/ t- GREEK FORESHADOWING^ OF MODERN METAPHYSICAL AND EPISTEMOLOGICAL THOUGHT BY LILLIAN KUPFER (A Thesis accepted for the Degree of Doctor of Philosophy in New York University, 1901) O O > 3 PRINTED BY J. S. CUSHLNG & CO. NORWOOD, MASS. 1901 U 1 The library of CONGRESS, Two Copies Received DEC, 1 1901 CWVRKJHT ENTRY CLASS Ou XXa No. i_ 2_ ^ v r^ copy a Copyright, 1901, By LILLIAN KUPFER. *3 CONTENTS PAGE Bibliography . 5 Introduction I. THE ESSENCE OF THINGS Conceptions of Ionians, Pythagoreans, Parmenides, Heraclitus, Em- pedocles, Anaxagoras, Leucippus and Democritus, Plato, Aris- totle, Stoics, Epicureans, and Skeptics .... v . 9 Comparisons with modern views, particularly those of Kepler, Gali- leo, Hobbes, Descartes, Spinoza, Berkeley, Leibniz, Fichte,,.-. Schelling, Hegel, Herbart, Lotze, and the Physicists -'*' . 13 II. THE WORLD GROUND Conceptions of Xenophanes, Heraclitus, Anaxagoras, Plato, Aris- totle, Stoics, Epicureans, Skeptics, and Neoplatonists . . 19 Comparisons with modern theism, pantheism, and atheism, and in particular with the views of Spinoza, Leibniz, Kant, Schelling, Hegel, and Spencer • . .25 III. SPACE AND TIME Conceptions of Parmenides, Zeno, Plato, Aristotle, and Epicureans 30 Comparisons with modern views as represented by Berkeley, Leibniz, Kant, Lotze, and Bowne 32 IV. CONCEPTIONS OF EVOLUTION Views of Ionians (especially Anaximander) , Heraclitus, Empedo- cles, Anaxagoras, Leucippus and Democritus, Plato, Aristotle, Stoics, and Epicureans 33 Comparisons with modern ideas, especially those of Leibniz, Darwin, Spencer, and the purely mechanical theories of evolution . . 36 3 CONTENTS V. CONCEPTIONS OF CAUSALITY PAGE Views of Ionians, Pythagoreans, Eleatics, Heraclitus, Empedocles, Anaxagoras, Protagoras, Democritus, Plato, Aristotle, Stoics, Epicureans, and Skeptics, (especially Aenesidemus) ... 39 Comparisons with modern ideas, particularly those of Bacon, Gali- leo, Hobbes, Descartes, Spinoza, Leibniz, Hume, Kant, Fichte, Schelling, Hegel, Positivists, Spencer, Lotze, Bowne, and Bradley 45 v VI. THE RELATION OF THOUGHT TO ITS OBJECT Epistemological views of Heraclitus, Parmenides, Zeno, Empedocles, Anaxagoras, Protagoras, Socrates, Democritus, Plato, Aristotle, Stoics, Epicureans, and Skeptics 49 Comparisons with ideas of modern philosophers, in particular those of Galileo, Hobbes, Descartes, Spinoza, Locke, Berkeley, Leib- niz, Wolff, Hume, Kant, Fichte, Positivists, Mill, Lotze, and Spencer 56 Conclusion 63 BIBLIOGRAPHY Aristotle Berkeley, George . Bowne, Borden P. . Bradley, F. H. . . . Bywater, I Descartes, Rene" . . Erdmann, J. E. . . Fairbanks, Arthur Falckenberg, Richard. Hegel, G. W. F. Hume, David Kant, Immanuel Ladd, J. Trumbull Lassalle, Ferd. . Leibniz, G. W. . Locke, John . . Metaphysics. Translated by John H. M'Mahon. London. 1891. Organon. Oxford. 1837. Physics. Translated by Thomas Taylor. Lon- don. 1806. Works. Edited by A. C. Fraser. 4 vols. Ox- ford. 1871. Metaphysics. New York. 1898. Theory of Thought and Knowledge. New York. 1899. Appearance and Reality. London. 1897. Heracliti Ephesii Reliquiae. Oxford. 1877. The Method, Meditations, and Principles. Trans- lated by John Veitch. Edinburgh. 1890. A History of Philosophy. 3 vols. London. 1891. The First Philosophers of Greece. New York. 1898. History of Modern Philosophy. Translated by A. C. Armstrong. New York. 1893. Logic. Translated by William Wallace. Ox- ford. 1892. Philosophy of Mind. Translated by William Wallace. Oxford. 1894. Vorlesungen tiber die Geschichte der Philosophic 3 vols. Berlin. 1833-1836. An Enquiry concerning the Human Understand- ing. Oxford. 1894. A Treatise on Human Nature. 2 vols. London. 1878. Critique of Pure Reason. Translated by Max Muller. New York. 1896. Philosophy of Knowledge. New York. 1897. Die Philosophic Herakleitos des Dunklen von Ephesos. 2 vols. Berlin. 1858. La Monadologie ; Nouveaux Essais. Paris. 1846. Essay on Human Understanding. 3 vols. Lon- don. 1812. 5 BIBLIOGRAPHY Lotze, Hermann Lucretius Cams, T Mill, John Stuart Mullach, F. W. A. Patrick, G. T. W. Patrick, Mary M. Plato .... Schleiermacher, Fr Spencer, Herbert Spinoza, B. de Ueberweg, Fr. Watson, John Weber, Alfred Windelband, W Zeller, E. Metaphysic. Edited by B. Bosanquet. 2 vols. Oxford. 1887. De Rerum Natura. rec. H. A. J. Munro. Cam- bridge. 1860. Examination of Sir William Hamilton's Philoso- phy. 2 vols. Boston. 1866. Eragmenta Philosophorum Graecorum. 3 vols. Paris. 1860, 1867, 1881. The Fragments of the Work of Heraclitus on Nature. Baltimore. 1889. Sextus Empiricus and Greek Skepticism. Cam- bridge. 1899. Dialogues. Translated by B. Jowett. 4 vols. New York. 1871. Herakleitos der Dunkle von Ephesos. Berlin. 1838. First Principles. New York. 1888. Ethics. Translated by R. H. M. Elwes. Lon- don. 1891. History of Philosophy. Translated by George S. Morris. 2 vols. New York. 1872 and 1874. Schelling 1 s Transcendental Idealism. Chicago. 1892. History of Philosophy. Translated by Frank Thilly. New York. 1897. A History of Philosophy. Translated by James H. Tufts. New York. 1893. A History of Greek Philosophy to the Time of Socrates. Translated by S. F. Alleyne. 2 vols. London. 1881. Socrates and the Socratic Schools. Translated by 0. J. Reichel. London. 1877. Plato and the Older Academy. Translated by S. F. Alleyne and Alfred Goodwin. London. 1876. Aristotle and the Earlier Peripatetics. Trans- lated by Castelloe and Muirhead. 2 vols. London. 1897. The Stoics, Epicureans, and Sceptics. Trans- lated by 0. J. Reichel. London. 1892. A History of Greek Eclecticism. Translated by S. F. Alleyne. London. 1881. INTRODUCTION One of the first and most urgent tasks of philosophy is the endeavor to discover beneath the ceaseless flux of things in common experience some immutable foundation. Does the history of philosophy itself, amid its ever-changing systems, bring to view any abiding principles, or must we regard it simply as a record of arbitrary standpoints assumed without sufficient reason and severally abandoned? Does each new system, discarding all the labors of its predecessors, start afresh in its attempt to explain the mysteries of the universe or is the new philosophy a development and consummation of the old? These questions must be faced by every student of the his- tory of philosophy. If the earlier systems are to be entirely repudiated and only the latest products of speculation admitted within the province of validity, then indeed must philosophy be condemned as the most futile of sciences and its objects be acknowledged as forever unattainable. To save philosophy from this reproach, we must find in it some permanent elements which persist amid its changes. Such abiding principles reveal themselves in certain funda- mental conceptions which, originating with the earliest philoso- phers, have appeared again and again in the history of thought, at [each revival in more definite form. To the objection that not one, but many and apparently opposing views of the world have been revived, we may answer that the impulses which at one time drive to the front one of these fundamental views and at another time another, may be explained by recognizing the fact that the spirit of the times, the state of culture, the social and political condition, and the aims, convictions, and 7 8 INTRODUCTION ideals of the people through whom a system of philosophy- receives its expression form a vital factor in the evolution of its type, while the special interest or personality of the repre- sentative individual thinkers — another important factor — accounts for the contemporaneous appearance of systems which approach the ever-recurring problems of philosophy from oppo- site standpoints. But, since the opposing theories often reveal, on closer analysis, agreements as striking as are their differ- ences, we may come to realize the fact that in the midst of many errors these rival systems all present some aspect of the truth. The purpose of this paper is to point out some of the endur- ing features of philosophy by calling attention to certain approximations of Greek conceptions to modern speculative thought. We shall try to show that many germs of truth which for ages lay inert have revealed their fructifying power when stirred to renewed life and activity by some philosophic demand similar to that to which they owed their origin; and that the forms in which the fundamental problems of philoso- phy present themselves to the human mind, as well as the general direction by which their solution is approached, have, in the course of history, undergone no change so radical as to debar us from attributing to them some elements of permanent validity. In order to keep the paper within proper bounds, no com- parison will be attempted in the field of ethics, psychology, or sociology, the scope of the treatment being limited, as the title suggests, to the most important problems of metaphysics and epistemology. THE ESSENCE OF THINGS The unreflecting mind accepts things as they appear, with- out question as to their origin or comment on their mutability. When the development of life, the movement of the heavenly bodies, the composition and dissolution of objects, and the countless phenomena of nature press for explanation, then, however crude may be the attempted solution of the problem, the first step has been taken in the direction of a philosophy. For a time further inquiry is silenced by the theory that super- natural beings are responsible for all such manifestations, but soon the spirit of investigation awakes in an effort to find some ultimate abiding principle from which may be directly deduced the changing phases of nature. It is at this point that the first philosophers appear upon the Greek stage with a philosophy of nature that directs its chief inquiry toward the origin of the universe. The Ionians, — Thales, Anaximander, and Anaximenes, — starting with the supposition that there exists some cosmic substance out of which are developed the complex and multi- form objects of the universe, direct their energies to the dis- covery of the nature of this physical element. Thales decides upon water as his material substratum, Anaximander on an infinite matter undetermined in quality (to a-rreipov), and Anax- imenes on air. Each of these elements is characterized by a mobility which lends color to the hylozoistic theory that it is endowed from eternity with the principle of life and motion. Viewed from a different standpoint, the same problem re- ceives through the Pythagoreans a totally different solution. While the Ionians were essentially physicists, the Pythago- 9 10 THE ESSENCE OF THINGS reans constituted a society of men banded together for the pur- pose of instituting moral reforms and cultivating the various arts and sciences. The mathematical sciences, in particular, were centered in this school ; but the Pythagoreans were also far advanced in the knowledge of astronomy and music. Consequently they became impressed with the harmony and order which govern alike the motions of the heavenly bodies, the laws of music, and the moral life. But just as musical har- mony is dependent on numerical relations, so, argue the Pythag- oreans, is all harmony conditioned. /Thus they arrive at the conclusion that all things are ordered in numerical relations, from which they deduce the further proposition that number is the essence of physical reality, and unity the essence of number. The whole world of becoming arises from the oppo- sition of the one and the many. In the detailed working out of their theory, the Pythagoreans assign to each number some special significance for reality. Thus physical qualities are symbolized by the number five ; light, health, and intellect by seven ; love and wisdom by eight ; perfection by ten, etc. The starting point of Parmenides is the thought that only being (defined as a space-filling substance) can exist, that there is no non-being ; in other words, no void. But if no non-being exists from which being can arise or into which it can disap- pear, then being must be eternal and unchangeable. Since without a void all motion is impossible, birth, change, plural- ity, and decay are mere appearance. The one eternal, invaria- ble, and indivisible being is conceived as a perfect sphere which includes within itself all possible determinations, even that of thought. As will be seen later, the antithesis of a permanent reality to the changing phenomena is closely connected with Parmenides' theory of knowledge, which contrasts the perma- nence and validity of knowledge derived from thought with the illusive nature of the content of sensation and experience. Heraclitus, on the contrary, becomes so deeply impressed with the flux of things that, so far from considering change the illusion which Parmenides would make of it, he sees in it the sole reality. As the most mobile and variable of all elements, V THE ESSENCE OE THINGS 11 he looks upon fire as the process of change, and therefore as the source of things. " All things are exchanged for fire, and fire for all things. 1 The transformations of fire are, first, the sea, and of the sea half is earth and half the lightning flash. 2 The world is an ever-living fire, kindled in due measure and in due measure extinguished." 3 The one thing abiding amidst the changing phenomena is the fixed law of change or becom- ing. In this alone is the essence of things expressed. From a combination of the Eleatic conception of an abid- ing being and the Heraclitic recognition of reality in becoming arise the philosophies of Empedocles, Anaxagoras, and the Atomists, which aim to reconcile the permanence of being with the change observable in phenomena. As a change in spatial relations seems to these philosophers the only change which can leave unaltered the qualities of being, they assume a num- ber of primal, unchangeable elements, through the combination of which all individual things arise and through the separation of which they pass away. Four elements in the system of Empedocles are substituted for the one posited by the lonians. "First I learned of the four roots of all things — fire and water and earth and the immense height of ether. From these have arisen whatever things have been, will be, or now are." 4 Two forces, love and hate, applied respectively to the mixture and separation of the four unchangeable but divisible ele- ments (pi£. THE WORLD GROUND 23 or the Eeason of the world; as a united whole containing in himself the germ of all things; as the connecting element in all things; as Universal Law, Nature, Destiny, Providence; as a perfect, happy, ever-kind, and all-knowing Being." 1 From the variety of epithets used to describe God, we perceive that the Stoic conception of Deity involves a combination of materialistic and spiritualistic ideas. Paradoxical as it may appear to designate God in one statement as Air, Fire, Nature, and in another as Soul, Law, Destiny, or Providence, the two views are united by the Stoics in their fundamental idea of the universe as a harmonious and all-embracing unity. The Epicureans look upon the world as a mechanism, and desire to know no more about its workings than appears to be essential for their happiness. Although Epicurus himself did not wholly renounce belief in the gods of the popular faith, the Epicurean philosophy has an avowed atheistical tendency, its aim being to free the mind from fear by denying the exist- ence of supernatural causes. Lucretius, in his poetical expo- sition of Epicureanism, states emphatically that "the nature of the world has by no means been made for us by a divine power." 2 The aim of Skepticism, like that of Stoicism and Epicure- anism, is mainly practical. The Skeptics seek happiness by way of tranquillity, and tranquillity through suspense of judg- ment. To justify this attitude they point out the contradic- tions involved in all the rival systems of philosophy. Among other criticisms they offer arguments to overthrow the ordinary conceptions of God, especially those of the Stoics. They point to the evil existent in the world as opposed to the theory of Design or Providence, and they call attention to contradictions in many of the accepted views of the Deity. If God is con- ceived as a separate, individual Being, they say, he cannot be regarded as infinite. If he is a living Being, he must be sus- ceptible of change and subject to death. Since virtue consists in overcoming one's own imperfections, God cannot be both 1 Zeller, Stoics, Epicureans, and Sceptics, pp. 148-150. 2 Lucretius, Be Rerum Natura, Bk. II, 180. 24 THE WORLD GROUND virtuous and perfect. If capable of receiving pleasure, he cannot be impervious to pain. Further difficulties appear in attempting to conceive of God as either limited or unlimited, the limited being incomplete and the unlimited immovable. The nature of God cannot therefore be expressed by any of the attributes commonly ascribed to him. The Skeptics do not deny the possibility of the existence of a being higher than man, but they refuse to grant that there must necessarily be a God conceived as a rational Being. The motive of the Neoplatonic speculation proceeds from the Platonic view of the dualism and opposition of spirit and matter conceived as an antithesis of good and evil. Matter, as completely destitute of form and idea being regarded as the cause of all evil, the Neoplatonists wish to place God entirely beyond its sphere. Yet while they thus insist on the tran- scendency of God above the world, they wish, at the same time, like the Stoics, to view the world as a unity. From the union of these two motives comes the conception of the world as a continuous whole proceeding from and returning to God in a manner analogous to the emanation of light from the sun. As opposed to the many, the original Being is the One, as opposed to the finite, the Infinite; but it is impossible to attribute to him any definite characterization. God is exalted even above the ideas, which are emanations from the Deity, as the soul is an emanation from the ideas and the phenomenal world an emanation from the soul. Kegarding all attributes as limitations of perfection, the Neoplatonists refuse to describe God by qualities of any kind, whether spiritual or material. God is not conscious, but transcends both the conscious and the unconscious; although the source of all intelligence and goodness, he himself is neither intelligent^ nor good. Think- ing or willing cannot be exercised by God without being directed to some object beyond himself; but the assumption of such an object would detract from the absolutism of God. As superior to all ideas, he transcends all conceptions. As the one which precedes all things he is nothing, but as the source of all things he is everything. Notwithstanding the transcendence of God, THE WORLD GROUND 25 however, man's purest longing is directed toward a reunion with him. This becomes possible by an elevation above the life of the senses and a constant contemplation of the primeval Being, which results in the state of blessedness known as ecstasy. This outline of the Neoplatonic system completes our sur- vey of Greek theories of the ground of the world, the enduring elements of which we shall now proceed to distinguish. Speaking of the origin of the universe, Herbert Spencer states that three suppositions are possible. We may assert that it is created by an external agency — the theistic view ; that it is self -existent — the pantheistic view; or that it is self-created — the atheistic view. All these views are repre- sented in the philosophy of the Greeks. The systems of Anaxagoras, Plato, and Aristotle are, to a greater or less extent, theistic; the views of Xenophanes, Heraclitus, the Stoics, and the Neoplatonists have pantheistic leanings ; while the doctrines of the Epicureans and the Skeptics reveal an atheistic tendency. Many of the characteristic attributes of the Deity, as represented by later philosophers, are developed in these early speculations. We find, on the one hand, conceptions of his infinity and eternity, of his goodness, intelligence, and power; on the other hand, the idea of God as an indefinable reality, devoid of all attributes, even of intelligence and will. Just as the teleological view of the universe leads Anax- agoras to the idea of the cause of all as vo9s, impels Plato to identify God with the Idea of the Good as the final cause of all becoming, and leads Aristotle to conceive of him as pure Form or Thought toward which all things, by their very nature, are compelled to strive, so Leibniz argues teleologically from the harmony subsisting among the non-interacting monads to God as the only possible source of such harmony. This dif- ference, however, is to be noted — that whereas the God of Leibniz preimposes the ends upon the monads he creates, and preestablishes the harmony that exists among them, the God of Plato or of Aristotle is not a creator of the world in the 26 THE WORLD GROUND mechanical sense, but all nature strives of necessity toward the Idea of the Good or toward pure Form as its final goal. The teleological view of the universe is also a prominent ele- ment in the earlier philosophy of Kant, although in the Critique of Pure Eeason he devotes a chapter to the exposition of the invalidity of the physico-theological proof, as he calls it, of the existence of God. He shows that "the physico-theologi- cal proof rests on the cosmological, and the cosmological on the ontological proof of the existence of one original Being as the Supreme Being; and as, besides these three, there is no other path open to speculative reason, the ontological proof, based exclusively on pure concepts of reason, is the only pos- sible one, always supposing that any proof of a proposition, so far transcending the empirical use of the reason, is possible at all." 1 Kant, therefore, derives his proof of the existence of God entirely from the postulates of the practical reason. The inconsistency in Plato's conception of the Idea of the Good, as both the highest in the series of ideas and the cause of all the others, is met again in Leibniz's view of God as the Monad of monads, the highest in the series and the source of all the lesser monads. Many thoughts analogous to Greek conceptions are present in the system of Spinoza. The starting point of his philoso- phy is his conception of Substance as "that which exists in itself and is conceived by itself; that which does not need the conception of any other thing in order to be conceived." 2 This is essentially like the Cartesian definition of substance, but Spinoza draws from it the logical conclusion, which Descartes failed to derive, that finite things are not substances, and that the sole Substance is God. Spinoza's God is endowed with infinite attributes (" what the intellect perceives as constituting the essence of Substance " 8 ) ; but of these only two, extension and consciousness, are manifested to us. Finite things are merely modes of God's attributes. God therefore exists in 1 Kant, Critique of Pure Reason, p. 507. 2 Spinoza, Ethics, Part I, Def. III. 8 Ibid., Part I, Def. IV. THE WORLD GROUND 27 finite things as their essence, and they exist in him as modes. God and nature are, in brief, identical. As the universal essence of things God is natara ?iaturans, but as the totality of his modes he is natura naturata. In this pantheistic view of the universe (to which Spinoza, like the Eleatics, is led by a desire to represent all reality as a unity) he agrees with Xen- ophanes, Heraclitus, and the Stoics. But the Stoic conception of God as a Providence or Reason, which creates the universe with a view to ends, Spinoza rejects. In this particular he is in agreement rather with the Epicureans, that it is absurd to speak of ends with relation to the Deity. Spinoza's disbelief in teleology is partly the result of his mathematical view of metaphysics, since mathematics knows no ends, but only grounds and consequences, and partly the outcome of his defi- nition of Substance, which forbids it to be conditioned by any ends outside itself. We remember that this idea, that objective ends would be limitations of God's perfection, leads Aristotle to deny the creative activity of God, to declare that God's thought can be his only object, and that his relation to the world is that of a transcendent Being. Spinoza, however, tries to reconcile this view with the immanence of God. He succeeds only in evading the difficulty by his mathematical conception that the world follows from the nature of God with the same necessity as it follows from the nature of a triangle that the sum of its three angles is equal to two right angles. God is merely the logical ground from which existence fol- lows as a necessary consequence. Spinoza's closest alliance, however, is with the Neoplatonists. Like them, he feels that the ascription of attributes to the Deity would destroy his unity and infinity since omnis determinatio est negatio. That Spinoza, notwithstanding this assertion, ascribes to God an infinite number of attributes is an inconsistency which some philosophers try to explain away by interpreting the attributes as merely human methods of conceiving God, not as expressions of his essential nature. But this would bring back the dualism of extension and consciousness, of the finite and the infinite, which Spinoza aimed to overcome, and would 28 THE WORLD GROUND leave no place in his system for the immanence of God. The truth is, that this doctrine of immanence is irreconcilable with that of indeterminateness, and leads of necessity to confusion of thought. Although Spinoza asserts that man has an ade- quate knowledge of God in the two attributes of extension and consciousness, it is difficult to conceive how this knowledge can be more adequate than that of Spencer's "Unknowable Reality," since Spinoza insists that God has neither intelli- gence nor will, in the human sense of the term, nor any other attribute. Spinoza's Infinite, like that of the Neoplatonists, becomes, through the denial of all qualities, a pure abstrac- tion, a form without content, totally lacking in any moving principle from which the world can be derived. That this empty form is, nevertheless, for Spinoza an object of love, and that he holds man's highest happiness to consist in love of God, is another inconsistency which he shares with the Neoplatonists. Erdmann tries to explain it by translating love of God into love of truth, " since everything is known in its necessity only if it is known as a necessary consequence of the Infinite Divine Being. . . . God, then, does not love us, but we love him if we have knowledge." * Schelling bears the same relation to the Greeks as does Spinoza, in so far as in his pantheistic system of iden- tity he adopts Spinoza's, view that mind and nature have a common basis in the Absolute, which itself, however, is neither mind nor body, but an essence indeterminate in con- tent, an indifference of object and subject, of the real and the ideal. Both Platonic and Stoic elements may be detected in Hegel's view of the Absolute as the Idea, and of the content of the Absolute Idea as the whole system. His assertion that the infinite, if beyond the finite, must by this very limitation cease to be infinite reechoes one of the Skeptical tropes; but Hegel solves the difficulty by declaring that "the infinite is the essence of the finite, and the finite is the manifestation of the infinite. Infinity determines itself, limits itself, sets i Erdmann, History of Philosophy , vol. II, p. 86. THE WORLD GROUND 29 boundaries to itself; in a word, it becomes the finite by the very fact that it gives itself existence." 1 With few exceptions, the various systems of philosophy, ancient and modern, have shown a tendency to represent the ground of the world by the highest or most absolute principles that their theories afforded. Differences in conceptions of this ground are due to various motives which have played their part in the past, as they do in the present, in influencing the special determinations. Modern philosophy, taken as a whole, shows a disposition toward a keener analysis and toward a checking of extravagant fancies by a study of the limitations of human knowledge ; but ever since the time of Kant there has also been manifest a tendency to grant to the practical reason a voice in the final decision. Whatever may be the out- come, it is reducible to one of the three general views of the ground of the universe expounded by the philosophers of Greece. Materialism and idealism, empiricism and rational- ism alike have their theistic, their pantheistic, and their atheistic representatives, each of whom tries to bring to the support of his arguments for his conception of the World Ground the full weight of his particular system of philosophy. 1 Weber, History of Philosophy, pp. 503, 504. Ill SPACE AND TIME The question of the nature of space and time constitutes for modern metaphysics a vital problem, affecting as it does our view of the reality of the external world. In attempting to institute comparisons on this subject between the old philoso- phy and the new, it may be well to state at the outset that any conscious expression of the subjectivity of space and time as expounded by Kant or developed by Lotze was foreign to Greek thought. The speculations of the Greeks were largely confined to debates concerning the finitude or infinity of space and time; and yet we shall see that they did not altogether ignore the problem of the metaphysical nature of these cate- gories, nor were they wholly blind to the difficulties involved. The first idea of space among the Physicists was that of a void, empty of matter. The confidence in such a principle as contrasted with the " full " (to irXiov) remained unshaken until the notion was challenged by the Eleatics. The emphatic assertion of Parmenides that only being exists, and that non-being is inconceivable, coupled with his identification of non-being with the void, proves, in effect, a denial of the reality of space as by him conceived ; but we must observe that it is the non-existence of empty space alone toward which the arguments of Parmenides are directed. His disciple, Zeno, comes nearer the appreciation of the real problem, and wrestles with it in one of its modern aspects. " If there is such a thing as place," he says, " it will be in something, for all being is in something, and that which is in something is in some place. Then this place will be in a place, and so on indefinitely. Accordingly, there is no such thing as place." 1 1 Fairbanks, First Philosophers of Greece, p. 116. 30 SPACE AND TIME 31 Space, according to Plato, is not a condition of reality, that is, of the idea, but is that in which all things appear, grow up, and decay. Plato represents time as a mere shadow or image of eternity. " The past and future are created species of time which we unconsciously, but wrongly transfer to the eternal essence. . . . When we say that what has become has become, and what is becoming is becoming, and that what will become will become, and that what is not is not, — all these are inaccurate modes of expression." 1 Time, therefore, and all things that appear in time are unreal. The unreality of time follows from the sole reality of the timeless idea. Aristotle finds the solution of the problem presented by Zeno in a new conception of space as a state or property of things. "It is not difficult," he says, "to solve Zeno's prob- lem that if space is anything it will be in some place, for nothing hinders the first place from being in something else, just as health exists in warm beings as a state, while warmth exists in matter as a property of it. So it is not necessary to assume an indefinite series of spaces." 2 Elsewhere Aristotle declares that " space is neither form nor matter nor limit, but the boundary of the containing body." 3 Both space and time are infinite. Time is implicit in motion, but cannot in reality exist without a soul, since number does not exist without a calculator, and the sole calculator is reason. Apart from the soul, therefore, time cannot exist, but only that which consti- tutes the essence of time — the reality which lies beneath it as a substratum of its existence. The Epicureans maintain that space exists from eternity, as a precondition of all motion, but that the sense of time comes from what is done in time. " Time exists not by itself, but simply from things which happen, the sense apprehends what has been done in time past as well as what is present and what is to follow after. No one feels time by itself abstracted from the motion and calm rest of things." 4 i Plato, Timaeus, 38. * Aristotle, Physics, Bk. IV, ch. V. s Aristotle, Physics, Bk. IV, ch. VI. 4 Lucretius, Be Rerum Natura, Bk. I, 462. 32 SPACE AND TIME When Berkeley defines space as the experience in unre- sisted organic movements, and time as the apprehension of changes in our ideas ; when Leibniz asserts that space and time are not real substances nor attributes thereof, but orders of coexistences and succession of things and phenomena; when Kant, arguing for the transcendental ideality of space and time, insists that they are no more than the subjective con- ditions of our sensibility and intuition, space being the form of all the phenomena of the external senses and time the form of the internal sense; when Lotze represents space as the " intellectual " relations of things which we translate into spatial language, and regards time not only as a subjective form of apprehension, but also as an unaccountable constitu- ent of the real, — although these modern philosophers differ in the kind of reality they accord to space and time, they agree among themselves, and with Zeno, Plato, Aristotle, and Lucretius, in just this point that they refuse to admit that space or time possesses any substantial reality. Zeno's argument against the reality of space recurs in many of the modern expositions of the contradictions involved in the ordinary conceptions. "The common notion," says Bowne, "of an independent space is repugnant to creation, for the necessity would ever pursue us of positing a previous space for the reception of the created one." x Although it should not be too strongly urged, the parallel- ism might be drawn between Aristotle and Kant that just as the former in one sense asserts the reality of time, and yet denies that it can exist apart from the soul, so Kant empha- sizes the thought that the transcendental ideality of space and time detracts in no measure from their empirical reality. The conclusion to be drawn from this comparison of the conceptions of space and time as developed in ancient and modern philosophy is that the Greeks, though not themselves sufficiently sure-footed to venture on the path that lay before them, were able at least to point out the road along which modern speculation is traveling. 1 Bowne, Metaphysics, p. 131. IV CONCEPTIONS OF EVOLUTION To cover the many conflicting systems of philosophy that lay claim to the title of evolution, it is necessary to use the term in its broadest sense. Evolution thus broadly defined includes all theories of the universe that view it as the result of a gradual development of indeterminate, simple, lower forms into determinate, complex, higher forms, through the opera- tion of causes immanent in the world. Thus considering evolution as a theory of development, it is the object of the present discussion to discover how far the modern evolutionary hypotheses were anticipated by the speculations of the Greeks. The first step toward the conception of development was taken by the early physicists — Thales, Anaximander, and Anaximenes — in their effort to explain the world as generated out of a primordial substance. Anaximander' s theory more specifically foreshadows later speculation in that it traces the origin of all determinate existence from an indeterminate infi- nite element, to airapov. The first principle of Anaximander, like that of Thales and Anaximenes, is without beginning, and indestructible. Anaximander interests us also by his attempt to explain the origin of man. " Man, " he tells us in one passage, " came into being from another animal, the fish; " l but elsewhere he says that " at the beginning man was generated from all sorts of animals, since all the rest can quickly get food for themselves, while man alone requires feeding for a long time." 2 Anaximander further declares that "destruction and far earlier generation have taken place since an indefinite time, as all things are involved in a cycle." 3 1 Fairbanks, First Philosophers of Greece, p. 13. 2 /&«?., p. 14. 3/6id.,p. 14. d 33 34 CONCEPTIONS OF EVOLUTION Besides emphasizing the fixed law of change, Heraclitus reiterates Anaximander's assertion of a continuous alternation of generation and destruction. " Life and death, waking and sleeping, youth and old age, are the same ; for the latter change and are the former, and the former change back to the latter." * In his doctrine of strife as the process of evolution, Heraclitus voices a still more pregnant thought. "Heraclitus blamed Homer for saying 'would that strife might perish from among gods and men. For then,' said he, 'all things would pass away. ' " 2 " All things are made by strife " {-n-avra Kar' tpw yiVeo-0cu). 8 Empedocles, as we have observed before, teaches that all things arise from the combination and separation of four primi- tive elements through the operation of the forces of love and hate. " There is no origination of anything that is mortal, nor yet any end in baneful death, but only mixture and separation. It is impossible that being should perish completely." 4 This statement repeats Anaximander's idea of the indestructibility and eternity of being. In the beginning there existed a com- pact mass in which love reigned supreme ; but by the develop- ment of the disruptive force — hate — the elements separated and individual things arose. Whenever the force of separation domiuates, individual things disappear. Thus we have alter- nate periods of growth and decay. According to Empedocles, organisms arose from formless lumps of earth and water, which shaped themselves into animal or human organs and members. The heads which at first "grew up without necks," the arms which "wandered about naked, bereft of shoulders," and the eyes which "roamed about alone with no foreheads," 5 came together by chance, and those that were adapted for union shaped themselves into living organisms. A countless number of combinations perished, while only those persisted which were by nature capable of surviving and of propagating them- 1 Bywater, Heracliti Ephesii Reliquiae, Frag. LXXVIII. 2 Fairbanks, First Philosophers of Greece, p. 35. 8 Bywater, Heracliti Ephesii Reliquiae, Frag. XL VI. 4 Fairbanks, First Philosophers of Greece, p. 1G3. e Ibid., p. 189. CONCEPTIONS OE EVOLUTION 35 selves. Plants arose first, then animals, the higher forms of life being compelled to pass through stages of the lower. "Before this," says Empedocles, "I was born once a boy and a maiden and a plant and a darting fish in the sea." 1 The only fruitful idea added by Anaxagoras to Empedo- cles' principles of development is the theory that the homoio- meriai, which were originally commingled in a chaotic mass, were, after separation by the vovs, remingled according to inner affinities. The theory of Leucippus and Democritus, which explains all development as a combination of atoms through an inher- ent force acting by necessity according to a universal law, con- tains the fundamental principle of all mechanical systems of cosmic evolution. The philosophy of Plato, which is concerned more with being than with becoming, leaves no legacy to the doctrine of evolution beyond the thought that the human race arose in the universe in ages infinitely remote. Influenced, no doubt, by his teleological view that all things have their purposes outside themselves in something better, Plato reverses the order of organic development in the assertion that the most perfect of animals — man — was first created, and that birds and beasts and fishes are transformations of light-minded or degenerate men. 2 To Aristotle nature appears as a scale of progressive development toward perfection, from lifeless matter through the various stages of life up to man. He rejects the fortuitous combinations of Empedocles in favor of the teleological concep- tion that nature produces first those organs that are necessary for the support of life. The Stoics accept from Anaximander and Empedocles the idea of successive periods of development and destruction of the universe, while the Epicureans reiterate the notion of for- tuitous beginnings. Lucretius, like Empedocles, speaks of the extinction of innumerable tribes unable to transmit life to 1 Fairbanks, First Philosophers of Greece, p. 207. 2 Plato, Timaeus, 42, 91, and 92. 36 CONCEPTIONS OF EVOLUTION their offspring. He further traces the evolution of man from an original state of beastlike savagery, the development of language from the sounds of animals, of music from the sounds in nature, and of religion from ideas presented in dreams and in hallucinations. Affinities between many of these Greek conceptions and the evolutionary hypotheses of the present are no less remark- able than they are manifest. Anax inlander's theory of the generation of all determinate forms of existence from an indeterminate element foreshadows vaguely Spencer's idea of progress from "an indefinite, inco- herent homogeneity to a definite, coherent heterogeneity." Further, Anaximander resembles Spencer in his theory of the alternation of development and destruction. " Apparently, " says Spencer, "the universally coexistent forces of attraction and repulsion, which necessitate rhythm in all minor changes throughout the universe, also necessitate rhythm in the totality of its changes, produce now an immeasurable period during which the attractive forces predominating cause universal con- centration, and then an immeasurable period during which the repulsive forces predominating cause universal diffusion — alternate eras of evolution and dissolution." 1 In the Heraclitean conception of strife as a condition of development we may see at least a suggestion of the principle of struggle for existence — a principle which Darwin has shown to be so significant a factor in biological evolution. Heracli- tus' recognition of a fixed and universal law, according to which all change proceeds, also suggests a significant element of all the modern theories of evolution. Empedocles' forces of love and hate are but other names for Herbert Spencer's forces of attraction and repulsion. In the light of this interpretation, it will be fruitful to compare the theory of Spencer, quoted above, with the assertion of Empedocles that when hate predominates individual things disappear. Empedocles also recognizes the principle of "sur- vival of the fittest " amid the destruction of innumerable types, 1 Spencer, First Principles, p. 537. CONCEPTIONS OF EVOLUTION 37 and of adaptation to environment as an important condition of fitness to survive. The Anaxagorean principle of the mixture of the original elements according to inner affinities, is faintly suggestive of the Spencerian theory of "a gradually completed segregation of like units into a group distinctly separated from neighbor- ing groups, which are severally made up of other kinds of units." * The atomistic system of Leucippus and Democritus con- tains, as we have already observed, the foundation principle of all the purely mechanical theories of evolution. Among their most enduring thoughts is the idea of the universal reign of law, which has been emphasized before in connection with the philosophy of Heraclitus. Aristotle's view of nature as a scale of progressive devel- opment reminds us of Leibniz's theory, which regards the monads as arranged on a graduated scale of development toward perfection. But there is one great difference to be noted between these two philosophers. Aristotle's principle of development from potentiality to actuality involves the change of one thing into another, whereas in the system of Leibniz, although a process of evolution occurs within each monad, no monad ever develops into another. The special contribution of Lucretius, which consists in his many-sided application of the doctrine of evolution to language, music, and religious ideas, as well as to nature and man, is a further approximation to the philosophy of Herbert Spencer. Recapitulating the results of this comparison, we find represented in the philosophy of the Greeks the idea of a basal identity of all existence, of the indestructibility of matter, of a fixed law of change, of the gradual development of higher from lower forms, of the immeasurable antiquity of man, of the dependence of progress on a constant struggle for existence, adaptation to environment, and survival of the fittest. Yet, in spite of their significance as anticipations, the 1 Spencer, First Principles, p. 459. 38 CONCEPTIONS OF EVOLUTION Greek conceptions were but flashes of insight resting on an insecure foundation of experience, while modern evolutionary- theories are rooted in science and owe the enthusiasm of their supporters to the remarkable results achieved in the field of science by the painstaking researches of such men as Darwin, Wallace, and Lamarck. When, however, overstepping the limits of science, these modern theories present themselves as complete systems of philosophy, competent to solve all the problems which properly belong within the sphere of meta- physics, it is necessary to emphasize the fact that evolution explains nothing beyond the process or order of development. All that evolution gives rise to must be potentially present in some germ or element, concerning the origin of which natural science is unable to enlighten us. The development of things in accordance with certain fixed laws throws no light either on ultimate origins or on the underlying causality which deter- mines the law of evolution itself. Greek philosophy shows us evolutionary conceptions in the state -that Spencer character- izes as un-unified knowledge; modern investigations have advanced them to the partially unified knowledge of science; but not yet has any system of evolution formulated such uni- versal propositions as Spencer demands for the completely unified knowledge of philosophy. CONCEPTIONS OF CAUSALITY Aristotle arraigned all his predecessors with the charge of having imperfectly conceived the problem of causality. That such inadequate conceptions should occur in the early history of philosophy is by no means surprising. Eather would it have been cause for wonder had this subtle category been exhaustively interpreted in the infancy of speculative science. The question of change presents itself to the Ionians as a problem requiring solution, but when they have reduced all generation to its lowest terms, in a primary substance, the problem seems to them completely solved. By regarding the principle of life and motion as inherent in their fundamental element, they stifle inquiry as to any cause of change or motion. Their investigations are therefore directed solely toward the discovery of a material cause. Of the four causes enumerated by Aristotle as active in all phenomena, — the material cause, the formal cause, the effi- cient cause, and the final cause, — the second is for the first time recognized by the Pythagoreans in their view of number as the formal cause of things. Since it is experience of change that first impresses on the mind the causal relation, the Eleatics, who regard change as mere illusion, manifest, as might be expected, little interest in the question of causality. The efficient cause, or cause of motion, is introduced for the first time by Heraclitus, although Empedocles usually receives the credit of having originated this conception. The mobility of Heraclitus' primitive fire is indeed suggestive of hylozoismj but if we are to find any intelligible meaning in 39 40 CONCEPTIONS OF CAUSALITY the famous sayings of Heraclitus — " All things arise and pass away through strife/' 1 " War is the father of all," 2 we must admit that he recognizes struggle, or the war of opposites, as the efficient cause of generation. Heraclitus, also, for the first time gives utterance to the thought that all change is subject to a fixed, unalterable law. Empedocles, although not the originator of the idea of an efficient cause, deserves the credit of giving to the thought a more emphatic recognition in the development of his system. In addition to the four elements, — earth, water, air, and fire, — assumed as the material principles of things, he posits further as efficient causes a combining force — love — and a separating force — hate. The combinations and separations of the elements effectuated through the action of these two forces account for all the variety in experience. A further advance on previous conceptions is made by Anaxagoras in his reflection that vovs, or Mind, is the world- ordering cause, both the source of motion, and the final end of all becoming. By this conception Anaxagoras introduces the final cause, the last of the four enumerated by Aristotle. But both Plato and Aristotle justly reproach him for having dis- covered this fruitful principle without being able to apply it. "I rejoiced," says Plato, "to think that I had found in Anax- agoras a teacher of the causes of things such as I desired. How grievously was I disappointed! As I proceeded, I found my philosopher altogether forsaking mind or any other prin- ciple of order, but having recourse to air and ether and water and other eccentricities." 3 And Aristotle tells us that " Anax- agoras employs mind as a machine for the production of the orderly system of the world; and when he finds himself in perplexity as to the cause why a thing necessarily is, he then drags it in by force to his assistance; but, in the other instances, he assigns, as a cause of the things that are being produced, everything else in preference to mind." 4 1 Bywater, Beracliti Ephesii Reliquiae, Frag. XLVI. a Tbid, t Frag. XLIV. 3 Plato, Phaedo, 97. * Aristotle, Metaphysics, Bk. I, ch. IV, § 4. CONCEPTIONS OF CAUSALITY 41 Protagoras, who regards sensation as the source of all knowledge, finding that causes and ultimate principles are not discoverable through sense perception, concludes that they are inaccessible to knowledge. Democritus does not ask for a ca,use of the atoms them^ selves, since believing them eternal he regards them as uncaused; but the coming together of the atoms in space, which gives rise to the universe and all existence, he attributes to mechanical necessity. The elements of Empedocles are brought together by the external force of love, those of Anax- agoras are guided by a designing mind; but the atoms of Democritus, constrained only by an innate necessity, range themselves together in space under the principle of similarity in form and magnitude. Democritus, however, protests against chance as vehemently as he does against design. Although all things, including the human mind, are produced by the pressure and impact of atoms, they proceed according to law and are bound together in an eternally necessary chain of cause and effect. In Plato's teleological view of nature the ideas are regarded as the final causes of phenomena, the idea of the good — the highest of all — being at the same time the ultimate efficient cause and the final cause of all becoming. In addition to the ideas, however, there are secondary or "cooperative causes which God uses as his ministers, when executing the idea of the best, as far as possible. They are thought by most men not to be the second, but the prime causes of all things, which they cool and heat and contract and dilate, and the like ; but this is not true, for they are incapable of reason or intellect. The only being which can properly have mind is the soul, and this is invisible ; whereas fire and water and earth and air are all of them visible bodies. Both kinds of causes should be considered of us, but a separation should be made of those which are endowed with mind and are the workings of things fair and good, and those which are deprived of intelligence and accomplish their several works by chance and without order." x 1 Plato, Timaeus, 46. 42 CONCEPTIONS OF CAUSALITY Aristotle, like Plato, regards nature as an adaptation of means to ends, but he gives more prominence than Plato to mechanical conditions as intermediate efficient causes. He combines, in a measure, the teleological and mechanical views of becoming. Aristotle conceives the process of development both from the standpoint of man's constructive activity, or the world of art, and from the standpoint of the organic world. In the world of art he distinguishes four causes as contribut- ing to the production of any object: first, a material cause (r) vXrj), second, a formal cause (to elSos), third, an efficient, or moving cause (to klvtjtlkov), and fourth, a final cause (t6 reAos). Thus in the case of the production of a statue, the marble con- stitutes the material cause; the idea, or plan of the statue in the mind of the artist, the formal cause; arms, hands, tools, etc., the efficient, or moving cause; and the motive that actu- ates the artist, the final cause. The change effected by the cooperation of these four causes is a transition from matter, the statue in potentiality, to the actual formed statue. In the case of organic creation, however, these four causes are reduci- ble to two, matter and form, since the final and efficient causes are here identical with the formal cause. The form arouses matter to move toward it as an end. All organisms display an immanent, although unconscious purpose to develop into their proper form. The universe is viewed by Aristotle as an organic whole, moving from the lowest stage, matter, or mere potentiality, to its end, the highest form, pure actuality, or God. Yet, in spite of his teleological view of nature, Aristotle recognizes in the world of experience an accidental element, which cannot be assigned to purpose or reduced to law. This he attributes to the mechanical causes which inhere in matter and oppose a certain resistance to form. The Stoics regard the universe as a living, connected whole, and its manifold phenomena as particular forms of a unitary being. For Aristotle's formal and material causes they sub- stitute a passive principle, unqualified substance, and an active principle, the reason immanent in matter. But this active principle, reason, which is the moving force of the world, is CONCEPTIONS OF CAUSALITY 43 in itself material. Although it is identical with the soul of the world, or God, it permeates all things as a material fire or breath (rrvevfjia) . This contradictory conception is due to two irreconcilable elements which enter into Stoic speculation. The Stoics adopt, on the one hand, the material view of the universe, which recognizes substantial matter as the sole reality; but, on the other hand, they perceive in nature an adaptation of means to ends, which they can ascribe only to a reasonable creator. God is therefore represented as a purpose- fully guiding Providence, but he is at the same time identified with Necessity or Destiny. The Stoics believe with Democri- tus that necessity governs all occurrence, that chance is an impossibility, and that all things are subject to a universal law. The Epicurean interest in the question of causality pro- ceeds from the thought that the discovery of natural causes, by removing superstitious fears, will add to tranquillity and hap- piness. As the materialistic theory of Democritus seems best to satisfy their demand, they adopt it with a significant modification. While they agree in general with Democritus in his theory of mechanical causation, they allow, at least in the beginning, a voluntary deviation of the atoms from their direct course, which admits, in the coming together of the atoms, an element of indeterminism, or chance. In the devel- opment of their theory, also, they find no occasion to lay stress upon the idea of the reign of law, which forms so prominent an element in the systems of Heraclitus, Democritus, and the Stoics. They deny, even more emphatically than did Democri- tus, the validity of the teleological interpretation of nature. " Nothing," says Lucretius, "was born in the body that we might use it, but that which is born begets for itself a use." 1 In conformity with their general attitude toward knowl- edge, the Skeptics doubt the possibility of knowing the ulti- mate causes of things. In order to justify their attitude of suspense of judgment, which seems to them a necessary con- dition of tranquillity, they submit the notion of aetiology to a 1 Lucretius, De Rerum Natura, Bk. IV, 834. 44 CONCEPTIONS OF CAUSALITY searching criticism, in the course of which they anticipate many modern objections. In eight tropes Aenesidemns at- tempts to prove that all aetiology is futile. He calls attention to the fact that aetiology, which treats of unseen things, can give no trustworthy evidence regarding phenomena, nor can phenomena tell us anything of these unseen things, which may act according to a law peculiar to themselves ; that all inves- tigation regarding the causes of things is one-sided, since from many possible theories each philosopher chooses the one most consistent with his own hypothesis concerning the elements of things, disregarding the equally plausible views of his oppo- nents; that the philosophers often assign causes devoid of order for things which happen in an orderly way, or give reasons for things which conflict directly with experience ; and that they attempt to explain occurrences by causes which are quite as inscrutable as are the events themselves. 1 These tropes are intended to establish the fact that a cause in har- mony with all the systems of philosophy, including skepti- cism, is not possible, since phenomena can give no clew to the unknown. Aenesidemus further submits to criticism the con- cept of causal interaction. He attempts to show that the trans- fer of motion from one thing to another is equally unintelligible whether we regard the efficient cause as material or immaterial. Since the effect must coincide in nature with the cause, the immaterial cannot produce the material, nor the latter the former. Contact, usually assumed as a necessary condition of interaction, simply introduces a new term without escaping the difficulty. The time relation of the cause to the effect is also difficult to determine. If the cause is synchronous with the effect, cause and effect merge into one and become indis- tinguishable. If the cause precedes the effect, it is impossible to determine a moment of time in which the cause passes over into its effect. So long as the cause is active the effect is absent, and as soon as the effect is present the cause has ceased to act. To conceive of the cause as following the effect — the only remaining alternative — would be absurd. The Skeptics 1 Sextus Empiricus, Pyrrhonic Sketches, Bk. I, ch. XVII. CONCEPTIONS OF CAUSALITY 45 also emphasize the important thought of the relativity of cause and effect. A cause is a cause, they say, not per se, but only in relation to its effect; and an effect likewise is not an effect in itself, but only in reference to its cause. The Skeptical refutation of aetiology is the last Greek con- tribution to the subject of causality. We are now prepared to ask the question, how far, in the field of this special inquiry, the Greeks anticipated modern thought. Crude as were the theories of material causation to which the Ionians confined themselves, they none the less contained in germ the principle of the modern materialistic schools that matter in motion is the sole cause of all phenomena, both phy- sical and psychical. But of all the materialistic conceptions of causality presented by the Greeks, the mechanical theory pro- pounded by Democritus has held the most enduring place in philosophic thought. In the reawakening of the scientific movement, the mechanical view of the world is first represented by Galileo and Hobbes, but is reaffirmed by Descartes, who, although he places the ultimate causality in God, attempts a comprehensive mechanical explanation of nature. The rejec- tion by Democritus and the Epicureans of final ends, in the interest of maintaining a purely natural theory of causation, is indorsed by most of the mechanical theories. Bacon con- siders teleology as one of the dangerous " idols of the tribe," or illusions common to human nature in general. Descartes emphatically refuses to admit final causes as explanations of nature, declaring it presumptuous to seek to comprehend the purposes of God in creation. Spinoza, whose notion of causa- tion is that of a logical, or mathematical, ground and conse- quence, declares, with even greater vehemence, that it is absurd to speak of purposes with relation to the Deity, that all tele- ology is a gross species of anthropomorphism. This anti- teleological tendency of viewing creation recurs in the purely mechanical evolutionary systems of the present day, including that of Herbert Spencer. These systems do not deny purposive adaptations in nature, but explain them as the result of purely natural causes. Animals do not have fur in order to protect 46 CONCEPTIONS OF CAUSALITY ' them from the cold, but because they have fur they are able to survive in spite of cold. Or, in the words of Lucretius, quoted before, " Xothing was born in the body that we might use it, but that which is born begets for itself a use." 1 The Positivists, also, who limit all knowledge to the sphere of phenomena, regard the conception of first causes or final ends as utterly absurd. Common to most of these thinkers, also, is the Heraclitic, Atomistic, and Stoic insistence on the uni- versal reign of law, on the subjection of all phenomena in the physical and mental realms to an unbroken chain of causes and effects. Yet Spencer and other English Positivists acknowl- edge that even determinism cannot be deduced as an absolute certainty from our limited experience. It is conceivable that the law we regard as uniform is not in reality universal. The relative alone is accessible to us ; we can never reach the absolute. The teleological view of causation, on the other hand, which was first enunciated by Anaxagoras, but more consist- ently developed by Plato and Aristotle, is emphasized by Leib- niz. He, however, denies the influence of the monads on one another and confines all change to the inner development of the monads, while our apparent experience of the interaction of objects is, as has been observed in another connection, due to a preestablished harmony grounded in God. Leibniz regards the world as a mechanism constructed to further the purposes of God. Thus he combines, as Aristotle in a different way attempted to do before him, the mechanical and teleological views of the universe. Kant, also, in the Critique of the Teleological Judgment, although he adopts the mechanical theory of nature, and insists that final ends are not satisfac- tory explanations of phenomena, yet leaves a place for tele- ology in experiences like that of life, which, while they are- from their very nature permanently unintelligible on any mechanical theory, force upon us the impression of purposive- ness. Teleology becomes an essential principle, also, in the German idealistic school, whose chief representatives are 1 Lucretius, De Reruin Natura, Bk. IV, 834. CONCEPTIONS OF CAUSALITY 47 Fichte, Schelling, and Hegel. " The spread of the mechanical way of regarding the world," says Windelband, "was met by the German philosophy with the fundamental thought that all that is known in this way is but the phenomenal form and vehicle of a purposefully developing inner world, and that the true comprehension of the particular has to determine the sig- nificance that belongs to it in a purposeful connected whole of life." 1 In Aristotle's insistence on a multitude of causes,- limited though they be in number, lies a suggestion of the modern notion that not one cause (or condition, as we should call it), but many, contribute to the reality of any individual existence. It is the principle that gives rise to the conception of a totality of causes as developed by Hegel, Lotze, Bowne, or Bradley. . From the Skeptical criticisms, which received their pri- mary inspiration from Protagoras, the outcome has been very fruitful for modern speculation. Although, as we have ob- served, Aenesidemus is inspired by a practical aim, while Hume simply draws the logical conclusions from his sensa- tionalists theory of knowledge, yet the Skeptic anticipates most of Hume's keen polemic against the concept of causality.' It never occurred to Aenesidemus, however, to criticise the doctrine from the standpoint of its origin ; and the theory that the belief in causality is a fiction arising from the habitual association of frequently conjoined ideas, originated with Hume. But the conclusion that the idea of causality admits of application only in the field of phenomena is derived by Hume, as well as by the Skeptics. When Hume tells us that so long as we lack knowledge of that power in the cause by which it is enabled to produce its effect, we have no adequate knowledge of causality, it is but another expression for the skeptical proposition that phenomena fail to reveal the un- known. It is Hume's special development of the Skeptical conclusions, together with the consideration that no experience can supply the element of necessary connection, that leads Kant to the conviction that the conception of causality, so far 1 Windelband, History of Philosophy, p. 624. 48 CONCEPTIONS OF CAUSALITY from being derived from experience, is a necessary condition of all experience. The Skeptical conception of the relativity of the causal relation is reemphasized by Hegel. " So far as we can speak of a definite content," he says, "there is no content in the effect that is not in the cause. ... It is in the effect that a cause first becomes actual and a cause. . . . The rain (the cause) and the wet (the effect) are the selfsame existing water. In point of form the cause (rain) is dissipated or lost in the effect (wet), but in that case the result can no longer be described as effect; for without the cause it is nothing, and we should have only the unrelated wet left." * Finally, all the Skeptical criticisms reappear in Lotze's critique of the common notions of causality, where the con- clusion is drawn that the connection between cause and effect must be more than the conditioning of one by the other — that voluntary activity is the sole causality. Modern investigations regarding the origin and validity of the concept of causality have led us to a fuller realization of the nature of the problem, a clearer formulation of its con- ditions, and a deeper insight into the difficulties surrounding its solution. Indeed, the problem as now apprehended, is scarcely recognizable as that over which the Greeks were strug- gling more than two thousand years ago; and yet the specula- tions of these early philosophers, despite the incompleteness of their conceptions and the one-sidedness of their development, have proved for all succeeding ages an invaluable heritage. i Wallace, The Logic of Hegel, p. 277. VI THE RELATION OE THOUGHT TO ITS OBJECT While any conscious epistemology, or definite shaping of a theory of knowledge, is foreign to early speculation, the search for an ultimate essence, an abiding element, a hidden cause, is in itself a tacit acknowledgment that absolute reality is not given in experience, but must be apprehended through reflection. Thus there arises very early in Greek philosophy the epistemological motif. Though not definitely expressed, there is implicit in the beginning of speculation, the question how knowledge can be valid for an extramental reality — how thought, a mere mental event, can represent a truth independ- ent of and beyond itself. Heraclitus, first among the philosophers of Greece, em- phasizes the idea that the senses are delusive and that truth is to be grasped through thought alone. "Eyes and ears," he says, "are bad witnesses to men having rude souls. 1 . . . The majority of people have no understanding of the things which they daily meet. 2 . . . Notwithstanding that all things happen according to reason, men act as though they never had any experience in regard to it. 8 . . . They do not understand how that which separates unites with itself. It is a unity of oppositions. 4 . . . Unite whole and part, agreement and disagreement, accordant and discordant, from all comes one, and from one all. 5 . . . The law of under- standing is common to all." 6 These brief fragments reveal, in addition to the rationalism of Heraclitus, other principles i Bywater, Heracliti Ephesii Reliquiae, Frag. IV. 4 Ibid., Frag. XLV. « Ibid., Frag. V. 5 md., Frag. LIX. 3 Ibid., Frag. II. 6 ibid., Frag. XCI. e 49 50 THE RELATION OF THOUGHT TO ITS OBJECT of great historic significance. Here we find the recognition of a universal element in the human understanding, and the assertion of the unity of opposites, a statement which in re- cent times has given rise to so much discussion regarding the true import of the theory of Heraclitus and his true rank in the history of philosophy. The central principle of the philosophy of Parmenides is, as we have seen, the idea that the sole reality is a unitary, unalterable being, and that all change and multiplicity are mere illusions. But since knowledge of this true being is attainable only by thought, and the senses delude us into an opinion of plurality, Parmenides, who in general stands opposed to Heraclitus, agrees with him in the opinion that the senses lead us astray, and that thought alone is capable of con- ducting us to the truth. Furthermore, since all that exists is one and homogeneous, if any reality is to be ascribed to thought, it must of necessity be identified with being. " Think- ing and that by reason of which thought exists, " says Parmeni- des, " are one thing ; " x or still more emphatically, " Thinking and being are one thing." x Zeno, the disciple of Parmenides, is the author of many famous arguments against the veracity of knowledge rely- ing on sensation. He recognizes as valid the principle that nothing can be real of which the same predicate must be both affirmed and denied. Thus he applies, although he does not distinctly formulate, the principle of contradiction. Since, in the systems of Empedocles and Anaxagoras, the basal elements of things are not cognizable through sense perception, but are discoverable only through a process of reasoning, these philosophers are ready to join the ranks of those who give no credence to perception, and insist that the path of reflection is the only road to truth. Empedocles gives expression to a primitive psychology in his statement that tilings are known to us by elements of like kind in ourselves. Further, he asserts that "all things have understanding and 1 Journal of Speculative Philosophy, vol. IV, 1, Parmenides on Nature, pp. 0, 7. THE EELATION OE THOUGHT TO ITS OBJECT 51 the power of thought " (jravra yap icrOi povr]criv ^X €iv Ka ^ vw/^aTos atcrav) . 1 With Protagoras the relativity implicit in the Heraclitean flux receives a definite expression. Abandoning all distinction between perception and thought, he occupies a purely sensa- tionalists standpoint. For him there is no truth save that which is experienced. If, therefore, the sensations fail to give us absolute truth, such truth is unattainable. But he finds it easy to show that things are as they appear only for an instant of perception, and that they thus exist only in the mind of the perceiving subject, whence he concludes that man is the measure of all things and that no universally valid truth exists. Since that which appears true to each man is true for him, perceptions, as such, are all true, but they convey no knowledge of the object which gives rise to them. By obser- vations such as these, Protagoras becomes the founder of the theory of the subjectivity of sense perception. He, for the first time, makes a conscious opposition of subject and object, and realizes that the subject must be at least a factor in the creation of phenomena. Perception, though distinguished from both subject and object, is, in the Protagorean theory, conditioned by both. From the hypothesis that virtue is dependent on knowl- edge, Socrates concludes that knowledge must be attainable, and therefore seeks for a principle of universal validity to transcend the Protagorean relativism. This principle he finds in the general notion, the concept, which contains the element common to the thought of many individuals. Democritus transcends the relativism of Protagoras, not by refuting the subjectivity of sense perception, but by refus- ing to acknowledge sensation as the only source of knowledge. Sensation gives us phenomenal reality, but reflection is neces- sary for the apprehension of the true constitutions of things, the atoms. Democritus, for the first time, makes the distinc- tion between what Locke calls primary and secondary qualities — primary qualities being those that follow from the combina- 1 Mullach, Fragmenta Philosophorum Graecorum, vol. I, p. 9. 52 THE RELATION OF THOUGHT TO ITS OBJECT tions of the atoms without dependence on the perceiving sub- ject (form, size, hardness, etc.); secondary qualities those which have no relation to the nature of things, but are depend- ent on our perception of the combination of the atoms (such as color, taste, sound, etc.). Democritus regards perception, which is directed to the secondary qualities, as obscure, in contrast to reflection, which gives a clear insight into the essential qualities of things. The starting point of Plato is the Socratic principle that knowledge is necessary for virtue ; but as the knowledge which virtue demands cannot consist in the changeable product of sensation, he agrees with his master that general conceptions alone constitute true knowledge. "Knowledge does not con- sist in impressions of sense, but in reasoning about them; in that only, truth and being can be attained." * But if concep- tual thinking gives true knowledge, while perception yields simply opinions, the content of such thought, the ideas, must have a permanent reality or being to distinguish it from the transitory phenomena of perception. "We participate in generation with the body and by perception; but we partici- pate with the soul by thought in true essence, which is always the same and immutable." 2 Thus arose the Platonic concep- tion of ideas as ontological realities, no longer mere products of the human mind, but the eternal prototypes, of which all things are copies. Plato assumes a definite relation of ideas to one another in a graded series ending with the idea of the good ; and he regards it as the business of philosophy, or dia- lectic, to discover and systemically set forth this relation. In the Meno and Phaedo he develops the doctrine of remi- niscence by which the ideas, conceived as metaphysical enti- ties, are most closely connected with his theory of knowledge. " Before we began to see or hear or to perceive in any way, we must have had a knowledge of absolute equality or we could not have referred to that the equals which are derived from the senses, and so of all the other ideas ; but if the knowledge which we acquired before birth was lost by us at birth, and i Plato, Theaetetus, 186. 2 Plato, Sophist, 248. THE EELATION OF THOUGHT TO ITS OBJECT 53 if afterwards, by the use of the senses, we recovered that which we previously knew, this would be recollection. . . . Learning is recollection only. 1 . . . The truth of all things always existed in the soul." 2 Plato distinguishes opinion as a stage intermediate between knowledge and ignorance. "What essence is to generation, that truth is to belief. 3 . . . Those who see the many beautiful, and who yet neither see nor can be taught absolute beauty, who see the many just and not absolute justice and the like — such persons may be said to have opinion, but not knowledge ; but those who see the abso- lute and eternal and immutable may be said to know." 4 In the Charmides Plato questions the possibility of a science of knowledge. "Wisdom alone," says Charmides, "is a sci- ence of other sciences and of itself." 5 But Socrates, not con- tent with this statement, proceeds to discuss it without, however, arriving at any definite conclusion. In the same dialogue Plato raises the question as to whether the knowledge of what we know is the same as the knowledge of what we do not know, whether " the science of science will not also be the science of the absence of science." 5 He also makes the impor- tant distinction between ivhat one knows, a olSev, and that one knows, on olSev. " If a man knows only, and has only knowl- edge of knowledge and no further knowledge, the probability is that he will only know that he knows something, but how will this knowledge or science teach him to know what he knows ? " 6 While Aristotle agrees with Plato that the universal is the proper object of knowledge and has a higher reality than the particular, he insists that the universal exists only in, and can be known only through, the particular; that essences and phenomena are inseparable. Although, therefore, the universal is first in value, the particular is, in time, the first step to knowledge. Induction must precede deduction. " The prior and more cognizable for us is what is nearer to sensation, but the absolutely prior and more cognizable is what is more i Plato, Phaedo, 75, 76. 3 Timaeus, 29. 5 Charmides, 166. 2 Meno, 86. ^ * Republic, 479. 6 iud., 170. 54 THE RELATION OF THOUGHT TO ITS OBJECT remote therefrom " (jrpbs 17/xas filv irporepa Kal yvonpi/JLUTepa, tol iyyvrepov rrjs alcrdrjcreoiSy a,7rAa>s 8e Trporepa kcu yvwpLfxwTepa ra irop- puirepov). 1 Aristotle, therefore, gives to sensation a very prominent place in his theory of knowledge. He regards sensuous perception as the result of qualities which exist potentially in the thing and actually in the perceiving sub- ject. To the process of demonstrative knowledge he recog- nizes two impassable limits ; on the one hand, the individual, the object of sense perception, which, as being contingent, can never be demonstrated; and, on the other hand, the most gen- eral principles or axioms, which must be apodictic, since all demonstration presupposes something more universal than that which is to be deduced. These ultimate principles are not derived from experience, but are innate in the soul. One of the most incontestable truths is the principle of contradiction. " It is impossible for the same thing to be and not to be at the same time." 2 Truth, according to Aristotle, consists in the agreement of thought with reality. " For indeed the assertion that entity does not exist and that non-entity does is false- hood, but that entity exists and that non-entity does not exist is truth." 3 Truth and error are found only in the judgment and in the imagination; perceptions, as such, never lead us astray. Eeason is in part active and in part passive. In his table of ten categories, Aristotle makes the first attempt to classify the highest concepts of the understanding. In the doctrine of the Stoics the only sources of knowl- edge are perceptions, and the conclusions based thereon; and the sole activity of the mind is directed toward converting into knowledge such material as the mind receives through the senses. The Stoics picture the soul at birth as an empty tablet (tabula rasa), upon which, in the course of time, the sensations register their impressions as a seal leaves its mark upon a piece of wax. They deny emphatically that any ideas are innate in the soul. The most significant feature of the Stoic theory of knowledge is the search for a criterion of truth. 1 Aristotle, Posterior Analytics, I, 2 (p. 184 of Orgunon). 2 Metaphysics, Bk. II, ch. II, § 3. « Ibid., Bk. Ill, ch. VIII, § 1. THE EELATIQN OE THOUGHT TO ITS OBJECT 55 This standard is found in the power of compelling belief inher- ent in certain perceptions. "By itself a perception does not necessarily carry conviction or assent, for there can be no assent until the faculty of judgment is directed toward the perception, either for the purpose of allowing or rejecting it — truth and error residing in judgment. Assent, therefore, generally speaking, rests with us. Some of our perceptions are, however, of such a kind that they at once oblige us to bestow on them assent, compelling us not only to regard them as probable, but also as true and conformable to the actual nature of things. Such perceptions produce in us that strength of conviction which the Stoics call a conception; they are therefore termed conceptional perceptions. Whenever a per- ception forces itself upon us in this irresistible form, we are no longer dealing with a fiction of the imagination, but with something real; but whenever the strength of conviction is wanting, we cannot be sure of the truth of our perception. Or, expressing the same idea in the language of Stoicism, con- ceptional or irresistible perceptions are the standard of truth." 1 The Epicureans adopt even more unreservedly than the Stoics the sensationalistic theory of knowledge. Their theo- retical criterion of truth is sensation, but their practical test is the feeling of pleasure or pain. Since sensation is the only source of knowledge, all perceptions must be true, for how could reason, which is dependent on sensation, refute the tes- timony of the senses? Error belongs not to sensation, but to the judgment which draws unwarranted inferences from the sensations caused by " pictures " of the object. The Skeptics doubt the possibility of any knowledge, whether derived from sensation or reflection. The aim of Skepticism is to secure first twox*], or suspense of judgment, and later drapa^ia, or imperturbability of spirit. The method is to oppose every argument adduced in rival theories by one of equal weight. It is the Skeptic's boast that he neither affirms nor denies, but maintains the attitude of ever seeking enlight- enment. His sole criterion is the phenomenon, which cannot 1 Zeller, Stoics, Epicureans, and Sceptics, pp. 88, 89. L.ofC. 56 THE RELATION OE THOUGHT TO ITS OBJECT be doubted, since it is based upon involuntary feeling. The question in dispute is not whether an object appears as it appears, but whether in reality it is as it appears to us. The Skeptical tropes attempt to prove that phenomena are so rela- tive and changing that no certain knowledge can be based on them. The most important of these tropes are those on aeti- ology, which have already been discussed, and the ten tropes on the relativity of sense perception. The latter call attention to the differences in the constitutions of the various animals, which prevent them from gaining the same ideas of objects through the senses; to diversities even among men; to differ- ences in the sense organs which cause the eye to assign to paintings elevations and depressions which to the touch appear as flat; to the varying effect on sense impressions of diverse physiological conditions as of satiety and sobriety ; to the dif- ferences in the appearance of objects caused by quantity and physical state, by distance and position, and by the medium through which the object is viewed; to the relativity of every- thing to other things and to the person judging; and to the variability in different countries of customs, laws, and religious and philosophical beliefs. 1 From these tropes the Skeptics con- clude that things in themselves cannot be known and that the only true philosophic attitude is that of doubt or suspense of judgment. This review shows that in the epistemology of the Greeks some of the significant tendencies of modern theories of knowl- edge had already come to light. The rationalism of Heraclitus, Panne n ides, Empedocles, Anaxagoras, Plato, and Democritus, anticipates that of Descartes, Spinoza, Leibniz, or Wolff; the sensationalism of Protagoras, the Stoics, and the Epicureans, is reproduced by that of Hobbes, Locke, Berkeley, Hume, Mill, and the Positivists; while the skepticism of the Sophists and the Skeptics has certain affinities with that of Hume. To consider, in greater detail, the anticipations in the field of epistemology, let us turn first to Heraclitus. In his recognition of universality as a test of validity, he particularly 1 Sextus Empiricus, Pyrrhonic Sketches, Bk. I, ch. XIV. THE RELATION -OF THOUGHT TO ITS OBJECT 57 foreshadows Kant, as also in his conception of a unity, which includes the manifold in itself. But it is in relation to the philosophy of Hegel that the utterances of Heraclitus assume the greatest significance. "Bei Heraklit," says Hegel, "ist also zuerst die philosophische Idee in ihrer speculativen Form anzutreffen. . . . Hier sehen wir Land. Es ist kein Satz des Heraklit den ich nicht in meine Logik auf genommen ; " 1 and Lasalle, further emphasizing the same view, says : " Hera- klit dagegen hat das Werden seinem Wahrhaften Begriffe nach gehabt, als die Einheit des absoluten Gegensatzes von Sein und Nichtsein und deren Uebergang in einander. Er hat die Bewegung als reine Negativitat gefaszt." 2 Dr. G. T. Patrick, in his comments on Hegel's interpretation of Heraclitus, sug- gests that the latter's idea of the unity of opposites applies only to physical change, that the significant expressions: "We are and we are not, " 3 " That which separates unites with itself ; it is a unity of oppositions," 4 evidence no more than a recog- nition on the part of Heraclitus of the obvious fact that differ- ent properties inhere in the same thing. Perhaps the truth lies somewhere between the extreme views of Hegel and of Patrick; but whatever interpretation we may put upon the obscure utterances of Heraclitus, we cannot deny that there were implicit in his system, though not consciously present to his own mind, some of the principles of the Hegelian philoso- phy. "The unlike is joined together," says Heraclitus, "and from differences results the most beautiful harmony. 5 . . . Unite whole and part, agreement and disagreement, from all comes one, and from one all." 6 " There is absolutely nothing," says Hegel, " in which we cannot and must not point to con- tradictions or opposite attributes ; " 7 and he lays great stress, also, upon the thought that " each conception with which the human mind has thought reality becomes a moment or factor, 1 Hegel, Vorlesungen iiber die Geschichte der Philosophie, vol. I, p. 328. 2 La Salle, Die Philosophie Herakleitos des Dunklen von Ephesos, vol. I, P- 7. 3 Bywater, Heracliti Ephesii Reliquiae, Frag. LXXXI. 4 Ibid., Frag. XLV. 5 Ibid., Frag. XLVI. 6 iud., Frag. LIX, 7 Wallace, The Logic of Hegel, p. 169. 58 THE RELATION OF THOUGHT TO ITS OBJECT which receives its full value only when introduced into the whole." * " All things take place by strife," 2 says Heraclitus. "Contradiction," says Hegel, "is the very moving principle of the world." 3 In the epistemology of Parmenides the most noteworthy feature is the identification of thought and being. Here, again, we have a fruitful principle imperfectly conceived. To identify the theory of Parmenides with modern idealism, as represented by Berkeley, Fichte, or Hegel, would be fallacious, since the Parmenidean philosophy lacks the element of spir- ituality. Paradoxical as it may sound, the identification of thought and being, as set forth by the Eleatic, may be described as materialistic idealism. Thought and being are one, not because matter is reduced to a phase of thought, but because thought is conceived as analogous to matter. Nevertheless, the motive to this identification — the impulse to represent existence as an all-embracing unity, and yet concede reality to thought — governs all the later systems of idealism. Zeno's application of the principle of contradiction, which takes more definite shape in Aristotle, meets us again in Leib- niz, who makes the absence of contradiction a fundamental condition of validity and a test of the principle of sufficient reason. Empedocles' opinion that all things have the power of thought also foreshadows Leibniz, who regards all the monads as souls having perception {petites perceptions), although he maintains that apperceptive self-consciousness belongs only to the higher monads. Through his theory of the subjectivity of sense perception, Protagoras becomes the legitimate forerunner of Berkeley, Hume, and all the subjective idealists whose epistemology rests upon a sensationalistic basis. Democritus, by his doctrine, derived from Protagoras, that sense qualities, such as colors, sounds, etc., are entirely 1 Windelband, History of Philosophy , p. 612. 2 Bywater, Heracliti Ephesii Reliquiae, Frag. XLVI. 8 Wallace, The Logic of Hegel, p. 223. THE EELATION. OF THOUGHT TO ITS OBJECT 59 subjective and, by his consequent limitation of things to quan- titative determinations, reminds us of Galileo, Hobbes, and Descartes, and still more forcibly of Locke, to whom (because he first applied the terms primary and secondary qualities to represent the distinction) the origination of this doctrine is often erroneously attributed. At first thought the Platonic philosophy, which regards ideas as the sole reality, suggests comparison with Berkeley, Fichte, and Hegel; but here again, as in the case of Par- menides, we must beware of rash conclusions. The Platonic idealism is mainly a system of metaphysics, and only in so far as it is connected with the doctrine of reminiscence has it any significance for the theory of knowledge. The ideas, as mere content of thought, having an existence independent of the mind, cannot legitimately be identified with the ideas of sub- jective or of absolute idealism, which are dependent on the mind's activity. Yet there are points in Plato that are sug- gestive of Hegel. Hegel himself awards to Plato the honor of having invented dialectic, and compares his own theory, that education or development is required to bring out into con- sciousness what is therein contained, with the Platonic doc- trine, that all learning is reminiscence, and that the truth of all things always existed within the soul. Plato's notion of a graded series of ideas is another principle that has become fruitful in the philosophy of Hegel. The view of Aristotle, the Stoics, and the Epicureans, that all error should be referred to the judgment, is upheld by Descartes, who maintains that we err only when we judge of what we do not clearly and distinctly perceive; and also by Locke, who insists that no ideas, as they appear in the mind, are either true or false, but that all truth and falsity belong to propositions which relate ideas. Like Aristotle, again, Leibniz recognizes two kinds of non-demonstrative or intuitive knowledge, — the contingent facts of experience and the uni- versal apodictic principles of reason. In his recognition of a passive and an active element in the mind, Aristotle may be compared with Kant, although the former makes the reason 60 THE RELATION OF THOUGHT TO ITS OBJECT partly active and partly passive, while the latter, differentiat- ing the faculties of the ruind, assigns its receptivity to the sensibility and its activity to reason. It should be noted, too, that Kant's doctrine of the spontaneity of reason, which regards the objects of thought as a product of the thinking process, differs radically from Aristotle's view, which regards these objects as existent independently of thought. Like Aristotle, also, Kant places much emphasis on the deduction of the categories of the understanding; but in the episte- mology of Kant a new significance is attached to the term. While the categories of Aristotle are simply the highest classes under which the objects of knowledge may be subsumed, or the most general forms in which being may be expressed, the categories of Kant constitute the formal element in the mind's activity, not an abstraction from experience, but a necessary condition of all experience. The search of the Stoics for a universal standard as the test of truth is repeated by Descartes, and their criterion of irresistibility or the power of carrying conviction varies but slightly from the Cartesian criteria of clearness and distinct- ness. In the doctrine of the sensational origin of knowledge, and in the limitation of the activity of the mind to the combination of perceptions, in the denial of innate ideas, and in the picturing of the soul at birth as an empty tablet, the epistemology of the Stoics bears a striking resemblance to that of Locke. The Skeptical tropes, which, as we have seen, tend mainly to establish the subjectivity of sense perception, embody the arguments which prompt Descartes to characterize as confused knowledge the impressions gained through the senses, and which induce Locke to make the distinction before alluded to between the primary and secondary qualities of things. The trope based upon the differences in perceptions gained through the various senses anticipates, in a measure, some of the most forcible arguments in Berkeley's New Theory of Vision. Still more suggestive is the trope which impresses the thought that things as we know them do not exist absolutely, but that THE RELATION OF THOUGHT TO ITS OBJECT 61 all things exist in mutual relation. This thought assumes great significance in the Hegelian system, and becomes a cen- tral principle in the philosophy of Lotze. We must look for the being of things, according to Lotze, " in the reality of the relations in which the things stand to each other. . . . Not to be at any place, not to have any position in the complex of other things, not to undergo any operation from anything, nor to display itself by the exercise of any activity upon anything — to be thus void of relation is just that in which we should find the nonentity of a thing if it was our purpose to define it." * The Skeptical conclusion that knowledge can apprehend nothing beyond phenomena is suggestive of Kant's distinc- tion of cognizable phenomena from the unknowable noumena, of Spencer's contrast of appearance with an unknowable reality, and of the attitude of Comte and other Positivists, who con- fine all their investigations within the field of phenomena and declare, with unhesitating assurance, that nothing absolute exists. Finally, the Skeptical tendency, as a whole, finds its chief analogue in Hume. He differs from the Skeptics, how- ever, in justifying inquiry within its proper sphere and in condemning only such assumptions as are not, and can never be, supported by the guaranty of sense perception, the ulti- mate source, according to Hume, of all our knowledge. " Should it be asked of me," says Hume, "whether I be really one of those Skeptics who hold that all is uncertain, and that our judgment is not in any thing possessed of any measures of truth and falsehood, I should reply that this question is en- tirely superfluous, and that neither I nor any other person was ever sincerely and constantly of that opinion. Nature, by an absolute and uncontrollable necessity, has determined us to judge as well as to breathe and feel." 2 "The great sub- verter of Pyrrhonism, or the excessive principles of skepticism, is action or employment, and the occupations of common life." 3 But there is a more moderate skepticism which " may be under- 1 Lotze, Metaphysic, vol. I, p. 39. 2 Hume, A treatise on Human Nature, vol. I, pp. 474 and 475. 3 Hume, Enquiry concerning Human Understanding ', p. 158. 62 THE RELATION OF THOUGHT TO ITS OBJECT stood in a very reasonable sense, and is a necessary preparative to the study of philosophy by preserving a proper impartiality in our judgments and weaning our mind from all those preju- dices which we may have imbibed from education or rash opinion. 1 . . . Another species of mitigated skepticism, which may be of advantage to mankind and which may be the natural result of the Pyrrhonian doubts and scruples is the limitation of our inquiries to such subjects as are best adapted to the narrow capacity of the human understanding." 2 Thus we catch glimpses in the philosophy of the Greeks of thoughts often regarded as the special contribution of modern theories of knowledge. With but a dim apprehension of the creative activity of the mind, the Greek philosophers did not clearly perceive the fact that the question of the validity of knowledge is inseparably bound up with the problem of the ultimate nature of things — that a rational metaphysics must of necessity rest upon a sound basis of epistemology. In their day epistemology never advanced to the dignity of a science, but they gathered together much of the material that has made that science a possibility. 1 Hume, Enquiry concerning Human Understanding, p. 150. 2/6icZ.,p. 162. CONCLUSION From a study of the various problems considered in this paper, as developed in Greek and modern philosophy, it becomes manifest that the germs, or fundamental elements, of the leading metaphysical and epistemological systems of mod- ern times existed already in the philosophy of the Greeks. Although the foremost philosophical systems of our day, with their more scientific equipment, their wider outlook, and their keener apprehension of problems, bear little resemblance on the surface to the speculations of Heraclitus, Parmenides, or Democritus, of Plato, Aristotle, or Aenesidemus, an analysis of both ancient and modern systems into their essential ele- ments not only brings to light many remarkable agreements, but discloses the fact that the leading ideas of the Greeks are as vital and vivifying to-day as they were more than two thou- sand years ago. We have seen virtually the same problems engaging the attention of philosophy throughout all ages j we have observed similar motives giving rise in widely separated times to similar solutions; and we have discovered, amid mul- tiform changes in method and detail, a unity of purpose which dominates the whole history of speculative thought. While each age has furnished its contribution to a constantly evolving philosophy, it has been the special work of modern thinkers to support, by observation and demonstration, the prophetic con- ceptions grasped by the Greeks through intuition; to correct one-sided tendencies, improve imperfections, and clear up cloudy and confused ideas ; and to systematize and coordinate uncorrelated truths. 63 1 COPY DEL, JO CAT, DIV, DEC 9 1901