NDUCTIVE LOGIG I Ballantine LIBRARY OF CONGRESS. Cliap.Ac..'_, Copyright No.,. Shelf_.B-2j UNITED STATES OF AMERICA. ^ Inductive Logic / WM. G. BALLANTINE President of Oberlin College S^'^^flfex >»1 !f5^«; ^/ASUU'"^ ^^ Boston, U.S.A., and London GINN & COMPANY, PUBLISHERS 18.96 THE LlBRAItY OF CONGRfiftft WA9HINGTOII Copyright, 1896 By WM. G. BALLANTINE ALL RIGHTS RESERVED PREFACE, ^^g-^ This book originated in the class-room, where the author was teaching Dr. Fowler's Elements of Induc- tive Logic. Its ambition is to reproduce some of the excellences of that bright and interesting book, while substituting a sounder analysis of fundamental princi- ples. The numerous extracts, introduced in the man- ner of Dr. Fowler, are designed both to elucidate the subject and to acquaint the student with the views and literary styles of a large variety of philosophical and scientific writers. Wherever anything has been found already well expressed, quotation has been preferred to restatement. The familiar manuals of inductive logic have been freely drawn upon, and their rich store of illustrations has been used without hesitation. Credit has generally been given ; but sometimes it was impos- sible to make specific acknowledgment. Mr. Mill is the greatest of all modern writers upon inductive logic, and upon his famous work all later authors have largely built. The school manuals are, for the most part, but outlines of his doctrine. But Mr. Mill's mind was a very peculiar one. It was impos- sible for one so acute not to see the truth, or for one so iv Preface. candid not to state it. But these statements of truth are rather his obiter dicta, while his main contention is often some paradox. A "higher critic" might easily divide the Logic into two documents, by authors of opposing tendencies. An outline of Mill's system, like Dr. Fowler's, does him injustice ; for it is just in what he thinks most important, that he is weakest. Freely acknowledging that most of what is true in this book has been learned from Mr. Mill, the author yet puts it forth with the hope that it will be found to contain a real, though small, contribution to the progress of science. Oberlin, Ohio, December i, 1895. CONTENTS. -^2-^ CHAPTER I. Introductory Inductive Logic defined, i. The pure sciences, i. The applied sciences, 2, Inductive and Deductive Logic not mutually exclusive, 2. Relations of Inductive and Deductive Logic, 3. The discovery of facts defined, 4. Quotation from Whately, 4. CHAPTER II. Facts 6 A fact defined, 6. Substantive facts and facts of relation, 6. Facts of Resemblance, 7. Facts of Coexistence, 7. Facts of Causation, 7. Facts of Succession, 8. Ultimate facts, 8. CHAPTER III. Observation 9 Observation defined, 9. Bagon quoted, 9. Observation the essential characteristic of Induction, 9. Observation and Experiment contrasted, 10. Fowler quoted, 10. Difficulty of making trustworthy observations, 11. Dr. Darwin's supposed gin, 11. Confusion of perceptions and in- ferences, 12, CHAPTER IV. Primary Inductions 14 An Induction defined, 14. Various kinds of inductions, 14. Uniform- ities in the existing order, 15. How we discover a uniformity, 15. The mill and stream, 16. Cliffs and crows of England, 17, Does induction rest upon the veracity of God ? 17. Inductio per Enwnerationetn Sim- plicem, 17. Correcting one generalization by another, 19. Uniformity of Nature defined, 19. Degrees of assurance in primary inductions, 20. vi Contents. PAGE Bain's definition of induction, 21. Bain's view discussed, 23. Great inductions of modern science, 24. Empirical and ultimate laws, 25. The maxim that " the exception proves the rule," 25. CHAPTER V. Secondary Inductions 28 A secondary induction defined, 28, Primary and secondary inductions mingled in every-day thinking, 29. Whately provided only for secondary inductions, 30. Uniformity of all nature not a necessary premise, 31. Failure of philosophers to recognize three classes of inductions, 31. Minto's criticism of Mill, 33. Inferring from particulars to particu- lars, 34. CHAPTER VI. Mixed Inductions 36 A mixed induction defined, 36. Masts of ships seen first, 36. Newton's discoveries, 36. The phases of Venus, 37. Mill's questions, 38, In- duction from a single instance, 39. Correctly defining the field, 40. CHAPTER VII. P^ACTS OF Resemblance 41 Resemblances in objects, 41. The possibility of language, 42. Argu- ments from facts of resemblance, 42. Anima and dme^ 43. Genesis of the horse, 44. CHAPTER VIII. Facts of Coexistence 47 Illustration from gold, 47. Coexistence as important as Causation, 47. Natural kinds and artificial kinds, 48. Infima species and stmimum ge7ius, 49. The true nature of species discussed by Asa Gray, 49. Agassiz's view, 50. Darwin's view, 5 1 . Linnaeus's definition, 51. Classi- fication, 52. Nomenclature, 53. Terminology, 53. CHAPTER IX. Facts of Causation and Facts of Succession . . .55 Causation defined, 55. Count Rumford's experiment, 56. Rumford's experiment discussed, 59. Energetic cause, 60. Conditional cause, 61. Material cause^ 61. Volitional cause, 62. Lotze on the authority of Contents. vii PAGE causal law, 63. Things may cause events, 64. Events may cause events, 65. Historical cause, 66. Events and states, 67. Occasional causes, 68. Incident in the life of Dr. Darwin, 69. Formal cause and final cause, 70. Negative cause, 70. Summing up of discussion of causation, 71. Do like causes produce like effects ? 72. Facts of succession not ultimate, 72. CHAPTER X. Mr. Mill's Doctrine of Causation 75 Mill's eminence, 75. Notion of cause the root of the whole theory of induction, 75. Uniformity of nature not the immediate major premise, 76. Deiinition of cause, ']']. All conditions equal, 78. Cause the sum total of conditions, 80. Cause and effect not necessarily successive, 83. Succession not between single antecedents and consequents, 85. Cause the total of immediately preceding conditions, 85. Unconditionalness, 85. Night not the cause of day, 86. The will under the law of causation, %"]. CHAPTER XL Canons for Isolating Facts of Causation . . . .91 Comprehensive cause defined, 91. Mechanical isolation, 92. Isolation in thought, 93. Canon for Test of Difference, 93. Empirical cause, 93. Four cases under the canon, 94. Expression of cases in symbols, 97. Use of the facts isolated, in making inductions, 98. Canon for Test of Agreement, 99. Schiller on moral decline and aesthetic culture, 100. Ex- pression of cases in symbols, loi. The Plurality of Causes, 102. CHAPTER Xn. Mr. Mill's Four Experimental Methods .... 103 The methods are fundamentally two, 103. The five canons, 104. The method of residues the same as the method of difference, 106. All the methods deductive, 106. Correction of instances, 107. The term " experi- mental," 107. Vagueness of terms and results, 107. Failure to hold fast the idea of sequence, 108. Investigation of crystallization, 108. Is the noun or the verb the cause ? 109. The joint method of agreement and difference an illusion, 109, Investigation of the cause of dew, no. Method of concomitant variations not distinct, iii. Mill exaggerates the im- portance of the methods, 112. Difference between ancient and modern thought, 113. viii Contents. CHAPTER XIII. PAGE Hypothesis 115 Hypothesis defined, 115. Theory, 115. No explanation of uniform- ities, 116. The " laws of. nature," 116. Incident in the life of Darwin, 117. Rules for legitimacy of hypotheses, 118. Vera causa, 118. Mill's defini- tion, 119. Discovery of planet Neptune, 120, Darwin's theory of coral islands, 121. Helmholtz on forming hypotheses, 124. Whewell on the Greek physical philosophy, 125. Davis on function of hypothesis, 126. Value of false hypotheses, 127. CHAPTER XIV. Inductive Arguments 129 Analogy, 129. Bishop Butler on probability, 129. Analogy a variety of primary induction, 130. Asa Gray on trees, 130. Robinson Crusoe, 133. The Cincinnati glacial dam, 133. Analysis of Wright's argument, 135. Verification, 136. Trials at law, 138. Testimony to observation, 139. Hume on the grounds for accepting testimony, 139. Relevancy, 142. CHAPTER XV. Fallacies 146 Bacon's " idols," 146. Non-observation or Prejudice, 150. Aristotle on the skull, 151. Bacon on wooden arrows, 152. Authority, 152. Modern teaching not dogmatic, 153. Scheiner and the. sun spots, 154. Partial Observation, or Neglect of Negative Instances, 154. Example from Brachet, 154. The Greek aorist, 156. The definition of a verb, 157. Signs of the weather, 157. Malobservation, 158. Mistake in Area, 159. "Adjacent cases," 159. The Indian prince, 159. Hume's mistake, 160. The law of motion, 160. Mistake in Isolation, 160, Experiment of Van Helmont, 161. Post hoc, ergo propter hoc, 162. Mutuality of Cause and Effect, 163. CHAPTER XVI. The Work of Bacon 165 Lord Macaulay on Bacon, 165. Reid's opinion, 165. Bacon's claim, 166. Minto's estimate, 167. Mill's criticism, 168. INDUCTIVE LOGIC CHAPTER I. INTRODUCTORY. Inductive Logic is the Science of the Discovery of Facts not directly observable. A few facts are known to us without discovery. Such are our personal iden- tity, moral freedom, and obligation. Certain truths also are recognized by the mind as certain as soon as they are suggested. Evidence is not required to establish them, nor can it in any w£.y confirm them. Of these are the axioms of Mathematics and the canons of Deductive Logic. This furniture is the same for all minds and the possession of it is what makes thinking possible. Only all minds do not with equal clearness analyze their own operations, and the most lack the patience, concentration, and strength to follow admitted principles to their ultimate con- sequences. Whole sciences have been built up by simply developing the necessary implications of the few simple but universal truths intuitively perceived by every mind. Deductive Logic and Mathematics are examples. One peculiarity of them is that they are the same for all minds, and that when the terms used 2 Inductive Logic. are precisely understood there is no difference of opinion possible among sane men. These are pure sciences; they do not depend upon the actual exist- ence of any person or thing, but we know that whatever does exist, necessarily conforms to them. If numbers or quantities of objects exist anywhere, they are in mathematical relations; if correct thinking upon any subject is done by rational beings anywhere, it i& done according to the rules of deductive logic. But the great bulk of our knowledge does not come to us by intuition. Beyond the few facts and truths with which the mind starts, lies the whole universe of reality, which we can know only through observation. Over against the pure sciences stand the applied sci- ences. The main value of the pure sciences is in the fact that they furnish the principles for constructing the applied sciences. The latter have no new formal principles of their own. This last point is of supreme importance for the purpose now in hand. It has been extensively sup- posed that the field of thinking was divided into two kingdoms, ruled by two sovereigns. Deductive and Inductive Logic, under dissimilar constitutions, and that what was bad law in one kingdom might be good law in the other. It has been assumed that sometimes two thoughts which could show no right to union in the domain of Deduction could cross the border and, by a sort of Gretna Green marriage, make a synthesis in the kingdom of Induction. A little reflection should have shown all this to be a huge mistake. The canons of deductive logic are the universal laws of thought. They are invariably true, if ever true. The only Introductory. 3 ground upon which we assent to any principle in deductive logic is our instant perception of its neces- sary and universal validity. If so, we cannot step into another province and escape its force. The limits of its domain are the same as those of correct thinking. Deductive and Inductive Logic are not two sister sciences which divide the empire of thinking between them. They are not mutually exclusive ; one does not stop where the other begins. One is not the inverse of the other. One does not proceed from generals to particulars, while the other moves from particulars to generals. It is not true that one infers from the known to the known, while the other infers from the known to the unknown. It is not true that one is rigorously required to draw conclusions no wider than its premises, while the other is warranted in concluding the universal from a part. Many such assertions have been made by philosophers, but it is obvious without discussion that, if there is any truth in deductive logic, all these assertions are false ; for deductive logic sways a universal scepter or none. There can be no legiti- mate thinking except according to its laws. Inductive Logic is simply deductive logic regulating our reason- ing upon our observations of the phenomena of the universe. It is deductive logic applied in the realm of reality. Whenever in our thinking a proposition is introduced the truth of which depends not upon its harmony with a previous admission, but directly upon observation, there our reasoning becomes Inductive. There is no new way of inferring peculiar to Induction. Deductive logic deals with the mutual harmony of propositions. Inductive logic deals with the harmony 4 Inductive Logic. between propositions and facts. No reasoning of any kind, deductive or inductive, can ever carry knowledge a step forward into the unknown, or do anything more than unfold what is contained in the premises. We can learn the unknown only by observation ; we can reason upon our observations in no other way than deductively ; for that is the only way men can reason at all. The rational action of the mind upon the data of observation is called Induction. In defining Inductive Logic as the science of the Discovery of Facts we use the word discovery in the strictest sense, as meaning the ascertainment of the absolutely unknown. To quote from Archbishop Whately : — - " There certainly are two kinds of ' New Truth ' and of ' Discovery,' if we take those words in the widest sense in which they are ever used. First, such truths as were, before they were discovered, absolutely unknown, being not implied in anything we previously knew, though we might perhaps suspect them as probable ; such are all matters of fact strictly so-called, when first made known to one who had not any such previous knowl- edge as would enable him to ascertain them a priori^ /. spirituous liquor. Whereupon the gentleman said, ' Come, come, Doctor, this won't do — though it is very kind of you to say so for my sake — for I know that you take a very large glass of hot gin and water every evening after your dinner.' So my father asked him how he knew this. The man answered, ' My cook was your kitchen-maid for two or three years, and she saw the butler every day prepare and take to you the gin and water.' The explanation was that my father had the odd habit of drinking hot water in a very tall and large glass after his dinner ; and the butler used first to put some cold water in the glass, which the girl mistook for gin, and then filled it up with boiling water from the kitchen boiler." i To quote from Dr. Fowler : — " That which is strictly matter of perception does not admit of being called in question ; it is the ultimate basis of all our reason- ing, and, if we are to repose any confidence whatever in the exercise of our faculties, must be taken for granted. But there are few of our perceptions, even of those which to the unphilosophical observer appear to be the simplest, which are not inextricably blended with inference. Thus, as is well known to every student of psychology, in what are familiarly called the perceptions of distance and of form, the only perception proper is that of the various tints of color acting on the retina of the eye, and it is by a combination of this with perceptions of touch, and the muscular sense, that the mind gains its power of determining form and distance. Now, a judgment of this kind, which is really due to inference, is, especially by the uneducated and unreflecting, per- petually mistaken for that which is due to direct observation ; and thus what is really only an inference from facts is often emphatically asserted to be itself a matter of fact." ^ To quote from Mr. Mill : — " One of the most celebrated examples of a universal error produced by mistaking an inference for the direct evidence of the senses, was the resistance made, on the ground of common sense, ^ Life and Letters, p. 15. ^ Inductive Logic, p. 273. Observation. • 13 to the Copernican system. People fancied that they saw the sun rise and set, the stars revolve in circles round the pole. We know that they saw no such thing ; what they really saw was a set of appearances, equally reconcilable with the theory they held and with a totally different one. It seems strange that such an instance as this of the testimony of the senses pleaded with the most entire conviction in favor of something which was a mere inference of the judgment, and, as it turned out, a false inference, should not have opened the eyes of the bigots of common sense, and inspired them with a more modest distrust of the competency of mere ignorance to judge the conclusions of cultivated thought. "In proportion to any person's deficiency of knowledge and mental cultivation is, generally, his inability to discriminate between his inferences and the perceptions on which they were grounded. Many a marvelous tale, many a scandalous anecdote, owes its origin to this incapacity. The narrator relates, not what he saw or heard, but the impression which he derived from what he saw or heard, and of which perhaps the greater part consisted of inference, though the whole is related not as inference but as matter of fact. The difficulty of inducing witnesses to restrain within any moderate limits the intermixture of their inferences with the narrative of their perceptions, is well known to experienced cross-examiners ; and still more is this the case when ignorant persons attempt to describe any natural phenomenon. " The simplest narrative,' says Dugald Stewart, 'of the most illiterate observer involves more or less of hypothesis ; nay, in general, it will be found that, in proportion to his ignorance, the greater is the number of conjectural principles involved in his statements. A village apothecary (and, if possible, in a still greater degree, an experienced nurse) is seldom able to describe the plainest case, without employing a phraseology of which every word is a theory: whereas a simple and genuine specification of the phenomena which mark a particular disease, a specification unsophisticated by fancy, or by preconceived opinions, may be regarded as unequivocal evidence of a mind trained by long and successful study to the most difficult of all arts, that of the faithful interpreta- tion of nature.' " ^ 1 Logic, p. 545. CHAPTER IV. PRIMARY INDUCTIONS. An Induction is a generalization, or an inference, based upon propositions that state observed facts. The truth inferred may be general or particular, but it must be one which we cannot perceive in a single act of observation. When we know the existence of anything by simply attending to it, we do not say that we know it inductively ': we know it directly. The word Induc- tion is applied both to the proposition enunciated and to the process of mind by which that proposition is reached. That "all men are mortal," I know by induc- tion, and the truth is itself an induction. Inductions are based either wholly upon observations, in which case we call them Pure Inductions ; or they are based partly upon observation and partly upon intuitively known truth, in which case we call them Mixed Inductions. Pure inductions are either Com- plete or Incomplete, according as we have or have not observed all the facts included in the statement. They are either Primary or Secondary, according as they are made directly by generalizing a number of observa- tions, or indirectly by combining syllogistically a single new observation with a previous induction. These distinctions will become clear as we advance. The present chapter deals with Primary Inductions. It soon becomes plain to every child, when he begins to observe the world, that there is an existing order of Primary hiductions. 15 things. It is perfectly easy to conceive of a world in which every object should be unique and every event a surprising novelty. Such a world would contradict no necessity of thought, although it would be hopelessly bewildering. But such is not our world. The child's earliest impression is of a certain permanence and uni- formity in its environment. The same objects and experiences remain or recur. This conviction of an existing order finds expression in language. The present tense in grammar does not denote a mere moment separating the past and the future ; it denotes a considerable and indefinite expanse of time. Such a proverb as " The burnt child shuns the fire " is stated in the present tense, as formulating a fact of the existing order. That experience falls largely into lines of uniformity is early perceived. The child learns that there are things called apples which are round and red and good to eat, and that there are things called cats which have soft fur and long tails and sharp claws, and that these things are liable to scratch. The profoundest question in the whole science of inductive logic is : How are these generalizations reached t How can we ever dis- cover that we are upon the line of a uniformity } But this is really only a sort of metaphysical puzzle, like the question of the possibility of motion. The exist- ence of lines of uniformity is every moment forced upon our observation, and the fact that they do extend is equally conspicuous. A Primary Induction is the statement of an observed uniformity. Do we reach it by any process of infer- ence } Philosophers have thought so. There is thought 1 6 Inductive Lozic. i3 to be here a new and peculiar kind of inference of which deductive logic knows nothing. Professor Davis says : " Induction is an immediate synthetic inference generalizing from and beyond experience." ^ But this does not appear to be a correct analysis. When there is an inference we necessarily look about for proposi- tions which can be syllogistically combined. Professor Davis claims that we intuitively know the Uniformity of Nature, and he unconsciously makes this his major premise. But the uniformity of nature can be known and defined only inductively, not intuitively. It is a discovery of induction, not the basis of it. No : if there is a permanent or recurring fact in nature, we ascertain it simply by generalization, not by inference. How do we know that the mill is standing by the river t We cannot be looking at it all of the time. Having seen it a hundred or a thousand times we have come to believe in its permanence. How do we know that the water is flowing over the mill-dam } We have seen it often and have come to' think it continuous. Here is a permanent fact — the mill, and a uniformity — the flow of the water ; how do we come to feel assured of them } Not by any process of inference, but simply by generalization. We have not reasoned about the future or the unknown, but about the present and the known. Whether the world will come to an end to-night, and the river and the mill be annihilated, we cannot predict from our observations upon them ; all that we know is that this permanence — the mill, and this uniformity — the flow of the stream, are facts of 1 Inductive Logic, p. 6. Primary Inductions. ij the existing order ; and since it would be irrational to act, without evidence, upon the supposition of the cessation of the existing order, we keep on carrying grist to the mill. A primary induction does not rest upon a process of inference any more than does our belief in any per- manent fact. That the cliffs of England are white is a permanent fact ; that the crows of England are black is a uniformity. We cannot be looking at the cliffs all the time, and we cannot examine all the crows ; but having looked at the cliffs frequently, and having seen a large number of crows, we rest in the assurance that we know the existing order. Should we wake up some morning and find the cliffs blackened, we should simply recognize that the order had changed. Should we find in visiting a remote part of the kingdom a flock of white crows, we should simply observe that we had passed beyond the former area of observation. If our expectation of finding the cliffs white and the crows black at the next observation rested upon any logical necessity, our not finding them so would require a doubt of our own sanity. The suggestion has been made that we base our belief in the truth of a primary induction upon our faith in the veracity of God. But surely such an induc- tion as that " the Cretans are always liars " cannot be based upon the veracity of God ; it rests merely upon observation of the uniform mendacity of those depraved people. The sort of induction we are now describing has been known, since Bacon's time, as Inductio per Enume- rationem Simplicem, Induction by Simple Count. "It 1 8 Inductive Logic. consists in ascribing the character of general truths to all propositions which are true in every instance that we happen to know of." Mr. Mill's attitude toward such inductions in the first edition of his Logic was curious. Although holding that the uniformity of Nature, the law of Causation, and the axioms of Mathe- matics are established only in this way, he yet inclined to deny to the process even the name of induction. He said : " This is the kind of induction, if it deserves the name, which is natural to the mind when unaccustomed to scientific methods." Later Mr. Mill omitted the clause "if it deserves the name"; but his disparaging tone continued and infected logical writers. Thus, Dr. Fowler says : — " But not only is the htductio per Enuinerationem Sijnplicem the mode of generalization natural to immature and uninstructed minds ; it is the method which, till the time of Bacon, or at least till the era of those great discoveries which shortly preceded the time of Bacon, was almost universal." " When men first begin to argue from their experience of the past to their expectation of the future, or from the observation of what immediately surrounds them to the properties of distant objects, they seem naturally to fall into this unscientific and unreflective mode of reasoning." ^ Bacon himself seems responsible for this sneer ; he says : — " Inductio quae procedit per enumerationem simplicem, res pueriHs est, et precario concludit, et periculo exponitur ab instantia contradictoria, et plerumque secundum pauciora quam par est, et his tantum modo quae praesto sunt pronunciat." ^ Still there remains an inconsistency in Mr. Mill's doctrine ; for he says most justly : — 1 hiductive Logic, pp. 280, 281. 2 JSfovum Orgamim, lib. i, aph. cv. Primary IndiLctions. 19 " Experience must be consulted in order to learn from it under what circumstances arguments from it will be valid. We have no ulterior test to which we subject experience in general ; but we make experience its own test. Experience testifies, that among the uniformities which it exhibits or seems to exhibit, some are more to be relied on than others ; and uniformity, therefore, may- be presumed from any given number of instances, with a greater degree of assurance, in proportion as the case belongs to a class in which the uniformities have hitherto been found more uniform. This mode of correcting one generalization by another, a narrower generalization by a wider, which common sense suggests and adopts in practice, is the real type of scientific induction." ^ The truth could not be better set forth than in the foregoing accurate and discriminating statement ; after all, the "real type of scientific induction" is merely an indiictio per enumerationeni simplicem, carefully made. Experience gives us not only uniformities, but uni- formities among uniformities. Not only does this ox uniformly chew the cud, but all oxen uniformly chew the cud, and all other sorts of animals with similar structure uniformly chew the cud. Not only does this piece of lead maintain a uniform specific gravity of 1 1.4, but there is a uniformity in specific gravity among all pieces of lead, and, moreover, every different sub- stance maintains a uniform specific gravity. What we call the "Principle of the Uniformity of Nature" is merely the wide primary induction that the various limited uniformities of nature persist. There is no other sense in which nature is uniform. It is not meant, of course, that every object is like every other object, and every event like every other event. 1 Logic, p. 232. 20 Inductive Logic. " Every person's consciousness assures him that he does not always expect uniformity in the course of events ; he does not always beUeve that the unknown will be similar to the known, that the future will resemble the past. Nobody believes that the succession of rain and fine weather will be the same in every future year as in the present. Nobody expects to have the same dreams repeated every night. On the contrary everybody mentions it as something extraordinary, if the course of nature is constant, and resembles itself in these particulars. To look for constancy where constancy is not to be expected, as for instance that a day which has once brought good fortune will always be a fortunate day, is justly accounted superstition." ^ The assurance with which a primary induction is held, depends upon the number of instances from which it is generalized. If the number is small, the assurance is imperfect : if the number of instances is practically infinite, the assurance is practically complete. Belief shades thus from faint presumption, by imperceptible increments, into positiveness. When at last we have examined all the instances, the induction is complete and we know. To quote Mr. Mill: — " Induction by simple enumeration — ■ in other words, generali- zation of an observed fact from the mere absence of any known instance to the contrary — affords in general a precarious and unsafe ground of assurance ; for such generalizations are inces- santly discovered, on further experience, to be false. Still, how- ever, it affords some assurance, sufficient, in many cases, for the ordinary guidance of conduct. It would be absurd to say, that the generahzations arrived at by mankind in the outset of their experience, such as these — food nourishes, fire burns, water drowns, — were unworthy of reliance. There is a scale of trust- worthiness in the results of the original unscientific induction; and on this diversity (as observed in the fourth chapter of the present 1 Mill's Logic, p. 226. Primary Inductions. 21 book) depend the rules for the improvement of the process. The improvement consists in correcting one of these inartificial gener- alizations by means of another. As has been already pointed out, this is all that art can do. To test a generalization, by showing that it follows from or conflicts with some stronger induction, some generalization resting on a broader foundation of experience, is the beginning and end of the logic of induction." ^ Quite a different view from the foregoing has, how- ever, been often taken. The name induction has been denied to the generalization of experience, and has been reserved exclusively for statements in regard to the unobserved. Professor Bain speaks as follows : — " Induction is the arriving at General Propositions, by m.eans of Observation or Fact. " In an induction there are three essentials: (i) the result must be a proposition — an affirmation of concurrence or non-concur- rence — as opposed to a Notion; (2) the Proposition must be general^ or applicable to all cases of a given kind; (3) the method must be an appeal to observation of fact. " The Propositions established by induction are general. A single individual concurrence, as ^ the wind is shaking the tree,' is in its statement a proposition, but not an induction. On such individual statements we base inductions, but one is not enough. If the coincidence recurs, we mark the recurrence; we are affected by the shock or flash of identity, a very important step in our knowledge. If, pursuing the suggestion, we remark that as often as the wind is high, the trees are shaken; that the two things have concurred within the whole course of our observation; that the same concurrence has been uniform in the observation of all other persons whose experience we have been informed of, — we are then entitled to make a still wider sweep, and to say, ' every time that a high wind has been observed, a waving of the trees has also been observed.' " Still, with all this multitude and uniformity of observations, 1 Logic, p. 401. 22 Inductive Logic. there is no proper Induction. What then remains ? The answer is, the extension of the concurrence from the observed to the unobserved cases — to \\\% future which has not yet come within observation, to the past before observation began, to the remote where there has been no access to observe. This is the leap, the hazard of Induction, which is necessary to complete the process. Without this leap our facts are barren; they teach us what has been, after the event ; whereas we want knowledge that shall instruct us before the event, that shall impart v/hat we have no means of observing. A complete induction, then, is a generaliza- tion that shall express what is conjoined everywhere, and at all times, superseding forever the labor of fresh observation. " We thus contrast Induction with that species of ' Induction improperly so-called,' where a general statement merely sums up the observed particulars. ^' If, after observing that each one of the planets shines by the sun's light, we affirm that ' all the planets shine by the sun's light,' we make a general proposition to appearance, but it falls short of an induction in the full sense of the term. The general statement is merely another way of expressing the particulars; it does not advance beyond them. But without such advance there is no real inference, no march of information, no addition to our knowledge. Induction is the instrument of multiplying and extending knowl- edge; it teaches us how, from a few facts observed, to affirm a great many that have not been observed. If, from the observa- tion of the planets now discovered, we make an assertion respect- ing all that have yet to be discovered, we make the leap implied in real or inductive inference. If the assertion had been made when only six planets were known, actual observation would have been the guarantee for those six, induction for the remaining hun- dred or upwards. " The sole method of attaining Inductive truths being the observation and comparison of particulars, the sole evidence for such truths is Universal Agreement. " A permanent or uniform concurrence can be established, in the last resort, only by the observation of its uniformity. That unsupported bodies fall to the ground, is a conjunction suggested by the observation of mankind, and proved by the unanimity of all Primmy Inductions. 23 observers in all times and places. What is found true, wherever we have been able to carry our observations, is to be accepted as universally true, until exceptions are discovered. " Through this method alone — of Universal Agreement in detail — can our most general and fundamental truths be dis- covered and proved. It is the only proper inductive jnethodP ^ This account of induction cannot be consistently ac- cepted. The Professor suggests no criterion by which one may know when he is justified in taking the hazard of a leap in the dark and making an induction. He does not say how many instances must be observed before the leap is warranted. If only that part of a generalization which refers to the unobserved is "induction proper," and if "the only proper inductive method is the observation of particulars," and if "the sole evidence for such truths is universal agree- ment," — it is impossible to see how we can have any induction at all. If " a permanent or uniform concur- rence can be established in the last resort, only by the observation of its uniformity," then it cannot be estab- lished by what Professor Bain calls induction ; for "proper induction" deals only with the unobserved. The puzzle here is simply what grows out of the mind's necessary assumption of the continuity of the existing order. Of course no one can prove the per- manence of a thing by observing it every moment. How do I know that the sun does not go out of existence whenever I cease to look at it } The answer is, that having no reason in experience to think that the existing order depends upon my attention, I must assume that it does not. The truth is that if, after observing 1 Logic : Deductive and Inductive, pp. 231, 232, 237. 24 Inductive Logic. that each of the planets shines by the sun's light, we affirm that "all the planets shine by the sun's light," we take the " hazard " of the continuance of the existing order, for we are not at this moment observing them. When we say, Salt preserves meat, we are not, according to Professor Bain, uttering an induction; because the preserved meat is now under our eyes; it is only when we say that salt will preserve meat, or that salt has preserved meat (referring strictly to the unobsei'ved cases in the past), that an induction is made: yet this can be established only by " the unanimity of all observers," which it is manifestly impossible to ascertain, and if it could be ascertained, the assertion would at once cease to be an induction (since no longer referring to the unobserved and making no addition to knowledge) : it would be a mere generalization, an "induction improperly so-called." It would be impossible to make a catalogue of all of the primary inductions held by the mind of a single person. They refer to every object and undergo constant revision and extension. They are not always, nor even usually, in the form of universal truths. That three-fifths of the wheat in the state is bad, and that on the average ten men in a thousand of a certain class die every year, are primary inductions. By combination of inductions of small extent, wider ones are. made, and a steady advance in generality is the result. It is the peculiar glory of modern science to have formulated such grand inductions as the law of Inertia, that is, that every body continues in its state of rest or motion unless acted upon ; the law of the persistence of energy; the lav/ of the persistence of matter; the law Primary Inductions. 25 that the will can transform some of the energy of the body. These laws generalized into a higher induction give us the great law of Causation; namely, that if any change occurs in things, the matter, the force, and the will concerned, can be found among previously existing things. Another generalization is, that as far as man can explore, the same order is found existing. So far as the sun and stars can be observed, they conform to the one existing order. How long the existing order will continue, we cannot, in any proper sense, be said to know. Reasoning can- not make any addition to knowledge. Up to the year 79 A.D., the volcano of Vesuvius had had, within the memory of man, no eruption. Experience seemed to have demonstrated that it was safe to live upon its slopes ; but the eruption came and proved the contrary. Manifestly, those uniformities which depend upon the co-operation of a number of causes are less stable than those which are simpler. Nothing is simpler than the law of gravitation; hence such a uniformity as the rising and setting of the sun is relied upon with vastly more faith than is the quiescence of a volcano. But that is only a matter of degree. Mr. Mill has made a distinction between Empirical Laws and Ultimate Laws. "An empirical law is an observed uniformity, presumed to be resolvable into simpler laws, but not yet resolved into them." The distinction is simple enough in thought, but in practice it is impossible to draw the line. It may be well, in closing this chapter, to say a few words upon the curious popular misunderstanding of the maxim that "The exception proves the rule." 26 Inductive Logic. When one has laid down with positiveness some sup- posed general principle, and his attention is called to a fact inconsistent with it, it is not uncommon to hear him say, rather triumphantly, " Oh, that is simply the exception that proves the rule"; and he seems some- how to feel better fortified in his position than before, his generalization being now provided with a necessary equipment. Even respectable writers fall into this absurd mode of speaking. The fallacy consists in taking as a principle, valid in the world of facts, what has no sense at all except in the world of statements. It is taken as if the finding of a black sheep were in some way a confirmation of the generalization that all sheep are white ; although, of course, every such case is just so much disproof. But if some person, a law- maker, an expert, or an authority of some sort, in mak- ing statements, excepts a person or thing, then it may be legitimately inferred that he assumes the rule to be the other way. If, for example, one who lives on the shore of Lake Erie speaks of a fine day in March with surprise, his so speaking is equivalent to testimony that bad weather then and there is the rule ; but a chance visitor, luckily enjoying bright skies, would not on that account more readily assent to the assertion that March weather on Lake Erie is generally bad. Those who in their youth have been compelled to learn the rules for Latin quantity, find it most convenient to remember them by the exceptions. Knowing that amicus is given as one of the exceptions in its class, I have no difficulty in recalling the rule that " Words in -icus shorten the penult"; but this proves only the statement of the grammarian, nothing more. In short, the word excep- Primary hidiictions. ^ 27 Hon has two senses ; first, it means the act of excepting ; secondly, the thing excluded ; the popular fallacy con- sists in substituting the second for the first sense, and in supposing that the discovery of a few words with long i before the termination -cus makes it easier to believe that i so situated is generally short ; when in truth the proof is wholly in the fact that a competent authority has declared these words to be exceptions. CHAPTER V. SECONDARY INDUCTIONS. Having by the slow, and often tedious, process of observing many particulars, established our primary inductions, we are prepared to advance with ease and rapidity in the making of Secondary Inductions. A primary induction, we have learned, is a generalization of experience, a truth established by repeated observa- tions. A Secondary Induction is the conclusion of a syllogism of which one premise is a primary induction, and the other premise is the statement of an observed fact. When, for example, it has once been admitted, as a primary induction, that specific gravities are con- stant, a single experiment upon a newly discovered metal is sufficient to establish its specific gravity to the satisfaction of the scientific world. The single observa- tion is combined deductively with the primary induction, thus : — All specific gravities are constant ; The specific gravity of this piece of Rubidium is 1.5; Therefore, the specific gravity of Rubidium is always 1.5. This illustration shows in an interesting manner how induction and deduction are combined. There is dis- covery here, but it is not reached by anything peculiar in the method of inference ; that is simply deductive. But each of the premises records a discovery made by observation ; hence the syllogism is inductive. It has Secondary Inductions. 29 been objected to such syllogisms, that the universal proposition could not be affirmed unless we already knew the conclusion, and that consequently there is only an apparent, and not a real advance in knowledge. The reply is, that no reasoning can ever make a sub- stantial advance in knowledge ; to give knowledge is the function of intuition and observation alone. Rea- soning can only display explicitly what was already involved implicitly. There is, however, in this case what comes very near to positive discovery. It has appeared in the last chapter that practical certainty is reached, regarding many of the uniformities of nature, long before all instances have been examined ; indeed, from the very character of most uniformities, it is impossible that all instances should be examined. We become satisfied that all men are mortal, upon knowl- edge of what is a very limited part of the experience of the race. When, therefore, it is observed that Socrates is a man, the conclusion that he is mortal comes very near to being a discovery. The fact that Socrates is a man is a discovery of observation ; Socrates might be the name of a dog or of a ship. This premise brings into the syllogism an advance in knowledge. In every-day thinking, primary and secondary induc- tions are constantly mingled, and almost all of our generalizations partake of the nature of both, or are proved in both ways. There is, for instance, a perpet- ually accumulating mass of experience that lead is heavy, that aluminum is light, and so on. Independ- ently of anything else, a primary induction can be made regarding each one of the metals. But at the same time the broader primary induction that specific 30 Inductive Logic. gravities are constant is receiving perpetual confirma- tion, so that each ■ single experience with lead or aluminum abundantly warrants a secondary induction covering the whole existing amount of that metal. After observing a thousand uniformities, every one perceives that objects and events in this world run in lines of similarity ; a strong presumption, therefore, arises that any given object is only one of a class. Finding several similar things, we combine the observa- tion with the previously established generalization that several similarities indicate the line of a uniformity, and make an induction accordingly. This is what Dr. Fow- ler has called ''the mode of generalization natural to immature and uninstructed minds"; but in truth it is the necessary procedure of all sane minds. The imma- turity and inexperience appear in neglecting care in determining the exact course and limits of the lines of uniformity. Archbishop Whately regarded the uniformity of the course of nature as the ultimate major premise in all inductions. That is, he did not provide for any primary inductions at all. But the uniformity of nature is too vast and indefinite an induction for immediate use, even in most cases of secondary induction. The doctrine does not mean that all objects are alike, and all events alike ; it only means that all particular lines of uni- formity persist. What these lines are, must be deter- mined simply by accumulating instances and making generalizations. We must have observed a number of lines of particular uniformity, before we could ascend to the induction of the general uniformity of nature. To quote Mr. Mill: — Secondary Inductions. 31 " But though it is a condition of the validity of every induction that there be uniformity in the course of nature, it is not a neces- sary condition that the uniformity should pervade all nature. It is enough that it pervades the particular class of phenomena to which the induction relates. An induction concerning the motions of the planets, or the properties of the magnet, would not be vitiated though we were to suppose that wind and weather are the sport of chance, provided it be assumed that astronomical and magnetic phenomena are under the dominion of general laws. Otherwise the early experience of mankind would have rested on a very weak foundation ; for in the infancy of science it could not be known that all phenomena are regular in their course." ^ The strangest fact in the history of inductive science is that writers have never distinctly recognized and stated the fundamental differences of the three great classes of inductions, but have persisted in attempting to make one comprehensive definition for all, as if the process of induction were always precisely the same thing. Thus Whately provides only for secondary inductions ; Bain, only for primary ones ; Minto and Davis, only for such secondary ones as fall under the primary induction of causation, which is but a fraction of the field of experience. Mr. Mill has thrown so much light upon the whole subject, and has made so many just discriminations, that it is all the more sur- prising that he has not gone a step farther. He says : — "Whatever be the most proper mode of expressing it, the proposition that the course of nature is uniform, is the funda- mental principle, or general axiom of Induction. It would yet be a great error to offer this large generaHzation as any explanation of the inductive process. On the contrary, I hold it to be itself an instance of induction, and induction by no means of the most obvious kind. Far from being the first induction we make, it is 1 Logic, p. 225, note. 32 Inductive Logic. one of the last, or at all events one of those which are latest in attaining strict philosophical accuracy. As a general maxim, indeed, it has scarcely entered into the minds of any but philoso- phers ; nor even by them, as we shall have many opportunities of remarking, have its extent and limits been always very justly con- ceived. The truth is, that this great generalization is itself founded on prior generalizations. The obscurer laws of nature were dis- covered by means of it, but the more obvious ones must have been understood and assented to as general truths before it was ever heard of. We should never have thought of affirming that all phenomena take place according to general laws, if we had not first arrived, in the case of a. multitude of phenomena, at some knowledge of the laws themselves ; which could be done no other- wise than by induction. In what sense, then, can a principle, which is so far from being our earliest induction, be regarded as our warrant for all the others ? In the only sense in which (as we have already seen) the general propositions which we place at the head of our reasonings when we throw them into syllogisms, ever really contribute to their validity. As Archbishop Whately remarks, every induction is a syllogism with the major premise suppressed ; or (as I prefer expressing it) every induction may be thrown into the form of a syllogism by supplying a major premise. If this be actually done, the principle which we are now consider- ing, that of the uniformity of the course of nature, will appear as the ultimate major premise of air inductions, and will, therefore, stand to all inductions in the relation in which, as has been shown at so much length, the major proposition of a syllogism always stands to the conclusion ; not contributing at all to prove it, but being a necessary condition of its being proved ; since no conclu- sion is proven, for which there cannot be found a true major premise." 1 In this passage the characteristic peculiarities of Mr. Mill's mind appear; he tells the truth most clearly, but at the same time contradicts and obscures it. If the uniformity of nature is a discovery of induction it cannot 1 Logic, p. 224. Secondary Inductions. 33 be the fundamental principle of induction. We cannot lift ourselves over the fence by our own boot-straps. Primary inductions are but generalizations and need no major premise; for they cannot be thrown into syllo- gistic form. Secondary inductions have for their major premises the particular uniformities which are proximate. We cannot take the uniformity of nature as a major premise, and making a single observation, proceed at once to a secondary induction, reasoning, This object is mortal ; But since nature is uniform ; All objects are mortal. The uniformity of nature is a generalization only regarding uniformities ; to use it at all we must, by accumulating particulars, ascertain the existence of a uniformity. And then we can reason. All uniformities persist ; This is a uniformity ; There- fore it will persist. The only inference that can be drawn from the uniformity of nature is the persistence of a newly discovered uniformity. Professor Minto says: — " In his antagonism to a supposed doctrine that all reasoning is from general to particular, Mill maintained simpliciter that all reasoning is from particulars to particulars. Now, this is true only secundum quid, and although, in the course of his argument, Mill introduced the necessary qualifications, the unqualified thesis was confusing. It is perfectly true that we may infer — we can hardly be said to reason — from observed particulars to unob- served. We may infer, and infer correctly, from a single case. The village matron, called in to prescribe for a neighbor's sick child, infers that what cured her own child will cure the neigh- bor's, and prescribes accordingly. And she may be right. But it is also true that she may be wrong, and that no fallacy is more common than reasoning from particulars to particulars without the requisite precautions." ^ 1 Logic, p. 266. 34 Inductive Logic. We cannot admit that there is any such thing as inferring, or reasoning, from one particular to another. The village matron does not infer from her child to the neighbor's grindstone or barn-door, and the fact that she does not is proof that she does not take particulars at random. Her process of thought is this : These two particulars (the children) belong to the same natural kind ; Things of the same natural kind are similarly affected by the same thing ; This medicine cured my child; Therefore, it will cure this one. The matron's reasoning is syllogistic throughout ; if she makes an error it is simply in observation as to whether the medicine did cure her own child, or as to whether the neighbor's child is in the same physical condition. The matron proceeds from primary inductions through particular observations to secondary inductions. The "requisite precautions" always include attention to these steps. In the first edition of his Logic, Mr. Mill said: — " The induction by which they [the mathematical axioms and the law of causation] are established is of that kind which can establish nothing but empirical laws; an empirical law, however, of which the truth is exemplified at every moment of time and in every variety of place or circumstance, has an evidence which sur- passes that of the most rigid induction, even if the foundation of scientific induction were not itself laid (as we have seen that it is) in a generalization of this very description." ^ In this remarkable passage, it was assumed that only secondary inductions are scientific inductions, and yet it was affirmed that they are based upon the primary, 1 Page 340. Secondary Inductions. 35 and that the primary are so firm that they would sur- pass the secondary, were it not that the secondary, being based upon them, must be exactly as strong. It is true that in the eighth, the last, edition of the Logic this passage is omitted; but the confusion of thought still attaches to Mr. Mill's doctrine, and appears in the books which, like Dr. Fowler's, are based upon his earlier editions. Mr. Mill's contention amounts simply to this, that a secondary induction made from one clear case in combination with one of our broadest primary inductions (say the law of causation), is far more trust- worthy than a new primary induction made independ- ently regarding a limited class of phenomena. And this is undoubtedly true. CHAPTER VI. MIXED INDUCTIONS. We know by intuition that if certain things are true, certain other things are also true. When, therefore, one of these facts of the first class has been estab- lished by observation, one of the facts of the second class can be established by making a syllogism, of which one premise is known to be true by intuition, and the other by observation; the conclusion will be a Mixed Induction. We know, mathematically, that if the surface of the sea is not flat, but curved, the masts of ships must appear before their hulls. We observe that the masts do actually appear first. The conclusion, that the sur- face of the sea is curved, is a mixed induction. The nature of mixed inductions is well illustrated in the famous discoveries of Sir Isaac Newton. We quote from Mr. Mill : — " Newton began by an assumption, that the force which at each instant deflects a planet from its rectilineal course, and makes it describe a curve round the sun, is a force tending directly towards the sun. He then proved that, if it be so, the planet will describe, as we know by Kepler's first law it does describe, equal areas in equal times; and, lastly, he proved that if the force acted in any other direction whatever, the planet would not describe equal areas in equal times. It being thus shown that no other hypothesis could accord with the facts, the assumption was proved; the hypothesis became a law, established by the method of difference. Not only did Newton ascertain by this hypothetical process the Mixed Inductions. 37 direction of the deflecting force ; he proceeded in exactly the same manner to ascertain the law of variation of the quantity of that force. He assumed that the force varied inversely as the square of the distance ; showed that from this assumption the remaining two of Kepler's laws might be deduced; and, finally, that any other law of variation would give results inconsistent with those laws, and inconsistent, therefore, with the real motions of the planets, of which Kepler's laws were known to be a correct expression." ^ That is, Newton showed mathematically that if the planets move in a given manner, they must be affected by a force acting toward the sun and varying inversely as the square of the distance; Kepler had shown that the planets do move in the given manner; the mixed induction was therefore established that there is such a force. It will be seen that Mr. Mill introduces this as an example of hypothesis, but it will also be seen that it was wholly unnecessary for Newton to make any con- jecture or assumption. All he had to do was to ask. The motions being as they are observed to be, what, mathematically, must be the direction and law of the force } It is not necessary to form an hypothesis that the surface of the sea is curved and then test that hypothesis by looking at an incoming ship. All that is necessary is to state the mathematical possibilities and then observe the facts; the conclusion follows of course. We take another fine illustration from Sir John Herschel : — " It had been objected to the doctrine of Copernicus, that, were it true, Venus (and, it might have been added. Mercury, as the other inferior planet) should appear sometimes horned like the 1 Logic, p. 351. 38 Inductive Logic. moon. To this he answered by admitting the conclusion, and averring that, should we ever be able to see its actual shape, it would appear so. It is easy to imagine with what force the application would strike every mind when the telescope confirmed this prediction, and showed the planet just as both the philosopher and his objectors had agreed it ought to appear." ^ Having considered the three kinds of induction, we are now ready to answer several questions proposed by Mr. Mill: — "In order to a better understanding of the problem which the logician must solve if he would establish a scientific theory of induction, let us compare a few cases of incorrect inductions with others which are acknowledged to be legitimate. Some, we know, which were believed for centuries to be correct, were, nevertheless, incorrect. That all swans are white, cannot have been a good induction, since the conclusion has turned out to be erroneous. The experience, however, on which the conclusion rested was genuine. From the earliest records, the testimony of all the inhabitants of the known world was unanimous on the point. The uniform experience of the inhabitants of the known world, agree- ing in a common result, is not always sufficient to establish a general conclusion. . . . When a chemist announces the existence and properties of a newly discovered substance, if we confide in his accuracy, we feel assured that the conclusions he has arrived at will hold universally, although the induction be founded but on a single instance. We do not withhold our assent, waiting for a repetition of the experiment; or if we do, it is from a doubt whether the one experiment was properly made, not whether, if properly made, it would be conclusive. Here, then, is a general law of nature, inferred without hesitation from a single instance; an universal proposition from a singular one. Now, mark another case and contrast it with this. Not all the instances which have been observed since the beginning of the world, in support of the general proposition that all crows are black, would be deemed a sufiicient presumption of the truth of the proposition, to outweigh 1 Discoicrse on the Study of N'atural Philosophy, § 299. Mixed Inductions. 39 the testimony of one unexceptionable witness who should affirm that in some region of the earth not fully explored, he had caught and examined a crow, and had found it to be gray. " Why is a single instance, in some cases, sufficient for a com- plete induction, while in others, myriads of concurring instances, without a single exception known or presumed, go such a very little way towards establishing an universal proposition? Who- ever can answer this question knows more of the philosophy of logic than the wisest of the ancients, and has solved the great problem of induction." ^ Our discussion up to this point has prepared the student to ansv^er Mr. Mill's question, and to claim the proud distinction of " knowing more of the philosophy of logic than the wisest of the ancients." It is plain that when a chemist determines for the first time the specific gravity of a new substance, rubidium, for exam- ple, he combines this one observation deductively with the acknowledged primary induction that chemical and physical properties of the several natural kinds are constant, and thus reaches at once the secondary induc- tion, that the specific gravity of rubidium will be always found 1.5, or whatever the determination may be. Whenever a single instance leads to an induction, it is a secondary induction or a mixed induction. Bacon called such instances "crucial instances," from the Latin crux, a finger-post ; since they point out the line of uniformity. No single instance can give a primary induction. In investigating the color of swans and crows we start with the well-established primary induc- tion that color is, in animals, an uncertain quality. Combining this with the observation that these crows are black, we, of course, reach no conclusion. We have, 1 Logic, p. 227. 40 Inductive Logic. however, made a primary induction that all English crows are black ; and this is correct. This leads us to remark that, in making an induction, it is necessary to define correctly the field under investigation. Having seen a thousand Chinamen in California, we conclude by induction that all Chinamen are, on the average, shorter than Americans. But when we learn that these men all came from one province, that of which Hong- Kong is the port, we change, not the induction, but the area of it ; it concerns not Chinamen but one sort of Chinamen. So the induction "All crows are black" was correct for England, but not certainly for the whole world. CHAPTER VII. FACTS OF RESEMBLANCE. The earliest activities of the infant mind must be in observing single facts. But there is one recurring fact of relation which must soon force itself upon the atten- tion ; this is the resemblance between many of these single facts. As we say, in popular language, the same phenomenon is repeated. The word same thus used means merely that a resembling phenomenon comes. Meeting a multitude of similar phenomena, the mind at length forms a general concept, and finally invents a name which we call a common noun, as mmi or tree. The existence of such words depends upon the fact of the existence of numbers of objects recognized by the mind as similar. And not only do objects resemble one another, but the changes and states of objects have also resemblances. The universe is perceived to be full of lines of resem- blance or, to use a more common term. Uniformity. The phenomena about us at this moment are like the phenomena of yesterday and of a year ago to-day. " That which hath been is that which shall be ; and that which hath been done is that which shall be done : and there is no new thing under the sun. Is there a thing whereof men say. See, this is nev/.? it hath been already, in the ages which were before us." ^ As previously remarked, a universe in which every object should be 1 Ecclesiastes, i. 9, 10. 42 Inductive Logic. unique and every event a surprising novelty is perfectly conceivable ; the conception contradicts no law of thought or, so far as we know, of being. But such is not the universe in which we live. As one who enters, for example, a large store of pottery, soon discovers that much of the stock is in lots, and that this cup is like other cups, and that platter like other platters, so the observer of nature perceives that things are in lots and are passing through similar changes. The possibility of language rests upon the recurrence of resemblances. Not only are objects alike, but their changes and relations are alike. The words used to describe the phenomena of yesterday are appropriate to-day. Nature may be divided into groups of similari- ties ; and the phrase " Uniformity of Nature " embodies the opinion that things remain essentially similar to themselves, and of course, therefore, similar to the other things which at any time resemble them. Our belief in the uniformity of nature is the belief that the quantities and qualities of matter and force, and the faculties of mind, remain as they are. The integrity of the existing order is unimpaired. Long inductive arguments may be constructed by successive judgments of resemblance, the intuitively known axiom that things that are equal to the same thing are equal to each other being the general major premise. These arguments are therefore mixed induc- tions. We will add two examples, one from the science of language and one from the science of geology. The following analysis of an inductive argument is taken from Fowler's Inductive Logic. — Facts of Re setnb lance. 43 " The Method of Concomitant Variations is that which is most frequently employed in the Science of Language. It is found, for instance, that between two dissimilar words employed at different epochs to express the same idea may be interpolated a number of intermediate forms employed at intermediate epochs, which make the transition gradual and natural. From this circumstance it is inferred that the word used at the later epoch is derived from that used at the earlier epoch, certain tendencies of speech being regarded as the cause of the divergence. ' Thus, at first sight,' says M. Brachet, ' it is hard to see that djne is derived from animaj but history, our guiding-line, shows us that in the thirteenth century the word was written anine^ in the eleventh aneme^ in the tenth anime^ which leads us straight to the Latin anijna.'' In this case there can be no doubt of the truth of the conclusion." ^ This analysis we cannot at all accept. The proof that ante is the same as anima is based upon a number of successive observations of facts of resemblance. Anima and anime are so much alike in look, sound, and meaning, that we pronounce them the same ; this is true also of anime and ane7ne, of aneme and anme, of anme and dme. We therefore construct the equation anima = dnime = aneme = anme = dme. .'. ani^na ^=dme. There is positively nothing here that varies concom- itantly with the word anima. The explanation that " certain tendencies of speech are the cause of the divergence" is just like the explanation that opium causes sleep because "it has a soporific quality"; it explains nothing. The method generally employed in philological investigations is that of direct observation of resemblances. The proposition that anima and d^ne are the same word is an induction, because it is the 1 Page 200. 44 Inductive Logic. statement of a fact not directly observable and the statement is based upon observations. It is really a mixed induction ; for it rests upon the axiom that things that are equal to the same thing are equal to each other. Let us try to analyze the following argument for the evolution of the horse, taken from Le Conte's Geology : — " Genesis of the Horse. — In conclusion, it will be interesting and instructive to run out one of these branches and show in more detail the genesis of one of the extreme forms. For this purpose we select the Horse, because it has been somewhat accurately traced by Huxley and by Marsh. About thirty-five or forty species of this family, ranging from the earliest Eocene to the Quaternary, are known in the United States. The steps of evo- lution may therefore be clearly traced. "In the lower part of the Eocene basin {Coryphodon beds') of Green River is found the earliest known animal in the direct line of descent of the horse family, viz., the recently described Eohippus of Marsh. This animal had three toes on the hind-foot and four perfect, serviceable toes on the fore-foot ; but, in addi- tion, on the fore-foot an imperfect fifth metacarpal (spHnt), and possibly a corresponding rudimentary fifth toe (the thumb), like a dew-claw. Also, the two bones of the leg and fore-arm were yet entirely distinct. This animal was no larger than a fox. Next, in the Middle Eocene (Bridger beds), came the Orohippiis of Marsh, an animal of similar size, and having similar structure, except that the rudimentary thumb or dew-claw is dropped, leav- ing only four toes on the fore-foot. Next came, in the Lower Miocene., the Mesohipptis., in which the fourth toe has become a rudimentary and useless splint. Next came, still in the Miocene., the Miohippus of the United States and nearly allied Anchithere of Europe, more horse-like than the preceding. The rudimentary fourth spHnt is now almost gone, and the middle hoof has become larger ; nevertheless, the two side-hoofs are still serviceable. The two bones of the leg have also become united, though still quite Facts of Resemblance. 45 distinct. T\As 2si\v[v3\^N2.'s> 2^ovi\. the size of a sheep. Next came, in the Upper Miocene, and Lower Pliocene, the Protohippus of the United States and allied Hipparion of Europe, an animal still more horse-like than the preceding, both in structure and size. Every remnant of the fourth spHnt is now gone ; the middle hoof has become still larger, and the two side-hoofs smaller and shorter, and no longer serviceable, except in marshy ground. It was about the size of the ass. Next came, in the Plioceiie, the Pliohippiis, almost a complete horse. The hoofs are reduced to one, but the splints of the two side-hoofs remain to attest the line of descent. It differs from the true horse in the skull, shape of the hoof, the less length of the molars, and some other less im- portant details. Last comes, in the Quaternary, the modern horse — Eqtius. The hoof becomes rounder, the splint-bones shorter, the molars longer, the second bone of the leg more rudi- mentary, and the evolutionary change is complete. " Similar gradual changes, becoming more and more horse-like, may be traced in the shape of the head and neck, and especially in the gradually increasing length and complexity of structure of the grinding teeth." "There can be no doubt that if we could trace the line of descent still further back we would find a perfect five-toed an- cestor. From this normal number of five, the toes have been successively dropped, according to a regular law. In the Perisso- dactyl line first the thumb. No. i, was dropped; then the little finger, No. 5 ; then the first and ring-fingers, Nos. 2 and 4, were shortened up more and more and finally disappeared, and only the middle finger, No. 3, remained in the modern horse. In the Artiodactyl line, after the dropping of No. i, then Nos. 2 and 5 of the four-toed foot were shortened and gradually disappeared, and Nos. 3 and 4 remained in the Ruminants. " " From the earliest and most generalized types, therefore, to the present specialized types, the principal changes have been, first, from plantigrade to digitigrade; second, from short-footed digitigrade to long-footed digitigrade, i.e., increasing elevation of the heel; third, from five toes to one toe in the Horse, or two toes in Ruminants ; and, fourth, from simple omnivorous molars to the complex herbivorous mill-stones of the Horse and the Ox. 4-6 Inductive Logic. "The change from plantigrade to digitigrade, with increasing elevation of the heel, when taken in connection with increasing size of the brain, and therefore presumably with increasing brain- power, shows a gradual improvement of structure adapted for speed and activity, and a pari-passu increase of nervous and muscular energy necessary to work the improved structure." ^ The foregoing argument is just like that regarding the words dme and a7iima ; Eohippus so closely resem- bles OrohippiLS that they must be the same ; Orohippus must be the same as Mesohippus ; Mesohippus must be the same as Protohippus; Protohippus is the same as Pliohippus ; Pliohipptts is the same as E quits ; there- fore the modern horse is the same as the Eohippus. The force of this argument will depend upon the strength of the impressions of resemblance made upon various minds. Professor Huxley regarded it as demonstrative. 1 Pages 540-543- CHAPTER VIII. FACTS OF COEXISTENCE. Every observer very quickly perceives that the various objects in the world may be divided into groups of permanent coexistences. Here is a mass of matter with specific gravity 19.34, a yellow color, malleable, ductile, etc., and there is another mass of matter in which the same phenomena coexist, and there is an- other. We call all these masses gold; and we say that gold is a kind of matter. Malleability, ductility, etc., are commonly called the properties of gold. But in truth we know absolutely nothing about gold except these properties. The weight does not possess the ductility, nor does the color possess the malleability; but the coexistence of all these phenomena is gold. No approach has been made by science to any reason why certain phenomena permanently coexist ; as, for instance, why the metal whose specific gravity is 19.34 should be yellow, and the metal whose specific gravity is 10.5 should be white. It is easy to say that all the properties probably depend upon some common fact of causation ; but in the present state of science such a remark has no meaninsr. A very large part of the work of science is in ascer- taining the various natural kinds of objects. Mr. Mill magnifies the notion of cause and calls it " the root of the whole theory of induction." But it is plain that the notion of coexistence is an equally important root. 48 Inductive Logic. We cannot reason that such and such things must coexist; we can only discover that they do. This work has nothing to do with causation. It has nothing to do with the unknown. It does not proceed by in- ference. It is the orderly arrangement of what we know. One vast attempt of Induction is to classify the objects in nature, that is, to discover and define all natural kinds. In this attempt it is soon perceived that there are groups within groups. Vegetables, for example, are a natural kind ; but the vegetable king- dom may be subdivided into more limited kinds, and these kinds may be again subdivided. A distinction is made between Natural and Artificial kinds. We may, for temporary convenience, divide objects according to some one property, as yellowness. And then gold and oranges and salmon will be of the same kind. Such a group is called an Artificial Kind. But Natural Kinds are so called because the objects which compose them resemble each other in a multi- tude of characteristics and appear, in fact, grouped together by nature. The great botanist Linnaeus systematized plants according to the numbers of sta- mens and pistils, neglecting other features. This was a convenient, but highly artificial, arrangement; since it brought into the same order plants on the whole utterly diverse. Modern botany takes into considera- tion a multitude of particulars in stem, leaf, flower, and fruit; and so reaches a natural system. No classifica- tion is natural which depends in the least degree upon the caprice of the investigator; it must force itself upon all observers as existing in nature. Facts of Coexistence. 49 That there is a kind of objects which we may call plants and another kind of objects which we may call animals is generally admitted. But when we come to subdivide the animal and vegetable kingdoms, differ- ences of opinion arise. It is obvious that certain individuals greatly resemble one another; they con- stitute natural groups, which may be called species. Certain species resemble one another ; they may be associated in larger groups and called genera. So the genera may be grouped into orders, and the orders into classes. Philosophers have discussed the question whether there is a point where natural subdivision ends. If there is such a point, then one of the smallest possible natural groups would be called an iiifima species. If, on the other hand, there be a group which cannot naturally be included in a larger, such a group would be called a summu7n gemts. The most interesting question in modern natural science is, whether the various natural groups of ani- mals and plants — species, genera, orders, etc. — are naturally separated by distinct lines. The discussion has taken the form of an inquiry into the true nature of species. The main points in it can be conveniently presented in the words of Professor Asa Gray : — "The ordinary and generally received view assumes the inde- pendent, specific creation of each kind of plant and animal in a primitive stock, which reproduces its like from generation to gen- eration, and so continues the species. Taking the idea of species from this perennial succession of essentially similar individuals, the chain is logically traceable back to a local origin in a single stock, a single pair, or a single individual, from which all the individuals 50 Inductive Logic. composing the species have proceeded by natural generation. Although the similarity of progeny to parent is fundamental in the conception of species, yet the likeness is by no means absolute ; all species vary more or less, and some vary remarkably — partly from the influence of altered circumstances, and partly (and more really) from unknown constitutional causes which altered condi- tions favor rather than originate. But these variations are sup- posed to be mere oscillations from a normal state, and in Nature to be limited if not transitory ; so that the primordial differences between species and species at their beginning have not been effaced, nor largely obscured, by blending through variation. Consequently, whenever two reputed species are found to blend in Nature through a series of intermediate forms, community of origin is inferred, and all the forms, however diverse, are held to belong to one species. Moreover, since bisexuality is the rule in Nature (which is practically carried out, in the long run, far more gener- ally than has been suspected), and the heritable qualities of two distinct individuals are mingled in the offspring, it is supposed that the general sterility of hybrid progeny interposes an effectual bar- rier against the blending of the original species by crossing. " From this generally accepted view the well-known theory of Agassiz, and the recent one of Darwin, diverge in exactly opposite directions. " That of Agassiz differs fundamentally from the ordinary view only in this, that it discards the idea of a common descent as the real bond of union among the individuals of a species, and also the idea of a local origin — supposing, instead, that each species originated simultaneously, generally speaking, over the whole geographical area it now occupies, or has occupied, and in per- haps as many individuals as it numbered at any subsequent period. " Mr. Darwin, on the other hand, holds the orthodox view of the descent of all the individuals of a species not only from a local birthplace, but from a single ancestor or pair ; and that each species has extended and established itself, through natural agen- cies, wherever it could ; so that the actual geographical distribu- tion of any species is by no means a primordial arrangement, but a natural result. He goes farther, and this volume \The Origin Facts of Coexistence. 51 of S;pecies'\ is a protracted argument intended to prove that the species we recognize have not been independently created as such, but have descended, Uke varieties, from other species. Varieties, on this view, are incipient or possible species ; species are varie- ties of a larger growth, and a wider and earlier divergence from the parent stalk ; the difference is one of degree, and not of kind."i "In applying his principle of natural selection to the work in hand, Mr. Darwin assumes, as we have seen : (i) Some variability of animals and plants in nature ; (2) the absence of any definite distinction between slight variations and varieties of the highest grade ; (3) the fact that naturalists do not practically agree, and do not increasingly tend to agree, as to what forms are species and what are strong varieties, thus rendering it probable that there may be no essential and original difference, or no possibility of ascer- taining it, at least in many cases ; also (4) that the most flourish- ing and dominant species of the larger genera on an average vary most (a proposition which can be substantiated only by extensive comparisons, the details of which are not given); and (5) that in large genera the species are apt to be closely but unequally allied together, forming little clusters round certain species — just such clusters as would be formed if we suppose their members once to have been satellites or varieties of a central or parent species, but to have attained at length a wider divergence and a specific character. The fact of such association is undeniable ; and the use which Mr. Darwin makes of it seems fair and natural. " The gist of Mr. Darwin's work is to show that such varieties are gradually diverged into species and genera through natural selection ; that natural selection is the inevitable resul* oi the struggle for existence which all living things are engaged in ; and that this struggle is an unavoidable consequence of several natural causes, but mainly of the high rate at which all organic beings tend to increase." ^ " Returning for a moment to De Candolle's article, we are dis- posed to notice his criticism of Linnaeus's 'definition ' of the term species {Philosophia Botanica, No. 157): ^Species tot numerainus quot diversae forrnae in principio S7int creatae'' — which he ^ Darwiniana, p. ii. ^ Ibid., p. 36. 52 Inductive Logic. declares illogical, inapplicable, and the worst that has been pro- pounded. ' So, to determine if a form is specific, it is necessary to go back to its origin, which is impossible. A definition by a character which can never be verified is no definition at all.' " Now, as Linnaeus practically applied the idea of species with a sagacity which has never been surpassed, and rarely equaled, and, indeed, may be said to have fixed its received meaning in natural history, it may well be inferred that in the phrase above cited he did not so much undertake to frame a logical definition, as to set forth the idea which, in his opinion, lay at the foundation of species ; on which basis A. L. Jussieu did construct a logical definition — 'Nunc rectius definitur perennis individuorum similium successio continuata generatione renascentium.' The fundamental idea of species, we would still maintain, is that of a chain of which genetically connected individuals are the links. That, in the prac- tical recognition of species, the essential characteristic has to be inferred, is no great objection — the general fact that like engen- ders like being an induction from a vast number of instances, and the only assumption being that of the uniformity of Nature. The idea of gravitation, that of the atomic constitution of matter, and the like, equally have to be verified inferentially. If we still hold- to the idea of Linnaeus, and of Agassiz, that existing species were created independently and essentially all at once at the beginning of the present era, we could not better the propositions of Linnaeus and of Jussieu. If, on the other hand, the time has come in which we may accept, with De Candolle, their successive origination, at the commencement of the present era or before, and even by derivation from other forms, then the ' /;/ principio ' of Linnaeus will refer to that time, whenever it was, and his proposition be as sound and wise as ever." ^ "... Species, as I have said (in Sillintan''s Journal articles) are not facts or things, but judgments, and, of course, fallible judgments. How fallible, the working naturalist knows and feels more than any one else." ^ Inductive Classificatio7i is the orderly arrangement of things in their natural groups or kinds. We may 1 Darwiniana, p. 201. ^ Letters., p. 657. Facts of Coexistence. 53 classify mental states or social movements, as well as physical forces and material objects, minerals, plants, and animals. Nomenclature is a system of names for the various things classified. In Botany the name of a plant is always in Latin, and consists of the name of the genus, followed by the name of the species, as Viola blanda, sweet white violet. Unfortunately, no one has yet thought of any way of forming botanical names from natural characteristics, so that the nomenclature, also, may be natural. On the contrary, the names of genera and species have been assigned by discoverers for trivial and often ridiculous reasons, and the whole scientific world has been forced to perpetuate the memory of silly caprices. This is an ignominy which no disciplined mind can think of without indignation. In Chemistry the names of substances are compounded of those of their elements, with prefixes and terminations suggest- ing their proportions. Chemical nomenclature is the best we have, but its development has lagged behind the general progress of the science. Mineralogy needs nothing more than an adequate nomenclature. A system of names suggesting both crystallography and chemical composition would be far preferable to smith- ite, jonesite, and brownite. Terminology is the precise vocabulary used in describ- ing the parts, qualities, and actions of the objects of science. Botany has a wonderfully copious vocabulary. This vocabulary is strictly inductive ; the meaning of each word is fixed by direct examination of typical specimens. Such words as serrate, dentate, crenate, runcinate, bipinnatifid, etc., are defined by exhibiting 54 Inductive Logic. to the learner the parts of plants which they describe, and each is ever afterwards used in precisely the same sense. By the use of a proper terminology, scientists can convey to one another, in a few words, accurate descriptions of phenomena, which pages of popular phraseology would leave still obscure. CHAPTER IX. FACTS OF CAUSATION AND FACTS OF SUCCESSION. It is a matter of observation that things in this universe react upon one another. It is further observed that after such reactions the things sometimes appear in new forms. This property of reacting, or of present- ing new forms, is called the power of Causation. The several reactions of things are called events. The things which react are said to be the causes of these events. If things appear in new forms, they are said to be, in their antecedent forms, the causes of them- selves in their subsequent forms. This power of affecting, or being affected, is an ultimate property of things. It is one of those ulti- mate properties the coexistence of which constitutes the existing order. Science never attempts the explana- tion of ultimate properties ; or rather, when science finds anything inexplicable she calls it ultimate. Things exist in space, and events occur in time. Time is marked and estimated by the succession of events. And these events are seen to have often a certain relation to one another. Just as there are cer- tain uniform coexistences of phenomena, so there are certain uniform successions. Yellowness and ductility present themselves simultaneously in gold ; contact with red-hot iron and pain in the flesh present them- 56 Inductive Logic. selves as antecedent and consequent events. The events of history seem to come in chains, one link drawing on the next. So impressed have some philoso- phers been with this appearance of concatenation among events, that they have attempted to define causation itself in terms of succession, and they have thus brought great confusion into the science of inductive logic. Perhaps it may be easier to define the difficult word Cause, and to show the relation of causation and suc- cession, in connection with a concrete example. We will, therefore, take an instance classic in the history of inductive science, one of the experiments of the illustrious Count Rumford upon heat. The illustration will be useful not only here but in subsequent chapters, and it is so interesting that we will give it at length, and in the Count's own words. " Being engaged lately in superintending the boring of cannon in the workshops of the miUtary arsenal at Munich, I was struck with the very considerable degree of heat which a brass gun acquires, in a short time, in being bored ; and with the still more intense heat, much greater than that of boiling water, as I found by experiment, of the metallic chips separated from it by the borer. From whence comes the heat actually produced in the mechanical operation above-mentioned? . . . "... Taking a cannon, a brass six-povi,ider, cast solid, and rough as it came from the foundry, and fixing it horizontally in the machine used for boring, and at the same time finishing the outside of the cannon by turning, I caused its extremity to be cut off ; and, by turning down the metal in that part, a solid cylinder was formed, 7|- inches in diameter, and c)-^^ inches long ; which, when finished, remained joined to the rest of the metal, that which, properly speaking, constituted the cannon, by a small cylindrical neck, only i\ inches in diameter, and 3^^^ inches long. This short cylinder, which was supported in its horizontal position, and Facts of Catisation and Facts of Succession. 57 turned round its axis, by means of the neck by which it remained united to the cannon, was now bored with the horizontal borer used in boring cannon ; but its bore, which was 3.7 inches in diameter, instead of being continued through its whole length, 9.8 inches, was only 7.2 inches in length ; so that a solid bottom was left to this hollow cylinder, which bottom was 2.6 inches in thickness. " The cyhnder being designed for the express purpose of gener- ating heat by friction, by having a blunt borer forced against its solid bottom at the same time that it should be turned round its axis by the force of horses, in order that the heat accumulated in the cylinder might from time to time be measured, a small round hole, 0.37 of an inch only in diameter, and 4.2 inches in depth, for the purpose of introducing a small cylindrical mercurial thermom- eter, was made in it, on one side, in a direction perpendicular to the axis of the cylinder, and ending in the middle of the solid part of the metal which formed the bottom of its bore. ^^ Exper. J. — A quadrangular oblong deal box, water-tight, iii English inches long, 9^^ inches wide, and 9^^^ inches deep, being provided, with holes or slits in the middle of each of its ends, just large enough to receive, the one, the square iron rod to the end of which the blunt steel borer was fastened, the other, the small cylindrical neck which joined the hollow cylinder to the cannon ; when this box was put into its place it was fixed to the machinery, in such a manner that its bottom being in the plane of the horizon, its axis coincided with the axis of the hollow metallic cylinder ; it is evident, from the description, that the hollow metallic cylinder would occupy the middle of the box, without touching it on either side ; and that, on pouring water into the box, and filling it to the brim, the cyhnder would be completely covered, and surrounded on every side, by that fluid. And further, as the box was held fast by the strong square iron rod which passed, in a square hole, in the centre of one of its ends, while the round or cylindrical neck, which joined the hollow cylinder to the end of the cannon, could turn round freely on its axis in the round hole in the centre of the other end of it, it is evident that the machinery could be put in motion, without the least danger of forcing the box out of its place, throwing the water out of it, or 58 Inductive Logic. deranging any part of the apparatus. Everything being ready, I proceeded to make the experiment I had projected, in the follow- ing manner. " The hollow cylinder having been previously cleaned out, and the inside of its bore wiped with a clean towel till it was quite dry, the square iron bar, with the blunt steel borer fixed to the end of it, was put into its place ; the mouth of the bore of the cylinder being closed at the same time, by means of the circular piston, through the centre of which the iron bar passed. The box was then put in its place, and the joinings of the iron rod, and of the neck of the cylinder, with the two ends of the box, having been made water-tight by means of collars of oiled leather, the box was filled with cold water (viz., at the temperature of (id^^, and the machine was put in motion. The result of this beautiful experi- ment was very striking, and the pleasure it afforded me amply repaid me for all the trouble I had had, in contriving and arrang- ing the complicated machinery used in making it. The cylinder, revolving at the rate of about 32 times in a minute, had been in motion but a short time, when I perceived, by putting my hand into the water, touching the outside of the cylinder, that heat was generated ; and it was not long before the water which surrounded the cylinder began to be sensibly warm. At the end of i hour, 1 found, by plunging a thermometer into the water in the box (the quantity of which fluid amounted to 18.77 lb. avoirdupois, or 2.\ wine gallons), that its temperature had been raised no less than 47 degrees, being now 107° of Fahrenheit's scale. When 30 minutes more had elapsed, or i hour and 30 minutes after the machinery had been put in motion, the heat of the water in the box was 142°. At the end of 2 hours, reckoning from the begin- ning of the experiment, the temperature of the water was found to be raised to 178°. At 2 hours 20 minutes it was at 200°; and at 2 hours 30 minutes it actually boiled. " It would be difficult to describe the surprise and astonishment expressed in the countenances of the by-standers, on seeing so large a quantity of cold water heated, and actually made to boil, without any fire. Though there was, in fact, nothing that could justly be considered as surprising in this event, yet I acknowledge fairly that it afforded me a degree of childish pleasure, which, Facts of Causation and Facts of Sziccession. 59 were I ambitious of the reputation of a grave philosopher, I ought most certainly rather to hide than to discover." ^ Here is a phenomenon — the heat of the water in Count Rumford's box. Let us inquire now what we are doing when we seek for its cause. Plainly the motion of the cylinder was an antecedent of the heat in the water in some pre-eminent and unique sense. Heat is an energy ; it could not appear in the wafer unless it passed out of some other material in which it previously existed as motion, or in some other mode. We know this by a very broad primary induc- tion. Indeed, we here come upon the grand generaliza- tion of the conservation, or, to use a better word, the persistence, of energy. A multitude of experiences have led men to believe that whenever energy newly appears, it has existed previously in another mode or in other materials. The necessary antecedent of energy in one mode or one body is the same energy in a pre- vious mode or in a different body. All machinery is contrived on this principle ; at some point energy is introduced, and it is then transferred or transformed, so that we get light, heat, electricity or motion, as desired. From the standpoint of the physicist the whole cause of the heat of the water was the motion of the cylinder. The degree of heat gained by the one was exactly measured by the amount of motion lost by .the other. There was only a transfer of energy. When in popular language we say that the motion is the cause of the heat, the physicist says that the motion is the heat, only in another mode. The law of causation, when applied to energy, is only the fact of persistence. 1 Fktl. Trans. Royal Soc. of London, vol. xviii, pp. 278-282. 6o Inductive Logic. When we say that energy here must have had a cause, we only mean that, having no reason to think that new energy has been added to the world, we must conse- quently assume that this apparently new energy is only the old in a new mode. When, therefore, we inquire for the cause of energy, we may be merely inquiring, Where and in what mode was this energy previously ? The answer to the question names the Energetic Cause. If it be asked. What was the cause of the motion in the cylinder ? the answer is. The motion of the horses. The energy might be further traced through physio- logical action in the bodies of the horses, and then through physiological action in the growth of the grain and hay upon which they had fed, until at last we should reach the sun's light and heat. One thing is now agreed upon, that the stream of energy in the world, like the Nile in the desert, receives no tributaries, but simply flows on identical with itself, its transforma- tions depending upon the qualities and collocations of matter. But why did motion in the cylinder become heat in the water .<* Here a cause is demanded in a different sense. The inquiry is for those properties and colloca- tions of matter which occasioned a transformation. The arrangement was such that motion could not be com- municated from the cylinder to any other part of the apparatus ; the motion, therefore, according to a per- manently coexisting property, transformed itself into heat. The different properties of energy and the dif- ferent properties of the several sorts of matter in rela- tion to energy, we know by primary inductions which cannot be resolved into simpler generalizations ; they Facts of Causation and Facts of Siiccession. 6 1 are the ultimate facts of the world. The motion of the cylinder changed into heat when the cylinder found itself in connection with certain other masses of matter of certain qualities and collocations. What were these ? The answer to this question will name the Conditional Canse. It will describe the environment in which the transformation took place. While the motion was the cause, and in one sense the sole cause, of the heat, it is yet true that, if left to itself, it would never have changed to heat ; it would have continued eternally as motion. The peculiar environment, then, is, in one sense, the sole cause of the heat, since but for that there would have been nothing but motion. If, instead of investigating the cause of the energy in this experiment, we should investigate the cause of the matter, asking not. What is the cause of the heat t but, What is the cause of the water ? we could go back in the same way along an unbroken line of materials. The cause of the water in the box was water in a river or a well, the cause of that was water in the clouds, the cause of that was the two gases oxygen and hydrogen, and so on. There is a persistence of matter as there is a persistence of force. When we ask for the cause of matter in one form or place we may be merely inquiring, Where and in what form was this matter previously .? The answer will name for us the Material Canse. Or we may seek the conditional cause for the matter, asking. What was the environment in which this matter came to be as it is ">. According to one of the grandest primary induc- tions of modern science, the two lines of energetic and material causation are absolutely continuous and com- 62 Inductive Logic. plete. In the physical world nothing is added and nothing is lost ; but the sum of things persists in its integrity. But approaching the analysis upon a different line, we find that Count Rumford himself was in a unique sense the cause of the heat. It was his, choice to per- form an experiment that eventuated in the heating. The Will of Count Rumford was neither the material cause, nor the energetic cause, nor the conditional cause of the heating of the water. It was the cause in a sense higher than any of these. We will call it the Volitional Cause. The relation of will to the physical universe is peculiar. It cannot originate matter or energy; but it can direct the transformation of a certain amount of the energy of the body. By taking advantage of this power, the Count originated a new chain of events, which terminated in the heating. When in pursuing a chain of events backward we come to a will, the mind recognizes a super-physical intervention ; the man is responsible, and if the events are injurious to the public welfare, he must pay the penalty. All of the power now in my arm was yester- day, or previously, in the beef, potatoes, and other food on the table. If I allow my arm to hang limp, physi- ological and chemical transformations will go forward in natural course, and the energy now potentially mine will pass away. For a brief space this stored energy lies subject to my order, like money in a bank. I can will its transformation into motion ; but I cannot increase or diminish its amount. A party of Arctic explorers, after many days of starvation and hard labor, attempted to draw their boat out of the water ; all Facts of Causation and Facts of Succession. 63 grasped it and at the accustomed signal put forth the usual volition for simultaneous action. But no effect followed ; their wills were as usual, but there was no stored energy for those wills to transform. Lotze has said : — "What constitutes the absolute authority of the causal law is not that every part of the finite sum of things actual must in the finite sphere be produced by fixed causes, according to universal laws, but that each constituent once introduced into this actual course continues to act according to these laws. We commonly speak only of every effect having its cause, but we should on the con- trary lay stress chiefly on the other form of the proposition — every cause has invariably its effect. The meaning of causahty consists not indeed exclusively, but (it seems to me) in its more essential part, in its securing to every element of the actual world, springing from no matter what source, means of acting energetic- ally on the other constituents of the world to which it belongs, at the same time preventing it from acting within that world otherwise than in harmony with the universal laws regulating all that takes place in it. Thus the world would be like a vortex swelled by new waves from all sides, which it does not itself attract or produce, but which, once within it, are forced to take part in its motion. We have another example of the same process in the relation of our own soul to our bodily organs ; the soul evolves from itself resolutions, starting-points for future movements ; none of them needs to be determined by and founded on phenomena in the bodily life on which it reacts ; but each, at the moment of its passing into that life, subordinates itself to the peculiar laws of the latter, and generates so much or so little motion and force as these permit of — motion too in the direction which they prescribe and no other. The universal course of things may at every moment have innumerable beginnings whose origin lies outside of it, but can have none not necessarily continued within it." ^ 1 Microcosmus, p. 260. I am indebted for this quotation to my col- league, Professor Henry C. King. 64 Inductive Logic. Lotze is wrong in saying that the will generates force and thus adds to the sum of physical things ; but he is right in saying that the spiritual acts upon the physical to transform energy, and that, once transformed, the energy goes on acting according to the uniformity of its coexistences, or what are commonly called its laws. The beginnings which lie outside of the uni- versal course of physical things are volitions, and their effects are transformations. The will is not the ener- getic cause any more than it is the material cause ; it is a cause stu generis, the volitional cause. So far we have spoken of Things as the causes of Things. Matter in one form or situation is the cause of the same matter differently disposed ; energy as motion is the cause of the same energy as heat ; a Will, by transforming the vital energy of the body into various motions, brings together matter and energy in new combinations. The causes so far considered are entities and the effects are entities. But things may also cause Events. Every kind of matter and every kind of energy has uniform properties ; it reacts in certain ways upon other things. These reactions are called its effects. In this aspect each thing may be called an Efficient Cause. In our exper- iment there were certain events, the moving of the cylinder, the heating of the water, etc. The energy concerned was the efficient cause of these events. Count Rumford was also an efficient cause of the events, since the action of his will was concerned in their production. But an entirely different line of investigation might have been pursued ; leaving things entirely out of view, Facts of Causation and Facts of Succession. 65 we might have attended solely to Events. One event may be said to cause another event. The ultimate qualities of matter and force remaining as they are, in every possible collocation of things (except that of perfect equilibrium), a certain reaction is inevitable. If, for example, it be the nature of water to absorb heat, then when a quantity of water, as in Count Rumford's box, finds itself in contact with a hot cylinder, the absorption will inevitably take place. But every physical event is simply a new distribution of forces and materials : hence (the properties of things remaining as they are) a further reaction is inevitable. Thus, like the bits of colored glass in a kaleidoscope, the things in the physical world fall at each moment into new relations each of which, if there be no inter- vention, is the necessary opportunity for the next. Thus one event is said to cause another event. This inevitableness of physical reaction is the very fact which opens the door for the interventions of will. By transforming the energy of the body into motion, and thus changing the collocations of a few things, men shunt on to other tracks the trains of events and transform the whole complexion of history. Recurring to the experiment, we may say that the moving of the cyhnder was an event which caused the heating of the water, another event. But when rigid definition is attempted it is found surprisingly difficult to define an event. The event was not merely the heating of some water, but the heating of it in a cer- tain box at a particular time and place and in peculiar circumstances. When all the circumstances, even the most remote, are taken into the account, they include 66 Inductive Logic. the situation of the whole universe. The successive events of history are the successive collocations of the totality of things. While this is true, the general facts of the universe are so permanent and so similar as factors in all events that they may be practically dis- regarded, and the more detailed and proximate elements alone considered as constituting an event. The name Historical Cause may be given to one event when regarded as the cause of another event. Notice how different is the sense of the word cause here from that which it bears when applied to things. An event is the cause of another event only in the sense that its occurrence is the coming of materials and forces into such a collocation that they are certain to react again in a particular way. The turning of the cylinder was an event ; but if a cylinder be turning under such circumstances, it is the ultimate property of motion to become heat and of water to absorb heat; consequently the turning was the historical cause of the heating. Between events there can be no connection but that of succession ; they are but the coming of things into collocations. The continuity is in the things, and each new event arises out of the ultimate properties which coexist in things. There is no efficiency in an event, or tendency of any kind to beget another event; but after each event there is a new possibility; and, the properties of matter and force remaining persistent, whatever is possible is inevitable. When a siphon has been filled with water and is left open, the force of gravity will cause the water to flow until the short end of the tube is exposed. The filling and opening of the siphon are events which leave a situation in which Facts of Causation and Facts of Succession. 6/ gravity can cause a flow, but those events have no efficiency in inducing the flow. Popularly, the fall- ing of a spark into a powder magazine is said to cause an explosion. Historically this is correct ; when a spark so falls there is a collocation in which heat will pass into materials which at that temperature will enter into new chemical combinations accompanied by that sudden distension which is called an explosion. The falling of the spark is the historical cause, the spark and the powder are the material cause, the heat of the spark and the chemical affinity of the substances con- stituting the powder are the energetic cause. In a loose way, an event may be said to be the cause of a State. A blackened pile of ruins may be pointed out as the effects of a conflagration, or the splintered trunk of a tree may be called the effect of lightning. But, strictly speaking, states have no causes. No reason need be given why things remain as they are ; for obviously, unless something happens, nothing hap- pens. If a ball is in motion, and no obstruction presents itself, we do not have to account for the motion ; but if the ball stops, there is an event to account for. An event is the coming of things into a new situation. If in this situation there is a com- parative equilibrium of forces, the situation may indefinitely continue. If the breaking of a dam allows the water to flow out, the event of the breaking is the historical cause of the event of the emptying. But the reservoir may never be filled again ; the state of empti- ness may continue permanently, and the cause for it will be said to be the breaking of the dam. This, however, is a very inexact use of language. Emptiness 6S Inductive Logic. is a mere negation. The thing to be accounted for is the change from the previous fullness. The breach in the dam leaves the water free to move, under the efficient cause, gravity ; once empty, the reservoir remains so without needing a cause of any kind. Human history moves on in the midst of a complex of materials and forces which have certain properties, and which are certain, in each given collocation, to react in one particular way. Physically speaking, whatever at any moment is possible is certain. There is no contingency, no alternative. A weight free to fall falls; a bit of iron in a jar of oxygen and sufficiently hot burns. Each event makes possible the next, and in that sense may be said to make it certain. But the human will has the wonderful power of choosing which of several events shall come to pass. It cannot create nor annihilate matter or energy ; but it can transform the energy of the body into motion. Thus materials and forces may be brought into collocations which would not otherwise have arisen and, although reacting according to their nature, may produce events very different from what would otherwise have been. The volitions of will do not arise by necessity out of fore- going situations; consciousness affirms freedom, and it is here our only organ of observation. The motives in view of which will acts are Occasional Causes, not efficient causes. In tracing the course of events in human history we find this interweaving of physical necessities and free volitions like the warp and woof of a tapestry : to unravel it, is the task of the historian in his search for the connections of things. A passage from the Life and Letters of Charles Darwin will show Facts of Causation and Facts of Succession. 69 how slight may be the connection between two events which are yet in a certain sense cause and effect : — "The following story shows what good guesses my father could make. Lord Shelburne, afterward the first Marquis of Lansdowne, was famous (as Macaulay somewliere remarks) for his knowledge of the affairs of Europe, on which he greatly prided himself. He consulted my father medically, and afterward harangued him on the state of Holland. My father had studied medicine at Leyden, and one day while there went on a long walk into the country with a friend who took him to the house of a clergyman (we will say the Rev. Mr. A , for I have forgotten his name), who had married an Englishwoman. My father was very hungry, and there was little for luncheon except cheese, which he could never eat. The old lady was surprised and grieved at this, and assured my father that it was an excellent cheese, and had been sent to her from Bowood, the seat of Lord Shelburne. My father wondered why a cheese should be sent to her from Bowood, but thought nothing more about it until it flashed across his mind many years afterwards, whilst Lord Shelburne was talking about Holland. So he answered, 'I should think from what I saw of the Rev. Mr. A , that he was a very able man, and well acquainted with the state of Holland.' My father saw that the Earl, who unmediately changed the conver- sation, was much startled. On the next morning my father received a note from the Earl, saying that he had delayed starting on his journey, and wished particularly to see my father. When he called, the Earl said, 'Dr. Darwin, it is of the utmost impor- tance to me and to the Rev. Mr. A to learn how you have discovered that he is the source of my information about Holland.' So my father had to explain the state of the case, and he supposed that Lord Shelburne was much struck with his diplomatic skill in guessing, for during many years afterwards he received many kind messages from him through various friends. I think that he must have told the story to his children ; for Sir C. Lyell asked me many years ago why the Marquis of Lansdowne (the son or grandson of the first marquis) felt so much interest about me, whom he had never seen, and my family. When forty new mem- 70 Inductive Logic. bers (the forty thieves, as they were then called) were added to the Athenaeum Club, there was much canvassing to be one of them ; and without my having asked any one. Lord Lansdowne proposed me and got me elected. If I am right in my supposi- tion, it was a queer concatenation of events that my father not eating cheese half-a-century before in Holland led to my election as a member of the Athenaeum." ^ This " queer concatenation " is a fair example of causation in human history. Dr. Darwin's not eating cheese was the cause of his son's being elected into the club, that is, it was a link in a chain of events, some of which were volitions and some physical neces- sities, and the election was a subsequent link. The very triviality of this incident makes it especially good as an illustration. We have termed the motives upon which the will reacts, occasional causes, since they furnish the occasions, but not the efificiency, of causa- tion. Here maybe distinguished the Formal Cause, or idea viewed as a distinct conception ; and Final Cause, the end, design, or object for which anything is done. A Negative Cause is the absence of anything which if present would have prevented a given phenomenon. It is obvious that any particular event would not have happened if it had been prevented. The absence of a violent earthquake was a negative cause of the heating of the water in Count Rumford's experiment. But the word cause is used here in a sense very remote from that which it bears in other connections. A little boy said that salt was the cause of a bad taste in potatoes when he did not put it on them. That is, in the absence of salt, potatoes have an insipid taste. To say "negative cause" is, indeed, to make a contradiction 1 Page 14. Facts of Causation and Facts of Succession. 71 in the adjective ; it is equivalent to "inactive agent." But in common life, and in ordinary discourse, it is convenient, when the absence of some usual factor in a collocation of things gives opportunity for some unusual event. Thus the absence of the signalman is said to be the negative cause of the railway accident, and the sleep of the sentinel is said to be the negative cause of the defeat of the army. A will may be a negative cause in a more active sense, since refusal to interfere, when interference is possible, involves at least consent to the occurrence of the event; hence, neglect may be criminal. Let us sum up now the results of our discussion of Causation. The cause of a phenomenon is that which gives it existence. Every mass of matter has a mate- rial cause, which is the same matter in a previous place or state. Every portion of energy has an energetic cause, which is the same energy in a previous mode or another mass of matter. Every portion of matter or of energy has a conditional cause for its present place and form, in the environment which has reacted upon it. One peculiar factor in the conditional cause may be a will whose reaction transforms energy, thus constitut- ing a volitional cause. A will acts in view of motives, occasional causes. Events are the reactions of things, which are their efficient causes. Is the law of causation, namely, that every phenome- non depends upon some other phenomenon, intuitively known } The question is too vague to admit of a single answer. That matter and energy persist is a very recently made primary induction from experience. The law of material and of energetic causation is, then. 72 Inductive Logic. not intuitively known. That every event has a thing as its cause is known by a mere analysis of the mean- ing of the terms employed, since events are the reactions of things, and there cannot be an action without an agent. That every event has some other event as its necessary historical cause is not proved either from intuition or experience. Gravitation causes the earth to revolve around the sun ; the causation is in the bodies and forces, not in any previous event. That a will acts in view of final and formal causes is plain ; but that, like matter, it always reacts in precisely the same way under the same stimulus is contradicted by consciousness. Do we know intuitively that "like causes always produce like effects " t The difficulty with this ques- tion is that the words cause and effect are correlatives, and must be defined in terms of each other. An affirmative answer would teach nothing but an identical proposition. The truth which the dictum seeks to express is better stated thus : We know by a primary induction that the existing order persists, and while things remain as they are they will act as they do. How long the existing order will continue we cannot even guess, since all of our reasoning about things is based upon primary inductions from the existing order. But neither have we any ground for expecting an end. The foregoing discussion of facts of causation makes it easy to deal with facts of succession. The facts of succession are seen to be all secondary. They are incidental results of facts of causation. Succession is not at all of the essence of causation. Gravitation keeps the earth revolving around the sun. This effect Facts of CaiLsation and Facts of Succession. 73 is the operation of a permanent cause — the two bodies reacting upon each other ; but there is no succession of cause and effect. Just so the needle is attracted toward the pole by a permanent cause, magnetism. Succession belongs to events in their mutual relations, not to things ; but things are the only efficient causes. Things coexist and persist ; they do not follow one another in time. It is true that between a thing and the material cause of it, that is, the same matter in an earlier form, there is a sort of succession. Ice may cause water, and water may cause steam ; one form follows another. But this is not at all that invariable sequence which constitutes a fact of succession. Things must be simultaneous with their own reactions. Pro- fessor Davis remarks: — " But it would, perhaps, be more accurate to say that every cause is simultaneous with its effect. For cause and effect are correla- tives — neither can exist without the other; they exist only as they coexist. A cause cannot be so named, except by anticipation, until there is an effect ; nor an effect, except by reference to what has already occurred, after the change or event has taken place. The order of succession is logical, not temporal." ^ The fact that events occupy time, and the fact that each event leaves a new collocation of things which makes a new reaction possible — these two facts give us the chain of history. Between two events, one of which is the historical cause and the other the his- torical effect, there is no other connection than that, after the first, things are in such a collocation that they cause the second. An event has as many possible historical causes as there are possible ways of bringing 1 Inductive Logic, p- 23. 74 Inductive Logic, things into the requisite collocation. For example, ice when in contact with salt at ordinary temperatures of the air rapidly liquefies. The efficient cause of the event, liquefaction, is the two bodies ice and salt, and they are simultaneous with it. But the historical cause of the event is any possible action which can bring the substances together, and thus open the possibility for their reaction. All facts of succession are thus conse- quences of facts of coexistence and causation. A succession is known empirically, and is susceptible of analysis into simpler elements. We may always hope to be able to tell why a given succession obtains, in terms of facts of coexistence and causation. Yet many successions were empirically known ages before they were analyzed, and many well-known successions still remain unanalyzed. Many persons are familiar with that historical succession of events which always ends in the production of ice-cream, who have never thought of the operation of the efficient causes. CHAPTER X. MR. MILL'S DOCTRINE OF CAUSATION. Mr. John Stuart Mill is unquestionably the most eminent and influential of all writers upon inductive logic since Bacon. His work is the most elaborate that has appeared, and his teachings, on many points, have been generally adopted. The science owes to him a very great debt. No one can justly claim to under- stand modern inductive logic who has not thoroughly studied Mr. Mill's doctrine of causation. In this chapter we shall seek to present this doctrine in a condensed form, but as nearly as possible in Mr. Mill's own words. According to Mr. Mill, the notion of cause is "the root of the whole theory of Induction." In this view he is followed by later writers. For example. Professor Davis says : " Such principles are evolved from the intuitive fact of causation, the root of all induction, and that which gives it validity." Yet Mr. Mill also holds that our first step in the knowledge of nature is to discover the particular uniformities; then that we generalize the uniformity of these uniformities ; and that this uniformity of uniformities is the law of the uniformity of nature. Strangely enough, the uniformity of nature is, to Mr. Mill, the same as the law of causation. " Whatever be the most proper mode of expressing it," he says, "the proposition that the course of nature is uniform, is the fundamental principle, or general axiom of induction." "J 6 Inductive Logic. It is a difficulty with this view that if inductive logic have to do solely with causation, the vast mass of facts of coexistence and of resemblance is left unprovided for. Such sciences as mineralogy and botany deal mainly with facts of coexistence, yet they are com- monly considered purely inductive. The definition provides no rightful place in inductive logic for the original discovery of uniformities; all of this work has been done before induction proper can begin. More- over, the law of uniformity of uniformities is something very much wider than the law of causation. It is largely concerned with the uniformities of coexistence. Thus we know the persistence of the several kinds of matter and the persistence of energy by so many inde- pendent primary inductions from multitudinous obser- vations of the several things. We not only know that a magnet attracts iron, which is a fact of causation; but that iron remains iron, that is, that that assemblage of coexisting qualities which we call iron persists, which is not a fact of causation. Mr. Mill does not regard the uniformity of nature as "the immediate major premise in every inductive argu- ment." " It is not a necessary condition that the uniformity should pervade all nature. It is enough that it pervades the particular class of phenomena to which the induction relates." That is, we may make a valid secondary induction from any sound, though limited, primary induction, without reference to the soundness of the root of the whole theory. In fact the so-called root is only a generalization of more limited primary inductions. Mr. Mill's definition of Cause is as follows : — Mr. Mill's Doctrine of Causation. J'J " We may define, therefore, the cause of a phenomenon, to be the antecedent, or the concurrence of antecedents, on which it is invariably and unconditionally consequent." In making this definition Mr. Mill began with no analysis of the different ways in which the word cause is used. He did not inquire whether the so-called effect is a thing or a reaction, or the so-called cause a material, an energy, a circumstance, a will, or a prior event. Starting with the notion of succession as fundamental, he attempted to frame a definition so general as to cover all values of the unknown terms of the relation. Yet it is plain in the course of his elaborate discussions that, generally, for him the "phenomenon" in the definition is a reaction, an event. For he says : — "And the universality of the law of causation consists in this, that every consequent is connected in this manner with some par- ticular antecedent, or set of antecedents. Let the fact be what it may, if it has begun to exist, it was preceded by some fact or facts, with which it is invariably connected. For every event there exists some combination of objects or events, some given concurrence of circumstances, positive and negative, the occur- rence of which is always followed by that phenomenon." "On the universality of this truth depends the possibility of reducing the inductive process to rules." ^ For Mr. Mill, then, an effect is an event, and a cause is a number of things in a collocation and with a history. In this complex of things, relations, and history, to which alone Mr. Mill, when speaking strictly, gives the name cause, all the factors are absolutely equal. The 1 Logic, p. 237. y8 Inductive Logic. difference between efficient causes and conditions is denied. Mr. Mill says : — "It is seldom, if ever, between a consequent and one single antecedent, that this invariable sequence subsists. It is usually between a consequent and the sum of several antecedents; the concurrence of them all being requisite to produce, that is, to be certain of being followed by, the consequent. In such cases it is very common to single out one only of the antecedents under the denomination of Cause, caUing the others merely Conditions. Thus, if a man eats of a particular dish, and dies in consequence, that is, would not have died if he had not eaten of it, people would be apt to say that eating of that dish was the cause of his death. There need not, however, be any invariable connection between eating of the dish and death; but there certainly is, among the circumstances which took place, some combination or other upon which death is invariably consequent : as, for instance, the act of eating of the dish, combined with a particular bodily constitution, a particular state of present health, and perhaps even a certain state of the atmosphere; the whole of which circumstances, per- haps, constituted in this particular case the conditions of the phenomenon, or in other words, the set of antecedents which determined it, and but for which it would not have happened. The real Cause, is the whole of these antecedents; and we have, philosophically speaking, no right to give the name of cause to one of them, exclusively of the others. What, in the case we have supposed, disguises the incorrectness of the expression, is this: that the various conditions, except the single one of eating the food, were not events (that is, instantaneous changes, or succes- sions of instantaneous changes) but states, possessing more or less of permanency; and might, therefore, have preceded the effect by an indefinite length of duration, for want of the event which was requisite to complete the required concurrence of conditions: while as soon as that event, eating the food, occurs, no other cause is waited for, but the effect begins immediately to take place: and hence the appearance is presented of a more immediate and closer connection between the effect and that one antecedent, than between the effect and the remaining conditions. But though we Mr. Mill's Doctrine of Causation. 79 may think proper to give the name of cause to that one condition the fulfillment of which completes the tale and brings about the effect without further delay, this condition has really no closer relation to the effect than any of the other conditions has. All the conditions were equally indispensable to the production of the consequent; and the statement of the cause is incomplete, unless, in some shape or other, we introduce them all. A man takes mercury, goes out of doors, and catches cold. We say, perhaps, that the cause of his taking cold was exposure to the air. It is clear, however, that his having taken mercury may have been a necessary condition of his catching cold; and though it might consist with usage to say that the cause of his attack was exposure to the air, to be accurate we ought to say that the cause was exposure to the air while under the effect of mercury. "If we do not, when aiming at accuracy, enumerate all the conditions, it is only because some of them will, in most cases, be understood without being expressed, or because for the purpose in view they may, without detriment, be overlooked. For example, when we say, the cause of a man's death was that his foot slipped in climbing a ladder, we omit, as a thing unnecessary to be stated, the circumstance of his weight, though quite as indispensable a condition of the effect which took place." " In all these instances the fact which was dignified by the name of cause, was the one condition which came last into exist- ence. But it must not be supposed that in the employment of the term, this or any other rule is always adhered to. Nothing can better show the absence of any scientific ground for the distinc- tion between the cause of a phenomenon and its conditions, than the capricious manner in which we select from among the condi- tions that which we choose to denominate the cause. However numerous the conditions may be, there is hardly any of them which may not, according to the purpose of our immediate discourse, obtain that nominal pre-eminence." ^ " Thus we see that each and every condition of the phenomenon may be taken in its turn, and with equal propriety in common parlance, but with equal impropriety in scientific discourse, may be 1 Logic, pp. 237, 238. 8o Inductive Logic. spoken of as if it were the entire cause. And in practice that particular condition is usually styled the cause whose share in the matter is superficially the most conspicuous, or whose requisite- ness to the production of the effect we happen to be insisting upon at the moment. So great is the force of this last considera- tion, that it often induces us to give the name of cause even to one of the negative conditions. We say, for example, the cause of the army's being surprised was the sentinel's being off his post. But since the sentinel's absence was not what created the enemy, or made the soldiers to be asleep, how did it cause them to be surprised ? All that is really meant is, that the event would not have happened if he had been at his duty. His being off his post was no producing cause, but the mere absence of a preventing cause : it was simply equivalent to his non-existence. From nothing, from a mere negation, no consequences can proceed. All effects are connected, by the law of causation, with some set of positive conditions; negative ones, it is true, being almost always required in addition. In other \vords, every fact or phenomenon which has a beginning, invariably arises when some certain combination of positive facts exists, provided certain other positive facts do not exist." ^ " The cause, then, philosophically speaking, is the sum total of the conditions, positive and negative, taken together; the whole of the contingencies of every description, which being realized, the consequent invariably follows." ^ In this great definition Mr. Mill provides for no effects but events, and for no causes but complexes of things, of collocations, and of history. " The state of the whole universe at any instant, we believe to be the consequence of its state at the previous instant : insomuch that one who knew all the agents which exist at the present moment, their collocation in space, and all their properties, in other words, the laws of their agency, could predict the whole subsequent history of the universe, at least unless some new volition of a power capable of controlling the universe should supervene." ^ 1 Logic, p. 239. 2 ibid.^ p. 241. 3 jbid.^ p. 250. Mr. Mill's Doctrme of Causation. 8i The cause of the heating of the water in Count Rumford's box, then, and the only thing to which a philosopher can give the name of cause, was the immediately previous state of the universe. And what we have learned from the experiment is the in- variable and unconditional succession between that state of the universe and the heating of just such a box of water. But since the universe never was before in just that state, and never will be again, it is hard to see that we have learned anything at all. Mr. Mill refuses to recognize any difference in the relations of the dif- ferent sorts of causes to the event. "All the positive conditions of a phenomenon are alike agents, alike active." ^ Although it was with the notion of succession that Mr. Mill began his definition of cause, yet he did not hold to it with great firmness. He inquires : — " Does a cause always stand with its effect in the relation of antecedent and consequent? Do we not often say of two simul- taneous facts that they are cause and effect — as when we say that fire is the cause of warmth, the sun and moisture the cause of vegetation, and the like? Since a cause does not necessarily perish because its effect has been produced, the two, therefore, do very generally coexist ; and there are some appearances, and some common expressions, seeming to imply not only that causes may, but that they must, be contemporaneous with their effects. Cessante causa, cessat et effectiis, has been a dogma of the schools : the necessity for the continued existence of the cause in order to the continuance of the effect, seems to have been once a general doctrine among philosophers. Kepler's numerous attempts to account for the motion of the heavenly bodies on mechanical principles, were rendered abortive by his always sup- 1 Logic, p. 243. 82 Inductive Logic. posing that the force which set those bodies in motion must continue to operate in order to keep up the motion which it at first produced. Yet there were at all times many familiar in- stances in open contradiction to this supposed axiom. A coup de soleil gives a man a brain fever : will the fever go off as soon as he is moved out of the sunshine ? A sword is run through his body : must the sword remain in his body in order that he may continue dead 1 A ploughshare once made, remains a plough- share, without any continuance of heating and hammering, and even after the man who heated and hammered it has been gath- ered to his fathers. On the other hand, the pressure which forces up the mercury in an exhausted tube must be continued in order to sustain it in the tube. This (it may be replied) is because another force is acting without intermission, the force of gravity, which would restore it to its level, unless counterpoised by a force equally constant. But again : a tight bandage causes pain, which pain will sometimes go off as soon as the bandage is removed. The illumination which the sun diffuses over the earth ceases when the sun goes down. " There is therefore a distinction to be drawn. The conditions which are necessary for the first production of a phenomenon, are occasionally also necessary for its continuance; but more com- monly its continuance requires no conditions except negative ones. Most things, once produced, continue as they are, until something changes or destroys them; but some require the perma- nent presence of the agencies which produced them at first. These may, if we please, be considered as instantaneous phenomena, requiring to be renewed at each instant by the cause by which they were at first generated. Accordingly, the illumination of any given point of space has always been looked upon as an in- stantaneous fact, which perishes and is perpetually renewed as long as the necessary conditions subsist. If we adopt this lan- guage, we are enabled to avoid admitting that the continuance of the cause is ever required to maintain the effect. We may say, it is not required to maintain, but to reproduce the effect, oi else to counteract some force tending to destroy it. And this may be a convenient phraseology. But it is only a phraseology. The fact remains that in some cases (though these are a minority) the con- Mr. Mill's Doctrine of Causation. 83 tinuance of the conditions which produced an effect is necessary to the continuance of the effect. " As to the ulterior question, whether it is strictly necessary that the cause, or assemblage of conditions, should precede, by ever so short an instant, the production of the effect (a question raised and argued with much ingenuity by a writer from whom we have quoted), we think the inquiry an unimportant one. There certainly are cases in which the effect follows without an interval perceptible to our faculties ; and when there is an interval, we cannot tell by how many intermediate lines imperceptible to us that interval may really be filled up. But even granting that an effect may commence simultaneously with its cause, the view I have taken of causation is in no way practically affected. Whether the cause and its effect be necessarily successive or not, causation is still the law of the succession of phenomena. Every- thing which begins to exist must have a cause; what does not begin to exist does not need a cause; what causation has to account for is the origin of phenomena, and all the successions of phenomena must be resolvable into causation. These are the axioms of our doctrine. If these be granted, we can afford, though I see no necessity for doing so, to drop the words ante- cedent and consequent as applied to cause and effect. I have no objection to define a cause, the assemblage of phenomena, which occurring, some other phenomenon invariably commences, or has its origin. Whether the effect coincides in point of time with, or immediately follows, the hindmost of its conditions, is immaterial. At all events it does not precede it ; and when we are in doubt, between two coexistent phenomena which is cause and which effect, we rightly deem the question solved if we can ascertain which of them preceded the other." ^ This admission cannot but be regarded as most damaging for the definition. Mr. Mill's confusion here arises from not having discriminated the various senses of the words cause and effect, and from not having dis- tinguished between matter, energy, persons, events, 1 Logic, pp. 247, 248. 84 Inductive Logic. states, and historical concatenations which are mere sequences of possibilities. The effects which Mr. Mill finds following their causes are states; the effects which are simultaneous with their causes are events. When a ball is struck, the motion of the bat passes into it; that effect is simultaneous. But the state of motion once begun continues indefinitely ; this effect there- fore follows its cause, the blow. Strictly speaking, the cause of an event cannot precede that event. Count Rumf ord existed, it is true, before his experiment ; and in that sense the cause preceded the effect. But, when living under the name of Benjamin Thompson in Con- necticut, he was in no proper sense the cause of the experiment years later in Munich. He might have been slain in the war of the Revolution and never have gone to Munich at all. He was not really the cause of the experiment until he performed it. Things exist permanently, and of course both precede and follow their effects. Particular events are always simultaneous with their causes, the things that react. States continue indefinitely after the events that intro- duce them. Events in history precede the events for which they open the way, and of which they are there- fore called the causes. Mr. Mill says: "The law of Causation, the recogni- tion of which is the main pillar of inductive science, is but the familiar truth that invariability of succession is found by observation to obtain between every fact in nature and some other fact which has preceded it." But this language is exceedingly liable to mislead a hasty reader into thinking that Mr. Mill means to say that each particular fact has some other particular fact Mr. Mill's Doctrine of Causation. 85 as its cause. " It is seldom, if ever, between a con- sequent and a single antecedent, that this invariable sequence subsists." In truth, the facts between which Mr. Mill asserts invariability of succession are states of the universe. "The cause," he says, "is the sum total of the conditions, positive and negative, taken together ; the whole of the contingencies of every description." "The state of the whole universe at any instant, we believe to be the consequence of its state at the previous instant." Mr. Mill understands his definition to mean that the cause is the sum total of the conditions "immediately, not remotely, preceding the effect." But it is hard to reconcile this interpretation with the explanations which place historical events among the antecedents. If taking mercury and subsequently being exposed to the air are among the conditions of a man's death, the cause cannot be the total of the immediately antecedent conditions. Mr. Mill escapes the difficulty by saying, that remote events are conditions of the conditions ; they are not the causes, but the causes of the causes ; or rather factors of the causes of factors of the cause. Mr. Mill felt that there must be something in causa- tion more than mere invariable succession. There must be something which other writers had attempted to express by the term necessity, and for this he 'selected the word unconditionalness . He says : — "Jf there be anything which confessedly belongs to the term necessity, it is uncojiditionalness. That which is necessary, that which 7nust be, means that which will be, whatever supposition we may make in regard to other things. The succession of day and night evidently is not necessary in this sense. It is conditional S6 Inductive Logic. on the occurrence of other antecedents. That which will be fol- lowed by a given consequent when, and only when, some third circumstance also exists, is not the cause, even though no case should ever have occurred in which the phenomenon took place without it." 1 Returning to the definition, we find the cause to be the antecedent or concurrence of antecedents, that is, a complex ; but a complex of what } Of conditions, all equally essential. It is the assemblage that constitutes the particular cause. When we are told that the con- sequent must be unconditionally consequent upon the assemblage of these conditions, what is that but to learn that the assemblage of conditions must lack no condition, that is, must be complete t What Mr. Mill wanted to say was that no superfluous circumstance, nothing that does not have some efficiency, must be counted among the conditions. But since, according to his doctrine, the cause, philosophically viewed, is the immediately previous state of the universe, and since inductive science knows nothing about efficiency, this is difficult to avoid. Let us revert, parenthetically, to the question whether day is the cause of night, and night the cause of day. This question illustrates the necessity of an analysis of terms before beginning to discuss about facts. All light is not day, nor is all darkness night. The darkness in the Mammoth Cave is not night, nor is the illumination of the cave, by the combustion of magnesium, day. A day is that portion of the sun's illumination which is cut off and individualized by two nights. As soon as this is stated, it is seen that night 1 Logic, p. 245. Mr. Mill's Doctrine of Causation. Sy is the cause of day. At the north pole there is but one day in the year, because there is but one night. But in what sense is night the cause of day ? It is not the efficient cause, nor the material cause, nor the conditional cause, but simply the historical cause. The event, an interruption of light by rotation, makes a possibility for a restoration of light by rotation. If one event did not occur, the other could not occur ; the occurrence of night is an essential condition of the occurrence of day. Mr. Mill holds that the actions of the Will are under exactly the same laws of causation as the reactions of matter. He says : — " The question, whether the law of causality applies in the same strict sense to human actions as to other phenomena, is the cel- ebrated controversy concerning the freedom of the will ; which, from at least as far back as the time of Pelagius, has divided both the philosophical and the religious world. The affirmative opinion is commonly called the doctrine of Necessity, as asserting human volitions and actions to be necessary and inevitable. The negative maintains that the will is not determined, like other phenomena, by antecedents, but determines itself ; that our volitions are not, properly speaking, the effects of causes, or at least have no causes which they uniformly and implicitly obey. " I have already made it sufficiently apparent that the former of these opinions is that which I consider the true one ; but the mis- leading terms in which it is often expressed, and the indistinct manner in which it is usually apprehended, have both obstructed its reception, and perverted its influence when received. The metaphysical theory of free will, as held by philosophers (for the practical feeling of it, common in a greater or less degree to all mankind, is in no way inconsistent with the contrary theory), was invented because the supposed alternative of admitting human actions to be necessary, was deemed inconsistent with every one's instinctive consciousness, as well as humiliating to the pride and 88 Inductive Logic. even degrading to the moral nature of man. Nor do I deny that the doctrine, as sometimes held, is open to these imputations ; for the misapprehension in which I shall be able to show that they originate, unfortunately is not confined to the opponents of the doctrine, but participated in by many, perhaps we might say by most of its supporters. " Correctly conceived, the doctrine called Philosophical Neces- sity is simply this : that, given the motives which are present to an individual's mind, and given likewise the character and disposi- tion of the individual, the manner in which he will act may be unerringly inferred ; that if we knew the person thoroughly, and knew all the inducements which are acting upon him, we could foretell his conduct with as much certainty as we can predict any physical event. This proposition I take to be a mere interpretation of universal experience, a statement in words of what every one is internally convinced of. No one who believed that he knew thoroughly the circumstances of any case, and the characters of the different persons concerned, would hesitate to foretell how all of them would act. Whatever degree of doubt he may in fact feel, arises from the uncertainty whether he really knows the circumstances, or the character of some one or other of the persons, with the degree of accuracy required ; but by no means from thinking that if he did know these things, there could be any uncertainty what the conduct would be. Nor does this full assurance conflict in the smallest degree with what is called our feeling of freedom. We do not feel ourselves the less free, because those to whom we are intimately known are well assured how we shall will to act in a particular case. We often, on the contrary, regard the doubt what our conduct will be, as a mark of ignorance of our character, and sometimes even resent it as an imputation. It has never been admitted by the religious philos- ophers who advocated the free-will doctrine, that we must feel not free because God foreknows our actions. We may be free, and yet another may have reason to be perfectly certain what use we shall make of our freedom. It is not, therefore, the doctrine that our volitions and actions are invariable consequents of our ante- cedent states of mind, that is either contradicted by our conscious- ness, or felt to be degrading. Mr. Mill's Doctrine of Causation. 89 "But the doctrine of causation, when considered as obtaining between our voHtions and their antecedents, is almost universally- conceived as involving more than this. Many do not believe, and very few practically feel, that there is nothing in causation but invariable, certain, and unconditional sequence. There are few to whom mere constancy of succession appears a sufficiently stringent bond of union for so peculiar a relation as that of cause and effect. Even if the reason repudiates, imagination retains, the feeling of some more intimate connection, of some peculiar tie, or mysterious constraint exercised by the antecedent over the consequent. Now this it is which, considered as applying to the human will, conflicts with our consciousness, and revolts our feelings. We are certain that, in the case of our volitions, there is not this mysterious constraint. We know that we are not compelled, as by a magical spell, to obey any particular motive. We feel, that if we wished to prove that we have the power of resisting the motive we could do so (that wish being, it needs scarcely be observed, a new antecedenf)^ and it would be humiliating to our pride, and paralyz- ing to our desire of excellence, if we thought otherwise. But neither is any such mysterious compulsion now supposed, by the best philosophical authorities, to be exercised by any cause over its effect. Those who think that causes draw their effects after them by a mystical tie, are right in believing that the relation between voHtions and their antecedents is of another nature. But they should go farther, and admit that this is also true of all other effects and their antecedents. If such a tie is considered to be involved in the word Necessity, the doctrine is not true of human actions ; but neither is it then true of inanimate objects. It would be more correct to say that matter is not bound by necessity, than that mind is so." ^ Mr. Mill escapes " the depressing effect of the fatalist doctrine " by saying that, while we must will as our character is, we can, if we desire, place ourselves in different circumstances, and these will work in us a different character, and then we shall will differently. 1 Logic, pp. 581, 582. 90 Inductive Logic. That is, our history having been what it has, we cannot will differently from what we do, but we can wish to will differently. But this is to suppose the same cause producing simultaneously a will in one direction and a wish in the other direction, — the same fountain send- ing forth sweet water and bitter. Mr. Mill says that "human actions are never ruled by any one motive with such absolute sway that there is no room for the influence of any other. The causes, therefore, on which an action depends are never uncontrollable." But it is precisely the characteristic of causation in physics that there is never an alternative unless some will intervenes. If human actions are never absolutely ruled by one motive, they differ from the reactions of matter, which are absolutely ruled in each case by one cause. The conviction made by a careful examination of Mr. Mill's doctrine of Causation is, that it lacks in clearness and self-consistency, and that it is an inadequate basis for the whole superstructure of Inductive Logic. CHAPTER XI. CANONS FOR ISOLATING FACTS OF CAUSATION. It is one task of Science, amid the crowd of phe- nomena, to distinguish between the coexistences ♦and successions which are accidental and those which rest upon real relations. For it is only by such knowledge that man can live among the terrific forces of nature and can make them the servants of his will. There are many groups of phenomena of which it may be known that when one is present, the others are present also. They are permanent coexistences. There are many events of which it may be known that when one has happened, the other or the others will be sure to follow. There is said to be a relation of causation between them. We have already, at great length, dis- cussed the word cause. An event is the reaction of certain substances and energies in a certain collocation. The reaction by which this collocation arose, or any previous reaction in the long line of history, is an his- torical cause of the event. This total of things, including the collocation, which is their mutual relation in space, and including their history in time, may be called the Comprehensive Cause of the event, and also of the things in their states after the event. ' Events are the actions of things. But every action is a reaction. This is a primary induction which men were long in making. The law of inertia, that every body remains in its state of rest or motion until acted g2 Inductive Logic. upon, is a subordinate generalization: the wider law is that it takes at least two to make, not only a bargain or a quarrel, but anything. This is often what is understood to be meant by the law of causation; and it seems to be regarded as intuitively known. But it is really an induction. If we can isolate two things so that we are sure that no third is present, and if then an event occurs, we are sure that it is a reaction between those two things. When a bit of glowing iron is lowered into a jar of oxygen and vivid combustion follows, we are sure that the iron and the oxygen are reacting; those two things are the sole material causes of the event. When a feather and a gold coin are supported in an exhausted receiver and then by the turn of a screw are left unsupported, we know that they are free from all particular influences and are reacting with the general mass of things as a whole : the fall therefore is caused by that reaction alone. This general reaction is called gravitation. It is plain that the presence of a third thing destroys the isolation and leaves us in doubt. The combustion of a bit of iron in common air, where nitrogen is present, could not be known, without investigation, to be a reaction of the iron and oxygen alone. It might be a mutual reaction of all three or a reaction of the iron and the nitrogen. But so crowded is the world with things, and so multitudinous are their reactions, that it is a rare good fortune to be able mechanically to separate a pair or a group of reagents. What cannot be done physically must be done in thought. We must make a mental elimination, or Cations for Isolating Facts of Causation. 93 perhaps a series of eliminations, and thus discover the various reagents that enter into the comprehensive cause of any event that may be in question. These eliminations are made in thought by the process of subtraction. Canon First. FOR ISOLATING FACTS OF CAUSATION BY THE TEST OF DIFFERENCE. In any two instances^ the circumstances which are not common are the causes of the events which are not common. This brief and general language requires explanation. By an instance is meant any group of phenomena which may be under investigation. By a circumstance is meant a substance, an energy, a will, a collocation, or a previous event. Consequently the cause dis- covered may be the material cause, the energetic cause, the conditional cause, the volitional cause, or the his- torical cause — the mere occurrence of the possibility of the reaction of the efficient causes. What is dis- covered is far more likely to be merely one factor of one of these causes than to be the whole of it ; there- fore, to avoid the tediousness of constantly saying "at least a part of one of the causes," we will adopt the name Empirical Cause. The circumstance dis- covered by this method is what ordinary experience leads unscientific people to speak of as the cause; and this crude use of experience is what is called empiricism. The validity of this canon is obvious. Since events are the reactions of things, whatever is different in the 94 Inductive Logic. events must come from differences in the things, or in their collocations, which afford the possibilities of reaction. But differences in collocation arise through events. Thus the whole of the differences in two groups of phenomena must be accounted for by the things, their collocations, and their history. Let us consider a concrete example. In a dark room some one touches a button, and immediately a brilliant illumination follows. There are here two instances, the room in darkness and the room illuminated. Viewed historically, the difference in circumstances is that the one instance includes the previous event of the touch of the button and the other does not. The touch of the button is therefore the historical cause of the illumination. But leaving out of view the history, it will be found that the two instances differ in the col- location of things. In the one case materials are so disposed that there is no continuous circuit for the electricity and in the other case there is a continuous circuit. Here is found the conditional cause. Fur- ther, the two instances differ, in that in one the electricity passes and in the other it does not ; hence we discover the energetic cause, which is the elec- tricity. By thus confining the attention successively to the history, the materials, the energy, or the con- ditions, the several kinds of cause may be elicited. Under this canon four cases may arise: — ^" Case I. On striking the balance between circum- stances and events in the two instances, a single circumstance and a single event may be left, hot com- mon to both instances. If so, that circumstance is manifestly the empirical cause of that event. If, for Canons for Isolating Facts of Causation. 95 example, into a glass containing some dilute sulphuric acid a few bits of marble be dropped, vigorous ebul- lition will ensue. The glass containing the acid, as it was before the dropping in of the marble, constitutes one instance; the same glass containing the marble in addition to the acid constitutes the second instance. Historically viewed, the only difference is that the one instance includes the previous event of the dropping in of the bits of marble; this therefore is the historical cause. But viewed materially, the sole difference is in the bits of marble, which were absent at first and afterwards present. The marble is therefore the material cause of the ebullition. But it is only the empirical material cause; it is not the comprehensive material cause, for in that the acid is as important a factor as the marble. When there are a number of things present and a new factor is introduced, we can- not tell by a single application of the canon how many of them co-operate with that new factor in a new com- prehensive cause. Case 2. On striking the balance, a group of circum- stances and a group of events may be left not common to the two instances. If so, those circumstances are the empirical causes of those events, but which are the causes of which, can be ascertained only by a further application of the canon to simpler instances. For example, Daniel Webster left the paternal farm and, after spending four years in Dartmouth College, graduated as an accomplished orator. The two instances are Webster without education and without eloquence, and Webster after his college education, delivering some eloquent oration. The two instances 96 Inductive Logic. differ in the group of circumstances constituting a college education. But this group is very complex, so that, while it is plain that among the circumstances are included the empirical causes of polished eloquence, it is not plain whether any particular circumstance, as the study of the Greek and Roman classics, was in any sense a cause. Indeed, it may have been a hindrance. Case J. On striking the balance, the difference may be found to be, that in the first instance there is more of one circumstance and more of one event than in the second instance. This case is but a variety of the first ; for an additional quantity is a new circumstance or a new event. For example, a youth ambitious for athletic honors may, by careful training, wonderfully increase his muscular strength. He has always taken some care of his health, and a little natural superiority may be that which awakens his ambition ; but with more care comes more power. Here the added care is a new circumstance and the addition of strength is a new event. Case /f.. On striking the balance, the difference may be found to be that in the first instance there is more of several circumstances and more of several events, the kinds remaining unchanged. This is merely a variety of Case 2 ; for the new quantities are new circumstances and new events. For example, after taking the Bachelor's degree, one may go on another year and take the Master's degree. He will become a more learned person, but we do not know any better than before, which of his studies have contributed to the group of results included in an education. Canons for Isolating Facts of Causation. 97 These four cases may be expressed in symbols as follows : — I. ABC def 2. ABCD efgh 3. AABC ddef 4. AABCDD efghh BC ef BC fg ABC def ABCD efgh A d A D e h A d A D e h Let capital letters represent circumstances and small letters represent events. On striking the bal- ance in Case i, the single circumstance A and the single event d are found not common. Since what is not common in the events must be owing to what is not common in the circumstances, A must be the empirical cause of d. In Case 2, A and D are not common among the circumstances, and e and h are not common among the events. A and D include, there- fore, the causes of e and h; but which is the cause of which, or whether one is inert and the other is the cause of both events, we cannot say. We must find another instance presenting A without D before we can make a further isolation. Case 3 gives the same result as Case i, and Case 4 gives the same result as Case 2. In the first case, as soon as we find the instance ABC def, we know that those circumstances are the causes of those events; for, unless we are sure that there are no other significant circumstances and events, we have not found the instance at all. Just so, as soon as we find the instance BC ef, we know that those circumstances are the causes of those events. We make these affirmations on the basis of the primary induction that all of the events in the world are the reactions of things in the collocations which permit those reactions. Therefore we know that A, the 98 Inductive Logic. circumstance in which the two instances differ, is the empirical cause of dy the event in which they differ. But it often happens that we can find no single instance BC ef, although we may know from previous observations that B is the cause of e and that C is the cause of /. This makes no difference in the reasoning or in the result. However the knowledge that B and C cause e and / has been obtained, we make the same use of it ; we subtract from the totals in the first in- stance those circumstances and events whose relations are already known, and the remaining circumstances and events are then known to be mutually related, or we know at least that among the circumstances are the causes of all the events not common. The same remark may be made mutatis mutandis of the three other cases. From the establishment of a single fact of causation we pass easily to a generalization. The primary inductions, that things persist, and that the qualities of things persist, are already made. What a thing causes once, it always causes under the same conditions. Therefore, after isolating a single fact of causation, we are warranted in the secondary induction, that the cir- cumstance, under the same conditions, will always cause the given event. The test of difference, when two good instances can be found or artificially produced, is quick and decisive. In the experiment of Count Rumford, it was easy to compare the apparatus when the water was cold and when the water was hot. It was easy also to see that the only circumstance in which the two instances differed was the motion of the cylinder. The event. Canons for Isolating Facts of Causation. 99 the heating, was therefore undoubtedly attributable to that circumstance as empirical cause. But it is not always possible to apply this canon, and then our only resource is one far less satisfactory. Canon Second. FOR ISOLATING FACTS OF CAUSATION BY THE TEST OF A GREEMENT. If in two instances the same event occurs, the common circumstances probably include the cause ; and the proba- bility rapidly increases with the member and variety of the instances. The word cause here still means merely empirical cause. Inexact as this test is, it is often our only expe- dient, and with care it is highly useful. For example, if twice after the imposition of a protective tariff, business is seen to flourish, a slight probability arises that the tariff is the cause of the prosperity. Yet there is a possibility in each case that some other circumstance, as unusual harvests, or discoveries of rich deposits of the precious metals, may have been the cause. Indeed, the only effect of the tariff may have been to diminish somewhat each time the total prosperity. But every instance in which a tariff is accompanied by prosperity rapidly increases the probability of a genetic connec- tion ; since otherwise we must suppose the fortuitous occurrence of some other beneficent cause every time Congress happens to be in favor of protection. The argument from the test of agreement often seems stronger than it is, from our unconsciously blending it with the argument from the test of differ- lOO IndtLctive Logic. ence. In the case of prosperity after the imposition of a tariff, we naturally compare the country as it was before the tariff and as it was soon after, and thus apply the test of difference ; but this gives to the argu- ment from agreement an appearance of strength not its own. It must be observed that, in the canon, the common circumstances are said simply to include, not necessa- rily all to be, the cause. The ashes of seaweeds were long known to possess valuable medicinal powers. The use of them in certain diseases was followed by beneficial effects. But it was not known which of the ingredients was efficient or whether all were efficient ; all were common circumstances, but some might be always inert, and some might even be obstructive. Later it was discovered that the useful substance was nothing but iodine ; the other things were better away. As an illustration of how the test of agreement may be applied, with some admixture of the test of differ- ence, we will quote an eloquent passage from Schiller's y^sthetical Essays : — " It is certainly a matter entitled to reflection that, at almost all the periods of history when art flourished and taste held sway, humanity is found in a state of decline ; nor can a single instance be cited of the union of a large diffusion of aesthetic culture with political liberty and social virtue, of fine manners associated with good morals, and of politeness fraternizing with truth and loyalty of character and life. As long as Athens and Sparta preserved their independence, and as long as their institutions were based on respect for the laws, taste did not reach its maturity, art remained in its infancy, and beauty was far from exercising her empire over minds. No doubt, poetry had already taken a sublime flight, but it was on the wings of genius, and we know Canons for Isolating Facts of Causation. loi that genius borders very closely on savage coarseness, that it is a light which shines readily in the midst of darkness, and which, therefore, often argues against, rather than in favor of, the taste of the time. When the golden age of art appears under Pericles and Alexander, and the sway of taste becomes more general, strength and liberty have abandoned Greece ; eloquence corrupts the truth, wisdom offends it on the lips of Socrates, and virtue in the life of Phocion. It is well known that the Romans had to exhaust their energies in civil wars, and, corrupted by Oriental luxury, to bow their heads under the yoke of a foreign despot, before Grecian art triumphed over the stiffness of their character. The same was the case with the Arabs : civihzation only dawned upon them when the vigor of their military spirit became softened under the Abbassides. Art did not appear in modern Italy till the glorious Lombard league was dissolved, Florence submitting to the Medici, and all those brave cities gave up the spirit of independence for an inglorious resignation. It is almost superfluous to call to mind the example of modern nations, with whom refinement has increased in direct proportion to the decline of their liberties. Wherever we direct our eyes in past times, we see taste and free- dom mutually avoiding each other. Everywhere we see that the beautiful only founds its sway on the ruins of heroic virtues." ^ Under this canon three cases may arise, represented by symbols as follows : — I. ABC def 2. ABC def 3. ABC def APE dgh ABE deg AFG deh A d AB de A de In the first case there is one common event and one common circumstance. In the second case there is a group of common events and a group of common cir- cumstances. In the third case there is a single common circumstance but a group of common events. This third case suggests a remark, vi^hich should be made also regarding the others. A serious element of ^ Bohn's Trans., p. 55. 102 Inductive Logic. uncertainty weakens the test of agreement, and that is what is called the Plurality of Causes. What is appar- ently the same event may be caused by different things. Light -may be made by electricity or by com- bustion. The canon asserts no more than that the common circumstances probably include the cause. Even in Case i, A^ the only common circumstance, may not be the cause of Z- misses sequence, 108. on the will, 87. on the root of the theory of induction, 47. vagueness of his canons, 107. mental characteristics, 32. Mill and river, 16. Minto, 31, quoted, 33, 116, 167. Mistake in area, 1 59. Mistake in isolation, 160. Mixed inductions, 14, 36. Motion, laws of, 160. Murray on coral islands, 123. Mutuality of cause and effect, 163. Natural kinds, 48. Negative cause, 70. Neglect of negative instances, 1 54. Neptune, 120. Newton's discoveries, 36. Night the cause of day, 86. Nomenclature, 53. Non-observation, 150. Noun or verb the cause, 109. Observation, 9. characteristic of induction, 9. contrasted with experiment, 10. Occasional cause, 68. Opium, 43. Partial observation, 154. Perceptions confused with infer- ences, 12. Planets, 22. Plurality of causes, 102. Poppies, 159. Pottery, 42. Post hoc, ergo propter hoc, 162. Prejudice, 150. Present tense, 15. Primary inductions, 14, 20, 29. Primary rule for inductive thinking, II. Probable evidence, 129. Problem of induction solved, 39. Pure inductions, 14. Pure sciences, 2. Reid on Bacon, 165. Relevancy, 142. 174 Index. Resemblance, facts of, 7, 41. Residue, same as difference, 106. Residues, method of, 104. Rodwell quoted, 162. Rubidium, 28, 39. Rumford quoted, 56. his experiment discussed, 59. Root of the theory of induction, 47. Secondary inductions, 28. Scheiner, 154. Schiller quoted, 100. Ship and iceberg, 119. Solidification and crystallization, 109. Socrates, 29. Species, 49. Agassiz on, 51. Darwin on, 51. De Candolle on, 51. Gray on, 49. States, d"]. Stephen quoted, 139, 142. Stewart on observation, 13. Substantive facts, 6.' Succession confused with cau- sation, 56, 72. Succession, facts of, ']2, Swans, 38. Symbols under Canon First, 97. under Canon Second, loi. Siphon, 66. Tariff, 99. Taste and freedom, 100. Terminology, 53. Testimony, 139. Theory, 115. Things causes of events, 64. causes of things, 64. Touching a button, 94. Trees, longevity of, 130. Trials at law, 139. Ultimate laws, 25. properties, 55. Unconditionalness, 85. Uniformities, how discovered, 15. Uniformity of nature, 19, 33, 41, 42. Uniformity not in course of events, 20. Unknown not discovered by rea- soning, 3. Vagueness of Mill's canons, 107. Van Helmont's experiment, 161. Varying the circumstances, 161. Vera causa, 118. Veracity of God, 17. Verb defined, 157. Verification, 136. Vesuvius, 25. Village matron, 33, 34. Volitional cause, 62. Weather on Lake Erie, 26. signs of, 157. Webster, 95. Whately quoted, 4. on induction, 30, 31. Whewell on Greek philosophy, 125. Will and wish, 90. Willow, 162. Wooden arrows, 152. Wright quoted, 133. ADVERTISEMENTS PHILOSOPHY. Empirical Psychology ; or, The Human Mind as Given in Consciousness. By Laurens P. Hickok, D.D., LL.D. Revised with the co-operation of Julius H. Seelye, D.D., LL.D.; Ex-Prest. of Amherst College. 12mo. 300 pages. Mailing Price, $1.25; Introduction, $1.12. nnUE publishers believe that this book will be found to be re- markably comprehensive, and at the same time compact and clear. It gives a complete outline of the science, concisely pre- sented, and in precise and plain terms. It has proved of special value to teachers, as is evidenced by its recent adoption for several Reading Circles. College, 0. : This new edition may be confideutly recommended as pre- senting a delineation of the mental faculties so clear and accurate that the careful student will hardly fail to recognize its truth in his own ex- perience. Jolm Bascom, formerhj Pres. Uni- versity of Wisconsin, 3'Iadison : It is an excellent book. It has done much good service, and, as revised by President Seelye, is prepared to do much more. I. W. Andrews, formerly Prof, of Intellectual Philosophy , Marietta Hiclioli's lUoral Science. By Laurens P. Hickok, D.D., LL.D. Eevised with the co-operation of Julius H. Seelye, D.D., LL.D., Ex-Prest. of Amherst College. 12mo. Cloth. 288 pages. Mailing Price, $1.25; Introduction, $1.12. A S revised by Dr. Seelye, it is believed that this work will be -^ found unsurpassed in systematic rigor and scientific precision, and at the same time remarkably clear and simple in style. G. P. Fisher, Prof, of Church His- tory, Yale College : The style is so perspicuous, and at the same time so concise, that the work is eminently adapted to serve as a text-book in colleges and higher schools. In mat- ter and manner it is a capital book, and I wish it God speed. 146 PHILOSOPHY. Lotze's Philosophical Outlines. Dictated Portions of the Latest Lectures (at Gottingen and Berlin) of Hermann Lotze. Translated and edited by George T. Ladd, Pro- fessor of Philosophy in Yale University. 12nio. Cloth. About 180 pages in each volume. Mailing price per volume, $1.00; for introduc- tion, 80 cents. rpHE Outlines give a mature and trustworthy statement, in language selected by this teacher of philosophy himself, of what may be considered as his final opinions upon a wide range of subjects. They have met with no little favor in Germany. These translations have been undertaken with the kind permis- sion of the German publisher, Herr S. Hirzel, of Leipsic. Ouilines of Metaphysic. This work consists of three parts — Ontology, Cosmology, Phenomenol- ogy. The first part contains chapters on the Conception of Being, the Content of the Existent, Reality, Change, and Causation ; the second treats of Space, Time, Motion, Matter, and the Coherency of Natural Events; the third, of the Subjectivity and Objectivity of Cognition. Outlines of the Philosophy of Religion. Lotze here discusses the Proof for the Existence of God, the Attributes and Personality of the Absolute, the Conceptions of the Creation, the Pre- servation and the Government of the World, and of the World-time. Outlines of Practical Philosophy. This contains a discussion of Ethical Principles, Moral Ideals, and the Freedom of the Will, and then an application of the theory to the Indi- vidual, to Marriage, to Society, and to the State. Many interesting remarks on Divorce, Socialism, Representative Government, etc., abound throughout the volume. Outlines of Psychology. The Outlines of Psychology treats of Simple Sensations, the Course of Representative Ideas, of Attention and Inference, of Intuitions, of Objects as in Space, of the Apprehension of the External World by the Senses, of Errors of the Senses, of Feelings, and of Bodily Motions. Its second part discusses the nature, position, and changeable states of the Soul, its rela- tions to time, and the reciprocal action of Soul and Body. Outlines of /Esthetics. The Outlines of Esthetics treats of the theory of the Beautiful and of Phantasy, and of the Realization and Different Species of the Beautiful. Then follow brief chapters on Music, Architecture, and Poetry. Outlines of Logic. This discusses both pure and applied Logic. The Logic is followed by a brief treatise on the Encyclopaedia of Philosophy, in which are set forth the definition and method of Theoretical Philosophy, of Practical Phi- losophy, and of the Philosophy of Religion. This volume makes an admirable brief text-book in Logic. PHILOSOPHY. 147 Our Notions of Number and Space. By Herbert Nichols, recently Instructor in Psychology in Harvard University. Assisted by William E. Parsons. 12mo. Cloth, vi + 201 pages. Mailing price, $1.10; for introduction, $1.00. n^HIS book is an experimental contribution to the Genetic Theory of Mind. It seeks to trace out the origin and development of our present perceptions — particularly those of ^Number and of Space — from the nature of our past experiences. Our experiences vary, for different regions of our limbs and body, according to their anatomy and use. Our perceptions of the same outer facts vary according to the regions which mediate them. The present work by coupling these two truths, and studying the parallel variations in each topographically, seeks to determine the intimate nature of perceptions and judgments in general. The Philosophical Review, A Bi-monthly Journal of General Philosophy, Edited by J. G. Schurmak, Dean of the Sage School of Philosophy and President of Cornell University, and J. E. Creighton, Associate Pro- fessor of Modern Philosophy in Cornell University. Subscription price, $3.00. Single copy, 75 cents. Foreign Agents : Great Britain, Edward Arnold, London ; Germany, Mayer & Miiller, Berlin ; France, E. Leroux, Paris ; Italy, E. Loescher, Rome. rpHE PHILOSOPHICAL REVIEW is intended as an organ for the publication of the results of investigation in every branch of Philosophy. It is made up of original articles, reviews of books, and classified summaries of periodical literature. All articles will Tae signed, and the writers alone will be responsible for their con- tents. Its domain is the still unoccupied field of General Philosophy ; that whole which includes, along with the older subjects of Logic, Metaphysics, and Ethics, the newer subjects of Psychology, Esthetics, Pedagogy, and Epistemology, both in their systematic form and in their historical development. Its field is as broad as mind. The Review aims to combine an impartiality and catholicity of tone and spirit. It will not be the organ of any institution, or of any sect, or of any interest. 148 PHILOSOPHY. A Brief History of Greek Philosophy. By B. C. Burt, M.A., formerly Decent of Philosophy, Clark University. 12mo. Cloth. xiv+ 296 pages. Mailing price, $1.25; for introduction, $1.12. ^HIS work attempts to give a concise but comprehensive account of Greek Philosophy. It is critical and interpretative, as well as purely historical. The volume contains a full topical table of contents, a brief bibliography of the subject it treats, and numerous foot-notes. G. Stanley Hall, President of Clark University , Worcester, Mass.: His book is the best of its kind upon the subject. W. T. Harris, U. S. Commissioner of Education : I have found this work in philosophy to possess high merit. His grasp of the history of the subject is rare and trustworthy. The Modalist: or, ne Laws of Rational conviction. A Text-Book in Formal or General Logic. By Edward John Hamil- ton, D.D., formerly Albert Barnes Professor of Intellectual Philosophy, Hamilton College, N.Y. 8vo. Cloth. 337 pages. Mailing price, $1.40; for introduction, $1.25. ^HIS book restores modal propositions and modal syllogisms to the place of importance which they occupied in the Logic of Aristotle. Mechanism and Personality . By Francis A. Shoijp, D.D., Professor of Analytical Physics, Univer- sity of the South. 12mo. Cloth, xvi + 341 pages. Mailing price, $1.30; for introduction, $1.20. nnHIS book is an outline of Philosophy in the light of the latest scientific research. Its object is to help the general reader and students of Philosophy find their way to something like definite standing-ground among the uncertainties of science and metaphysics. It begins with physiological psychology, treats of the development of the several modes of personality, passes on into metaphysic, and ends in ethics, following, in a general way, the thouQ'ht of Lotze. George Trumbull Ladd, Professor of Philosophy, Yale University: I find it an interesting and stimulating little book. Written, as it is, by one whose points of view are somewhat outside of those taken by profes- sional students of philosophy, it is the fresher and more suggestive on that account. PHILOSOPHY. 149 ETHICAL SERIES. UNDER THE EDITORIAL SUPERVISION OF Professor E. Hershey Sxeath of Yale University. T^HE primary object of the series is to facilitate the study of the History of Ethics in colleges. This History will be in the form of a series of small volumes, each devoted to the presentation of a representative system of JModern Ethics in selections from the original works. The selections will be accompanied by notes, and prefaced by a brief biographical sketch of the author, a statement of the relation of his system to preceding and subsequent ethical thought, a brief exposition of the system, and a bibliography. All teachers will doubtless concede the advisability of placing original works in the hands of students instead of mere expo- sitions — such as are contained in the various Histories of Ethics. In a number of instances, however, the original editions are exhausted, and only a few copies are available ; and, in other instances, the books are too elaborate and expensive, if a number of systems are to be studied. The series will make provision for these difficulties by presenting each system in carefully edited extracts, and in a form which will entail comparatively little expense upon the student. See also the Announcements. The Ethics of Hume. By Dr. J. H. Hyslop, of Columbia College. 12ino. Cloth. 275 pages. Mailing price, $1.10 ; for introduction, $1.00. rPHE present volume contains the whole of the third book of the Treatise of Human Nature, and such portions of the second book as throw light upon or are connected with Hume's moral theory. The analysis and criticism of his system follows lines somewhat different from that of Green, and are designed to present Hume in another light. In all respects it is hoped that the volume may prove helpful to those who wish to study the ethical system of Kant's predecessor. 150 PHILOSOPHY. The Ethics of Hegel, Translated Selections from his "Rechtsphilosophie." With an Intro- duction by J. Macbride Stkrrett, D.D., Professor of Philosophy in the Columbian University, Washington, D.C. 12mo. Cloth, xii-i-216 pages. Mailing price, $1.10 ; foy introduction, $1.00. rpHE great revival of interest and work in the department of Ethics during the present quarter of a century has had its chief inspiration and source in the idealistic philosophy of Ger- many. Of this philosophy Hegel was the culmination and crown. Apart from the empirical evolutionary school, nearly all the prominent writers on Ethics in England have been following quite the spirit and substance of Hegel. These " Selections " have been made from his Philosophie des Mechts, embracing one-half of its contents, supplemented with some extracts from his Plidnomenologie des Geistes, Philosophie des Geistes and his Philosophy of Plistory (translation). E. H. Capen, President of Tufts College : I feel certain it is a contri- bution to the department of ethical studies. I expect to find it useful in my own classes. G. B. Newcomb, Professor of Mental Science in the College of the City of New York : Its value for students is much enhanced by the clear and readable introduction. The Psychic Factors of Civilization. Department of Special Publication. — By Lester F. Ward. 8vo. Cloth. XX 4- 369 pages. By mail, postpaid, $2.00. T^HIS work is an original contribution to both psychology and sociology, and is, in fact, a combination of these two depart- ments of science. It is the first attempt that has been made to show in a systematic and fundamental way the workings of mind in social phenomena. 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