant of the laws by which it is regulated ? Yet, while in saying that any phenomena appear capricious or fortuitous, we simply admit our igno- rance of the laws by which they are governed, no ESSAY I. m.] UNIFORMITY OF NATURE. 103 inductive philosopher for a moment doubts that they are regulated by some laws. To take an example: the apparently irregular Example. Distribu- mode of distribution of the fixed stars through the tion of fixed stars. heavens, might seem, at first sight, to justify the belief that their arrangement and position in the universe might be wholly fortuitous) and such pro- bably may be the idea in uninstructed minds, and they may perhaps feel disposed to ridicule the some- what bold but characteristic idea of Des Cartes*, who says that he meditates an attempt to investigate the cause of the position of every fixed star. Yet the very fact that these masses at least have the property of transmitting light to us, and consist of matter of some kind, and have been in some instances proved to be subject to the law of gravitation, in- stantaneously asserts for them a sort of claim of kindred with matter around us and with ourselves, and dispels every shadow of doubt that they are disposed according to some physical law, under the influence of some determinate physical forces. When we come to examine the masterly and pro- struve's re- searches. found researches of Struve (disclosed in the " Etudes * Epist. 67. ii 4 104 UNIFORMITY OF NATURE. [ESSAY I. ill. d'Astronomie Stellaire ") we begin to feel more con- vinced that even iu the seemingly capricious dis- tribution of these remote masses through the abysses of space, we obtain a glimpse of order, if only from the mere fact that by the consideration of averages, some sort of classification is effected ; and from that happy combination of arguments brought together from such various sources, which none but an in- ductive genius of the highest order could have planned, and nothing but consummate mathematical skill could have worked out, conclusions of high generality and profound interest are elicited in a subject, at first sight, seeming to baffle inquiry. Geological Nothing would appear, at first sight, more devoid elevations. of all order, or apparently fortuitous, than the directions assumed by those elevations and fractures of strata which diversify the surface of the earth with mountains and valleys, precipices and plains. Yet the accurate observations of geologists, combined with the theoretical indications of dynamical science, have even now begun to throw some light on the probable laws of these seemingly arbitrary manifesta- tions of power, and to connect them with the all- pervading principles of regularity ; and though we ESSAY I. m.] UNIFORMITY OF NATURE. 105 may not be disposed to assent to the precise theory of Elie de Beaumont, yet it at least gave a right direction to inquiry, and the exact deductions of Mr. Hopkins, place the general dynamical principle of lines of upheaval beyond question ; and leave no doubt that a comprehensive mechanical theory will eventually be worked out, and the most monstrous geo- logical " catastrophes" reduced to order and system. Among the ancients we know the several forms of Fate and chance ex- belief in blind fate or chance were not merely popular excluded - delusions, but deliberate persuasions, which divided philosophical sects : the advocates of the fixed neces- sity and eternal destiny of the world, and the sup- porters of the Epicurean doctrine of the formation of the material universe out of a fortuitous concourse of atoms. But in the age and under the influence of the inductive philosophy, no such dreams can for a moment obtrude themselves. The definite and posi- tive spirit of this system strikes at the root of such vague and unmeaning expressions the mere dis- guises of human ignorance. It demands what chance and fate are. It appeals to the great principle of uniformity, and the regularity of physical causes; and feels warranted in affirming that in all cases, 106 UNIFORMITY OF NATURE. [ESSAY I. m. however incapable they may at first appear of re- duction to any kind of system, there yet must be in reality as perfect, though to us unknown, ob- servance of determinate laws in their production, as in any cases we are most familiar with. Pro- foundly adjusted order is utterly inconsistent with blind destiny, mechanical causes with chance. NO limits to It is the proper business of inductive science to the applica- ^ tion of in- analyse whatever comes before it. We cannot say duction. 1 i . that any physical subject proposed is incapable of such analysis, or not a proper subject for it, until it has been tried and found to fail; and even then, the result is not unprofitable ; we know the precise point at which the failure has taken place, and the exact cause of its occurrence. It is a main charac- teristic of sound philosophy, that it draws the line precisely between the known and the unknown; and teaches us not only why we understand the one part, but why we do not understand the other. Yet the unknown regions on the frontier of science enjoy at least a twilight from its illumination, and are still brightened by the rays of present conjecture, and the hope of future discovery. We can never say that we have arrived at such a boundary as shall ESSAY I. m.] UNIFORMITY OF NATURE. 107 place an impassable limit to all future advance, provided the attempts at such advance be always made in a strictly inductive spirit. To the truly inductive philosopher, the notion of limit to inquiry is no more real than the mirage which seems to bound the edge of the desert, yet through which the traveller will continue his march to-morrow, as uninterruptedly as to-day over the plain.* When the inductive inquirer finds himself involved Limits of our present in some great apparent difficulty, and among pheno- knowledge mena which no existing; resources of science are from those of nature. able to explain, which appear to stand forth as irre- ducible anomalies, and to baffle all attempts at ex- planation ; however hopeless the problem may seem, he can never really suppose the case to be in its own nature incapable of analysis, or that the mass of facts is not really reducible to some principles of order, analogy, and causation, to the dominion of laws as yet indeed unknown, and of causes not as yet conjec- tured, yet as perfectly regular and strictly harmonious as those which govern the most common daily occur- rences, the fall of a stone, or the ascent of vapour. * See note at the end of the section. 108 UNIFORMITY OF NATURE. [ESSAY I. in. No real in- terruptions in the order of nature. Anomalies only appa- rent. Anomalies referred to laws as yet unknown. A real break in the connection and continuity of physical causes cannot exist in the nature of things. If such breaks often appear, they are due solely to our ignorance. Every advance tends to fill them up ; and indeed each physical discovery is nothing else than an extension of the evidence of continuity, a fresh link in the connexion of phenomena into one consistent whole. There is no such thing as any class of phenomena really standing out isolated from all others uncon- nected by any analogous principle, and truly ano- malous in regard to the rest of nature. Yet every class of phenomena has at some time seemed so ; but it is an illusion in whatever instance it may now seem to be the case; and one which time will assuredly clear away, as it has already done so many similar or greater illusions. In all apparent anomalies, the inductive philo- sopher will fall back on the primary maxim, that it is always more probable thai events of an unaccount- able and marvellous character are parts of some great fixed order of causes unknown to us, than that any real interruption occurs. And further, what may now appear the most mysterious, and at present least ESSAY I. m.] UNIFORMITY OF NATUKE. 109 understood, will yet hereafter be explained by the future extension of discovery. It may, indeed, be difficult or impossible to apply these considerations in detail, and to suggest parti- cular interpretations in subordination to these para- mount principles ; yet this will not invalidate their general truth ; nor need it lead us into extravagant and gratuitous speculations to bring about a precise explanation for which the circumstances do not fur- nish sufficient data. A truly rational inquirer will be content to let such difficulties await their solution : and, so far from always seeking such explanations in precise theories, he will admit, on the contrary, that too minute a solicitude to refer every case to KNOWN causes, may tend to keep out of sight the broader prin- ciple that they may be referable to some causes as yet UNKNOWN, but still parts of the same universal order; and may even lead to the disparagement of that prin- ciple when, in any instance, such more particular mode of explanation is found to fail. For example : in the present state of science, of instances. all subjects, that on which we know least is, perhaps, the connexion of our bodily and mental nature, the action of the one on the other, and all the vast 110 UNIFORMITY OF NATURE. [ESSAY I. iir. range of sensations, sympathies, and influences in which those effects are displayed, and of which we have sometimes such extraordinary manifestations in peculiar states of excited cerebral or nervous action, somnambulism, spectral impressions, the phenomena of suspended animation, double consciousness, and the like.* In such cases science has not yet ad- vanced to any generalisations ; results only are pre- sented which have not as yet been traced to laws* Yet no inductive inquirer for a moment doubts that these classes of phenomena are all really connected by some great principles of order. If, then, some peculiar manifestations should ap- pear of a more extraordinary character, still less apparently reducible to any known principles, it could not be doubted by any philosophic mind that they were in reality harmonious and conspiring parts of some higher series of causes as yet undiscovered. Anomalies The most formidable outstanding apparent ano- will be cleared up malies will at some future time undoubtedly be by future discovery, found to merge in great and harmonious laws, the connexion will be fully made out, and the * The reader is referred to " Letters on the Truths contained in Popular Superstitions," by the late Herbert Mayo, M.D. 1849. ESSAY I. in.] UNIFORMITY OF NATURE. Ill claims of order, continuity, and analogy, eventually vindicated. Inductive philosophy has within itself a pro- phetical warrant to foresee that a time will come when those things which seem most obscure will become clear. The well-known prediction of such a disclosure in the case of the celestial motions uttered long ago by Seneca *, and fulfilled in Newton, is not less applicable at the present time, and points to equally grand openings in all branches of physical science, which will as assuredly be made at other future epochs of scientific revelation. When we arrive at any such seeming boundary of No com- mencement present investigation, still this brings us to no new of a new order of world in which a different order of things prevails ; things, it merely points to what will assuredly be a fresh starting point for future research. It is an un- warrantable presumption to assert, that at a mere point of difficulty or obscurity we have reached the boundary of the dominion of physical law, and must suppose all beyond to be arbitrary and inscrutable to * " Veniet tempus, quo ista quse nunc latent, in lucem dies extrahat, et longioris sevi diligentia : ad inquisitionem tantorum aetas una non sufficit; veniet tempus quo posteri nostri tarn aperta nos nescisse mi- rentur." Nat. Qutzst,, viii. 25. 112 UNIFORMITY OF NATURE. [EssAY I. m. our faculties. It is the mere refuge and confession of ignorance and indolence to imagine special inter- ruptions, and to abandon reason for mysticism. Conclusion. The consideration of the uniformity of nature leads directly to a more precise a higher view of the same great conclusion to which we before ad- verted generally. Evidence of All induction begins and ends in the conception a supreme mind. of order, arrangement, and uniformity throughout nature ; and this, however inadequately compre- hended by our science, is again the evidence of supreme mind, and the universality of order in time and space, the manifestation of the universality and eternity of that supreme mind. It has been eloquently observed, " Humboldt thought he could show why and how this world, and the universe itself, is a kosmos, a divine whole of life and intellect, namely, by its all-pervading eternal laws. Law is the supreme rule of the uni- verse ; and that law is wisdom, is intellect, is rea- son, whether viewed in the formation of planetary systems, or in the organisation of the worm."* * Chevalier Bunsen's reply to the President's Address, on delivering the medal to Humboidt, Royal Society Anniversary, 1852. ESSAY I. ni.] UNIFORMITY OF NATURE. 113 And in a similar spirit CErsted has said : " The progress of discovery continually produces fresh evi- dence that Nature acts according to eternal laws, and that these laws are constituted as the mandates of an infinite perfect reason ; so that the friend of Nature lives in a constant rational contemplation of the Omnipresent Divinity."* . . . " The laws of Nature are the thoughts of Nature ; and these are the thoughts of Grod."f * Soul in Nature, p. 196. f Ib. p. 20. NOTE TO P. 107. Of the Baconian philosophy, it has been said by a masterly writer, " It is a philosophy which never rests ; which has never attained, which is never perfect. Its law is progress. A point which yesterday was invisible is its goal to-day, and will be its starting post to-morrow." (Macaulay's Essay on Lord Bacon, p. 113. small ed.) But while I cannot refrain from citing this brilliant sentence with all the admiration it deserves (and indeed many others in the same essay are not less worthy of ad- miration), I feel bound to express my dissent from the exclusively practical view which the author takes of the objects of inductive science, and must regard it as hardly less than a profanation of the name of Bacon, to associate it with such unmixed and grovelling utilitarianism as he would represent to be its aim. 114 IV. THE THEORY OF CAUSATION. 16G6. Vel huic philosophandi modo, vel veriori alicui. NEWTON, Pref. in Princip. Desire to AMONG our various intellectual propensities, there seek causes. is none more powerful or more seductive than the desire to penetrate into the causes of things. We perceive events going on or results produced in the natural world ; we recognise a number of different powers or agents at work ; and to these, under the ESSAY I. iv.] THEORY OF CAUSATION. 115 name of causes, or, more strictly, physical, or, ac- cording to some, secondary causes, men are prone in imagination to ascribe a sort of energetic power, or a coercive efficiency, by virtue of which these physical agents produce, or bring about, certain results : a Natural to imagine species of active influence by which matter is ima- efficient power. gined to act upon matter, and produce a different state of things, in a way exactly analogous to, if not identical with, that in which a voluntary agent exercises his volition on material objects within his control ; and thus there is supposed to exist a re- lation of a peculiar and intimate, yet hidden and unknown kind, not to be traced by our faculties or further explained, yet the essential condition of all real philosophic investigation; and views more or less similar to these seem to have been very generally entertained among philosophers in former times. But when Hume, in his essay on Necessary Con- But unphi- losophical. nexion, showed that of the existence of this kind of mysterious influence or imaginary power a there neither was, nor could be, any evidence; that in physical events all we could really infer was the mere fact of the invariable sequence of the one event called the effect, after the other called the cause, a doctrine so 1 2 116 THEORY OF CAUSATION. [ESSAY I. iv. opposed to the favourite mysticism, which delights in investing scientific truth in a veil of abstruseness, and will not condescend to acknowledge any thing in- telligible to be true philosophy, was of course not received without much open hostility from some parties ; while from others, who felt constrained to acknowledge the strictness of the conclusion, it objections obtained a reluctant and modified acceptance. It to simple view. was complained of as a meagre, empty, unsatis- factory doctrine, tending to degrade philosophic speculation to mere matter of fact, and not pene- trating below the surface. Thus Lord Kames, though admitting that no connexion of cause and effect is discoverable by reason, yet contended that it nevertheless really exists ; for we feel and acknow- ledge that every effect implies a cause, and that nothing can begin to exist without a cause of its existence.* That men are prone to feel and acknow- ledge such a notion is perfectly true ; but the very question at issue is, do they do so correctly, or on any real philosophic ground ? Without here pretending to go into the various * See Burton's Life of Hume, i. 427. ESSAY I. iv.] THEORY OF CAUSATION. 117 discussions of the subject which have taken place Different opinions at amonor subsequent philosophers, and disclaiming all the present day. controversy, I will merely remark that at the present day the question is still kept up by advocates of each extreme the one party contending for the old idea of efficient causation and necessary connexion, and the other adopting the view of Hume, modified by one or two qualifications, yet maintaining the prin- ciple of a simple, invariable (or as Mr. Mill terms it, "unconditional") sequence of events; and agreeing therein with the French school of positive philosophy, as expounded by M. Comte, in totally rejecting the idea of causation in physical phenomena, in the sense of efficient power, as a notion wholly beyond our capacities to define or reason upon, and therefore unphilosophical. My own views of the subject have been expressed General view of the in a work published long ago*; but it may be de- case, sirable to offer some further explanation of them, after a careful examination of what has been ad- vanced since, whether in support and elucidation of * The Connexion of Natural and Divine Truth, London, 1838. See also my Essay on Necessary and Contingent Truth, Oxford, Ashmolean Memoirs, 1849. I 3 118 THEOEY OF CAUSATION. [ESSAY I. iv. the great step made by Hume, or in attempting a retrograde movement and a revival of the exploded, but naturally popular notion, of efficient agency ; the personification of matter and mechanical forces, de- rived from an imaginary analogy between physical action and that of voluntary agents. I conceive that all real philosophical analysis of the case must end in an entire repudiation of such fanciful notions, in- volving, as they appear to me to do, a confusion of Distinction ideas, which I think may be completely avoided of physical and moral by the simple distinction between physical causation causation. or the action of matter on matter ', and moral causa- tion, or the action of mind on matter. To take the simplest example : I throw a stone, which brings down a bird ; my volition is said to be the cause of the stone's flight ; the impact of the stone is the cause of the bird's fall. The word " cause " is here used in two totally different senses : in the first instance, signifying moral; in the latter, physical causation. Rejecting altogether the idea of efficient causation, as wholly inapplicable in relation to phy- Physicai sical effects, however pleasing to the fancy, I con- cause im- . n -i i plies se- ceive that the true theory of physical causation relation. includes the simple idea of an invariable or " uncon- ESSAY I. iv.] THEORY OF CAUSATION. 119 ditional" sequence of facts (meaning sequence in relation not necessarily in time) ; yet I contend that there is implied also a connexion, not in the events in the way of physical agency, but in the reason and logical dependence of the two ideas. The phenome- non or property assigned as the cause or antecedent has undoubtedly a necessary connexion with the effect or consequent, when it supplies the explanation of it : when the latter is a consequence in reason and Necessary connexion theory from the former, when, in a word, the cause " reason not in the is a more general and better understood class or genus events. of phenomena to which we can refer the effect, as a particular species. For example : friction is the cause of retarda- Example : Friction and tion of motion. There is a mere sequence of two retardation. phenomena. Yet there is also a necessary con- nexion between them, though not in the sense of efficient power ; for we conceive the notion of fric- tion, and we then reason from it, that retardation will be a necessary consequence. But there are many cases where this kind of connexion is less strong and instructive. Friction is the cause of heat; Friction and heat. but we do not know enough of the nature of friction to be quite certain why or how it produces heat, i 4 120 THEORY OF CAUSATION. [Ess AY I. Iv. though we may conjecture it to a certain extent. Here, then, the connexion is not so necessary. Friction Again, friction (in certain bodies) evolves electricity. and electri- city- Here we know still less of the connexion, and see only a sequence. In other words, physical causation admits of degrees. But this kind of connexion in reason, even its highest degree, is totally remote from any analogy with moral causation, or the sense of power or effort in a voluntary agent. Fallacies Cases are sometimes alleged of particular inci- tobe avoided. dental events which are the immediate means, or " Cause " sometimes instruments, or occasions for other events taking used for 'occasion." place, and are thence called their causes: as the opening of floodgates is said to be the cause of the flow of water. Yet it is urged gravitation or pres- sure might, with equal or greater truth, be called the cause ; that is, we here use the words cause in a more limited sense. When we speak of physical causes in a philosophical sense, we must recur to the idea not of mere sequence of events, but of sequence in reason. The pressure of the fluid is doubtless the physical cause of its overflowing : the particular case of floodgates is only an incidental occasion for its Sequence action. Some writers, again, fall into, or perplex in time. ESSAY I. iv.] THEOKY OF CAUSATION. 121 themselves with, what is nothing more than the old fallacy of f( post hoc ergo propter hoc ; " mistaking a succession in time for a succession in reason and relation ; as in objecting that we thus make day the cause of night, and the like. In fact, the circumstance of time is wholly irre- Order of time irre- levant to the idea of cause and eifect. We may levant, convince ourselves of this by referring to the nu- merous instances where the phenomena are cotem- poraneous. Thus the pressure and the density of elastic fluids Cause and effect often are cotemporaneous conditions: yet the first is the coexistent, cause of the second. Evolution of heat with con- densation, and absorption of it with expansion, are coexistent. Chemical decomposition in the elements of a galvanic battery, and the production of the galvanic current, are simultaneous. In these and Connexion in reason many similar cases, then, of cause and eifect, there admits of degrees. is no sequence at all in time. The question is as to a sequence in reason, and this admits of many degrees. In the last instance of chemical action and gal- vanism, the effects are not only simultaneous, but also convertible. Chemical action is the cause of 122 THEORY OF CAUSATION. [ESSAY I. iv. galvanism; and galvanism is also the cause of chemical action. This, however, is no contradiction or confusion of ideas : it depends simply on the relation in which in some we view the case. What is meant is, that chemical cases cause and effect action, in the instance of the qalvanic battery ', is the relative terms. cause of the galvanic current ; and again, the galvanic current, in the instance of an experiment performed by that battery, is the cause of chemical decomposition. We are speaking of different cases. Thus, in these instances, the use of the terms cause and effect is relative to the circumstances and conditions which we are at the time supposing. Sometimes Or again, it is said "magnetism is the cause of convertible. electricity, and electricity is the cause of magnetism; " but what is meant is, that in certain experiments, magnetism is so applied as to produce electricity ; and in certain others, electricity is so applied as to produce magnetism. They are not cause and effect convertibly in the same sense, or under the same circumstances. We view them as thus convertible in different relations. Mr. Grove * has considered these .cases, and has * See Correlation of Forces, p. 6. ESSAY I. iv.] THEORY OF CAUSATION. 123 been led to the conclusion that, " abstract secondary causation does not exist," or, in other words, cause and effect are purely relative terms, in such cases as those he has considered, which is exactly what has here been shown. This is equally true for the other cases which form the subject of Mr. Grove's valuable discussion. The mutual actions of all the imponderable agents, he shows, are correlative, or convertible into each other, but no one the essential cause of the other. They are so in different points of view, or on dif- ferent grounds of relation, as just explained. But again,, as to the nature of the connexion between in these cases no the facts in either case : In the instance of pressure higher con- nexion in and density of elastic fluid, we perceive a necessary reason. connexion in reason ; by abstract mathematical rea- soning we can infer the one from the other, starting with a definition of an elastic fluid. In the instance of galvanism and chemical action, we know less of the connexion, and perhaps cannot show abstractedly why one must accompany the other. In the same way in the mutual actions of the other imponderable agents, we cannot reason abstractedly to the effects. Where no relation in 124 THEORY OF CAUSATION. [EssAY I. iv. reason is yet made out, we can only recur to the mere law as experimentally established, and traceable to no higher principle. In such a case, either pheno- menon may be cause or effect relatively to the other, as seen under different points of view, in higher But in other cases where we have attained a cases no convert!- higher and more satisfactory view of a connexion in bility. reason, physical causation is more substantially de- termined. When we can ascend to an abstract principle, and reason conclusively from that prin- ciple, that such a result must take place as a con- sequence of it, we assign a positive and fixed physical cause in that principle to which we refer; and we cannot reverse the order of relation. We could not speak of (e. g.^) gravitation and the tides as cause and effect to each other convertibly : or of the connexion of ethereal vibrations and periodical colours as relative or interchangeable* Whenever we can thus mutually convert causes into effects, it only shows the little advance yet made in theoretic generalisation in that particular subject. While, again, in regard to the particular cases of the imponderable agents just considered, it is extremely probable that future discovery will show ESSAY I. TV.] THEORY OF CAUSATION. 125 them to be all merely different modifications of one common principle, and thus easily capable of con- vertibility in their effects. We thus place the theory of causes in its proper Relation of causation relation to that of inductive laws. In assigning to inductive laws. physical causes, we refer a particular phenomenon to a more general, we refer an event to a law ; and the more strictly we analyse our conceptions the more clearly does it appear that we can never arrive at, or need require, any higher or more intimate connexion than that of successively higher genera- lisation; by virtue of which to trace a real and satisfactory relation between physical phenomena and the higher abstract principles which combine them together by a " necessary connexion" of reason, as parts of a great harmonious whole. Yet against this view, it is urged that it is unsatis- Prejudices opposed to factory ; that the mind still craves a more intimate this view, sense of the connexion of events; and that the universal opinion, and common sense of mankind, rejects such cold and dry abstractions, and naturally adopts the more congenial belief in " efficient " causes, and active power in bringing about physical phenomena. This, however, is nothing more than 126 THEORY OF CAUSATION. [ESSAY I. iv. an instance of the general reluctance with which the untaught mind adopts any strict philosophical conclusions : all exact analysis of physical phenomena seems cold and distasteful to the unpractised con- ceptions, and as men soon dislike what they cannot easily understand, this doubtless is often the origin of the vulgar prejudice and hostility against the higher views of science, and the spirit of abstract philosophy. General be- But even were this persuasion as to efficient cau- lief no proof. sation really universal, were it not in fact opposed by as large a section of philosophers as those who uphold it, still, universal belief would be no proof of its truth. All mankind, three centuries ago, had a universal belief in the geocentric system. Such general per- suasion, if anything, would rather suggest a caution that the popular notion may be a popular delusion. In this, as in another sense, we may say, " argumen- tum pessimi turba est." And doubtless nothing is more difficult to the unphilosophical mind than to be satisfied with negation : to learn the humiliating lesson of its own ignorance, idea of effi- Some writers have dwelt upon the idea of causa- cient cause . supposed tion as arising out of some fundamental principle in natural. ESSAY I. iv.] THEORY OF CAUSATION. 127 the constitution of our minds, and have enlarged on the relation of cause and effect as one under which we are constrained to arrange our perceptions, just as the nature of a machine determines the changes of matter subjected to its action. But all this is beside the present question, which relates to what is the relation in question; and the natural proneness, or necessity, if it be so, is nothing more than a disposition to create in imagination a kind of connexion which does not exist, and to overlook the real and simple relation in which the necessity is simply a necessity of logical sequence, applied to a sequence or relation of facts. The notion of efficient causes is doubtless capti- vating to the imagination as seeming to let us more But deiu- intimately into the secrets of Nature. Yet it must be sternly rejected by those philosophers who would adhere strictly to the cautious and positive spirit of the Baconian induction. In fact, there is an inherent inconsistency in such an appeal to efficient causation. For if this myste- and in- volves in- rious idea be that which alone supplies a satisfactory consisten- cies. insight into the mechanism of the natural world, it must follow, that of the real causes of phenomena we know nothing, even in the cases supposed to be most 128 THEORY OF CAUSATION. [ESSAY I. iv. fully and satisfactorily established : e. g. if anywhere surely in the principle of gravitation we must ac- knowledge a cause which furnishes a complete ex- planation of the planetary motions ; yet the nature of gravity as an efficient cause is confessedly wholly unknown. To the advocates of this view, therefore, the theory of gravitation must be wholly unsatisfac- tory, and we cannot be said to have attained any real knowledge of the cause of the celestial motions. Yet it has been urged by those of this school that the notion of a mere sequence is utterly insufficient, that it is little to say such a phenomenon is produced Logical by virtue of such a law, that a law of action is not connexion of sequence action ; and the like: nor does the mere reference sufficient to a bare sequence of events afford any very substan- tial answer to the objection. The view, however, above explained seems to remove such difficulties. The reference of any class of phenomena to a higher genus is really an explanation of its nature : to assign such a governing principle is to show on what the phenomena depends in the connexion of reasoning, which is the only real idea of its necessary relation to a cause. According to the theory of efficient causes, a spe- cies of active power is imagined to reside in natural ESSAY I. iv.] THEOKY OF CAUSATION. 129 agents, or to act through them, which constitutes the Efficient causation alleged necessary connection of physical effects with leads to fanciful their causes. This is always affirmed to be some- physical theories. thing of a nature not at all cognisable by our facul- ties, and dependent on conditions of an occult and mysterious kind. Hence it seems to be supposed that anomalous deviations occasionally arise, and the idea of efficient causes is specially favoured by those who are fond of imagining marvellous influences of a kind, distinct from, and even interrupting, the ordinary course of natural events. Such, we must suppose, are the cata- strophes and convulsions of nature failures in crea- tion random scatterings of matter, and other like notions which are sometimes resorted to as a con- solation to the wearied theorist when matter-of-fact inferences seem for a moment to have reached their limit. Such ideas, however, are not only delusive in opposed to immuta- themselves, but are radically opposed to the grand wnty of physical truth of the uniformity of nature, the unity of order, arrangement and design, and by consequence so far would tend to impugn the evidence of higher truths. Yet we hear the notion of " efficient causation" in K 130 THEOKY OF CAUSATION. [ESSAY I. iv. Confusion nature upheld by some as of a peculiarly religious of second causes and tendency ; while (with strange inconsistency") in First Cause. popular estimation the study of " secondary causes" is accused of being hostile to the belief in a " First Cause." And (from the same confusion of ideas) the denial of efficient causes, and the assertion of a mere sequence of phenomena and laws, is charged with having the same dangerous tendency even in a higher degree. charge Thus, Leibnitz brought against the Newtonian against the Newtonian philosophy the strange accusation, " that it deserts system. mechanical causes, and is built upon miracles, and recurs to occult qualities."* It seems to have been under the belief of this sin- gular charge that Pope originally wrote the well- known lines which appear in the earlier editions of the " Duiiciad," " Philosophy that reached the heavens before, Shrinks to her hidden cause, and is no more ;" which, had the fact been as supposed, would have conveyed as perfectly just a censure in the second line, as it does the characteristic of a true philosophy in the first, as leading to, not starting from, the belief in a Deity. * See Edleston's Correspondence of Newton, p. 153. ESSAY. I. iv.] THEORY OF CAUSATION. 131 Whereas, when undeceived as to the fact, the lines which he substituted in the later editions, " Philosophy that leaned on Heaven before, Shrinks to her second cause, and is no more," embody the whole vulgar misconception and con- fusion of ideas respecting First and Second Causes, while they are, in any sense, as wholly inapplicable to the Newtonian philosophy, as the former. A recurrence to (what is at least) the simple Difficulties removed. and intelligible view above expounded, would remove altogether the whole mass of difficulty, confusion, and objection, in which we are thus entangled, and which is involved in the notion, so commonly alleged, of an eternal succession of secondary causes, ex- cluding the idea of a First Cause, and the like. If we say that every event must have a cause, it means that every species of phenomenon belongs to a class more comprehensive ; that class to a still larger, and so on. The 6{ summum genus" of all (if any in- duction could reach it) would be nothing else than an ultimate physical principle of the whole universe ; but would still be so far from trenching upon the idea of a supreme moral Cause, as to be, on the con- trary, the very highest and crowning proof of the K 2 132 THEORY OF CAUSATION. [ESSAY I. iv. influence of mind, in the evidence it would give of the ultimate principle of universal order. Conclusion. The connection and subordination of inductive laws and generalisations is what we carefully distin- guish as physical causation. But material unity, system, and order, are the indications of mind ; and the connected series of physical causation is the ma- nifestation of moral causation. Thus, the truly inductive philosopher recognises presiding Mind, the supreme moral Cause of all things, everywhere revealed by the same outward manifes- tations of universal order and harmony ; everywhere indicated by the same external attributes, symmetry, uniformity, continuity; and attended by the same ministering agents, invariable laws, and physical causes. * Hume's view of causation was censured by some of his opponents as leaving the connexion of all events so loose as to open the door to the supposition of causes sometimes failing to produce their effects or effects occurring without causes, or of all things being abandoned to chance or destiny. Though, as has been well observed by his biographer, Mr. Burton, such objections are of a vulgar class, and not such as a philosopher would entertain, yet it may be worth noticing how completely the possibility of falling into such absurd misconceptions is avoided by the view taken above. Life of Hume, i. 81. NOTE TO PAGE 116. It should be observed that the opinion quoted of Lord Kames, besides the objection noticed in the text, involves also an instance of the entire confusion of the idea of physical and moral causation here dwelt upon. 133 V._ FINAL CAUSES, AND NATURAL THEOLOGY. Kara riva ycu^eTplK-rj Trpovotav. PAPPUS. THE theory of causation has been much mixed up Final causes. with the argument evincing design in the arrange- ments of nature; and under the name of " Final Causes " that argument has been involved in no small confusion of ideas : and notwithstanding much which has been urged on the other side, still, along with Dugald Stewart and others, I cannot but agree in thinking that the term " Final Cause " is most ., , The term unhappily chosen to express the true meaning, and m chosen. 134 FINAL CAUSES, [ESSAY I. v. has tended to convey an idea no}; only too limited, but altogether confused and misleading. Nor can I doubt that much of the obloquy which has been cast on natural theology generally by writers of a sceptical school, has arisen out of the narrow views thus implied, especially when the argument has been almost wholly restricted to physio- logy, and the very idea of intention represented as the essential characteristic of organisation, and this branch of science imagined to involve principles different from those prevailing in other branches ; all which might therefore naturally be imagined barren of such application, ejection j^ \~ j conceive, solely as being understood in this from too narrow a narrow sense, that " final causes " are so vehemently view of final assailed by Comte and writers of his school ; and it cannot be denied that among the advocates of natural theology there exists too common a dis- position to narrow and restrict the application of the argument by confining the proofs of design to those instances of adaptation of means to a perceptible end of which we doubtless find such abundant in- stances, throughout organised nature, instead of taking a more expanded view. causes. ESSAY I. v.] AND NATURAL THEOLOGY. 135 The instances in which we can trace a use and a Means adapted to purpose in nature, striking as they are, after all con- an end not the highest stitute but a very small and subordinate portion of idea of de- sign. the vast scheme of universal order and harmony of design which pervades and connects the whole. Throughout the immensely greater part of nature we can trace symmetry and arrangement, but not the end for which the adjustment is made. But this is in no way a less powerful proof of design and intel- ligence than the former. The most exact and re- condite adaptation of means to accomplish an obvious end is no more peculiarly an evidence of design, than the universal arrangement according to determinate laws which pervades the depths of cosmical space, where we are least able to trace any end. Sym- metry and beauty are results of mind of at least as symmetry a proof of high an order as mechanical efficiency. A mere design, numerical relation invariably preserved, but no further connected with any imaginable purpose, or a systematic arrangement of useless parts or abortive organs on a regular plan, are just as forcible indica- tions of intelligence, as any results of immediate practical utility. That the one class of results are more immediately K 4 136 FINAL CAUSES, [ESSAY I. v. Proofs of striking and obvious to minds of every capacity with design equally in little study or inquiry is true ; and that the appre- symmetry and in an ciation of the claims of symmetry even in unor- end an- swered, ganised structures, the harmony of profoundly ad- justed laws, and the conspiring tendency of all these laws towards a grand pervading unity throughout the physical world, is not so easily caught, and is per- haps fully appreciable only by the cultivated and philosophic mind, is equally true. But this is a differ ence merely in degree, and as applicable to different classes of minds. In a philosophic analysis of our convictions there can be no real difference in kind between the two classes of conclusions. In a strictly philosophical point of view the in- ference that everything "has a use" may certainly be regarded as a generalisation which carries with it a high degree of probability. We find that many things have a manifest use ; but then we find in most innumerable others for which we can discover no cases no purpose use, and by which no visible end or purpose is traceable. answered, but it is not an unfair extension of the inference that, in these cases, some unknown end is answered; that, in fact, everything in nature is adapted to other things and to the whole ; though in ESSAY I. v.] AND NATUKAL THEOLOGY. 137 by far the greater part of nature we fail to perceive what the particular relation or dependence may be. It may suffice to convince us of this, if we merely ask for what purpose is life itself conferred ? or, to what end does the material universe altogether exist? \ Again : the usual argument for design in organised in some, purpose ap- structures is, that the various adjustments point to parentiy defeated, the designed end of life and enjoyment to which they are subservient ; but it is an obvious objection that these ends in numberless cases are not attained ; there is malformation and suffering, disorganisation and disease ; and, finally, the whole design is always defeated and put an end to by death. It is hence manifest that to take a satisfactory view of the case, we must not rely on the mere consideration of an end answered, but must recur to a higher prin- ciple that of symmetry, order, unity of plan, and composition of organised frames : and this too, as only one branch of the yet wider scheme of universal order. It is, however, fairly to be admitted, that many But in cer- tain cases instances occur where we should least expect it of an end an- swered utility in natural arrangements. Thus it is argued whe . n not 138 FINAL CAUSES, [ESSAY I. v. by some that an apparent waste is not necessarily a real one ; for the sustenance of one single species or individual, a numberless combination of conditions must co-exist ; if one condition were altered, all the rest would fail in their co-operation, and the indi- vidual, or even the whole species, would perish. Thus all, even the most apparently remote, arrange- ments of things which seem to have no relation to animal life are yet essential to it ; and thus the bar- ren desert and the void ocean are not wasted, but essential parts in the economy of the minutest forms of animal life in the most distant hemisphere of our globe. In the same point of view (Ersted has beautifully observed, " There is no inactive void in the remote distances between the planets. The space is filled by ether, and is penetrated by the attractive forces by which the whole universe is held together. The ether itself is an ocean whose waves form light, that great connecting link which conveys messages from globe to globe and from system to system."* Yet the least consideration shows that we must not press such arguments beyond their due limits ; * Soul in Nature, p. 55. ESSAY I. v.] AND NATURAL THEOLOGY. 139 and still less make them the exclusive view of the subject. Though the ancients* reasoned justly and ad- Views of the ancients mirably on final causes in certain familiar instances, on ttnal J causes. and in the limited sense of the adaptation of means to a known end, yet the state of their physical philo- sophy absolutely prohibited wider views of unity and order. Under a system which could not go beyond the assignment of each class of phenomena to some peculiar unknown efficient cause, unconnected with others, no such generalisation as unity of design could have been legitimately attained. The remark of Bacon f that final causes are not in Final causes misplaced themselves to be rejected, but have been wrongly in philo- sophy. placed in philosophy, is one of more value than seems generally understood. It may be very true that sometimes hints towards inductive investigation have been obtained from the consideration of the ends to be answered by certain observed conditions. But it is in general a more safe and philosophical rule, that we may in all cases argue from physical * We cannot have a more striking instance than in the well-known and justly admired passage Xenophon, Memorabilia, i. 4. t De Augmentis, lib. iii. c. 4. 140 FINAL CAUSES, [ESSAY I. & v. Improved views now required. Extension of argu- ment for design to unity of composition in physi- ology. inductions to final causes, but not from final causes to physical inductions. The old and limited view of final causes will not meet the increasing demands of scientific enlighten- ment ; it will not suffice now to argue solely on the adaptation of means to a known purpose, or a prac- tical design evinced, and an obvious end answered. If we cannot discard the term, we must enlarge its meaning. We may speak of " design " with refer- ence solely to " order " and " arrangement," without looking to the idea of practical utility. Such modes of expression are far preferable, as not leading the mind to any undue expectation of what it will not realise. Thus in reference to physiology, the higher argu- ment acquires an expansion in proportion to the progress of the science. We obtain more enlarged ideas of design as we advance from the more con- fined views of the older schools towards the wider principle of symmetry and unity of composition. So that (( final causes " properly understood, so far from receding (as some pretend) before the advance of modern science in the wider and more philosophic sense, eminently derive increasing evidence from its ESSAY I. v.] AND NATURAL THEOLOGY. 141 progress. The study of the higher principle of symmetry and unity of composition can in no way prejudice that of adaptation ; the latter being but a part of the same great argument. Nor is it just to accuse those of the modern school who are engaged, as their special and legitimate object, in investigating the former, of undervaluing the latter. The celebrated case of the cells of bees deserves The ceils of the honey- more particular consideration, inasmuch as it offers an comb. instance in which the proof of mind is independent of the idea of mere utility. It is scarcely necessary to observe that the supposition adopted by some of a mere pressure upon a cylindrical cell producing the hexagonal form is wholly insufficient : the main point to be accounted for is the highly artificial mode of termination of the cell by three rhombs* inclined at the precise angle (70 31') which calculation requires for the minimum surface, which is also the acute angle of the rhomb. The argument points to a highly intellectual operation either performed by the bee, or implied in the arrangement of its organs, so as mechanically to effect it. On either alternative the proof of mind is independent of the consider- * See Vignette at the beginning. 142 FINAL CAUSES, [ESSAY I. v. ation of a useful end answered : it depends on the conception and solution of what is to our intellects an abstract mathematical problem, by no means of an elementary or evident nature ; and which is equally remarkable whether any purpose were ful- filled by its application, or not. Argument Paley expressly held that the mechanism of the from astro- J J uomy. heavens was a branch of science the least susceptible of this kind of application: according to the prin- ciple here advocated, it forms the highest and most satisfactory. stability of j>ut a more special argument has been raised on the plane- tary system, -j-he g roun d that the planetary perturbations have been shown so to compensate each other, that no permanent derangement can arise; and Laplace pointed out that this stability of the planetary system is the necessary consequence of certain conditions, not themselves necessary ; viz. the smallness of the inclinations and eccentricities, the motions all in the same direction, the comparatively vast mass of the sun, and the incommensurability of the periods. Professor Play fair * justly enlarges on this as an * Playfair's Works, iv. 294. 318. ESSAY I. v.] AND NATURAL THEOLOGY. 143 argument for design ; but if the conditions thus as- signed were necessary (i. e. necessary consequences of each other or of something else), he thinks we could not infer design. They, however, are not necessary : each might be otherwise, the rest remaining. Their existence then, he argues, not arising from necessity, nor from mechanical causes, nor from chance, must be from design and intelligence. But I would ask, Suppose they were necessary con- sequences of each other or of some higher principle, or did arise from mechanical causes, would not that higher principle, or those causes, so arranged as to produce them, be an equal proof of design, or even a higher ? So singularly deep-seated is the prejudice, that design can only be inferred when we cease to trace laws, or when conditions appear arbitrary. The idea of "mechanical necessity" (derived pro- Mechanical bably from the school philosophy) as something dis- tinct from the result of systematic plan in the order of the universe, has long continued to haunt the ideas of writers on the subject, and to be the source of many cavils. Thus in past times the Newtonian discoveries were accused by many of having an irreligious tendency in 144 FINAL CAUSES, [Ess AY I. v. reducing everything to " mechanical necessity." And even so enlightened an advocate as Cotes,* instead of showing the fallacy involved in that very term, replies by contrasting " necessity " with ff design," when it might have been pointed out that such neces- sity of reason is the highest proof of design. Other philosophers we find sometimes questioning whether certain results may have been brought about by the direct interposition of "the First Cause," or by some unknown " secondary cause," as if the two were opposed to each other ; or, as if science could have any evidence of the first except through the channel of the second. Uniformity From the inductive philosophy we derive our of natural causes. belief in the harmony, order, and uniformity of natural causes, perpetually maintained in a univer- sally connected chain of dependence. And hence it is, that we arrive at those sublime ideas of a pre- siding Intelligence of which law and uniformity, universal mechanism once for all adjusted, are the proper external manifestations. * " Naturae leges ... in quibus multa sane sapientissimi consilu, nulla necessitatls, apparent vestigia." Pref. to 2d edition of Principia, (p. xxix.). ESSAY I. v.J AND NATURAL THEOLOGY. 145 To the truly inductive philosopher, fate and chance, necessity and accident, are words without meaning. To him, the world is made up of recon- dite combinations of physical laws, and the existence and maintenance of those laws are the very indi- cation of a Supreme Mind. But chance is irrecon- cilable with laws, fate with mind, regulated and fixed order with blind destiny, fortuitous accident, or arbitrary interruption. All rational natural theology advances by tracing Natural theology the immediate mechanical steps and particular pro- strength- ened by the cesses in detail, and the physical causes in which chain of causes. the influences of the Great Moral Cause or Supreme Mind are manifested. The greater the number and extent of such secondary steps and intermediate pro- cesses through which we can trace it, the greater the complexity and wider the ramifications of the chain of causes, the more powerful and convincing the instruction they convey as to the existence and operation of the Divine wisdom and power. Yet it is a common mode of illustration to speak of Mistaken ideas. the chain of secondary causes reaching up to the First Cause. Or, again, fears are entertained of tracing secondary causes too far, so as to entrench on the L 146 FINAL CAUSES, [ESSAY I. v. supremacy of the First Cause. But this is an erro- neous analogy : the maker or designer of a chain is no more at one end of it than at the other. The length of the chain in no way alters our conviction of its skilful structure, except to enhance it. If the number of links were truly infinite, so much the more infinite the skill of its framer. Mr. F. Newman* observes, I think most truly, that the common arguments from what are called " secondary causes " to the " First Cause " are unsatis- factory : and I would trace this to the confused sense in which those terms are commonly used, as already explained ; and which, I think, might be entirely re- moved by attention to the distinctions above laid down. While, on the other hand, I fully acknow- ledge that those arguments, when correctly under- stood, lead only to a very limited conclusion ; and one which falls infinitely short of those high moral and spiritual intuitions on which Mr. F. Newman grounds his religious system, yet in no way dis- credits them. Again, by some well-meaning but confused rea- * Soul, p. 35. ESSAY I. v.] AND NATURAL THEOLOGY. 147 soners, the argument is often put in reverse order ; Confusion in the order and so stated as to appear as if the assumption of a of argu- ment. Supreme Mind or an " efficient and intelligent Cause " were really the basis of our belief in the uniformity of nature, instead of the conclusion from it. Yet if this were so, what would it be but to render the whole proof of a Deity, an argument in a circle? So, in like manner, some would set out by insisting on the idea of tf a purpose answered" and "an intention" as an essential antecedent part of our conception of an organised being : and then,, from the study of or- ganised beings, would deduce the conclusion of design and intention 1 Thus Coleridge observes, " Assume the existence of God, and then the harmony and fitness of the phy- sical creation may be shown to correspond with, and support, such an assumption: but to set about proving the existence of a God by such means, is a mere circle, a delusion ! " ; Now I would observe that for the theological idea of God, the natural argument is no doubt insufficient, but still it is no argument in a circle; it is strictly logical as * Table Talk, p. 307. L 2 148 FINAL CAUSES, [ ESSAY I. v. far as it goes, though that is but to a very limited extent. Again, the same author asks, " How did the Atheist get his idea of that God whom he denies ? " * The answer is unhappily obvious, that he usually takes it up from the narrow and unworthy representations of dogmatic systems or puerile recollections, instead of the ideas suggested by a sound philosophy. Mistakes Among some writers of an eminently religious arising from ideas of spirit at the present day, we cannot but notice the causation. unhappy influence of that confusion of ideas on the subject of causation, as well the want of due appre- ciation of the grounds and nature of physical philo- sophy in reference to the inferences of natural theology, which it has been the object of the fore- going remarks to obviate. Thus Sterling f observes, " Physical results prove nothing but a physical cause." Again, " It is thoughtless to say that, because all things we know have each their cause, therefore the whole must have one cause." "Every phenomenon within nature has a cause ; but this does not entitle * Table Talk, p. 307. f Essays, ii. 121, 122. ESSAY I. v.] AND NATURAL THEOLOGY. 149 us to go beyond and look at nature from without, and say this, too, must have a cause." The real ground he maintains is very different, and is suggested by the question, " Why is the view of the universe so weary, fearful and unsatisfactory ? The sense that we need a God is an infallible indica- tion that there is one" &c. After what has been before observed, it is hardly necessary to point out, in detail, how completely all this perplexity would have been removed by better views of physical philosophy, the want of which, so serious in discussing a subject essentially founded on physical truth, the author's literary attainments, poetic imagination, and high devotional feeling, were incompetent to supply. The very idea of " looking at nature from with- out," evinces this perplexity; and the unhappy view of the universe as " weary, fearful, and unsatisfac- tory," would be banished at once by the juster contemplations of an enlarged inductive philosophy, investing the whole with the cheering light of uni- versal beauty, order, and harmony. If, indeed, the author meant simply to transfer the belief in a Deity altogether from the domain of L 3 150 FINAL CAUSES, [ESSAY I. v. Erroneous notions of of nature. reason., to place it in that of feeling; to ground it on the sole consciousness of internal emotion, or the intuitive impressions of individual experience, this would be a view to which the philosophical argument offers no disparagement., though it does not reach up to it. Some, however, would assert, that after all physical the limits explanations, there remains the same ultimate incom- prehensibility in natural causes ; and that even in nature we find ourselves surrounded by wonders and miracles: ideas which only evince a total absence of distinct philosophical thought, and confound the limits of nature with the limits of our PRESENT knowledge of it unexplained phenomena with viola- tions of physical order. They are fond of speaking of the limits of nature, of a region of inscrutable mystery by which the frontiers of science are on all sides surrounded, im- penetrable to our faculties, and forbidding advance. If by mystery they mean something into which we neither can, nor ought, to inquire, then in accord- ance with what was before observed,* in science there No hin- drance to advance. See above, p. 106. ESSAY I. v.] AND NATURAL THEOLOGY. 151 are no mysteries, no inductive inquiry can ever brin