CHAPTER III.. The Theorists of Knowledge

THE THEORISTS OF KNOWLEDGE

LOCKE, BERKELEY, HUME, KANT.

Epistemology, or theory of knowledge, did not begin in modern times. Among the Greeks it goes back, at least, to Empedocles, and figures largely in the programmes of the later schools. And Descartes's universal doubt seems to give the question, How can we be sure of anything? a foremost place in speculation. But the singular assurance with which the Cartesian metaphysicians presented their adventurous hypotheses as demonstrated certainties showed that with them the test of truth meant whatever told for that which, on other grounds, they believed to be true. In reality, the thing they called reason was hardly more than a covert appeal to authority, a suggestion that the duty of philosophy was to reconcile old beliefs with new. And the last great dogmatist, Leibniz, was the one who practised this method of uncritical assumption to the utmost extent.

LOCKE.

It is the peculiar glory of John Locke (1632-1704) to have resumed that method of doubt which Descartes had attempted, but which his dogmatic prepossessions had falsified almost at the first start. This illustrious thinker is memorable not only for his services to speculation, but for the example of a genuinely philosophic life {66} entirely devoted to truth and good--a character in which personal sweetness, simplicity, and charm were combined with strenuous, disinterested, and fearless devotion to the service of the State. Locke was a Whig when Whiggism meant advanced Liberalism in religion and politics, and when that often meant a choice between exile and death. Thus, after the fall of his patron, Lord Shaftesbury, the philosopher had to take refuge in Holland, remaining there for some years, lying hid even there for some time to escape an extradition order for which the Government of James II. had applied. It was in Holland that he wrote the Essay Concerning Human Understanding.

This revolutionist in thought was no solitary recluse, but, in the best sense, a thorough man of the world. Educated at Westminster and Christ Church, he had, in the German poet's phrase, the supreme happiness of combining the seriousness of an enthusiast with the sagacity of a statesman, so that great statesmen recognised him as one of themselves. With the triumph of the Whig cause at a time when diplomacy demanded the utmost tact and skill, it was proposed to send Locke as Ambassador to the Court of Brandenburg, and, as that would not have suited his sober habits, to the Court of Vienna. Weak health obliging him to decline this also, he received office in the Ministry at home, taking a department where business talents were eminently required. In that capacity he bore a leading part in the restoration of the coinage, besides inspiring the Toleration Act and the Act for Unlicensed Printing. Even the wisest men make mistakes; and it must be noticed with regret that Locke's theory of toleration excluded Roman Catholics on the one side and atheists on the other--the former because their {67} creed made persecution a duty, the latter because their want of a creed left them no sanction for any duties whatever. To say that Locke had not our experience does not excuse him, for in both cases the expediency of toleration can be proved a priori. Romanists must be expected to suppress a heresy whose spokesman declares that when he has the power he will suppress their Church; and, if atheists are without moral principle, they will propagate, under cover of orthodoxy, negations that they are not allowed openly to profess.

Locke was brought up by a Puritan father; and, although in after life he wandered far from its doctrinal standards, he no doubt always retained a sense of that close connection between religion and morality which Puritanism implies. Telling about the train of thought that started his great Essay, he refers it to a conversation between himself and some friends, in which they "found themselves quickly at a stand by the difficulties that rose on every side;" and, according to an intimate friend of his, the discussion turned "on the principles of morality and revealed religion." It then occurred to him that they should first ascertain "what objects their understandings were or were not fitted to deal with." And the mottoes prefixed to the essay prove that the results were of a decidedly sceptical cast. Indeed, his successors, though not himself, were destined to develop them into what is now called Agnosticism.

We have further to note that, while his Continental rivals were mathematicians, our English philosopher never went deeply into mathematics, but was by calling a physician. In this he resembles Aristotle and Sextus Empiricus among the Greeks; and so it is quite in order that, with the same sort of training, he should {68} adopt Aristotle's method of experience as against Platonic transcendentalism, and the sceptical relativism of Sextus as against the dogmatism of the schools.

Locke begins his essay with a vigorous polemic against the doctrine of Innate Ideas. The word "idea," as he uses it, is ambiguous, serving to denote perceptions, notions, and propositions; but this confusion is of no practical importance, his object being to show that all our knowledge originates in experience; whereas the reigning belief was that at least the first principles of knowledge had a more authoritative, if not a mystical, source. Hobbes had been beforehand with him in deriving every kind of knowledge from experience, but had been content to assume his case; whereas Locke supports his by a formidable array of proofs. The gist of his argument is that intellectual and moral principles supposed to be recognised by all mankind from their infancy are admitted only by some, and by those only as the result of teaching.

As we saw, the whole inquiry began with questions about religion and morality; and it is precisely in reference to the alleged universality and innateness of the belief in God and the moral law that Locke is most successful. And the more modern anthropology teaches us about primitive man, the stronger becomes the case against the transcendental side in the controversy. Where his analysis breaks down is in dealing with the difficult and important ideas of Space, Time, Substance, and Causality--with the fatal result that such questions as, How is experience itself possible? or, How from a partial experience can we draw universal and necessary conclusions? find no place in his theory of knowledge. Of course, his contemporaries are open to the same {69} criticism--nor, indeed, had the time come even for the statement of such problems. Meanwhile, the facility with which the founder of epistemology accepts fallacies whence Spinoza had already found his way out shows how little he was master of his means. According to Locke, it is "a certain and evident truth that there is an eternal, most powerful, and most knowing being, which whether anyone will please to call God it matters not." On examination the proof appears to involve two unproved assumptions. The first is that nothing can begin to exist without a cause. The second is that effects must resemble their causes. And from these it is inferred that an all-powerful being must have existed from all eternity. The alternative is overlooked that a succession of more limited beings would answer the purpose equally well, while it would also be more consistent with our experience. But a far more fatal objection to Locke's theism results from his second assumption. This, although not explicitly stated, is involved in the assertion that for knowledge such as we possess to originate from things without knowledge is impossible. For, on the same principle, matter must have been made by something material, pain by something that is pained, and evil by something that is evil. It would not even be going too far to say that by this logic I myself must have existed from all eternity; for to say that I was created by a not-myself would be to say that something may come from nothing.

We have seen how Locke refused toleration to atheists on the ground that their denial of a divine lawgiver and judge destroys the basis of morality. He did not, like Spinoza, believe that morality is of the nature of things. For him it is constituted by the will of God. Possibly, if pressed, he might have explained {70} that what atheism denies is not the rule of right, but the sanction of that rule, the fear of supernatural retribution. Yet being, like Spinoza and Leibniz, a determinist, he should have seen that a creator who sets in motion the train of causes and effects necessarily resulting in what we call good or bad human actions has the same responsibility for those actions as if he had committed them himself. To reward one of his passive agents and to punish another would be grossly unjust and at the same time perfectly useless. But how do we know that he will, on any theory of volition, reward the good and punish the bad? "Because we have his word for it." And how do we know that he will keep his word? "Because he is all-good." But that, on Locke's principles, is pure assumption; and God, being quite sure that he has no retribution to fear, must be even more irresponsible than the atheist.

The principle that nothing can come from nothing, so far from proving theism, leads logically either to pantheism or to a much more thorough monadism than the system of Leibniz. And, metaphysics apart, it conflicts with a leading doctrine of the essay--that is the fundamental distinction between the primary and the secondary qualities of matter. We think of bodies as in themselves extended, resisting and mobile, but not in themselves as coloured, sonorous, odorous, hot, cold, or sapid. They cause our special sensations, but cause them by an unknown power. Again we perceive--or think we perceive--both primary and secondary qualities in close union as properties of a single object, and this object in which they jointly inhere is called a substance. And to the question, What is substance? Locke admits that he has no answer except something we know not what. He has returned to the agnostic standpoint of the {71} Cyrenaic school. This something, for aught we know, might have created the world.

Continental historians regard the whole rationalistic movement of the eighteenth century, or what in Germany is called the Enlightenment (Aufklaerung), as having been started by Locke. But the sort of arguments that he adduces for the existence of a God prove that in theology at least his rationalism had rather narrow limits. Both his theism and his acceptance of Christianity on the evidence of prophecy and miracles show no advance on medieval logic. In this respect Spinoza and Bayle (1622-1709) were far more in line with the modern movement. Still, assuming scripture as an authoritative revelation, Locke shows that, rationally interpreted, it yields much less support to dogmatic orthodoxy than English Churchmen supposed. And whatever may have been the letter of his religious teaching, there can be little doubt that the English Deists, Toland, Shaftesbury, and Anthony Collins, represented its true spirit more faithfully than the philosopher himself.

Representative government and the subordination of ecclesiastical to secular authority--or, better still, their separation--are both good things in themselves and favourable conditions to the life of reason. Another condition is that children should be trained to exercise their intelligence instead of relying blindly on authority. In these respects also Locke's writings acted powerfully on the public opinion of the next century, especially through the agency of French writers; France, as Macaulay justly claims, being the interpreter between England and the world. Our present business, however, is not with the diffusion but the development of thought, and to trace this we must return to British philosophy. {72}

BERKELEY.

George Berkeley (1684-1753) was born and educated in Ireland. The fact is of no racial or national importance, but interests us as accounting for his having received a better training in philosophy than at that time was possible in England. For the study of Locke, then proscribed at Oxford, had already been introduced into Dublin when Berkeley was an undergraduate there; and it was as a critical advance on Locke that his first publication, the New Theory of Vision (1709), was offered. Next year came the epoch-making Principles of Human Knowledge, followed in 1713 by the more popular Dialogues. At twenty-nine his work was done, and although he lived forty years longer, rising to be a Bishop in the Irish Church, after projecting a Christian Utopia for the civilisation of the North American Indians that never came to anything, and practising "every virtue under heaven," he made no other permanent contribution to thought.

Berkeley is at once a theorist of knowledge and a metaphysician, combining, in a way, the method of Locke with the method of Descartes and his successors. The popular notion of his philosophy is that it resolved the external world into a dream, or at least into something that has no existence outside our minds. But this is an utter misconception, against which Berkeley constantly protested. His quarrel was not with common sense, but with the theorists of perception. To understand this we must return for a moment to Locke's teaching. It will be remembered in what a tangle of difficulties the essay had left its author. Matter had two sets of qualities, primary and secondary, the one belonging to things in themselves, the other existing only {73} in our minds; yet both somehow combined in real substances independent of us, but acting on our senses. Substance as such is an unknown and unknowable postulate; nevertheless, we know that it was created by God, of whom our knowledge is, if anything, inconveniently extensive. Now Berkeley, to find his way out of these perplexities, begins by attacking the distinction between primary and secondary qualities. For this purpose his Theory of Vision was written. It proves--or attempts to prove--that extension is not a real attribute of things in themselves, but an intellectual construction, or what Locke would have called an "idea of reflection." Till then people had thought that its objectivity was firmly established by the concurrent testimony of two senses, sight and touch. Berkeley shows, on the contrary, that visible and tangible extension are not the same thing, that the sensations--or, as he calls them, the ideas--of sight and touch are two different languages whose words we learn by experience to interpret in terms of each other without their being necessarily connected. A man born blind would not at first sight know how to interpret the visual signs of distance, direction, and magnitude; he would have to learn them by experience. These, in fact, are ideal relations only existing in the mind; and so we have no right to oppose mind as inextended to an extended or an external world.

Having thus cleared the ground, our young idealist proceeds in his next and greatest work, Of the Principles of Human Knowledge, to attack the problem from another side. The world of objects revealed through sensation and reflection is clearly no illusion, no creation of our own. We find it there, changing, when it changes, without or even very much against our will. {74} What, then, is its origin and nature? Locke's view, which is the common view, tells us that it consists of material bodies, some animated and some not. And matter, the supposed substance of body, is made known to us by impressions on our organs of sense. But when we try to think of matter apart from these sensible qualities and the relations between them it vanishes into an empty abstraction. Now, according to Berkeley there are no abstract ideas--i.e., no thoughts unassociated with some mental image besides a mere word; and Matter or inanimate substance would be such an idea, therefore it does not exist. There is nothing but mind and its contents--what we call states of consciousness, what Locke and Berkeley called ideas. Whence, then, come the objects of our consciousness, and whither do they go when we cease to perceive them? At this point the new metaphysical system intervenes. Berkeley says that all things subsist in the consciousness of God, and by their subsistence his existence is proved. The direct apprehension of a reality that is not ourselves only becomes possible through what would be called in modern language a subjective participation in the divine consciousness, more feebly reflected, as would seem, in the memories, imaginations, and reasonings of our finite minds.

In pursuing these wonderful speculations Berkeley deviated widely from the direct line of English philosophy, and it is difficult not to believe that the deflection was determined by the influence of Malebranche, especially when we find that the writings of the Oratorian Father were included in his college studies. Moreover, a parallel line of idealistic development derived from the same source was evolving itself at {75} the same time in English thought. John Norris (1657-1711), a correspondent of the Platonist Henry More, an opponent of Locke, and a disciple of Malebranche, had himself found an enthusiastic admirer in Arthur Collier (1680-1732), whose Clavis Universalis professed to be "a demonstration of the non-existence or impossibility of an external world" (1713). Both Norris and Collier, like Malebranche and Berkeley, were Churchmen; but so strong was the drift towards idealism that Leibniz, a layman and a man of science, contributed by his Monadology to the same current. Malebranche neither was nor could he be a complete idealist in the sense of denying the reality of matter; for the dogma of transubstantiation bound him, as a Catholic, to its acceptance, while Berkeley, Collier, and Leibniz, as Protestants, were under no such obligation. His idealism agreed more nearly with the Neo-Platonic doctrine of Archetypes in the divine Reason among which Matter was one. On the other hand, Berkeley probably borrowed from him the notion of a direct contact with God, the difference being that with the Cartesian it is conceived as an objective vision, with Locke's disciple as (if the expression may be permitted) a subjective con-consciousness. Leibniz, again, while abolishing Matter, retains an external world composed indeed of spirits and so far immaterial, but existing independently of God.

All these systems involve the negation of two fundamental scientific principles. The first is that every change must be explained by reference to an antecedent change to which it bears a strict quantitative relation. The second is that no particular change can be referred to another change as its necessary antecedent unless it can be shown by experience that a precisely similar {76} couple of changes are, in fact, always so connected. Let me illustrate these principles by an example. I leave a kettle full of cold water on the fire, and on returning after a sufficient interval of time I find the water boiling. Had I stayed by the fire and watched the process, my kettle would--a popular proverb to the contrary notwithstanding--have certainly boiled as soon, but also no sooner for being helped by my consciousness. The essential thing is that energy of combustion in the fire should be turned into energy of boiling in the water. Now, what is Berkeley's interpretation of the facts? Fire, kettle, water, and ebullition are what in his writings are called "ideas"--i.e., phenomena occasionally in my mind, but always in God's mind. And according to this view the necessary antecedent to the boiling of the water is not the fire's burning, but God's consciousness of its burning, his perception being the essence of the operation. But it is proved by experience that neither my perception nor anyone else's ever made a single drop of water boil. In other words, perception is not in this instance a vera causa. Why, then, should the perception of any other mind, however exalted, have that effect?

Nor is this all. How does Berkeley know that God exists? Because, he says, to exist is to be perceived, and therefore for the universe to exist implies a universal Percipient. But he got the idea of God from other men, who certainly did not come by it as a generalisation from their perceptions; they got it by generalising from their voluntary actions, which do produce the changes that perception cannot produce. It will be said that volitions and the feelings that prompt them exist only in consciousness. In whose consciousness? In that of a spirit. And what is spirit apart from {77} sensation, thought, feeling, and volition? Simply one of those abstract ideas whose existence Berkeley himself denied.

HUME.

The next step in the evolution of English thought was to consist in a return to Locke's method, involving a complete breach with seventeenth-century Platonism, and with the Continental metaphysics that it had inspired. This decisive movement was effected by one in whom German criticism has recognised the greatest of all British philosophers. David Hume (1711-1776) was born and bred at Edinburgh, which also seems to have been through life his favourite residence. But his great work, the Treatise on Human Nature, was written during a stay in France, between the ages of twenty-three and twenty-six. Thus his precocity was even greater than Berkeley's. Indeed, such maturity of thought so early reached is without a parallel in history. But Hume's style had not then acquired the perfection--the inimitable charm, Kant calls it--of his later writings; and, whether for this or for other reasons, the book, in his own words, "fell dead-born from the press." In middle life the office of librarian of the Advocates' Library at Edinburgh gave him access to the materials for his History of England, which proved a source of fame and profit. A profound historical scholar, J. S. Brewer, tells us that Hume "possessed in a pre-eminent degree some of the highest excellences of a historian." Other historians have treated their subjects philosophically; he furnishes the sole instance of a great speculative genius who has also produced a historical masterpiece of the first order. But morally it is a blot on his fame. It is sad that a philosopher should have deliberately perverted the truth, that one who has {78} [Illustration: DAVID HUME.] performed priceless services to freedom of thought should have made himself the apologist of clericalising absolutism, and, still more, that a master of English played this part to some extent through hatred of the great English people engendered by disappointed literary ambition. It may be mentioned, however, as a possible extenuation that towards the middle of the eighteenth century the highest English ability had thrown itself, with few exceptions, on the Tory side. It must be mentioned {79} also that in private life Hume's character was entirely admirable--cheerful, generous, and gentle, without a frailty and without a stain. His opinions were unpopular; but his life offered no handle for obloquy, although his studious retirement was more than once exchanged for the responsibilities of political office, and the freedom from pedantry so conspicuous in his writings bears witness to habits of well-bred social intercourse.

Hume's philosophy is best understood when we consider it as, in the first place, a criticism of Berkeley, just as Berkeley's had been a criticism of Locke. It will be remembered that the founder of subjective idealism discarded the notion of material substance as an "abstract idea," an unintelligible figment devoid of any sensuous or imaginative content. The only true substances are the subjects of what we call experience communicating through sensation with God, the infinite spirit whose eternal consciousness is reality itself. Hume applied the same tests to spiritual substance, and found that it equally disappeared under his introspective analysis. He begins by dividing the contents of consciousness into two classes, impressions and ideas--the second being copies of the first, and distinguished from them by their relative faintness. Now, from these perceptions (which he called thoughts) Descartes had passed by an immediate inference to the ego or self, which he affirms as the primary fact of consciousness, using it as a basis for sundry other conclusions. But Hume stops him at once, and will not grant the existence of the metaphysical self--that is, a simple and continued substance, as distinguished from particular states of consciousness. We are, he declares, "nothing but a bundle of different perceptions, which {80} succeed each other with an inconceivable rapidity, and are in a perpetual flux and movement." "There is properly no simplicity in it [the self] at one time, nor identity in different [times]; whatever natural propensity we may have to imagine that simplicity and identity." So much being assumed, Berkeley's whole argument for a new theology founded on subjective idealism is bound to collapse, as also is the argument for natural immortality derived from the supposed simplicity and identity of the thinking substance.

Modern critics have rightly insisted, as against Hume, that isolated perceptions without a self are abstractions not less unintelligible than a self without perceptions. But the metaphysical argument for human immortality has not benefited by this more concrete interpretation of epistemology; and probably Hume was really more interested in destroying this than in maintaining the sceptical paradox which does not recur in his later writings.

A word must be added about Hume's division of perceptions into impressions and ideas. The point left out of sight in this analysis is that impressions of sense habitually find their reflexes not in revived sensations, but in expressions, in motor reactions which, with human beings, mostly take the form of words uttered or thought. These, no doubt, are associated to some small extent with revived sensations; but they are more commonly grouped with other words, with movements of the limbs, and with actions on the material or human environment of the percipient. Such expressions are incomparably easier to revive in memory, imagination, or expectation than the impressions that originally excited them; and, indeed, it is in connection with them that such revivals of sensation {81} as we actually experience take place. And it is probable that to this active side of our consciousness that we may trace those associative processes which Hume studies next in his analysis of human knowledge.

Putting aside principles of doubtful or secondary value, the relations between states of consciousness that first offer themselves to view are, according to Hume, Co-existence and Succession (united under the name of Contiguity), Resemblance, and Causation. It is with the account he gives of this last category that his name is inseparably associated, for from it all subsequent speculation has taken rise. Yet primarily he seems to have had no other object in view than to simplify the laws of knowledge by resolving one of them into a particular case of another, and thus reducing his three categories to two. The relation of cause and effect, he tells us, is no more than a certain relation between antecedent and consequent in time where the sequence is so habitual as to establish in our minds a custom of expecting the one whenever the other occurs. The sequence is not necessary, for one can think, without any self-contradiction, of a change which has not been preceded by another change; nor is it, like the truths of geometry, something that can be known a priori. Without experience no one could tell that bread will nourish a man and not nourish a lion, nor even predict how a billiard-ball will behave when another ball strikes it. Should it be objected that the a priori knowledge of a general principle need not involve an equal knowledge of nature's operations in particular cases, Hume would doubtless reply by saying that there is no abstract idea of causation apart from its concrete exemplifications.

It is possible to accept Hume's theory in principle {82} without pledging oneself to all his incidental contentions. Causation, as a general law, may be known only by experience, whether we can or cannot think of it as a pure abstraction. And we may interpret it in terms of unconditional antecedence and consequence, while discarding his apparent assumption of an inscrutable connection between the two; a mysterious necessity for the production of the one by the other, for which it is felt that a reason exists, but for which our reason cannot account. It is inconceivable that our knowledge of any given sequence could be increased, except by the disclosure of intermediate sequences, making their continuity, in space and time, more absolute than we had before perceived, until the whole process has been resolved into a transference of momentum from one molecule to another--a change for which, according to Hume, no reason can be given. Nor, on his principles, would it help us to explain such transferences by bringing them under the law of the Conservation of Energy. For, although this would be a great triumph for science, his philosophy demands a reason why the quantity of energy should remain unalterable for ever.

It is a mistake, shared by Hume with his opponents, to suppose that the common sense of mankind ever saw more than invariable sequence in the relation of cause and effect, or ever interpolated a mysterious power between them. In the famous verse, "Let there be light, and there was light," it is the instantaneity of succession, not the interpolation of any exerted effort, that so impresses the imagination. And when Shakespeare wants to illustrate logical compulsion in conduct, his reference is to an instance of invariable succession:-- {83}

This above all,--to thine own self be true; And it must follow, as the night the day, Thou canst not then be false to any man.

Indeed, I think it will be found on examination that when we associate the idea of power, or of necessity, with causal sequences, it is not in connection with a case of causation here and now, but rather in reference to similar effects that may be expected from the same cause elsewhere or at another time. And that "custom," by which Hume seeks to explain our belief in the "power" of the cause to produce its effect as well as the "necessity" of the connection between them, rather acts negatively by eliminating all other antecedents as possible causes than positively by setting up a habit of thinking about a particular antecedent and consequent at the same time. And that is why a burnt child needs no repetition of the experiment to be convinced that contact with fire was the cause of its pain. The very novelty of the experiment was enough to eliminate any explanation other than that of contact with the flame.

The child, as it grows older, may learn to speak of the fire as having a power to burn. But that merely means, "if I touch it, it will burn me--or light paper if I hold the paper to it." Power, in fact, is incomplete causation, the presence of every condition but that one which, in Aristotelian phrase, turns potency into act. And it is in contradistinction to that idea of possibility that the idea of necessary connection comes in. When all the elements of the causal antecedent are combined the effect necessarily supervenes. Furthermore, the causal antecedent is thought of as necessary in contrast with the contingency of other antecedents whose connection with the effect is merely accidental. Finally, {84} the idea of production has been quoted as vitally distinguishing true causation from invariable sequence. But various myths, of which the story of Oedipus is the best known, show that primitive folk regard day and night as alternately producing one another, just as Polonius quotes their sequence as a type of logical necessity.

Hume professed himself a Deist, but probably with no more seriousness than when he, or when Gibbon, called Christianity "our religion." At any rate, his philosophy destroys every argument for the existence of a Creator advanced in his own or in the preceding century. Nor need his particular theory of causation be invoked for the purpose. The most telling attack is on the argument from design. The apparent adaptation of means to ends in living organisms is quoted as evidence of their having been planned by a conscious intelligence. But, answers Hume, such an intelligence would itself exhibit marks of design, and so on for ever. Why not, then, stop at the animal organism as an ultimate fact? It was Shelley's unlucky demand for a solution of this difficulty that led to his expulsion from Oxford.

It has been shown how the new analysis of mind cut the ground from under Berkeley's theism, and from under the metaphysical argument for human immortality. By denying the substantiality of the ego it also confirmed the necessitarianism of Spinoza. Hume seemed to think he could abate the unpopularity of this doctrine by interpreting the constant motivation of human actions as a mere relation of antecedence and consequence. But the decisive point was that he assimilated sequences in conscious behaviour to the unconscious sequences in physical events. Thus, for {85} the vulgar and the theologians, he remained what would now be called a materialist.

KANT.

The English philosophy of experience and the Continental philosophy of a priori spiritualism, after their brief convergence in the metaphysics of Berkeley, parted company once more, the empirical tradition being henceforth represented, not only by Hume, but in a more or less anti-Christian and much more superficial form by Voltaire, Rousseau, and the French Encyclopaedists; while the Leibnizian philosophy was systematised and taught in Germany by Wolf, and a dull but useful sort of modernised Aristotelianism was set up under the name of "common sense" by Thomas Reid (1710-1796) and his school in the Scottish Universities.

The extraordinary genius who was to re-combine the parted currents in a speculative movement of unexampled volume, velocity, and depth showed nothing of the precocity that had distinguished Berkeley and Hume. Immanuel Kant (1724-1804), the son of a saddler of Scottish extraction, was born at Koenigsberg in Prussia, where he spent his whole life, holding a chair at the University from 1770 to 1797. It is related that on the day of his death a small bright cloud was seen sailing alone across the clear blue sky, of such a remarkable appearance that a crowd assembled on the bridge to watch it. One of them, a common soldier, exclaimed, "That is Kant's soul going to heaven!"--a touching and beautiful tribute to the illustrious German, whose lofty, pure, and luminous spirit it was uniquely fitted to characterise.

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(Copyright B. P. C.)

{87} Kant grew up among the Pietists, a school which played much the same part in Germany that the Methodists and the Evangelicals played in England; indeed, it was from them that John Wesley received his final inspiration. The Koenigsberg student came in time to discard their theology while retaining the stern Puritan morality with which it was wedded, and even, Rationalist as he became, some of their mystical religiosity. What drew him away to philosophy seems to have been first the study of classical philology and then physical science, especially as presented to him in Newton's works. And so the young man's first ambition, after settling down as a University teacher at Koenigsberg, was to extend the Newtonian method still further by explaining, on mechanical principles, the origin and constitution of that celestial system whose movements Newton had reduced to law, but whose beginning he had left unaccounted for except by--what was not science--the direct fiat of omnipotence.

Kant offered a brilliant solution of the problem in his Natural History of the Heavens (1755), a work embodying the celebrated nebular hypothesis rediscovered forty years later by Laplace. It has been well observed that great philosophers are mostly, if not always, what at Oxford and Cambridge would be called "double-firsts"--that is, apart from their philosophy, they have done first-class work in some special line of investigation, as Descartes by creating analytical geometry, Spinoza by applying Biblical criticisms to theology, Leibniz by discovering the differential calculus, Locke by his theory of constitutional government, Berkeley by his theory of vision, Hume by his contributions to history and political economy. Kant's cosmogony may have been premature and mistaken in its details; but his idea of the heavenly bodies as having originated from the condensation of diffused gaseous matter still holds its {88} ground; and although the more general idea of natural evolution as opposed to supernatural creation is not modern but Greek, to have revived and reapplied it on so great a scale is a service of extraordinary merit.

The next great event in Kant's intellectual career is his rejection of Continental apriorism in metaphysics for the empiricism of the English school, especially as regards the idea of causation. For a few years (1762-1765) Kant accepts Hume's theory that there is nothing in any succession of events or in change generally to prove on grounds of pure reason that there must be more in it than a customary sequence. To believe that anything may happen without a cause does not involve a logical contradiction; and at that time he believed nothing to be known a priori except that the denial of which involves such a contradiction. But on reconsidering the basis of mathematical truth it seemed to him to be something other than the logical laws of Identity and Contradiction. When we say that seven and five are twelve we put something into the predicate that was not affirmed in the subject, and also when we say that a straight line is the shortest distance between two points. Yet the second proposition is as certain as the first, and both are certain in the highest degree, more certain than anything learned from experience, and needing no experience to confirm them.

So much being admitted, we have to recognise a fundamental division of judgments into two classes, analytic and synthetic. Judgments in which the predicate adds nothing to the subject are analytic. When we affirm all matter to be extended, that is an instance of the former, for here we are only making more explicit what was already contained in the notion of matter. On the other hand, when we affirm that all matter is heavy, that is an {89} instance of the latter or synthetic class, for we can think of matter without thinking that it has weight. Furthermore, this is not only a synthetic judgment, but it is a synthetic judgment a posteriori; for the law of universal gravitation is known only by experience. But there are also synthetic judgments a priori; for, as we have just seen, the fundamental truths of arithmetic and geometry belong to this class, as do also by consequence all the propositions logically deduced from these--that is to say, the whole of mathematical science.

Up to this point Kant would have carried the whole Cartesian school, and, more generally, all the modern Platonists, along with him; while he would have given the English empiricists and their French disciples a rather hard nut to crack. For they would have had to choose between admitting that mathematics was a mass of identical propositions or explaining, in the face of Hume's criticism, what claims to absolute certainty its truths, any more than the Law of Causation, possess. Now, the great philosophical genius of Kant is shown by nothing more than by this, that he did not stop here. Recognising to the same extent as Locke and Hume that all knowledge comes from experience--at any rate, in the sense of not coming by supernatural communication, as Malebranche and Berkeley thought--he puts the famous question, How are synthetic judgments a priori possible? Or, as it might be paradoxically expressed, How come we to know with the most certainty the things that we have not been taught by experience? The answer is, that we know them by the most intimate experience of all--the underlying consciousness that we have made them what they are. Our minds are no mere passive recipients, in which a mass of sensations, poured in from some external {90} source, are then arranged after an order equally originated from without; there is a principle of spontaneity in our own subjectivity by which the objective order of nature is created. What Kant calls the Matter of knowledge is given from without, the Form from within. And this process begins with the imposition of the two great fundamental Forms, Space and Time, on the raw material of sensation by our minds.

By space and time Kant does not mean the abstract ideas of coexistence and succession; nor does he call them, as some critics used incorrectly to suppose, forms of thought, but forms of intuition. We do not build them up with the help of muscular or other feelings, but are conscious of them in a way not admitting of any further analysis. The parts of space, no doubt, are coexistent, but they are also connected and continuous; more than this, positions in space do not admit of mutual substitution; the right hand and left hand glove are perfectly symmetrical, but the one cannot be superimposed on the other. Besides, all particular spaces are contained in universal space, not as particular conceptions are contained in a general conception, but as parts of that which extends to infinity, and where each has an individual place of its own, repeating all the characters of space in general except its illimitable extension. And the same is true of time, with this further distinction from abstract succession, that succession may be reversed; whereas the order of past, present, and future is irreversibly maintained.

The contemporary school of Reid in Scotland, and the subsequent Eclectic school of Victor Cousin in France, would agree with Kant in maintaining that sensuous experience will not account for our knowledge of space and time. But they would protest, in the name {91} of common sense, against the reduction of these apparently fundamental elements to purely subjective forms. They would ask, with the German critic Trendelenburg, Why cannot space and time be known intuitively and yet really exist? Kant furnishes no direct answer to the question, but he has suggested one in another connection. Mathematical truth is concerned with spatial and temporal relations, and for that truth to be above suspicion and exception we must assume that the objects with which it deals are wholly within our grasp--that our knowledge of them is exhaustive. But there could be no such assurance on the supposition that, besides the space and time of our sensuous experience, another space and time existed independently of our consciousness as attributes of things in themselves--possibly differing in important respects from ours--as, for example, a finite, or a non-continuous, or a four-dimensional space, and a time with a circular instead of a progressive movement.

This easy assumption that reality accommodates itself to our intellectual convenience, instead of our being obliged to accommodate our theories of knowledge to reality, runs through and vitiates the whole of Kant's philosophy. But, taking the narrower ground of logical consistency, one hardly sees how his principles can hold together. We are told that the subjectivity of space and time is not presented as a plausible hypothesis, but as a certain and indubitable truth, for in no other way can mathematical certainty be explained. The claim is questionable, but let it be granted. Immediately a fresh difficulty starts up. What is the source of our certainty that space and time are subjective forms of intuition? If the answer is, because that assumption guarantees the certainty of mathematics, then Kant is {92} reasoning in a circle. If he appeals--as in consistency he ought--to another order of subjectivity as the sanction of his first transcendental argument, such reasoning involves the regress to infinity.

Again, on Kant's theory, time is the form of intuition for the inner sense. So when we become conscious of mental events we know them only as phenomena; we remain ignorant of what mind is in itself. But before the publication in 1770 of Kant's inaugural dissertation on The Sensible and the Intelligible World every one, plain men and philosophers alike, believed that the consciousness of our successive thoughts and feelings was the very type of reality itself; and they held this belief with a higher degree of assurance than that given to the axioms of geometry. By what right, then, are we asked to give up the greater for the less, to surrender our self-assurance as a ransom for Euclid's Elements or even for Newton's Principia?

Once more, surely mathematics is concerned not with space and time as such, but with their artificial delimitations as points, lines, figures, numbers, moments, etc. And it may be granted that these are purely subjective in the sense of being imposed by our imagination (with the aid of sensible signs) on the external world. What if this subjectivity were the true source of that peculiar certainty belonging to synthetic judgments a priori? True, Kant counts in our judgments about the infinity and eternity of space and time with other accepted characteristics of theirs as intuitive certainties. But there are thinkers who find the negation of such properties not inconceivable, so that they cannot be adduced as evidence of a priority, still less of subjectivity.

Eleven years after the inaugural dissertation Kant {93} published his most important contribution to philosophy, The Critique of Pure Reason (1781). Pure Reason means the faculty by which ideas are obtained independently of all experience, and the critic's object is to ascertain how far such ideas are valid. As a preliminary to that inquiry the question is also mooted, How is experience possible? It is answered by a critique of the understanding or faculty of conception; and as conception implies perception, this again is prefaced by a section in which Kant's theory of space and time is repeated and reinforced.

It will be remembered that what started the whole of the new criticism was Hume's sceptical analysis of Causation; and the central interest of The Critique of Pure Reason lies in the effort to reconstitute the causal law in the light of the new theory of knowledge; but so enormous is the mass of technicalities piled up for this purpose as largely to conceal it from view, and, on its disclosure, to give the idea of a gigantic machine set in motion to crack a nut. And the nut after all is not cracked; the shell slips from between the grappling surfaces long before they meet.

We have seen how Kant interpreted every judgment as a synthesis of subject and predicate. Now, whether the synthesis be a priori or a posteriori, a study of the forms of judgment as enumerated in the common logic shows that there are four, and only four, ways in which it can be effected. All judgments fall under the following classes: Quantity, Quality, Relation, and Modality--terms whose meaning will be presently explained. And each of these again is tripartite. We may say (i.) that one A is B, or that some A's are B, or that all A's are B; (ii.) that A is B, that A is not B, that not all A's are B; (iii.) that A is B, that A {94} is B if C is D, that A is either B, C, or D; or (iv.) that A may be B, that A is B, or that A must be B. The reason why there are four and only four classes is that judgment has to do with the subject in reference to the predicate, which gives Quantity; with the predicate in reference to the subject, which gives Quality; with the connection between the two, which gives Relation; and with the synthesis between them in reference to our knowledge of it, which gives Modality.

Now, according to Kant, that there should be so many kinds of judgment and no more implies that our understanding contributes a formal element to the constitution of all knowledge, consisting of four combining principles, without which experience would be impossible. He calls these Categories, and they are enumerated in the following table:--

(i.) Quantity.

Unity, Plurality, Totality.

(ii.) Quality.

Reality, Negation, Limitation.

(iii.) Relation.

Substance and Accident; Cause and Effect; Action and Reaction (Reciprocity).

(iv.) Modality.

Possibility and Impossibility; Existence and Non-Existence; Necessity and Contingency.

A study of the Categories suggests some rather obvious criticisms on the Critical Philosophy itself. (i.) The first two terms in each triad evidently form an antithetical couple, of which the third term is the synthesis. Here we have the first germ of a disease by which the systems of Kant's successors were much more seriously infected. In the table it is shown by {95} the intrusion of Limitation, a wholly superfluous adjunct to Reality and Negation; in the conversion of Reciprocity into a wholly fictitious synthesis of Substantiality with Causation; and in the complete absurdity of making Necessity a combination of Possibility with Existence. (ii.) Innate ideas, after they had been exploded by Locke, are reintroduced into philosophy by a sufficiently transparent piece of legerdemain. For assuming that the human intelligence possesses a power of organising and drilling the sensuous appearances which without its control would appear only as a disorderly mob, it by no means follows that they must thereby be referred to an extraphenomenal principle. But such a principle is plainly implied by the category of Substance. Used in a scholastic sense, it does not mean the sensuous attributes of a thing taken altogether, but something that underlies and supports them. And Kant himself seems to take his category in that significance. For he claims to deduce from it the law of the indestructibility of matter; as if I could not say snow is white without committing myself to the assertion that the ultimate particles of snow have existed and will exist for ever. (iii.) The substitution of Causation for logical sequence, as implicated in the hypothetical judgment of Relation, is perfectly scandalous; and still more scandalous is substitution of Reciprocity or Action and Reaction for Disjunction. The last points require to be examined a little more in detail.

The sequence of an effect to its cause has only a verbal resemblance to the sequence of a logical consequent to its reason. We declare categorically that every change has a cause which precedes it. Logical sequence is, on the other hand, as the very name of the {96} judgment shows, hypothetical, and may possibly not represent any actual occurrence, besides being, what causation is not, independent of time. A particular case of causation may be hypothetical in respect to our belief that it actually occurred; never the law of causation itself as a general truth. And the same distinction applies with even greater force to the alleged connection between a logical disjunction and a physical reaction. When I say A is either B or C, but not both, there is only this much resemblance, that both cases involve the ideas of equality and of opposition. From the admission that A is not B, I infer that it is C, or, contrariwise, from the admission that it is B, I infer that it is not C, and in both instances with the same certainty; but this does not prove that the earth attracts the moon as much as the moon attracts the earth, only in opposite directions; nor yet that in certain instances all the heat lost by one body is gained by another.

Kant had learned this much from Hume, that causation is essentially a relation of antecedence and consequence in time; and apparently his way of "categorising" the relation--i.e., of proving its apriority--is to represent it as the logical form of reason and consequent masquerading, so to speak, under the intuitional time-form. Yet he frequently speaks of our senses as being affected by things in themselves, implying that the resulting sensations are somehow caused by those otherwise unknown entities. But since things in themselves do not, according to Kant, exist in space and time, they cannot be causally related to phenomena or to anything else.

In his criticism of Pure Reason, properly so called--that is, of inferences made by human faculty with {97} regard to questions transcending all experience--Kant shows that of such things nothing can be known. The ideality of time and space once taken as proved, this amount of agnosticism seems to follow as a matter of course. It is idle to speculate about the possible extent or duration of a universe that cannot be described in terms of coexistence and succession. For each of us at the dissolution of our bodily organism time itself, and therefore existence as alone we conceive it, comes to an end. The law of causation, applying as it does to phenomena alone, offers no evidence for the existence of a God who transcends phenomena. Kant, however, is not satisfied with such a simple and summary procedure as this. He tries to show, with most unnecessary pedantry, that the conditional synthesis of the Understanding inevitably leads thought on to the unconditional synthesis of the Reason only to find itself lost in a hopeless welter of paralogisms and self-contradictions.

At this stage we are handed over to the guidance of what Kant calls the Practical Reason. This faculty gives a synthesis for conduct, as Pure Reason gave a synthesis for intelligence. All reason demands uniformity, order, law; only what in theory is recognised as true has in practice to be imposed as right. In this way Kant arrives at his formula of absolute morality: Act so that the principle of thy conduct may be the law for all rational beings. He calls this the Categorical Imperative, as distinguished from such hypothetical imperatives as: Act this way if you wish to be happy either here or hereafter; or, act as public opinion tells you. Moreover, the motive, as distinguished from the end of moral action, should not be calculating self-interest nor uncalculating impulse, but simply desire to fulfil the law as such. Previous moralists had set up {98} the greatest happiness of the greatest number as the end of action, and such an aim does not lie far from Kant's philosophy; but they could think of no better motive for pursuing it than self-love or a rather undefined social instinct; and their summum bonum would take the happiness of irrational animals into account, while Kant absolutely subordinates the interests of these to human good. A further coincidence between the Utilitarian and the Kantian ethics is that in the latter also the happiness of others, not their perfection, should be the end and aim of each. Finally, the philosophy of Pure Reason adopts from contemporary French thought as the governing idea of political organisation what was long to be a principle of English Utilitarianism--"the liberty of each, bounded only by the equal liberty of all."

Nevertheless, the old postulate of a necessary connection between virtue and individual happiness reappears in Kant's ethical theory, and leads to the construction of a new religious philosophy. His critique had left no place for the old theology, nor yet for that doctrine of free-will so dear to most theologians. Its whole object had been to vindicate against Hume the necessity and universality of causation. Human actions then must, like all other phenomena, form an unbroken chain of antecedents and consequents. Nor does Kant conceal his conviction that, with sufficient knowledge and powers of calculation, a man's whole future conduct might be foretold. Nevertheless, under the eighteenth-century idea of man as naturally the creature of passion or self-interest, he claims for us, as moral agents, the power of choosing to obey duty in preference to either. And this freedom is supposed to be made conceivable by the subjectivity of time and causation, outside of which, {99} as a thing in itself, stands the moral will. That morality, whether as action or mere intention, involves succession in time is utterly ignored. Nor is this all. Assuming without warrant that the moral law demands an ultimate coincidence between happiness and virtue, made impossible in this life by human weakness, Kant argues that there must be an unending future life to secure time enough for working out a problem whose solution is infinitely remote. And, finally, there must be an omnipotent moral God to provide facilities for undertaking that somewhat gratuitous Psyche's task. Before Kant moral theology had argued that the Judge of all the world must do right, apportioning happiness to desert. It was reserved for him to argue, conversely, that for right to be done such a Judge must exist, and that therefore he does exist.

In appreciating the services of Kant to philosophy we must guard ourselves against being influenced by the extravagant panegyrics of his countrymen, whose passion for square circles he so generously gratifies. Still, after every deduction for mere Laputian pedantry has been made, the balance of fruitful suggestion remains vast. (i.) The antithesis of object and subject, although not counted among the categories of his Critique, has remained a prime category of thought ever since. (ii.) The idea of a necessary limit to human knowledge, given by the very theory of that knowledge, as distinguished from the Scepticism of the Greeks--in other words, what we now call Agnosticism--may not be final, but it still remains to be dealt with. (iii.) The possibility of reducing a priori knowledge to a form of unconscious experience has put an end to dogmatic metaphysics. (iv.) The problems of Time and Space have taken a central place in speculation; it has been {100} shown--what Hume did not see--that Causation has the certainty of a mathematical axiom; and it has been made highly probable that all these difficulties may find their solution in a larger interpretation of experience. (v.) Morality has been definitely dissociated from the appeal to selfish interests, whether in this life or in another.

We have now to trace, within the limits prescribed by the nature of this work, the development of philosophy under Kant's German successors.

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