A Commentary to Kant's 'Critique of Pure Reason'

by Norman Kemp Smith

INTRODUCTION

I. TEXTUAL

KANT’S METHOD OF COMPOSING THE ‘CRITIQUE OF PURE REASON’

SELDOM, in the history of literature, has a work been more conscientiously and deliberately thought out, or more hastily thrown together, than the Critique of Pure Reason. The following is the account which Kant in a letter to Moses Mendelssohn (August 16, 1783) has given of its composition:

”[Though the Critique is] the outcome of reflection which had occupied me for a period of at least twelve years, I brought it to completion in the greatest haste within some four to five months, giving the closest attention to the content, but with little thought of the exposition or of rendering it easy of comprehension by the reader—a decision which I have never regretted, since otherwise, had I any longer delayed, and sought to give it a more popular form, the work would probably never have been completed at all. This defect can, however, be gradually removed, now that the work exists in a rough form.”[2]

These statements must be allowed the greater weight as Kant, in another letter (to Garve, August 7, 1783), has given them in almost the same words:

“I freely admit that I have not expected that my book should meet with an immediate favourable reception. The exposition of the materials which for more than twelve successive years I had been carefully maturing, was not composed in a sufficiently suitable manner for general comprehension. For the perfecting of its exposition several years would have been required, whereas I brought it to completion in some four to five months, in the fear that, on longer delay, so prolonged a labour might finally become burdensome, and that my increasing years (I am already in my sixtieth year) would perhaps incapacitate me, while I am still the sole possessor of my complete system.”[3]

The twelve years here referred to are 1769-1780; the phrase “at least twelve years” indicates Kant’s appreciation of the continuity of his mental development. Hume’s first influence upon Kant is probably to be dated prior to 1760. The choice, however, of the year 1769 is not arbitrary; it is the year of Kant’s adoption of the semi-Critical position recorded in the Inaugural Dissertation (1770).[4] The “four to five months” may be dated in the latter half of 1780. The printing of the Critique was probably commenced in December or January 1780-1781.

But the Critique is not merely defective in clearness or popularity of exposition. That is a common failing of metaphysical treatises, especially when they are in the German language, and might pass without special remark. What is much more serious, is that Kant flatly contradicts himself in almost every chapter; and that there is hardly a technical term which is not employed by him in a variety of different and conflicting senses. As a writer, he is the least exact of all the great thinkers.

So obvious are these inconsistencies that every commentator has felt constrained to offer some explanation of their occurrence. Thus Caird has asserted that Kant opens his exposition from the non-Critical standpoint of ordinary consciousness, and that he discloses the final position, towards which he has all along been working, only through repeated modifications of his preliminary statements. Such a view, however, cannot account either for the specific manner of occurrence or for the actual character of the contradictions of which the Critique affords so many examples. These are by no means limited to the opening sections of its main divisions; and careful examination of the text shows that they have no such merely expository origin. The publication of Kant’s Reflexionen and Lose Blätter, and the devoted labours of Benno Erdmann, Vaihinger, Adickes, Reicke and others, have, indeed, placed the issue upon an entirely new plane. It can now be proved that the Critique is not a unitary work, and that in the five months in which, as Kant tells us, it was “brought to completion” (zu Stande gebracht), it was not actually written, but was pieced together by the combining of manuscripts written at various dates throughout the period 1772-1780.

Kant’s correspondence in these years contains the repeated assertion that he expected to be able to complete the work within some three or six months. This implies that it was already, at least as early as 1777, in great part committed to writing. In 1780 Kant must therefore have had a large body of manuscript at his disposal. The recently published Lose Blätter are, indeed, part of it. And as we shall have constant occasion to observe, the Critique affords ample evidence of having been more or less mechanically constructed through the piecing together of older manuscript, supplemented, no doubt, by the insertion of connecting links, and modified by occasional alterations to suit the new context. Kant, it would almost seem, objected to nothing so much as the sacrifice of an argument once consecrated by committal to paper. If it could be inserted, no matter at what cost of repetition, or even confusion, he insisted upon its insertion. Thus the Subjective and Objective Deductions of the first edition can, as we shall find, be broken up into at least four distinct layers, which, like geological strata, remain to the bewilderment of the reader who naturally expects a unified system, but to the enlightenment of the student, once the clues that serve to identify and to date them have been detected. To cite another example: in the Second Analogy, as given in the first edition, the main thesis is demonstrated in no less than five distinct proofs, some of which are repetitions; and when Kant restated the argument in the second edition, he allowed the five proofs to remain, but superimposed still another upon them. Kant does, indeed, in the second edition omit some few passages from various parts of the Critique; but this is in the main owing to his desire to protect himself against serious misunderstanding to which, as he found, he had very unguardedly laid himself open. The alterations of the second edition are chiefly of the nature of additions.

Adickes’ theory[5] that Kant in the “four to five months” composed a brief outline of his entire argument, and that it was upon the framework of this outline that the Critique was elaborated out of the older manuscript, may possibly be correct. It has certainly enabled Adickes to cast much light upon many textual problems. But his own supplementary hypothesis in regard to the section on the Antinomies, namely, that it formed an older and separate treatise, may very profitably be further extended. Surely it is unlikely that with the expectation, continued over many years, of completion within a few months, Kant did not possess, at least for the Aesthetic, Dialectic, and Methodology, a general outline, that dated further back than 1780. And doubtless this outline was itself altered, patched, and recast, in proportion as insight into the problems of the Analytic, the problems, that is to say, which caused publication to be so long deferred, deepened and took final form.

The composite character of the Critique is largely concealed by the highly elaborate, and extremely artificial, arrangement of its parts. To the general plan, based upon professedly logical principles, Kant has himself given the title, architectonic; and he carries it out with a thoroughness to which all other considerations, and even at times those of sound reasoning, are made to give way. Indeed, he clings to it with the unreasoning affection which not infrequently attaches to a favourite hobby. He lovingly elaborates even its minor detail, and is rewarded by a framework so extremely complicated that the most heterogeneous contents can be tidily arranged, side by side, in its many compartments. By its uniformity and rigour it gives the appearance of systematic order even when such order is wholly absent.

But we have still to consider the chief reason for the contradictory character of the contents of the Critique. It is inseparably bound up with what may perhaps be regarded as Kant’s supreme merit as a philosophical thinker, especially as shown in the first Critique,—namely, his open-minded recognition of the complexity of his problems, and of the many difficulties which lie in the way of any solution which he is himself able to propound. Kant’s method of working seems to have consisted in alternating between the various possible solutions, developing each in turn, in the hope that some midway position, which would share in the merits of all, might finally disclose itself. When, as frequently happened, such a midway solution could not be found, he developed his thought along the parallel lines of the alternative views.

“You know that I do not approach reasonable objections with the intention merely of refuting them, but that in thinking them over I always weave them into my judgments, and afford them the opportunity of overturning all my most cherished beliefs. I entertain the hope that by thus viewing my judgments impartially from the standpoint of others some third view that will improve upon my previous insight may be obtainable.... Long experience has taught me that insight into a subject which I am seeking to master is not to be forced, or even hastened, by sheer effort, but demands a fairly prolonged period during which I return again and again to the same concepts, viewing them in all their aspects and in their widest possible connections, while in the intervals the sceptical spirit awakens, and makes trial whether my conclusions can withstand a searching criticism.”[6] “In mental labour of so delicate a character nothing is more harmful than preoccupation with extraneous matters. The mind, though not constantly on the stretch, must still, alike in its idle and in its favourable moments, lie uninterruptedly open to any chance suggestion which may present itself. Relaxations and diversions must maintain its powers in freedom and mobility, so that it may be enabled to view the object afresh from every side, and so to enlarge its point of view from a microscopic to a universal outlook that it adopts in turn every conceivable standpoint, verifying the observations of each by means of all the others.”[7] “I am not of the opinion of the well-meaning writer who has recommended us never to allow doubts in regard to a matter upon which we have once made up our minds. In pure philosophy that is not feasible. Indeed the understanding has in itself a natural objection to any such procedure. We must consider propositions in all their various applications; even when they may not seem to require a special proof, we must make trial of their opposites, and in this way fight for delay, until the truth becomes in all respects evident.”[8]

That these are no mere pious expressions of good intention, but represent Kant’s actual method of working, is amply proved by the contents of the Critique. We find Kant constantly alternating between opposed standpoints, to no one of which he quite definitely commits himself, and constantly restating his principles in the effort to remove the objections to which, as he recognises, they continue to lie open. The Critique, as already stated, is not the exposition of a single unified system, but is the record of Kant’s manifold attempts to formulate and to solve his many-sided problems. Even those portions of the Critique which embody his latest views show that Kant is still unwilling to sacrifice insight to consistency. When he is guilty of special pleading—for he cannot be altogether absolved even from that charge—it is in the interests of his logical architectonic, for which, as I have said, he cherishes a quite unreasoning affection, and not of his central principles. So far from concealing difficulties, or unduly dwelling upon the favouring considerations, Kant himself emphasises the outstanding objections to which his conclusions remain subject. If his teaching is on certain points very definite, it is in other hardly less important respects largely tentative.

The value of Kant’s Critique as an introduction to modern philosophy is greatly enhanced by this method of procedure. The student who has steeped himself in the atmosphere of the Critique, however dissatisfied he may perhaps be with many of its doctrines, has become familiar with the main requirements which a really adequate metaphysics must fulfil, or at least will have acquired a due sense of the complexity of the problems with which it deals.

Recognition of the composite nature of the text will safeguard us in two ways. In the first place, citation of single passages is quite inconclusive. Not only must all the relevant passages be collated; they must be interpreted in the light of an historical understanding of the various stages in Kant’s development. We must also be prepared to find that on certain main questions Kant hesitates between opposed positions, and that he nowhere definitively commits himself to any quite final expression of view.

Secondly, we cannot proceed on the assumption that Kant’s maturest teaching comes where, had the Critique been a unitary work, composed upon a definite and previously thought out plan, we should naturally expect to find it, namely, in its concluding portions. The teaching of much of the Dialectic, especially in its account of the nature of the phenomenal world and of its relation to the knowing mind, is only semi-Critical. This is also true of Kant’s Introduction to the Critique. Introductions are usually written last; and probably Kant’s Introduction was written after the completion of the Aesthetic, of the Dialectic, and of the Analytic in its earlier forms. But it bears all the signs of having been composed prior to the working out of several of his most characteristic doctrines in the central parts of the Analytic.

Thus both Kant’s introductory statements of the aims and purposes of the Critique, and his application of his results in the solution of metaphysical problems, fail to represent in any adequate fashion the new and revolutionary principles to which he very gradually but successfully worked his way. The key to the Critique is given in the central portions of the Analytic, especially in the Deduction of the Categories. The other parts of the Critique reveal the Critical doctrines only as gradually emerging from the entangling influence of pre-Critical assumptions. Their teaching has to be radically remodelled before they can be made to harmonise with what, in view both of their intrinsic character and of the corresponding alterations in the second edition, must be regarded as Kant’s maturest utterances.

This was a task which Kant never himself attempted. For no sooner had he attained to comparative clearness in regard to his new Critical principles and briefly expounded them in the Analytic of the first edition, than he hastened to apply them in the spheres of morality, aesthetics, and teleology. When the Critique appeared in 1781 he was fifty-seven years of age; and he seems to have feared that if he allowed these purely theoretical problems, which had already occupied his main attention for “at least twelve years,” to detain him longer, he would be debarred from developing and placing on permanent record the new metaphysics of ethics which, as the references in the first Critique show, had already begun to shape itself in his mind. To have expended further energy upon the perfecting of his theoretical philosophy would have endangered its own best fruits. Even the opportunity in 1787 of a second edition of the Critique he used very sparingly, altering or adding only where occasional current criticism—his puzzled contemporaries having still for the most part maintained a discreet silence—had clearly shown that his modes of exposition were incomplete or misleading.

II. HISTORICAL

KANT’S RELATION TO HUME AND TO LEIBNIZ

Kant’s manner of formulating his fundamental problem—How are synthetic a priori judgments possible?—may well seem to the modern reader to imply an unduly scholastic and extremely rationalistic method of approach. Kant’s reasons for adopting it have, unfortunately, been largely obscured, owing to the mistaken interpretation which has usually been given to certain of his personal utterances. They have been supposed to prove that the immediate occasion of the above formula was Hume’s discussion of the problem of causality in the Enquiry into the Human Understanding. Kant, it is argued, could not have been acquainted with Hume’s earlier and more elaborate Treatise on Human Nature, of which there was then no translation; and his references to Hume must therefore concern only the later work.

Vaihinger has done valuable service in disputing this reading of Kant’s autobiographical statements. Kant does not himself make direct mention of the Enquiry, and the passages in the Critique and in the Prolegomena[9] in which Hume’s teaching is under consideration seem rather to point to the wider argument of the Treatise. This is a matter of no small importance; for if Vaihinger’s view can be established, it will enable us to appreciate, in a manner otherwise impossible, how Kant should have come to regard the problem of a priori synthesis as being the most pressing question in the entire field of speculative philosophy.

The essential difference between the Treatise and the Enquiry, from the standpoint of their bearing upon Critical issues, lies in the wider scope and more radical character of the earlier work. The Enquiry discusses the problem of causality only in the form in which it emerges in particular causal judgments, i.e. as to our grounds for asserting that this or that effect is due to this or that cause. In the Treatise, Hume raises the broader question as to our right to postulate that events must always be causally determined. In other words, he there questions the validity of the universal causal principle, that whatever begins to exist must have a cause of existence; and he does so on the explicit ground that it demands as necessary the connecting of two concepts, that of an event and that of an antecedent cause, between which no connection of any kind can be detected by the mind. The principle, that is to say, is not self-evident; it is synthetic. The concept of an event and the concept of a cause are quite separate and distinct ideas. Events can be conceived without our requiring to think antecedent events upon which they are dependent. Nor is the principle capable of demonstration. For if it be objected that in questioning its validity we are committing ourselves to the impossible assertion that events arise out of nothing, such argument is only applicable if the principle be previously granted. If events do not require a cause, it is as little necessary to seek their source in a generation out of nothing as in anything positive. Similarly, when it is argued that as all the parts of time and space are uniform, there must be a cause determining an event to happen at one moment and in one place rather than at some other time or place, the principle is again assumed. There is no greater difficulty in supposing the time and place to be fixed without a cause than in supposing the existence to be so determined. The principle, Hume concludes, is non-rational in character. It is an instrument useful for the organisation of experience; and for that reason nature has determined us to its formation and acceptance. Properly viewed, it expresses a merely instinctive belief, and is explicable only in the naturalistic manner of our other propensities, as necessary to the fulfilling of some practical need. “Nature has determined us to judge as well as to breathe and feel.”

From this naturalistic position Hume makes a no less vigorous attack upon the empirical philosophies which profess to establish general principles by inductive inference from the facts of experience. If the principles which lie at the basis of our experience are non-rational in character, the same must be true of our empirical judgments. They may correctly describe the uniformities that have hitherto occurred in the sequences of our sensations, and may express the natural expectations to which they spontaneously give rise; but they must never be regarded as capable of serving as a basis for inference. In eliminating a priori principles, and appealing exclusively to sense-experience, the empiricist removes all grounds of distinction between inductive inference and custom-bred expectation. And since from this standpoint the possibility of universal or abstract concepts—so Hume argues—must also be denied, deductive inference must likewise be eliminated from among the possible instruments at the disposal of the mind. So-called inference is never the source of our beliefs; it is our fundamental natural beliefs, as determined by the constitution of our nature in its reaction upon external influences, that generate those expectations which, however they may masquerade in logical costume, have as purely natural a source as our sensations and feelings. Such, briefly and dogmatically stated, is the sum and substance of Hume’s teaching.[10]

Now it was these considerations that, as it would seem, awakened Kant to the problem of a priori synthesis. He was, and to the very last remained, in entire agreement with Hume’s contention that the principle of causality is neither self-evident nor capable of logical demonstration, and he at once realised that what is true of this principle must also hold of all the other principles fundamental to science and philosophy. Kant further agreed that inductive inference from the data of experience is only possible upon the prior acceptance of rational principles independently established; and that we may not, therefore, look to experience for proof of their validity. Thus with the rejection of self-evidence as a feature of the a priori, and with the consequent admission of its synthetic character, Kant is compelled to acquiesce in the inevitableness of the dilemma which Hume propounds. Either Hume’s sceptical conclusions must be accepted, or we must be able to point to some criterion which is not subject to the defects of the rationalist and empirical methods of proof, and which is adequate to determine the validity or invalidity of general principles. Is there any such alternative? Such is Kant’s problem as expressed in the formula: How are synthetic a priori judgments possible?

It is a very remarkable historical fact that notwithstanding the clearness and cogency of Hume’s argument, and the appearance of such competent thinkers as Thomas Reid in Scotland, Lambert and Crusius in Germany, no less than thirty years should have elapsed before Hume found a single reader capable of appreciating the teaching of the Treatise at its true value.[11] Even Kant himself was not able from his reading of the Enquiry in 1756-1762 to realise the importance and bearing of the main problem.[12] Though in the Enquiry the wider issue regarding the general principle of causality is not raised, the bearing of Hume’s discussion, when interpreted in the light of Kant’s own teaching, is sufficiently clear; and accordingly we cannot be absolutely certain that it was not a re-reading of the Enquiry or a recalling of its argument[13] that suggested to Kant the central problem of his Critical philosophy. The probability, however, is rather that this awakening took place only indirectly through his becoming acquainted with the wider argument of the Treatise as revealed in James Beattie’s extremely crude and unsympathetic criticism of Hume’s philosophy.[14] Beattie had great natural ability, and considerable literary power. His prose writings have a lucidity, a crispness, and a felicity of illustration which go far to explain their widespread popularity in the latter half of the eighteenth century. Their literary quality is, however, more than counterbalanced by the absence of any genuine appreciation of the deeper, speculative implications and consequences of the problems discussed. And this being so, he is naturally at his worst in criticising Hume. In insisting, as he does, upon the absurd practical results[15] that would follow from the adoption of Hume’s sceptical conclusions, he is merely exploiting popular prejudice in the philosophical arena. That, however, may be forgiven him, if, as would seem to be the case, the quotations which he gives verbatim from Hume’s Treatise really first revealed to Kant the scope and innermost meaning of Hume’s analysis of the causal problem.

The evidence in support of this contention is entirely circumstantial. The German translation of Beattie’s Essay on the Nature and Immutability of Truth was published at Easter 1772, i.e. in the year in which Kant, in the process of his own independent development, came, as is shown by his famous letter to Herz,[16] to realise the mysterious, problematic character of a priori knowledge of the independently real. He was then, however, still entirely unconscious of the deeper problem which at once emerges upon recognition that a priori principles, quite apart from all question of their objective validity, are synthetic in form. We know that Kant was acquainted with Beattie’s work; for he twice refers to Beattie’s criticism of Hume.[17] What more probable than that he read the translation in the year of its publication, or at least at some time not very long subsequent to the date of the letter to Herz? The passages which Beattie quotes from the Treatise are exactly those that were necessary to reveal the full scope of Hume’s revolutionary teaching in respect to the general principle of causality. There seems, indeed, little doubt that this must have been the channel through which Hume’s influence chiefly acted. Thus at last, by a circuitous path, through the quotations of an adversary, Hume awakened philosophy from its dogmatic slumber,[18] and won for his argument that appreciation which despite its cogency it had for thirty years so vainly demanded.

Let us now turn our attention to the rationalist philosophy in which Kant was educated. Hume’s contention that experience cannot by itself justify any inductive inference, forms the natural bridge over which we can best pass to the contrasting standpoint of Leibniz. Hume and Leibniz find common ground in denouncing empiricism. Both agree in regarding it as the mongrel offspring of conflicting principles. If rationalism cannot hold its own, the alternative is not the finding of firm foothold in concrete experience, but only such consolation as a sceptical philosophy may afford.[19] The overthrow of rationalism means the destruction of metaphysics in every form. Even mathematics and the natural sciences will have to be viewed as fulfilling a practical end, not as satisfying a theoretical need. But though Leibniz’s criticism of empiricism is, in its main contention, identical with that of Hume, it is profoundly different both in its orientation and in the conclusions to which it leads. While Hume maintains that induction must be regarded as a non-rational process of merely instinctive anticipation, Leibniz argues to the self-legislative character of pure thought. Sense-experience reveals reality only in proportion as it embodies principles derived from the inherent character of thought itself. Experience conforms to a priori principles, and so can afford an adequate basis for scientific induction.

There is a passage in Hume’s Enquiry which may be employed to illustrate the boldly speculative character of Leibniz’s interpretation of the nature and function of human thought. “Nothing ... [seems] more unbounded than the thought of man, which not only escapes all human power and authority, but is not even restrained within the limits of nature and reality.... While the body is confined to one planet, along which it creeps with pain and difficulty, the thought can in an instant transport us into the most distant regions of the universe.... What never was seen, or heard of, may yet be conceived; nor is anything beyond the power of thought, except what implies an absolute contradiction.” This passage in which Hume means to depict a false belief, already sufficiently condemned by the absurdity of its claims, expresses for Leibniz the wonderful but literal truth. Thought is the revealer of an eternal unchanging reality, and its validity is in no way dependent upon its verification through sense. When Voltaire in his Ignorant Philosopher remarks that “it would be very singular that all nature, all the planets, should obey eternal laws, and that there should be a little animal, five feet high, who, in contempt of these laws, could act as he pleased, solely according to his caprice,”[20] he is forgetting that this same animal of five feet can contain the stellar universe in thought within himself, and has therefore a dignity which is not expressible in any such terms as his size may seem, for vulgar estimation, to imply. Man, though dependent upon the body and confined to one planet, has the sun and stars as the playthings of his mind. Though finite in his mortal conditions, he is divinely infinite in his powers.

Leibniz thus boldly challenges the sceptical view of the function of reason. Instead of limiting thought to the translating of sense-data into conceptual forms, he claims for it a creative power which enables it out of its own resources to discover for itself, not only the actual constitution of the material world, but also the immensely wider realm of possible entities. The real, he maintains, is only one of the many kingdoms which thought discovers for itself in the universe of truth. It is the most comprehensive and the most perfect, but still only one out of innumerable others which unfold themselves to the mind in pure thought. Truth is not the abstracting of the universal aspects in things, not a copy of reality, dependent upon it for meaning and significance. Truth is wider than reality, is logically prior to it, and instead of being dependent upon the actual, legislates for it. Leibniz thus starts from the possible, as discovered by pure thought, to determine in an a priori manner the nature of the real.

This Leibnizian view of thought may seem, at first sight, to be merely the re-emergence of the romantic, rationalistic ideal of Descartes and Malebranche. So to regard it would, however, be a serious injustice. It was held with full consciousness of its grounds and implications, and reality was metaphysically reinterpreted so as to afford it a genuine basis. There was nothing merely mystical and nothing undefined in its main tenets. Leibniz differs from Malebranche in being himself a profound mathematician, the co-discoverer with Newton of the differential calculus. He also differs from Descartes in possessing an absorbing interest in the purely logical aspects of the problem of method; and was therefore equipped in a supreme degree for determining in genuinely scientific fashion the philosophical significance and value of the mathematical disciplines.

Hume and Leibniz are thus the two protagonists that dwarf all others. They realised as neither Malebranche, Locke, nor Berkeley, neither Reid, Lambert, Crusius, nor Mendelssohn ever did, the really crucial issues which must ultimately decide between the competing possibilities. Each maintained, in the manner prescribed by his general philosophy, one of what then appeared to be the only two possible views of the function of thought. The alternatives were these: (a) Thought is merely a practical instrument for the convenient interpretation of our human experience; it has no objective or metaphysical validity of any kind; (b) Thought legislates universally; it reveals the wider universe of the eternally possible; and prior to all experience can determine the fundamental conditions to which that experience must conform. Or to interpret this opposition in logical terms: (a) The fundamental principles of experience are synthetic judgments in which no relation is discoverable between subject and predicate, and which for that reason can be justified neither a priori nor by experience; (b) all principles are analytic, and can therefore be justified by pure thought.

The problem of Kant’s Critique, broadly stated, consists in the examination and critical estimate of these two opposed views. There is no problem, scientific, moral, or religious, which is not vitally affected by the decision which of these alternatives we are to adopt, or what reconciliation of their conflicting claims we hope to achieve. Since Kant’s day, largely owing to the establishment of the evolution theory, this problem has become only the more pressing. The naturalistic, instrumental view of thought seems to be immensely reinforced by biological authority. Thought would seem to be reduced to the level of sense-affection, and to be an instrument developed through natural processes for the practical purposes of adaptation. Yet the counter-view has been no less powerfully strengthened by the victorious march of the mathematical sciences. They have advanced beyond the limits of Euclidean space, defining possibilities such as no experience reveals to us. The Leibnizian view has also been reinforced by the successes of physical science in determining what would seem to be the actual, objective character of the independently real. Kant was a rationalist by education, temperament, and conviction. Consequently his problem was to reconcile Leibniz’s view of the function of thought with Hume’s proof of the synthetic character of the causal principle. He strives to determine how much of Leibniz’s belief in the legislative power of pure reason can be retained after full justice has been done to Hume’s damaging criticisms. The fundamental principles upon which all experience and all knowledge ultimately rest are synthetic in nature: how is it possible that they should also be a priori? Such is the problem that was Kant’s troublous inheritance from his philosophical progenitors, Hume and Leibniz.[21]

III. GENERAL

In indicating some of the main features of Kant’s general teaching, I shall limit myself to those points which seem most helpful in preliminary orientation, or which are necessary for guarding against the misunderstandings likely to result from the very radical changes in terminology and in outlook that have occurred in the hundred and thirty years since the publication of the Critique. Statements which thus attempt to present in outline, and in modern terms, the more general features of Kant’s philosophical teaching will doubtless seem to many of my readers dogmatic in form and highly questionable in content. They must stand or fall by the results obtained through detailed examination of Kant’s ipsissima verba. Such justification as I can give for them will be found in the body of the Commentary.

I. THE NATURE OF THE A PRIORI

The fundamental presupposition upon which Kant’s argument rests—a presupposition never itself investigated but always assumed—is that universality and necessity cannot be reached by any process that is empirical in character. By way of this initial assumption Kant arrives at the conclusion that the a priori, the distinguishing characteristics of which are universality and necessity, is not given in sense but is imposed by the mind; or in other less ambiguous terms, is not part of the matter of experience but constitutes its form. The matter of experience is here taken as equivalent to sensation; while sensation, in turn, is regarded as being the non-relational.

The explanation of Kant’s failure either to investigate or to prove this assumption has already been indicated. Leibniz proceeds upon the assumption of its truth no less confidently than Hume, and as Kant’s main task consisted in reconciling what he regarded as being the elements of truth in their opposed philosophies, he very naturally felt secure in rearing his system upon the one fundamental presupposition on which they were able to agree. It lay outside the field of controversy, and possessed for Kant, as it had possessed for Hume and for Leibniz, that authoritative and axiomatic character which an unchallenged preconception tends always to acquire.

The general thesis, that the universal and necessary elements in experience constitute its form, Kant specifies in the following determinate manner. The form is fixed for all experience, that is to say, it is one and the same in each and every experience, however simple or however complex. It is to be detected in consciousness of duration no less than in consciousness of objects or in consciousness of self. For, as Kant argues, consciousness of duration involves the capacity to distinguish between subjective and objective succession, and likewise involves recognition[22] with its necessary component self-consciousness. Or to state the same point of view in another way, human experience is a temporal process and yet is always a consciousness of meaning. As temporal, its states are ordered successively, that is, externally to one another; but the consciousness which they constitute is at each and every moment the awareness of some single unitary meaning by reference to which the contents of the successive experiences are organised. The problem of knowledge may therefore be described as being the analysis of the consciousness of duration, of objectivity, and of self-consciousness, or alternatively as the analysis of our awareness of meaning. Kant arrives at the conclusion that the conditions of all four are one and the same.[23]

Kant thus teaches that experience in all its embodiments and in each of its momentary states can be analysed into an endlessly variable material and a fixed set of relational elements. And as no one of the relational factors can be absent without at once nullifying all the others, they together constitute what must be regarded as the determining form and structure of every mental process that is cognitive in character. Awareness, that is to say, is identical with the act of judgment, and therefore involves everything that a judgment, in its distinction from any mere association of ideas, demands for its possibility.

Kant’s position, when thus stated, differs from that of Leibniz only in its clearer grasp of the issues and difficulties involved, and consequently in the more subtle, pertinacious, and thoroughgoing character of the argument by which it is established. Its revolutionary character first appears when Kant further argues, in extension of the teaching of Hume, that the formal, relational elements are of a synthetic nature. The significance and scope of this conclusion can hardly be exaggerated. No other Kantian tenet is of more fundamental importance.[24] With it the main consequences of Kant’s Critical teaching are indissolubly bound up. As the principles which lie at the basis of our knowledge are synthetic, they have no intrinsic necessity, and cannot possess the absolute authority ascribed to them by the rationalists. They are prescribed to human reason, but cannot be shown to be inherently rational in any usual sense of that highly ambiguous term. They can be established only as brute conditions, verifiable in fact though not demonstrable in pure theory (if there be any such thing), of our actual experience. They are conditions of sense-experience, and that means of our knowledge of appearances, never legitimately applicable in the deciphering of ultimate reality. They are valid within the realm of experience, useless for the construction of a metaphysical theory of things in themselves. This conclusion is reinforced when we recognise that human experience, even in its fundamental features (e.g. the temporal and the spatial), might conceivably be altogether different from what it actually is, and that its presuppositions are always, therefore, of the same contingent character. Even the universality and necessity which Kant claims to have established for his a priori principles are of this nature. Their necessity is always for us extrinsic; they can be postulated only if, and so long as, we are assuming the occurrence of human sense-experience.

Thus Kant is a rationalist of a new and unique type. He believes in, and emphasises the importance of, the a priori. With it alone, he contends, is the Critique competent to deal. But it is an a priori which cannot be shown to be more than relative. It does, indeed, enable us to conceive the known as relative, and to entertain in thought the possibility of an Absolute; but this it can do without itself possessing independent validity. For though the proof of the a priori is not empirical in the sense of being inductive, neither is it logical in the sense of being deduced from necessities of thought. Its “transcendental” proof can be executed only so long as experience is granted as actual; and so long as the fundamental characteristics of this experience are kept in view.

Lastly, the a priori factors are purely relational. They have no inherent content from which clues bearing on the supersensible can be obtained. Their sole function is to serve in the interpretation of contents otherwise supplied.

The a priori, then, is merely relational, without inherent content; it is synthetic, and therefore incapable of independent or metaphysical proof; it is relative to an experience which is only capable of yielding appearances. The a priori is as merely factual as the experience which it conditions.

Even in the field of morality Kant held fast to this conviction. Morality, no less than knowledge, presupposes a priori principles. These, however, are never self-evident, and cannot be established by any mere appeal to intuition. They have authority only to the extent to which they can be shown to be the indispensable presuppositions of a moral consciousness that is undeniably actual.[25]

That the a priori is of this character must be clearly understood. Otherwise the reader will be pursued by a feeling of the unreality, of the merely historical or antiquarian significance, of the entire discussion. He may, if he pleases, substitute the term formal or relational for a priori. And if he bears in mind that by the relational Kant is here intending those elements in knowledge which render possible the relations constitutive of meaning, he will recognise that the Critical discussion is by no means antiquated, but still remains one of the most important issues in the entire field of philosophical enquiry.

2. KANT’S CONTRIBUTION TO THE SCIENCE OF LOGIC

The above conclusions have an important bearing upon logical doctrine. Just as modern geometry originates in a sceptical treatment of the axiom of parallels, so modern, idealist logic rests upon Kant’s demonstration of the revolutionary consequences of Hume’s sceptical teaching. If principles are never self-evident, and yet are not arrived at by induction from experience, by what alternative method can they be established? In answer to this question, Kant outlines the position which is now usually entitled the Coherence theory of truth.[26] That theory, though frequently ascribed to Hegel, has its real sources in the Critique of Pure Reason. It expresses that modification in the Leibnizian rationalism which is demanded by Hume’s discovery of the synthetic character of the causal axiom. Neither the deductive methods of the Cartesian systems nor the inductive methods of the English philosophies can any longer be regarded as correctly describing the actual processes of scientific proof.

General principles are either presuppositions or postulates. If a priori, they are presupposed in all conscious awareness; as above indicated, they have a de facto validity within the experience which they thus make possible. If more special in nature, they are the postulates to which we find ourselves committed in the process of solving specific problems; and they are therefore discovered by the method of trial and failure.[27] They are valid in proportion as they enable us to harmonise appearances, and to adjudicate to each a kind of reality consistent with that assigned to every other.

Proof of fact is similar in general character. The term fact is eulogistic, not merely descriptive; it marks the possession of cognitive significance in regard to some body of knowledge, actual or possible. It can be applied to particular appearances only in so far as we can determine their conditions, and can show that as thus conditioned the mode of their existence is relevant to the enquiry that is being pursued. The convergence of parallel lines is fact from the standpoint of psychological investigation; from the point of view of their physical existence it is merely appearance. Ultimately, of course, everything is real, including what we entitle appearance;[28] but in the articulation of human experience such distinctions are indispensable, and the criteria that define them are prescribed by the context in which they are being employed.

Thus facts cannot be established apart from principles, nor principles apart from facts. The proof of a principle is its adequacy to the interpretation of all those appearances that can be shown to be in any respect relevant to it, while the test of an asserted fact, i.e. of our description of a given appearance, is its conformity to the principles that make insight possible.

Though the method employed in the Critique is entitled by Kant the “transcendental method,” it is really identical in general character with the hypothetical method of the natural sciences. It proceeds by enquiring what conditions must be postulated in order that the admittedly given may be explained and accounted for.[29] Starting from the given, it also submits its conclusions to confirmation by the given. Considered as a method, there is nothing metaphysical or high-flying about it save the name. None the less, Kant is in some degree justified in adopting the special title. In view of the unique character of the problem to be dealt with, the method calls for very careful statement, and has to be defended against the charge of inapplicability in the philosophical field.

The fundamental thesis of the Coherence theory finds explicit formulation in Kant’s doctrine of the judgment: the doctrine, that awareness is identical with the act of judging, and that judgment is always complex, involving both factual and interpretative elements. Synthetic, relational factors are present in all knowledge, even in knowledge that may seem, on superficial study, to be purely analytic or to consist merely of sense-impressions. Not contents alone, but contents interpreted in terms of some specific setting, are the sole possible objects of human thought. Even when, by forced abstraction, particulars and universals are held mentally apart, they are still being apprehended through judgments, and therefore through mental processes that involve both. They stand in relations of mutual implication within a de facto system; and together they constitute it.

This is the reason why in modern logic, as in Kant’s Critique, the theory of the judgment receives so much more attention than the theory of reasoning. For once the above view of the judgment has been established, all the main points in the doctrine of reasoning follow of themselves as so many corollaries. Knowledge starts neither from sense-data nor from general principles, but from the complex situation in which the human race finds itself at the dawn of self-consciousness. That situation is organised in terms of our mental equipment; and this already existing, rudimentary system is what has made practicable further advance; to create a system ab initio is altogether impossible. The starting-point does not, however, by itself alone determine our conclusions. Owing to the creative activities of the mind, regulative principles are active in all consciousness; and under their guidance the experienced order, largely practical in satisfaction of the instinctive desires, is transformed into a comprehended order, controlled in view of Ideal ends. Logic is the science of the processes whereby this transformation is brought about. An essentially metaphysical discipline, it cannot be isolated from the general body of philosophical teaching; it is not formal, but transcendental; in defining the factors and processes that constitute knowledge, its chief preoccupation is with ultimate issues.

In calling his new logic “transcendental” Kant, it is true, also intends to signify that it is supplementary to, not a substitute for, the older logic, which he professes to accept.[30] Moreover his intuitional theory of mathematical science, his doctrine of the “pure concept,” his attributive view of the judgment—all of them survivals from his pre-Critical period[31]—frequently set him at cross-purposes with himself. His preoccupation, too, with the problem of the a priori leads him to underestimate the part played in knowledge by the merely empirical. But despite all inconsistencies, and notwithstanding his perverse preference for outlandish modes of expression, he succeeds in enforcing with sufficient clearness the really fundamental tenets of the Coherence view.

3. THE NATURE OF CONSCIOUSNESS

I shall now approach Kant’s central position from another direction, namely, as an answer to the problem of the nature of consciousness. We are justified, I think, in saying that Kant was the first in modern times to raise the problem of the nature of awareness, and of the conditions of its possibility. Though Descartes is constantly speaking of consciousness, he defines it in merely negative terms, through its opposition to matter; and when he propounds the question how material bodies can be known by the immaterial mind, his mode of dealing with it shows that his real interest lies not in the nature of consciousness but in the character of the existences which it reveals. His answer, formulated in terms of the doctrine of representative perception, and based on the supposed teaching of physics and physiology, is that material bodies through their action on the sense-organs and brain generate images or duplicates of themselves. These images, existing not in outer space but only in consciousness, are, he asserts, mental in nature; and being mental they are, he would seem to conclude, immediately and necessarily apprehended by the mind. Thus Descartes gives us, not an analysis of the knowing process, but only a subjectivist interpretation of the nature of the objects upon which it is directed.

Quite apart, then, from the question as to whether Descartes’ doctrine of representative perception rests on a correct interpretation of the teaching of the natural sciences—Kant was ultimately led to reject the doctrine—it is obvious that the main epistemological problem, i.e. the problem how awareness is possible, and in what it consists, has so far not so much as even been raised. Descartes and his successors virtually assume that consciousness is an ultimate, unanalysable form of awareness, and that all that can reasonably be demanded of the philosopher is that he explain what objects are actually presented to it, and under what conditions their presentation can occur. On Descartes’ view they are conditioned by antecedent physical and physiological processes; according to Berkeley they are due to the creative activity of a Divine Being; according to Hume nothing whatsoever can be determined as to their originating causes. But all three fail to recognise that even granting the objects to be of the character asserted, namely, mental, the further problem still remains for consideration, how they come to be consciously apprehended, and in what such awareness consists.

Certain interpretations of the nature of the knowing process are, of course, to be found in the writings of Descartes and his successors. But they are so much a matter of unexamined presupposition that they never receive exact formulation, and alternate with one another in quite a haphazard fashion. We may consider three typical views.

1. There is, Descartes frequently seems to imply—the same assumption is evident throughout Locke’s Essay—a self that stands behind all mental states, observing and apprehending them. Consciousness is the power which this self has of contemplating both itself and its ideas. Obviously this is a mere ignoring of the issue. If we assume an observer, we ipso facto postulate a process of observation, but we have not explained or even defined it.

2. There is also in Descartes a second, very different, view of consciousness, namely, as a diaphanous medium analogous to light. Just as light is popularly conceived as revealing the objects upon which it falls, so consciousness is regarded as revealing to us our inner states. This view of consciousness, for reasons which I shall indicate shortly, is entirely inadequate to the facts for which we have to account. It is no more tenable than the corresponding view of light.

3. In Hume we find this latter theory propounded in what may at first sight seem a more satisfactory form, but is even less satisfactory. Sensations, images, feelings, he argues, are states of consciousness, one might almost say pieces of consciousness, i.e. they are conceived as carrying their own consciousness with them. Red, for instance, is spoken of as a sensation, and is consequently viewed both as being a sense-content, i.e. something sensed or apprehended, and also at the same time as the sensing or awareness of it. This view is unable to withstand criticism. There is really no more ground for asserting that red colour carries with it consciousness of itself than for saying that a table does. The illegitimacy of the assertion is concealed from us by the fact that tables appear to exist when there is no consciousness present, whereas redness cannot be proved to exist independently of consciousness—it may or may not do so. Many present-day thinkers, continuing the tradition of the English associationists, hold to this pre-Kantian view. Sensations, feelings, etc., are, it is implied, pieces of consciousness, forms of awareness; through their varying combinations they constitute the complex experiences of the animal and human mind.

Kant’s teaching is developed in direct opposition to all such views. If we discard his antiquated terminology, and state his position in current terms, we find that it amounts to the assertion that consciousness is in all cases awareness of meaning. There is no awareness, however rudimentary or primitive, that does not involve the apprehension of meaning. Meaning and awareness are correlative terms; each must be studied in its relation to the other. And inasmuch as meaning is a highly complex object of apprehension, awareness cannot be regarded as ultimate or as unanalysable. It can be shown to rest upon a complexity of generative conditions and to involve a variety of distinct factors.

There are thus, from the Kantian standpoint, two all-sufficient reasons why the diaphanous view of consciousness, i.e. any view which treats consciousness merely as a medium whereby the existent gets itself reported, must be regarded as untenable. In the first place, as already remarked, it is based on the false assumption that consciousness is an ultimate, and that we are therefore dispensed from all further investigation of its nature. Kant claims to have distinguished successfully the many components which go to constitute it; and he also professes to have shown that until such analysis has been made, there can be no sufficient basis for a philosophical treatment either of the problems of sense-perception or of the logical problems of judgment and inference. The diaphanous view, with its mirror-like mode of representation, might allow of the side-by-sideness of associated contents; it can never account for the processes whereby the associated contents come to be apprehended.

Secondly, the diaphanous view ignores the fundamental distinction between meaning and existence. Existences rest, so to speak, on their own bottom; they are self-centred even at the very moment of their reaction to external influences. Meaning, on the other hand, always involves the interpretation of what is given in the light of wider considerations that lend it significance. In the awareness of meaning the given, the actually presented, is in some way transcended, and this transcendence is what has chiefly to be reckoned with in any attempt to explain the conscious process. Kant is giving expression to this thesis when he contends that all awareness, no matter how rudimentary or apparently simple, is an act of judgment, and therefore involves the relational categories. Not passive contemplation but active judgment, not mere conception but inferential interpretation, is the fundamental form, and the only form, in which our consciousness exists. This, of course, commits Kant to the assertion that there is no mode of cognition that can be described as immediate or unreflective. There is an immediate element in all knowledge, but our consciousness of it is always conditioned and accompanied by interpretative processes, and in their absence there can be no awareness of any kind.

By way of this primary distinction between existence and meaning Kant advances to all those other distinctions which characterise our human experience, between appearance and reality, between the real and the Ideal, between that which is judged and the criteria which control and direct the judging process. Just because all awareness is awareness of meaning, our human experience becomes intelligible as a purposive activity that directs itself according to Ideal standards.

The contrast between the Kantian and the Cartesian views of consciousness can be defined in reference to another important issue. The diaphanous view commits its adherents to a very definite interpretation of the nature of relations. Since they regard consciousness as passive and receptive, they have to maintain that relations can be known only in so far as they are apprehended in a manner analogous to the contents themselves. I do not, of course, wish to imply that this view of relational knowledge is in all cases and in all respects illegitimate. Kant, as we shall find, has carried the opposite view to an impossible extreme, assuming without further argument that what has been shown to be true of certain types of relation (for instance, of the causal and substance-attribute relations) must be true of all relations, even of those that constitute space and time. It cannot be denied that, as William James and others have very rightly insisted, such relations as the space-relations are in some degree or manner presentational. This does not, however, justify James in concluding, as he at times seems inclined to do, that all relations are directly experienced. Such procedure lays him open to the same charge of illegitimate reasoning. But even if we could grant James’s thesis in its widest form, the all-important Critical question would still remain: in what does awareness, whether of presented contents or of presented relations, consist, and how is it possible? In answering this question Kant is led to the conclusion that consciousness must be regarded as an activity, and as supplying certain of the conditions of its own possibility. Its contribution is of a uniform and constant nature; it consists, as already noted, of certain relational factors whose presence can be detected in each and every act of awareness.

There is one other respect in which Kant’s view of consciousness differs from that of his Cartesian predecessors.[32] Consciousness, he maintains, does not reveal itself, but only its objects. In other words, there is no awareness of awareness. So far as our mental states and processes can be known at all, they are known in the same objective manner in which we apprehend existences in space.[33] Now if that be so, a very important consequence follows. If there is no awareness of awareness, but only of meanings all of which are objective, there can be no consciousness of the generative, synthetic processes that constitute consciousness on its subjective side. For consciousness, being an act of awareness in which meaning is apprehended, has a twofold nature, and must be very differently described according to the aspect which at any one time we may have in view. When we regard it on its objective side as awareness of meaning, we are chiefly concerned with the various factors that are necessary to meaning and that enter into its constitution. That is to say, our analysis is essentially logical. When, on the other hand, we consider consciousness as an act of awareness, our problem is ontological or as it may be entitled (though the term is in this reference somewhat misleading, since the enquiry as defined by Kant is essentially metaphysical) psychological in character. Between these two aspects there is this very important difference. The logical factors constitutive of meaning can be exhaustively known; they are elements in the meanings which consciousness reveals; whereas the synthetic processes are postulated solely in view of these constituent factors, and in order to account for them. The processes, that is to say, are known only through that which they condition, and on Kant’s teaching we are entirely ruled out from attempting to comprehend even their possibility.[34] They must be thought as occurring, but they cannot be known, i.e. their nature cannot be definitely specified. The postulating of them marks a gap in our knowledge, and extends our insight only in the degree that it discloses our ignorance. As consciousness rests upon, and is made possible by, these processes, it can never be explained in terms of the objective world to which our sense-experience, and therefore, as Kant argues, our specific knowledge, is exclusively limited. The mind can unfold its contents in the sunshine of consciousness, only because its roots strike deep into a soil that the light does not penetrate. These processes, thus postulated, Kant regards as the source of the a priori elements, and as the agency through which the synthetic connections necessary to all consciousness are brought about.

According to Kant’s Critical teaching, therefore, consciousness, though analysable, is not such as can ever be rendered completely comprehensible. When all is said, it remains for us a merely de facto form of existence, and has to be taken just for what it presents itself as being. It is actually such as to make possible the logical processes of judgment and inference. It is actually such as to render possible a satisfactory proof of the scientific validity, within the field of sense-experience, of the principle of causality, and of such other principles as are required in the development of the positive sciences. It is also such as to render comprehensible the controlling influence of Ideal standards. But when we come to the question, how is consciousness of this type and form possible, that is, to the question of its metaphysical significance and of the generative conditions upon which it rests, we find, Kant maintains, that we have no data sufficient to justify any decisive answer.

The ontological, creative, or dynamical aspect of consciousness, I may further insist, must be constantly borne in mind if the Critical standpoint is to be properly viewed. The logical analysis is, indeed, for the purposes of the central portions of the Critique much the more important, and alone allows of detailed, exhaustive development; but the other is no less essential for an appreciation of Kant’s attitude towards the more strictly metaphysical problems of the Dialectic.

Hegel and his disciples have been the chief culprits in subordinating, or rather in entirely eliminating, this aspect of Kant’s teaching. Many of the inconsistencies of which they accuse Kant exist only if Kant’s teaching be first reduced to a part of itself. To eliminate the ontological implications of his theory of consciousness is, by anticipation, to render many of his main conclusions entirely untenable, and in particular to destroy the force of his fundamental distinction between appearance and reality. If consciousness knows itself in its ultimate nature—and such is Hegel’s contention—one half of reality is taken out of the obscurity in which, on Kant’s reading of the situation, it is condemned to lie hidden. Man is more knowable than nature, and is the key to nature; such is Hegel’s position, crudely stated. Contrast therewith the teaching of Kant. We can know nature more completely (though still very incompletely) than we can ever hope to comprehend the conditions that make possible and actual man’s spiritual life. The moral consciousness is an autonomously acting source of independent values, and though a standing miracle, must be taken for all that on independent and separate enquiry it is found to be. Hegel, in his endeavour to establish an intellectual monism, does violence to some of the highest interests which he professes to be safeguarding. Kant, while outlining in Idea a Kingdom of Ends, remains satisfied with a pluralistic distinction between the intellectual and the moral categories. The antithesis of the two philosophies is in some degree the ancient opposition between Aristotle and Plato, restated in modern terms.

4. PHENOMENALISM, KANT’S SUBSTITUTE FOR SUBJECTIVISM

The revolutionary character of the above conclusions is shown by the difficulty which Kant himself found in breaking away from many of the presuppositions that underlie the views which he was renouncing; and this is nowhere more evident than in his constant alternation throughout the Critique between a subjectivism[35] that is thoroughly Cartesian—we might almost, allowing for his rationalism, say Berkeleian—in character, and a radically different position which may be entitled phenomenalism. The latter is alone genuinely Critical, and presents Kant’s teaching in its maturest form. For though first formulated only in those portions of the Analytic that are late in date of writing, and in those passages of the second edition which supplement them, it would seem to be the only logical outcome of Kant’s other main doctrines.

I have especially in mind Kant’s fundamental distinction between appearance and reality; it has an all-important bearing upon the Cartesian opposition between the mental and the material, and especially upon the question as to what view ought to be taken of our so-called subjective experiences. The objective is for the Cartesians the independently real; the subjective is asserted to have an altogether different kind of existence in what is named the field of consciousness. Kant’s phenomenalist restatement of this distinction is too complex and subtle to be made intelligible in the brief space available in this Introduction—it is expounded in the body of the Commentary[36]—but its general character I may indicate in a few sentences. All subjectivist modes of stating the problem of knowledge, such as we find in Hume and in Leibniz no less than in Descartes, Locke, and Berkeley, are, Kant finally concluded, illegitimate and question-begging. Our so-called subjective states, whether they be sensations, feelings, or desires, are objective in the sense that they are objects for consciousness.[37] Our mental states do not run parallel with the system of natural existences; nor are they additional to it. They do not constitute our consciousness of nature; they are themselves part of the natural order which consciousness reveals. They compose the empirical self which is an objective existence, integrally connected with the material environment in terms of which alone it can be understood. The subjective is not opposite in nature to the objective, but a sub-species within it. While, however, the psychical is thus to be regarded as a class of known appearances, and as forming together with the physical a single system of nature, this entire order is, in Kant’s view, conditioned by an underlying realm of noumenal existence; and when the question of the possibility of the knowing, that is, of the experiencing of such a comprehensive natural system, is raised, it is to this noumenal sphere that we are referred. Everything experienced, even a sensation or feeling, is an event, but the experiencing of it is an act of awareness, and calls for an explanation of an altogether different kind.

Thus the problem of knowledge, stated in adequate Critical terms, is not how we can advance from the merely subjective to knowledge of the independently real,[38] but how, if everything known forms part of a comprehensive natural system, consciousness and the complex factors which contribute to its possibility are to be interpreted. On this latter question, as already indicated, Kant, though debarring both subjectivism and materialism, otherwise adopts a non-committal attitude. So long as we continue within the purely theoretical domain, there are a number of alternatives between which there are no sufficient data for deciding. To debar subjectivism is not to maintain the illusory or phenomenal character of the individual self; and to rule out materialism is not to assert that the unconscious may not generate and account for the conscious. In other words, they are ruled out not for any ulterior reasons derived from their supposed metaphysical consequences, but solely because they are based on palpable misinterpretations of the cognitive situation that generates those very problems to which they profess to be an answer.

5. THE DISTINCTION BETWEEN HUMAN AND ANIMAL INTELLIGENCE

The inwardness of Kant’s Critical standpoint may perhaps be made clearer by a brief consideration of his view of animal intelligence. We are accustomed nowadays to test a psychology of human consciousness by its capacity to render conceivable an evolution from lower forms. How does Kant’s teaching emerge from such a test?

It may at once be admitted that Kant has made no special study of animal behaviour, and was by no means competent to speak with authority in regard to its conditions. Indeed it is evident that anything which he may have to say upon this question is entirely of the nature of a deduction from results obtained in the human sphere. But when this has been admitted, and we are therefore prepared to find the problems approached from the point of view of the difference rather than of the kinship between man and the animals, we can recognise that, so far as the independent study of human consciousness is concerned, there is a certain compensating advantage in Kant’s pre-Darwinian standpoint. For it leaves him free from that desire which exercises so constant, and frequently so deleterious an influence, upon many workers in the field of psychology, namely, to maintain at all costs, in anticipation of conclusions not yet by any means established, the fundamental identity of animal and human intelligence. This besetting desire all too easily tends to the minimising of differences that may perhaps with fuller insight be found to involve no breach of continuity, but which in the present state of our knowledge cannot profitably be interpreted save in terms of their differentiating peculiarities.

The current controversy between mechanism and vitalism enforces the point which I desire to make. Biological problems, as many biologists are now urging, can be most profitably discussed in comparative independence of ultimate issues, entirely in view of their own domestic circumstances. For only when the actual constitution of organic compounds has been more completely determined than has hitherto been possible can the broader questions be adequately dealt with. In other words, the differences must be known before the exact nature and degree of the continuity can be defined. They cannot be anticipated by any mere deduction from general principles.

The value of Kant’s analysis of human consciousness is thus closely bound up with his frank recognition of its inherent complexity. Not simplification, but specification, down to the bedrock of an irreducible minimum of correlated factors, is the governing motive of his Critical enquiries. His results have therefore the great advantage of being inspired by no considerations save such as are prescribed by the actual subject-matter under investigation. As already noted, Kant maintains that human consciousness is always an awareness of meaning, and that consequently it can find expression only in judgments which involve together with their other factors the element of recognition or self-consciousness.

This decides for Kant the character of the distinction to be drawn between animal and human intelligence. As animals, in his view, cannot be regarded as possessing a capacity of self-consciousness, they must also be denied all awareness of meaning. However complicated the associative organisation of their ideas may be, it never rises to the higher level of logical judgment. For the same reason, though their ideas may be schematic in outline, and in their bearing on behaviour may therefore have the same efficiency as general concepts, they cannot become universal in the logical sense. “Animals have apprehensions, but not apperceptions, and cannot, therefore, make their representations universal.”[39] In support of this position Kant might have pointed to the significant fact that animals are so teachable up to a certain point, and so unteachable beyond it. They can be carried as far as associative suggestion will allow, but not a step further. To this day it remains true—at least I venture the assertion—that no animal has ever been conclusively shown to be capable of apprehending a sign as a sign. Animals may seem to do so owing to the influence of associated ideas, but are, as it would appear, debarred from crossing the boundary line which so sharply distinguishes associative suggestion from reflective knowledge.

But Kant is committed to a further assertion. If animals are devoid of all awareness of meaning, they must also be denied anything analogous to what we must signify by the term consciousness. Their experience must fall apart into events, that may, perhaps, be described as mental, but cannot be taken as equivalent to an act of awareness. “Apprehensio bruta without consciousness,”[40] such is Kant’s view of the animal mind. Its mental states, like all other natural existences, are events in time, explicable in the same naturalistic fashion as the bodily processes by which they are conditioned; they can not be equated with that human consciousness which enables us to reflect upon them, and to determine the conditions of their temporal happening.

The distinction which Kant desires to draw is ultimately that between events and consciousness of events. Even if events are psychical in character, consisting of sensations and feelings, there will still remain as fundamental the distinction between what is simply a member of the causal series of natural events and the consciousness through which the series is apprehended. Kant’s most explicit statements occur in a letter to Herz.[41] He is referring to data of the senses which cannot be self-consciously apprehended:

“I should not be able to know that I have them, and they would therefore be for me, as a cognitive being, absolutely nothing. They might still (if I conceive myself as an animal) exist in me (a being unconscious of my own existence) as representations ..., connected according to an empirical law of association, exercising influence upon feeling and desire, and so always disporting themselves with regularity, without my thereby acquiring the least cognition of anything, not even of these my own states.”[42]

As to whether Kant is justified in maintaining that the distinction between animal and human consciousness coincides with the distinction between associative and logical or reflective thinking, I am not concerned to maintain. This digression has been introduced solely for the purpose of defining more precisely the central tenets of Kant’s Critical teaching.

6. THE NATURE AND CONDITIONS OF SELF-CONSCIOUSNESS

We have still to consider what is perhaps the most serious of all the misunderstandings to which Kant has laid himself open, and which is in large part responsible for the widespread belief that his Critical principles, when consistently developed, must finally eventuate in some such metaphysics as that of Fichte and Hegel. I refer to the view that Kant in postulating synthetic processes as conditioning consciousness is postulating a noumenal self as exercising these activities, and is therefore propounding a metaphysical explanation of the synthetic, a priori factors in human experience.[43]

Kant’s language is frequently ambiguous. The Leibnizian spiritualism, to which in his pre-Critical period he had unquestioningly held, continued to influence his terminology, and so to prevent his Critical principles from obtaining consistent expression. This much can be said in support of the above interpretation of Kant’s position. But in all other respects such a reading of his philosophy is little better than a parody of his actual teaching. For Kant is very well aware that the problem of knowledge is not to be solved in any such easy and high-handed fashion. In the Critique he teaches quite explicitly that to profess to explain the presence of a priori factors in human experience by means of a self assumed for that very purpose would be a flagrant violation, not only of Critical principles, but even of the elementary maxims of scientific reasoning. In the first place, explanation by reference to the activities of such a self would be explanation by faculties, by the unknown; it is a cause that will explain anything and everything equally well or badly.[44] Self-consciousness has, indeed, to be admitted as a fact;[45] and from its occurrence Kant draws important conclusions in regard to the conditions which make experience possible. But, in so doing, Kant never intends to maintain that we are justified in postulating as part of those conditions, or as condition of those conditions, a noumenal self. The conditions which make experience possible, whatever they may be, are also the conditions which make self-consciousness possible. Since the self is known only as appearance, it cannot be asserted to be the conditioning ground of appearance.

This first objection is not explicitly stated by Kant, but it is implied in a second argument which finds expression both in the Deduction of the Categories and in the chapter on the Paralogisms. The only self that we know to exist is the conscious self. Now, as Kant claims to have proved, the self can be thus conscious, even of itself, only in so far as it is conscious of objects. Consequently we have no right to assume that the self can precede such consciousness as its generating cause. That would be to regard the self as existing prior to its own conditions, working in darkness to create itself as a source of light.

But there is also a third reason why Kant’s Critical solution of the problem of knowledge must not be stated in spiritualist terms. Self-consciousness, as he shows, is itself relational in character. It is a fundamental factor in human experience, not because the self can be shown to be the agency to which relations are due, but solely because, itself a case of recognition, it is at the same time a necessary condition of recognition, and recognition is indispensably presupposed in all consciousness of meaning.[46] Awareness of meaning is the fundamental mystery, and retains its profoundly mysterious character even when self-consciousness has been thus detected as an essential constituent. For self-consciousness does not explain the possibility of meaning; it is itself, as I have just remarked, only one case of recognition, and so is itself only an instance, though indeed the supreme and most important instance, of what we must intend by the term meaning. All awareness, not excepting that of the knowing self, rests upon noumenal conditions whose specific nature it does not itself reveal. Only on moral grounds, never through any purely theoretical analysis of cognitive experience, can it be proved that the self is an abiding personality, and that in conscious, personal form it belongs to the order of noumenal reality.

7. KANT’S THREEFOLD DISTINCTION BETWEEN SENSIBILITY, UNDERSTANDING, AND REASON

Even so summary a statement of Critical teaching as I am attempting in this Introduction would be very incomplete without some reference to Kant’s threefold distinction between the forms of sensibility, the categories of the understanding, and the Ideas of Reason.

On investigating space and time Kant discovers that they cannot be classed either with the data of the bodily senses or with the concepts of the understanding. They are sensuous (i.e. are not abstract but concrete, not ways of thinking but modes of existence), yet at the same time are a priori. They thus stand apart by themselves. Each is unique in its kind, is single, and is an infinite existence. To describe them is to combine predicates seemingly contradictory. In Kant’s own phrase, they are monstrosities (Undinge), none the less incomprehensible that they are undeniably actual. To them, primarily, are due those problems which have been a standing challenge to philosophy since the time of Zeno the Eleatic, and which Kant has entitled “antinomies of Reason.”

In contrast of sensibility Kant sets the intellectual faculties, understanding and Reason. In the understanding originate certain pure concepts, or as he more usually names them, categories. The chief of these are the categories of “relation”—substance, causality and reciprocity. They combine with the forms of sensibility and the manifold of sense to yield the consciousness of an empirical order, interpretable in accordance with universal laws.

To the faculty of Reason Kant ascribes what he entitles Ideas. The Ideas differ from space, time, and the categories in being not “constitutive” but “regulative.” They demand an unconditionedness of existence and a completeness of explanation which can never be found in actual experience. Their function is threefold. In the first place, they render the mind dissatisfied with the haphazard collocations of ordinary experience, and define the goal for its scientific endeavours. Secondly, they determine for us the criteria that distinguish between truth and falsity.[47] And thirdly, in so doing, they likewise make possible the distinction between appearance and reality, revealing to us an irreconcilable conflict between the ultimate aims of science and the human conditions, especially the spatial and temporal conditions under which these aims are realised. The Ideas of Reason are the second main factor in the “antinomies.”

The problem of the Critique, the analysis of our awareness of meaning, is a single problem, and each of the above elements involves all the others. Kant, however, for reasons into which I need not here enter, has assigned part of the problem to what he entitles the Transcendental Aesthetic, and another part to the Transcendental Dialectic. Only what remains is dealt with in what is really the most important of the three divisions, the Transcendental Analytic. But as the problem is one and indivisible, the discussions in all three sections are condemned to incompleteness save in so far as Kant, by happy inconsistency, transgresses the limits imposed by his method of treatment. The Aesthetic really does no more than prepare the ground for the more adequate analysis of space and time given in the Analytic and Dialectic, while the problem of the Analytic is itself incompletely stated until the more comprehensive argument of the Dialectic is taken into account.[48] Thus the statement in the Aesthetic that space and time are given to the mind by the sensuous faculty of receptivity is modified in the Analytic through recognition of the part which the syntheses and concepts of the understanding must play in the construction of these forms; and in the Dialectic their apprehension is further found to involve an Idea of Reason. Similarly, in the concluding chapter of the Analytic, in discussing the grounds for distinguishing between appearance and reality, Kant omits all reference to certain important considerations which first emerge into view in the course of the Dialectic. Yet, though no question is more vital to Critical teaching, the reader is left under the impression that the treatment given in the Analytic is complete and final.

Partly as a consequence of this, partly owing to Kant’s inconsistent retention of earlier modes of thinking, there are traceable throughout the Critique two opposed views of the nature of the distinction between appearance and reality. On the one view, this distinction is mediated by the relational categories of the understanding, especially by that of causality; on the other view, it is grounded in the Ideas of Reason. The former sets appearance in opposition to reality; the latter regards the distinction in a more tenable fashion, as being between realities less and more comprehensively conceived.[49]

A similar defect is caused by Kant’s isolation of immanent from transcendent metaphysics.[50] The former is dealt with only in the Analytic, the latter only in the Dialectic. The former, Kant asserts, is made possible by the forms of sensibility and the categories of the understanding; the latter he traces to an illegitimate employment of the Ideas of Reason. Such a mode of statement itself reveals the impossibility of any sharp distinction between the immanent and the transcendent. If science is conditioned by Ideals which arouse the mind to further acquisitions, and at the same time reveal the limitations to which our knowledge is for ever condemned to remain subject; if, in other words, everything known, in being correctly known, must be apprehended as appearance (i.e. as a subordinate existence within a more comprehensive reality), the distinction between the immanent and the transcendent falls within and not beyond the domain of our total experience. The meaning which our consciousness discloses in each of its judgments is an essentially metaphysical one. It involves the thought, though not the knowledge, of something more than what the experienced can ever itself be found to be. The metaphysical is immanent in our knowledge; the transcendent is merely a name for this immanent factor when it is falsely viewed as capable of isolation and of independent treatment. By Kant’s own showing, the task of the Dialectic is not merely to refute the pretensions of transcendent metaphysics, but to develop the above general thesis, in confirmation of the positive conclusions established in the Analytic. The Critique will then supply the remedy for certain evils to which the human mind has hitherto been subject.

“The Critique of Pure Reason is a preservative against a malady which has its source in our rational nature. This malady is the opposite of the love of home (the home-sickness) which binds us to our fatherland. It is a longing to pass out beyond our immediate confines and to relate ourselves to other worlds.”[51]

8. THE PLACE OF THE CRITIQUE OF PURE REASON IN KANT’S PHILOSOPHICAL SYSTEM

The positive character of Kant’s conclusions cannot be properly appreciated save in the wider perspectives that open to view in the Critique of Practical Reason and in the Critique of Judgment. Though in the Critique of Pure Reason a distinction is drawn between theoretical and moral belief, it is introduced in a somewhat casual manner, and there is no clear indication of the far-reaching consequences that follow in its train. Unfortunately also, even in his later writings, Kant is very unfair to himself in his methods of formulating the distinction. His real intention is to show that scientific knowledge is not coextensive with human insight; but he employs a misleading terminology, contrasting knowledge with faith, scientific demonstration with practical belief.

As already indicated, the term knowledge has, in the Critical philosophy, a much narrower connotation than in current speech. It is limited to sense-experience, and to such inferences therefrom as can be obtained by the only methods that Kant is willing to recognise, namely, the mathematico-physical. Aesthetic, moral and religious experience, and even organic phenomena, are excluded from the field of possible knowledge.

In holding to this position, Kant is, of course, the child of his time. The absolute sufficiency of the Newtonian physics is a presupposition of all his utterances on this theme. Newton, he believes, has determined in a quite final manner the principles, methods and limits of scientific investigation. For though Kant himself imposes upon science a further limitation, namely, to appearances, he conceives himself, in so doing, not as weakening Newton’s natural philosophy, but as securing it against all possible objections. And to balance the narrow connotation thus assigned to the term knowledge, he has to give a correspondingly wide meaning to the terms faith, moral belief, subjective principles of interpretation. If this be not kept constantly in mind, the reader is certain to misconstrue the character and tendencies of Kant’s actual teaching.

But though the advances made by the sciences since Kant’s time have rendered this mode of delimiting the field of knowledge altogether untenable, his method of defining the sources of philosophical insight has proved very fruitful, and has many adherents at the present day. What Kant does—stated in broad outline—is to distinguish between the problems of existence and the problems of value, assigning the former to science and the latter to philosophy.[52] Theoretical philosophy, represented in his system by the Critique of Pure Reason, takes as its province the logical values, that is, the distinction of truth and falsity, and defining their criteria determines the nature and limits of our theoretical insight. Kant finds that these criteria enable us to distinguish between truth and falsity only on the empirical plane. Beyond making possible a distinction between appearance and reality, they have no applicability in the metaphysical sphere.

The Critique of Practical Reason deals with values of a very different character. The faculty of Reason, which, as already noted,[53] renders our consciousness a purposive agency controlled by Ideal standards, is also, Kant maintains, the source of the moral sanctions. But whereas in the theoretical field it subdues our minds to the discipline of experience, and restrains our intellectual ambitions within the limits of the empirical order, it here summons us to sacrifice every natural impulse and every secular advantage to the furtherance of an end that has absolute value. In imposing duties, it raises our life from the “pragmatic”[54] level of a calculating expediency to the higher plane of a categorical imperative.

The categorical imperative at once humbles and exalts; it discloses our limitations, but does so through the greatness of the vocation to which it calls us.

“This principle of morality, just on account of the universality of the legislation which makes it the formal supreme determining principle of our will, without regard to any subjective differences, is declared by the Reason to be a law for all rational beings.... It is, therefore, not limited to men only, but applies to all finite beings that possess Reason and Will; nay, it even includes the Infinite Being as the Supreme Intelligence.”[55]

Consequently, in employing moral ends in the interpretation of the Universe, we are not picturing the Divine under human limitations, but are discounting these limitations in the light of the one form of value that is known to us as absolute.

“Duty! ... What origin is worthy of thee and where is to be found the root of thy noble descent ... a root to be derived from which is the indispensable condition of the only worth that men can give themselves.”[56]

In his earlier years Kant had accepted the current, Leibnizian view that human excellence consists in intellectual enlightenment, and that it is therefore reserved for an élite, privileged with the leisure and endowed with the special abilities required for its enjoyment. From this arid intellectualism he was delivered through the influence of Rousseau.

“I am by disposition an enquirer. I feel the consuming thirst for knowledge, the eager unrest to advance ever further, and the delights of discovery. There was a time when I believed that this is what confers real dignity upon human life, and I despised the common people who know nothing. Rousseau has set me right. This imagined advantage vanishes. I learn to honour men, and should regard myself as of much less use than the common labourer, if I did not believe that my philosophy will restore to all men the common rights of humanity.”[57]

These common rights Kant formulates in a purely individualist manner. For here also, in his lack of historic sense and in his distrust alike of priests and of statesmen, he is the child of his time. In the education and discipline of the soul he looks to nothing so artificial and humanly limited—Kant so regards them—as religious tradition and social institutions. Human rights, he believes, do not vary with time and place; and for their enjoyment man requires no initiation and no equipment beyond what is supplied by Nature herself. It is from this standpoint that Kant adduces, as the twofold and sufficient inspiration to the rigours and sublimities of the spiritual life, the starry heavens above us and the moral law within. They are ever-present influences on the life of man. The naked eye reveals the former; of the latter all men are immediately aware. In their universal appeal they are of the very substance of human existence. Philosophy may avail to counteract certain of the hindrances which prevent them from exercising their native influence; it cannot be a substitute for the inspiration which they alone can yield.

Thus the categorical imperative, in endowing the human soul with an intrinsic value, singles it out from all other natural existences, and strengthens it to face, with equanimity, the cold immensities of the cosmic system. For though the heavens arouse in us a painful feeling of our insignificance as animal existences, they intensify our consciousness of a sublime destiny, as bearers of a rival, and indeed a superior, dignity.

In one fundamental respect Kant broke with the teaching of Rousseau, namely, in questioning his doctrine of the natural goodness and indefinite perfectibility of human nature.[58] Nothing, Kant maintains, is good without qualification except the good will; and even that, perhaps, is never completely attained in any single instance. The exercise of duty demands a perpetual vigilance, under the ever-present consciousness of continuing demerit.

“I am willing to admit out of love of humanity that most of our actions are indeed correct, but if we examine them more closely we everywhere come upon the dear self which is always prominent....”[59] “Nothing but moral fanaticism and exaggerated self-conceit is infused into the mind by exhortation to actions as noble, sublime and magnanimous. Thereby men are led into the delusion that it is not duty, that is, respect for the law, whose yoke ... they must bear, whether they like it or not, that constitutes the determining principle of their actions, and which always humbles them while they obey it. They then fancy that those actions are expected from them, not from duty, but as pure merit.... In this way they engender a vain high-flying fantastic way of thinking, flattering themselves with a spontaneous goodness of heart that needs neither spur nor bridle, nor any command....”[60]

In asserting the goodness and self-sufficiency of our natural impulses Rousseau is the spokesman of a philosophy which has dominated social and political theory since his day, and which is still prevalent. This philosophy, in Kant’s view, is disastrous in its consequences. As a reading of human nature and of our moral vocation, it is hardly less false than the Epicurean teaching, which finds in the pursuit of pleasure the motive of all our actions. A naturalistic ethics, in either form, is incapacitated, by the very nature of its controlling assumptions, from appreciating the distinguishing features of the moral consciousness. Neither the successes nor the failures of man’s spiritual endeavour can be rightly understood from any such standpoint. The human race, in its endurance and tenacity, in its dauntless courage and in its soaring spirit, reveals the presence of a prevenient influence, non-natural in character; and only if human nature be taken as including this higher, directive power, can it assume to itself the eulogy which Rousseau so mistakenly passes upon the natural and undisciplined tendencies of the human heart. For as history demonstrates, while men are weak, humanity is marvellous.

“There is one thing in our soul which, when we take a right view of it, we cannot cease to regard with the highest astonishment, and in regard to which admiration is right and indeed elevating, and that is our original moral capacity in general.... Even the incomprehensibility of this capacity,[61] a capacity which proclaims a Divine origin, must rouse man’s spirit to enthusiasm and strengthen it for any sacrifices which respect for his duty may impose on him.”[62]

We are not here concerned with the detail of Kant’s ethical teaching, or with the manner in which he establishes the freedom of the will, and justifies belief in the existence of God and the immortality of the soul. In many respects his argument lies open to criticism. There is an unhappy contrast between the largeness of his fundamental thesis and the formal, doctrinaire manner in which it is developed. Indeed, in the Critique of Practical Reason the individualist, deistic, rationalistic modes of thinking of his time are much more in evidence than in any other of his chief writings; and incidentally he also displays a curious insensibility—again characteristic of his period—to all that is specific in the religious attitude. But when due allowances have been made, we can still maintain that in resting his constructive views upon the supreme value of the moral personality Kant has influenced subsequent philosophy in hardly less degree than by his teaching in the Critique of Pure Reason.[63]

The two Critiques, in method of exposition and argument, in general outcome, and indeed in the total impression they leave upon the mind, are extraordinarily different. In the Critique of Pure Reason Kant is meticulously scrupulous in testing the validity of each link in his argument. Constantly he retraces his steps; and in many of his chief problems he halts between competing solutions. Kant’s sceptical spirit is awake, and it refuses to cease from its questionings. In the Critique of Practical Reason, on the other hand, there is an austere simplicity of argument, which advances, without looking to right or left, from a few simple principles direct to their ultimate consequences. The impressiveness of the first Critique consists in its appreciation of the complexity of the problems, and in the care with which their various, conflicting aspects are separately dealt with. The second Critique derives its force from the fundamental conviction upon which it is based.

Such, then, stated in the most general terms, is the manner in which Kant conceives the Critique of Pure Reason as contributing to the establishment of a humanistic philosophy. It clears the ground for the practical Reason, and secures it in the autonomous control of its own domain. While preserving to the intellect and to science certain definitely prescribed rights, Kant places in the forefront of his system the moral values; and he does so under the conviction that in living up to the opportunities, in whatever rank of life, of our common heritage, we obtain a truer and deeper insight into ultimate issues than can be acquired through the abstruse subtleties of metaphysical speculation.

I may again draw attention to the consequences which follow from Kant’s habitual method of isolating his problems. Truth is a value of universal jurisdiction, and from its criteria the judgments of moral and other values can claim no exemption. Existences and values do not constitute independent orders. They interpenetrate, and neither can be adequately dealt with apart from the considerations appropriate to the other. In failing to co-ordinate his problems, Kant has over-emphasised the negative aspects of his logical enquiries and has formulated his ethical doctrines in a needlessly dogmatic form.

These defects are, however, in some degree remedied in the last of his chief works, the Critique of Judgment. In certain respects it is the most interesting of all Kant’s writings. The qualities of both the earlier Critiques here appear in happy combination, while in addition his concrete interests are more in evidence, to the great enrichment of his abstract argument. Many of the doctrines of the Critique of Pure Reason, especially those that bear on the problems of teleology, are restated in a less negative manner, and in their connection with the kindred problems of natural beauty and the fine arts. For though the final decision in all metaphysical questions is still reserved to moral considerations, Kant now takes a more catholic view of the field of philosophy. He allows, though with characteristic reservations, that the empirical evidence obtainable through examination of the broader features of our total experience is of genuinely philosophical value, and that it can safely be employed to amplify and confirm the independent convictions of the moral consciousness. The embargo which in the Critique of Pure Reason, in matters metaphysical, is placed upon all tentative and probable reasoning is thus tacitly removed; and the term knowledge again acquires the wider meaning very properly ascribed to it in ordinary speech.

A COMMENTARY TO KANT’S “CRITIQUE OF PURE REASON”

TITLE: KRITIK DER REINEN VERNUNFT

THE term critique or criticism, as employed by Kant, is of English origin. It appears in seventeenth and eighteenth century English, chiefly in adjectival form, as a literary and artistic term—for instance, in the works of Pope, who was Kant’s favourite English poet. Kant was the first to employ it in German, extending it from the field of aesthetics to that of general philosophy. A reference in Kant’s Logic[64] to Home’s Elements of Criticism[65] would seem to indicate that it was Home’s use of the term which suggested to him its wider employment. “Critique of pure reason,” in its primary meaning, signifies the passing of critical judgments upon pure reason. In this sense Kant speaks of his time as “the age of criticism (Zeitalter der Kritik).” Frequently, however, he takes the term more specifically as meaning a critical investigation leading to positive as well as to negative results. Occasionally, especially in the Dialectic, it also signifies a discipline applied to pure reason, limiting it within due bounds. The first appearance of the word in Kant’s writings is in 1765 in the Nachricht[66] of his lectures for the winter term 1765-1766. Kant seldom employs the corresponding adjective, critical (kritisch). His usual substitute for it is the term transcendental.

Pure (rein) has here a very definite meaning. It is the absolutely a priori. Negatively it signifies that which is independent of experience. Positively it signifies that which originates from reason itself, and which is characterised by universality and necessity.[67] By “pure reason” Kant therefore means reason in so far as it supplies out of itself, independently of experience, a priori elements that as such are characterised by universality and necessity.

Reason (Vernunft) is used in the Critique in three different meanings. In the above title it is employed in its widest sense, as the source of all a priori elements. It includes what is a priori in sensibility as well as in understanding (Verstand). In its narrowest sense it is distinct even from understanding, and signifies that faculty which renders the mind dissatisfied with its ordinary and scientific knowledge, and which leads it to demand a completeness and unconditionedness which can never be found in the empirical sphere. Understanding conditions science; reason generates metaphysic. Understanding has categories; reason has its Ideas. Thirdly, Kant frequently employs understanding and reason as synonymous terms, dividing the mind only into the two faculties, sensibility and spontaneity. Thus in A 1-2, understanding and reason are used promiscuously, and in place of reine Vernunft we find reiner Verstand. As already stated, the term reason, as employed in Kant’s title, ought properly to be taken in its widest sense. Sensibility falls within reason in virtue of the a priori forms which it contains. Kant does not himself, however, always interpret the title in this strict sense. The triple use of the term is an excellent example of the looseness and carelessness with which he employs even the most important and fundamental of his technical terms. Only the context can reveal the particular meaning to be assigned in each case.

The phrase “of pure reason” (der reinen Vernunft) has, as Vaihinger points out,[68] a threefold ambiguity. (1) Sometimes it is a genitive objective. The critical enquiry is directed upon pure reason as its object. This corresponds to the view of the Critique as merely a treatise on method. (2) Sometimes it is a genitive subjective. The critical enquiry is undertaken by and executed through pure reason. This expresses the view of the Critique as itself a system of pure rational knowledge. (3) At other times it has a reflexive meaning. Pure reason is subject and object at once. It is both subject-matter and method or instrument. Through the Critique it attains to self-knowledge. The Critique is the critical examination of pure reason by itself. The first view would seem to be the original and primary meaning of the title. The second view very early took its place alongside it, and appears in many passages. The third view must be taken as representing Kant’s final interpretation of the title; it is on the whole the most adequate to the actual content and scope of the Critique. For the Critique is not merely a treatise on method; it is also a system of pure rational knowledge. It professes to establish, in an exhaustive and final manner, the a priori principles which determine the possibility, conditions, and limits of pure rational knowledge.[69]

MOTTO

DE nobis ipsis silemus: De re autem, quae agitur, petimus: ut homines eam non opinionem, sed opus esse cogitent; ac pro certo habeant, non sectae nos alicuius, aut placiti, sed utilitatis et amplitudinis humanae fundamenta moliri. Deinde ut suis commodis aequi ... in commune consulant ... et ipsi in partem veniant. Praeterea ut bene sperent, neque instaurationem nostram ut quiddam infinitum et ultra mortale fingant, et animo concipiant; quum revera sit infiniti erroris finis et terminus legitimus.

This motto, which was added in the second edition, is taken from the preface to Bacon’s Instauratio Magna, of which the Novum Organum is the second part. As the first part of the Instauratio is represented only by the later, separately published, De Augmentis Scientiarum, this preface originally appeared, and is still usually given, as introductory to the Novum Organum.

The complete passage (in which I have indicated Kant’s omissions) is rendered as follows in the translation of Ellis and Spedding:[70]

“Of myself I say nothing; but in behalf of the business which is in hand I entreat men to believe that it is not an opinion to be held, but a work to be done; and to be well assured that I am labouring to lay the foundation, not of any sect or doctrine, but of human utility and power. Next, I ask them to deal fairly by their own interests [and laying aside all emulations and prejudices in favour of this or that opinion], to join in consultation for the common good; and [being now freed and guarded by the securities and helps which I offer from the errors and impediments of the way] to come forward themselves and take part [in that which remains to be done]. Moreover, to be of good hope, nor to imagine that this Instauration of mine is a thing infinite and beyond the power of man, when it is in fact the true end and termination of infinite error.”

The opening sentence of Bacon’s preface might also have served as a fitting motto to the Critique:

“It seems to me that men do not rightly understand either their store or their strength, but overrate the one and underrate the other.”

Or again the following:

“I have not sought nor do I seek either to enforce or to ensnare men’s judgments, but I lead them to things themselves and the concordances of things, that they may see for themselves what they have, what they can dispute, what they can add and contribute to the common stock.... And by these means I suppose that I have established for ever a true and lawful marriage between the empirical and the rational faculty, the unkind and ill-starred divorce and separation of which has thrown into confusion all the affairs of the human family.”

DEDICATION
TO
FREIHERR VON ZEDLITZ

Karl Abraham, Freiherr von Zedlitz had been entrusted, as Minister (1771-1788) to Frederick the Great, with the oversight and direction of the Prussian system of education. He held Kant in the highest esteem.[71] In February 1778 we find him writing to thank Kant for the pleasure he had found in perusing notes of his lectures on physical geography, and requesting the favour of a complete copy.[72] A week later he invited Kant to accept a professorship of philosophy in Halle,[73] which was then much the most important university centre in Germany. Upon Kant’s refusal he repeated the offer, with added inducements, including the title of Hofrat.[74] Again, in August of the same year, he writes that he is attending, upon Mendelssohn’s recommendation (and doubtless also in the hope of receiving from this indirect source further light upon Kant’s own teaching in a favourite field), the lectures on anthropology of Kant’s disciple and friend, Marcus Herz. The letter concludes with a passage which may perhaps have suggested to Kant the appropriateness of dedicating his Critique to so wise and discerning a patron of true philosophy.

“Should your inventive power extend so far, suggest to me the means of holding back the students in the universities from the bread and butter studies, and of making them understand that their modicum of law, even their theology and medicine, will be immensely more easily acquired and safely applied, if they are in possession of more philosophical knowledge. They can be judges, advocates, preachers and physicians only for a few hours each day; but in these and all the remainder of the day they are men, and have need of other sciences. In short, you must instruct me how this is to be brought home to students. Printed injunctions, laws, regulations—these are even worse than bread and butter study itself.”[75]

A Minister of Education who thus ranks philosophy above professional studies, and both as more important than all academic machinery, holds his office by divine right.

PREFACE TO THE FIRST EDITION

Detailed discussion of the Prefaces is not advisable. The problems which they raise can best be treated in the order in which they come up in the Critique itself. I shall dwell only on the minor incidental difficulties of the text, and on those features in Kant’s exposition which are peculiar to the Prefaces, or which seem helpful in the way of preliminary orientation. I shall first briefly restate the argument of the Preface to the first edition, and then add the necessary comment.

Human reason is ineradicably metaphysical. It is haunted by questions which, though springing from its very nature, none the less transcend its powers. Such a principle, for instance, as that of causality, in carrying us to more and more remote conditions, forces us to realise that by such regress our questions can never be answered. However far we recede in time, and however far we proceed in space, we are still no nearer to a final answer to our initial problems, and are therefore compelled to take refuge in postulates of a different kind, such, for instance, as that there must be a first unconditioned cause from which the empirical series of causes and effects starts, or that space is capable of existing as a completed whole. But these assumptions plunge reason in darkness and involve it in contradictions. They are the sources of all the troubles of the warring schools. Error lies somewhere concealed in them—the more thoroughly concealed that they surpass the limits of possible experience. Until such error has been detected and laid bare, metaphysical speculation must remain the idlest of all tasks.

In the latter part of the eighteenth century metaphysics had fallen, as Kant here states, into disrepute. The wonderful success with which the mathematical and natural sciences were being developed served only to emphasise by contrast the ineffectiveness of the metaphysical disciplines. Indifference to philosophy was the inevitable outcome, and was due, not to levity, but to the matured judgment of the age, which refused to be any longer put off with such pretended knowledge. But since the philosophical sciences aim at that knowledge which, if attainable, we should be least willing to dispense with, the failure of philosophy is really a summons to reason to take up anew the most difficult of all its tasks. It must once and for all determine either the possibility or the impossibility of metaphysics. It must establish

“...a tribunal which will assure to reason its lawful claims, and which will also be able to dismiss all groundless pretensions, not by despotic decrees, but in accordance with its own eternal and unalterable laws. This tribunal is no other than the Critique of Pure Reason.”[76] “Our age is, in especial degree, the age of criticism (Kritik), and to such criticism everything must submit. Religion, through its sanctity, and law-giving, through its majesty, may seek to exempt themselves from it. But they then awaken just suspicion, and cannot claim the sincere respect which reason accords only to that which has been able to sustain the test of free and open examination.”[77]

As has already been emphasised in the preceding historical sketch, Kant had learnt to trust the use of reason, and was a rationalist by education, temperament, and conviction. He here classifies philosophies as dogmatic and sceptical; and under the latter rubric he includes all empirical systems. ‘Empiricism’ and ‘scepticism’ he interprets as practically synonymous terms. The defect of the dogmatists is that they have not critically examined their methods of procedure, and in the absence of an adequate distinction between appearance and reality have interpreted the latter in terms of the former. The defect of the empiricists and sceptics is that they have misrepresented the nature of the faculty of reason, ignoring its claims and misreading its functions, and accordingly have gone even further astray than their dogmatic opponents. All knowledge worthy of the name is a priori knowledge. It possesses universality and necessity, and as such must rest on pure reason. Wherever there is science, there is an element of pure reason. Whether or not pure reason can also extend to the unconditioned is the question which decides the possibility of constructive metaphysics. This is what Kant means when he declares that the Critique is a criticism of the power of reason, in respect of all knowledge after which it may strive independently of experience. Pure reason is the subject-matter of the enquiry; it is also the instrument through which the enquiry is made.[78] Nothing empirical or merely hypothetical has any place in it, either as subject-matter or as method of argument.

From this position Kant draws several important consequences. First, since pure reason means that faculty whereby we gain knowledge independently of all experience, it can be isolated and its whole nature exhaustively determined. Indeed pure reason (Kant seeks to prove) is so perfect a unity that if “its principle” should be found insufficient to the solution of a single one of all the questions which are presented to it by its own nature, we should be justified in forthwith rejecting it as also incompetent to answer with complete certainty any one of the other questions. In metaphysics it must be either all or nothing,[79] either final and complete certainty or else absolute failure.

“While I am saying this I can fancy that I detect in the face of the reader an expression of indignation mingled with contempt at pretensions seemingly so arrogant and vainglorious; and yet they are incomparably more moderate than the claims of all those writers who on the lines of the usual programme profess to prove the simple nature of the soul or the necessity of a first beginning of the world.”[80]

In so doing they pretend to define realities which lie beyond the limits of possible experience; the Critique seeks only to deal with that faculty of reason which manifests itself to us within our own minds. Formal logic shows how completely and systematically the simple acts of reason can be enumerated. Aristotle created this science of logic complete at a stroke. Kant professes to have established an equally final metaphysics; and as logic is not a science proper, but rather a propaedeutic to all science, metaphysics, thus interpreted, is the only one of all the sciences which can immediately attain to such completeness.

“For it is nothing but the inventory of all our possessions through pure reason, systematically arranged. In this field nothing can escape us. What reason produces entirely out of itself cannot lie concealed, but is brought to light by reason itself immediately the common principle has been discovered.”[81]

Secondly, the Critique also claims certainty. With the removal of everything empirical, and the reduction of its subject-matter to pure reason, all mere opinion or hypothesis is likewise eliminated. Probabilities or hypotheses can have no place in a Critique of Pure Reason.[82] Everything must be derived according to a priori principles from pure conceptions in which there is no intermixture of experience or any special intuition.

This Preface to the first edition, considered as introductory to the Critique, is misleading for two reasons. First, because in it Kant is preoccupied almost exclusively with the problems of metaphysics in the strict ontological sense, that is to say, with the problems of the Dialectic. The problems of the Analytic, which is the very heart of the Critique, are almost entirely ignored. They are, it is true, referred to in A x-xi, but the citation is quite externally intercalated; it receives no support or extension from the other parts of the Preface. This results in a second defect, namely, that Kant fails to indicate the more empirical features of his new Critical standpoint. Since ultimate reality is supersensuous, metaphysics, as above conceived, can have no instrument save pure reason. The subjects of its enquiry, God, freedom, and immortality, if they are to be known at all, can be determined only through a priori speculation. This fact, fundamental and all-important for Kant, was completely ignored in the popular eclectic philosophies of the time. They professed to derive metaphysical conclusions from empirical evidence. They substituted, as Kant has pointed out,[83] “a physiology of the human understanding” for the Critical investigation of the claims of reason, and anthropology for ethics. They were blind to the dogmatism of which they are thereby guilty. They assumed those very points which most call for proof, namely, that reason is adequate to the solution of metaphysical problems, and that all existence is so fundamentally of one type that we can argue from the sensuous to the supersensuous, from appearance to reality. When they fell into difficulties, they pleaded the insufficiency of human reason, and yet were all the while unquestioningly relying upon it in the drawing of the most tremendous inferences. Such, for instance, are the assumptions which underlie Moses Mendelssohn’s contention that since animals as well as men agree in the apprehension of space, it must be believed to be absolutely real.[84] These assumptions also determine Priestley’s assertion that though every event has its cause, there is one causeless happening, namely, the creative act to which the existence of the world is due.[85] On such terms, metaphysics is too patently easy to be even plausible. “Indifference, doubt, and, in final issue, severe criticism, are truer signs of a profound habit of thought.”[86] The matter of experience affords no data for metaphysical inference. In the a priori forms of experience, and there alone, can metaphysics hope to find a basis, if any basis is really discoverable.

This is Kant’s reason for so emphatically insisting that the problem of the Critique is to determine “how much we can hope to achieve by reason, when all the material and assistance of experience is taken away.”[87] But in keeping only this one point in view Kant greatly misrepresents the problems and scope of the Critique. Throughout the Preface he speaks the language of the Aufklärung. Even in the very act of limiting the scope of reason, he overstresses its powers, and omits reference to its empirical conditions. It is well to contrast this teaching with such a passage as the following:

“The position of all genuine idealists from the Eleatics to Berkeley is contained in this formula: ‘All cognition through the senses and experience is nothing but mere illusion, and only in the ideas of pure understanding and Reason is there truth.’ The fundamental principle ruling all my idealism, on the contrary, is this: ‘All cognition of things solely from pure understanding or pure Reason is nothing but mere illusion, and only in experience is there truth.’”[88]

But that passage is equally inadequate as a complete expression of Kant’s Critical philosophy. The truth lies midway between it and the teaching of the Preface to the first edition. Pure reason is as defective an instrument of knowledge as is factual experience. Though the primary aim of metaphysics is to determine our relation to the absolutely real, and though that can only be done by first determining the nature and possible scope of a priori principles, such principles are found on investigation to possess only empirical validity. The central question of the Critique thus becomes the problem of the validity of their empirical employment. The interrelation of these two problems, that of the a priori and that of experience, and Kant’s attitude towards them, cannot be considered till later. The defects of the Preface to the first edition are in part corrected by the extremely valuable Preface substituted in the second edition. But some further points in this first Preface must be considered.

Prescribed by the very nature of reason itself.[89]—Metaphysics exists as a “natural disposition,” and its questions are not therefore merely artificial.

“As natural disposition (Naturanlage) ... metaphysics is real. For human reason, without being moved merely by the idle desire for extent and variety of knowledge, proceeds impetuously, driven on by an inward need, to questions such as cannot be answered by any empirical employment of reason, or by principles thence derived. Thus in all men, as soon as their reason has become ripe for speculation, there has always existed and will always continue to exist some kind of metaphysics.”[90]

Hence results what Kant entitles transcendental illusion.

“The cause of this transcendental illusion is that there are fundamental rules and maxims for the employment of Reason, subjectively regarded as a faculty of human knowledge, and that these rules and maxims have all the appearance of being objective principles. We take the subjective necessity of a connection of our concepts, i.e. a connection necessitated for the advantage of the understanding, for an objective necessity in the determination of things in themselves. This is an illusion which can no more be prevented than we can prevent the sea from appearing higher at the horizon than at the shore, since we see it through higher light rays; or to cite a still better example, than the astronomer can prevent the moon from appearing larger at its rising, although he is not deceived by this illusion.... There exists, then, a natural and unavoidable dialectic of pure Reason, not one in which a bungler might entangle himself through lack of knowledge, or one which some sophist has artificially invented to confuse thinking people, but one which is inseparable from human Reason, and which, even after its deceiving power has been exposed, will not cease to play tricks with it and continually to entrap it into momentary aberrations that will ever and again call for correction.”[91]

Dogmatism.[92]—According to Kant there are three possible standpoints in philosophy—the dogmatic, the sceptical, and the critical. All preceding thinkers come under the first two heads. A dogmatist is one who assumes that human reason can comprehend ultimate reality, and who proceeds upon this assumption. He does not, before proceeding to construct a metaphysics, enquire whether it is possible. Dogmatism expresses itself (to borrow Vaihinger’s convenient mode of definition[93]) through three factors—rationalism, realism, and transcendence. Descartes and Leibniz are typical dogmatists. As rationalists they hold that it is possible to determine from pure a priori principles the ultimate nature of God, of the soul, and of the material universe. They are realists in that they assert that by human thought the complete nature of objective reality can be determined. They also adopt the attitude of transcendence. Through pure thought they go out beyond the sensible and determine the supersensuous. Scepticism (Kant, as above stated,[94] regards it as being in effect equivalent to empiricism) may similarly be defined through the three terms, empiricism, subjectivism, immanence. A sceptic can never be a rationalist. He must reduce knowledge to sense-experience. For this reason also his knowledge is infected by subjective conditions; through sensation we cannot hope to determine the nature of the objectively real. This attitude is also that of immanence; knowledge is limited to the sphere of sense-experience. Criticism has similarly its three constitutive factors, rationalism, subjectivism, immanence. It agrees with dogmatism in maintaining that only through a priori principles can true knowledge be obtained. Such knowledge is, however, subjective[95] in its origin, and for that reason it is also only of immanent application; knowledge is possible only in the sphere of sense-experience. Dogmatism claims that knowledge arises independently of experience and extends beyond it. Empiricism holds that knowledge arises out of sense-experience and is valid only within it. Criticism teaches that knowledge arises independently of particular experience but is valid only for experience.

The following passages in the Methodology give Kant’s view of the historical and relative values of the two false methods:

“The sceptic is the taskmaster who constrains the dogmatic reasoner to develop a sound critique of the understanding and reason. When the latter has been made to advance thus far, he need fear no further challenge, since he has learned to distinguish his real possessions from that which lies entirely beyond them, and to which he can therefore lay no claim.... Thus the sceptical procedure cannot of itself yield any satisfying answer to the questions of reason, but none the less it prepares the way by awakening its circumspection, and by indicating the radical measures which are adequate to secure it in its legitimate possessions.”[96] “The first step in matters of pure reason, marking its infancy, is dogmatic. The second step is sceptical, and indicates that experience has rendered our judgment wiser and more circumspect. But a third step, such as can be taken only by fully matured judgment, is now necessary.... This is not the censorship but the critique of reason, whereby not its present bounds but its determinate [and necessary] limits, not its ignorance on this or that point, but in regard to all possible questions of a certain kind, are demonstrated from principles, and not merely arrived at by way of conjecture. Scepticism is thus a resting-place for human reason, where it can reflect upon its dogmatic wanderings and make survey of the region in which it finds itself, so that for the future it may be able to choose its path with more certainty. But it is no dwelling-place for permanent settlement. That can be obtained only through perfect certainty in our knowledge, alike of the objects themselves and of the limits within which all our knowledge of objects is enclosed.”[97]

Locke.[98]—Cf. A 86 = B 119; A 270 = B 327; B 127.

On the unfavourable contrast between mathematics and metaphysics.[99]—Cf. Ueber die Deutlichkeit der Grundsätze (1764), erste Betrachtung, and below, pp. 40, 563 ff.

The age of criticism.[100]—Kant considered himself as contributing to the further advance of the eighteenth century Enlightenment.[101] In view, however, of the contrast between eighteenth and nineteenth century thought, and of the real affiliations and ultimate consequences of Kant’s teaching, it seems truer to regard the Critical philosophy as at once completing and transcending the Aufklärung. Kant breaks with many of its most fundamental assumptions.

The Critique of Pure Reason.[102]—Kant here defines the Critique as directed upon pure reason.[103] Further, it is a criticism of knowledge which is “independent of all experience,” or, as Kant adds “free from all experience.” Such phrases, in this context, really mean transcendent. The Critique is here taken as being a Critical investigation of transcendent metaphysics, of its sources, scope, and limits.[104]

Opinion or hypothesis not permissible.[105]—Cf. below, p. 543 ff.

I know no enquiries, etc.[106]—The important questions raised by this paragraph are discussed below, p. 235 ff.

Jean Terrasson (1670-1750).[107]—The quotation is from his work posthumously published (1754), and translated from the French by Frau Gottsched under the title Philosophie nach ihrem allgemeinen Einflusse auf alle Gegenstände des Geistes und der Sitten (1762). Terrasson is also referred to by Kant in his Anthropologie, §§ 44 and 77. Terrasson would seem to be the author of the Traité de l’infini créé which has been falsely ascribed to Malebranche. I have translated this latter treatise in the Philosophical Review (July 1905).

Such a system of pure speculative reason.[108]—The relation in which this system would stand to the Critique is discussed below, pp. 71-2. Speculative does not with Kant mean transcendent, but merely theoretical as opposed to practical. Cf. B 25, A 15 = B 29, A 845 = B 873.

Under the title: Metaphysics of Nature.[109]—No such work, at least under this title, was ever completed by Kant. In the Kantian terminology “nature” signifies “all that is.” Cf. below, p. 580.

PREFACE TO THE SECOND EDITION

I SHALL again give a brief explanatory paraphrase, before proceeding to detailed comment. The main points of the preface of the first edition are repeated. “Metaphysics soars above all teaching of experience, and rests on concepts only. In it reason has to be her own pupil.”[110] But Kant immediately proceeds to a further point. That logic should have attained the secure method of science is due to its limitation to the mere a priori form of knowledge. For metaphysics this is far more difficult, since it “has to deal not with itself alone, but also with objects.”[111]

The words which I have italicised form a very necessary correction of the first edition preface, according to which the Critique would seem to “treat only of reason and its pure thinking.” A further difference follows. The second edition preface, in thus emphasising the objective aspect of the problem, is led to characterise in a more complete manner the method to be followed in the Critical enquiry. How can the Critique, if it is concerned, as both editions agree in insisting, only with the a priori which originates in human reason, solve the specifically metaphysical problem, viz. that of determining the independently real? How can an idea in us refer to, and constitute knowledge of, an object? The larger part of the preface to the second edition is devoted to the Critical solution of this problem. The argument of the Dialectic is no longer emphasised at the expense of the Analytic.

Kant points out that as a matter of historical fact each of the two rational sciences, mathematics and physics, first entered upon the assured path of knowledge by a sudden revolution, and by the adoption of a method which in its general characteristics is common to both. This method consists, not in being led by nature as in leading-strings, but in interrogating nature in accordance with what reason produces on its own plan. The method of the geometrician does not consist in the study of figures presented to the senses. That would be an empirical (in Kant’s view, sceptical) method. Geometrical propositions could not then be regarded as possessing universality and necessity. Nor does the geometrician employ a dogmatic method, that of studying the mere conception of a figure. By that means no new knowledge could ever be attained. The actual method consists in interpreting the sensible figures through conceptions that have been rigorously defined, and in accordance with which the figures have been constructively generated. The first discovery of this method, by Thales or some other Greek, was “far more important than the discovery of the passage round the celebrated Cape of Good Hope.”[112]

Some two thousand years elapsed before Galileo formulated a corresponding method for physical science. He relied neither on mere observation nor on his own conceptions. He determined the principles according to which alone concordant phenomena can be admitted as laws of nature, and then by experiment compelled nature to answer the questions which these principles suggest. Here again the method is neither merely empirical nor purely dogmatic. It possesses the advantages of both.

Metaphysics is ripe for a similar advance. It must be promoted to the rank of positive science by the transforming power of an analogous method. The fundamental and distinguishing characteristic of mathematical and physical procedure is the legislative power to which reason lays claim. Such procedure, if generalised and extended, will supply the required method of the new philosophy. Reason must be regarded as self-legislative in all the domains of our possible knowledge. Objects must be viewed as conforming to human thought, not human thought to the independently real. This is the “hypothesis” to which Kant has given the somewhat misleading title, “Copernican.”[113] The method of procedure which it prescribes is, he declares, analogous to that which was followed by Copernicus, and will be found to be as revolutionary in its consequences. In terms of this hypothesis a complete and absolutely certain metaphysics, valid now and for all time, can be created at a stroke. The earliest and oldest enterprise of the human mind will achieve a new beginning. Metaphysics, the mother of all the sciences, will renew her youth, and will equal in assurance, as she surpasses in dignity, the offspring of her womb.

From this new standpoint Kant develops phenomenalism on rationalist lines. He professes to prove that though our knowledge is only of appearances, it is conditioned by a priori principles. His “Copernican hypothesis,” so far from destroying positive science, is, he claims, merely a philosophical extension of the method which it has long been practising. Since all science worthy of the name involves a priori elements, it can be accounted for only in terms of the new hypothesis. Only if objects are regarded as conforming to our forms of intuition, and to our modes of conception, can they be anticipated by a priori reasoning. Science can be a priori just because, properly understood, it is not a rival of metaphysics, and does not attempt to define the absolutely real.

But such a statement at once suggests what may at first seem a most fatal objection. Though the new standpoint may account for the a priori in experience and science, it can be of no avail in metaphysics. If the a priori concepts have a mental origin, they can have no validity for the independently real. If we can know only what we ourselves originate, things in themselves must be unknown, and metaphysics must be impossible. But in this very consequence the new hypothesis first reveals its full advantages. It leads to an interpretation of metaphysics which is as new and as revolutionary[114] as that which it gives to natural science. Transcendent metaphysics is indeed impossible, but in harmony with man’s practical and moral vocation, its place is more efficiently taken by an immanent metaphysics on the one hand, and by a metaphysics of ethics on the other. Together these constitute the new and final philosophy which Kant claims to have established by his Critical method. Its chief task is to continue “that noblest enterprise of antiquity,”[115] the distinguishing of appearances from things in themselves. The unconditioned is that which alone will satisfy speculative reason; its determination is the ultimate presupposition of metaphysical enquiry. But so long as the empirical world is regarded as true reality, totality or unconditionedness cannot possibly be conceived—is, indeed, inherently self-contradictory. On the new hypothesis there is no such difficulty. By the proof that things in themselves are unknowable, a sphere is left open within which the unconditioned can be sought. For though this sphere is closed to speculative reason, the unconditioned can be determined from data yielded by reason in its practical activity. The hypothesis which at first seems to destroy metaphysics proves on examination to be its necessary presupposition. The “Copernican hypothesis” which conditions science will also account for metaphysics properly conceived.

Upon this important point Kant dwells at some length. Even the negative results of the Critique are, he emphasises, truly positive in their ultimate consequences. The dogmatic extension of speculative reason really leads to the narrowing of its employment, for the principles of which it then makes use involve the subjecting of things in themselves to the limiting conditions of sensibility. All attempts to construe the unconditioned in terms that will satisfy reason are by such procedure ruled out from the very start. To demonstrate this is the fundamental purpose and chief aim of the Critique. Space and time are merely forms of sensuous intuition; the concepts of understanding can yield knowledge only in their connection with them. Though the concepts in their purity possess a quite general meaning, this is not sufficient to constitute knowledge. The conception of causality, for instance, necessarily involves the notion of time-sequence; apart from time it is the bare, empty, and entirely unspecified conception of a sufficient ground. Similarly, the category of substance signifies the permanent in time and space; as a form of pure reason it has a quite indefinite meaning signifying merely that which is always a subject and never a predicate. In the absence of further specification, it remains entirely problematic in its reference. The fact, however, that the categories of the understanding possess, in independence of sensibility, even this quite general significance is all-important. Originating in pure reason they have a wider scope than the forms of sense, and enable us to conceive, though not to gain knowledge of, things in themselves.[116] Our dual nature, as being at once sensuous and supersensuous, opens out to us the apprehension of both.

Kant illustrates his position by reference to the problem of the freedom of the will. As thought is wider than sense, and reveals to us the existence of a noumenal realm, we are enabled to reconcile belief in the freedom of the will with the mechanism of nature. We can recognise that within the phenomenal sphere everything without exception is causally determined, and yet at the same time maintain that the whole order of nature is grounded in noumenal conditions. We can assert of one and the same being that its will is subject to the necessity of nature and that it is free—mechanically determined in its visible actions, free in its real supersensible existence. We have, indeed, no knowledge of the soul, and therefore cannot assert on theoretical grounds that it possesses any such freedom. The very possibility of freedom transcends our powers of comprehension. The proof that it can at least be conceived without contradiction is, however, all-important. For otherwise no arguments from the nature of the moral consciousness could be of the least avail; before a palpable contradiction every argument is bound to give way. Now, for the first time, the doctrine of morals and the doctrine of nature can be independently developed, without conflict, each in accordance with its own laws. The same is true in regard to the existence of God and the immortality of the soul. By means of the Critical distinction between the empirical and the supersensible worlds, these conceptions are now for the first time rendered possible of belief. “I had to remove knowledge, in order to make room for belief.”[117] “This loss affects only the monopoly of the schools, in no respect the interests of humanity.”[118]

Lastly, Kant emphasises the fact that the method of the Critique must be akin to that of dogmatism. It must be rational a priori. To adopt any other method of procedure is “to shake off the fetters of science altogether, and thus to change work into play, certainty into opinion, philosophy into philodoxy.”[119] And Kant repeats the claims of the preface of the first edition as to the completeness and finality of his system. “This system will, as I hope, maintain through the future this same unchangeableness.”[120]

Logic.[121]—For Kant’s view of the logic of Aristotle as complete and perfect, cf. below, pp. 184-5. Kant compares metaphysics to mathematics and physics on the one hand, and to formal logic on the other. The former show the possibility of attaining to the secure path of science by a sudden and single revolution; the latter demonstrates the possibility of creating a science complete and entire at a stroke. Thanks to the new Critical method, metaphysics may be enabled, Kant claims, to parallel both achievements at once.

Theoretical and practical reason.[122]—Such comment as is necessary upon this distinction is given below. Cf. p. 569 ff.

Hitherto it has been supposed that all knowledge must conform to the objects.[123]—This statement is historically correct. That assumption did actually underlie one and all of the pre-Kantian philosophies. At the same time, it is true that Kant’s phenomenalist standpoint is partially anticipated by Hume, by Malebranche and by Leibniz, especially by the first named. Hume argues that to condemn knowledge on the ground that it can never copy or truly reveal any external reality is to misunderstand its true function. Our sense perceptions and our general principles are so determined by nature as to render feasible only a practical organisation of life. When we attempt to derive from them a consistent body of knowledge, failure is the inevitable result.[124] Malebranche, while retaining the absolutist view of conceptual knowledge, propounds a similar theory of sense-perception.[125] Our perceptions are, as he shows, permeated through and through, from end to end, with illusion. Such illusions justify themselves by their practical usefulness, but they likewise prove that theoretical insight is not the purpose of our sense-experience. Kant’s Copernican hypothesis consists in great part of an extension of this view to our conceptual, scientific knowledge. But he differs both from Malebranche and from Hume in that he develops his phenomenalism on rationalist lines. He professes to show that though our knowledge is only of the phenomenal, it is conditioned by a priori principles. The resulting view of the distinction between appearance and reality has kinship with that of Leibniz.[126] The phenomena of science, though only appearances, are none the less bene fundata. Our scientific knowledge, though not equivalent to metaphysical apprehension of the ultimately real, can be progressively developed by scientific methods.

The two “parts” of metaphysics.[127]—Kant is here drawing the important distinction, which is one result of his new standpoint, between immanent and transcendent metaphysics. It is unfortunate that he does not do so in a more explicit manner, with full recognition of its novelty and of its far-reaching significance. Many ambiguities in his exposition here and elsewhere would then have been obviated.[128]

The unconditioned which Reason postulates in all things by themselves, by necessity and by right.[129]—Points are here raised the discussion of which must be deferred. Cf. below, pp. 429-31, 433-4, 558-61.

The Critique is a treatise on method, not a system of the science itself.[130]—Cf. A xv.; B xxxvi.; and especially A 11 = B 24, below pp. 71-2.

The Copernican hypothesis.[131]—Kant’s comparison of his new hypothesis to that of Copernicus has generally been misunderstood. The reader very naturally conceives the Copernican revolution in terms of its main ultimate consequence, the reduction of the earth from its proud position of central pre-eminence. But that does not bear the least analogy to the intended consequences of the Critical philosophy. The direct opposite is indeed true. Kant’s hypothesis is inspired by the avowed purpose of neutralising the naturalistic implications of the Copernican astronomy. His aim is nothing less than the firm establishment of what may perhaps be described as a Ptolemaic, anthropocentric metaphysics. Such naturalistic philosophy as that of Hume may perhaps be described as Copernican, but the Critical philosophy, as humanistic, has genuine kinship with the Greek standpoint.

Even some of Kant’s best commentators have interpreted the analogy in the above manner.[132] It is so interpreted by T. H. Green[133] and by J. Hutchison Stirling.[134] Caird in his Critical Philosophy of Kant makes not the least mention of the analogy, probably for the reason that while reading it in the same fashion as Green, he recognised the inappropriateness of the comparison as thus taken. The analogy is stated in typically ambiguous fashion by Lange[135] and by Höffding.[136] S. Alexander, while very forcibly insisting upon the Ptolemaic character of the Kantian philosophy, also endorses this interpretation in the following terms:

“It is very ironical that Kant himself signalised the revolution which he believed himself to be effecting as a Copernican revolution. But there is nothing Copernican in it except that he believed it to be a revolution. If every change is Copernican which reverses the order of the terms with which it deals, which declares A to depend on B when B had before been declared to depend on A, then Kant—who believed that he had reversed the order of dependence of mind and things—was right in saying that he effected a Copernican revolution. But he was not right in any other sense. For his revolution, so far as it was one, was accurately anti-Copernican.”[137]

As the second edition preface is not covered by the published volumes of Vaihinger’s Commentary, the point has not been taken up by him.

Now Kant’s own statements are entirely unambiguous and do not justify any such interpretation as that of Green and Alexander. As it seems to me, they have missed the real point of the analogy. The misunderstanding would never have been possible save for our neglect of the scientific classics. Kant must have had first-hand acquaintance with Copernicus’ De Revolutionibus, and the comparison which he draws assumes similar knowledge on the part of his readers. Copernicus by his proof of the “hypothesis” (his own term) of the earth’s motion sought only to achieve a more harmonious ordering of the Ptolemaic universe. And as thus merely a simplification of the traditional cosmology, his treatise could fittingly be dedicated to the reigning Pope. The sun upon which our terrestrial life depends was still regarded as uniquely distinct from the fixed stars; and our earth was still located in the central region of a universe that was conceived in the traditional manner as being single and spherical. Giordano Bruno was the first, a generation later, to realise the revolutionary consequences to which the new teaching, consistently developed, must inevitably lead. It was he who first taught what we have now come to regard as an integral part of Copernicus’ revolution, the doctrine of innumerable planetary systems side by side with one another in infinite space.

Copernicus’ argument starts from the Aristotelian principle of relative motion. To quote Copernicus’ exact words:

“All apprehended change of place is due to movement either of the observed object or of the observer, or to differences in movements that are occurring simultaneously in both. For if the observed object and the observer are moving in the same direction with equal velocity, no motion can be detected. Now it is from the earth that we visually apprehend the revolution of the heavens. If, then, any movement is ascribed to the earth, that motion will generate the appearance of itself in all things which are external to it, though as occurring in the opposite direction, as if everything were passing across the earth. This will be especially true of the daily revolution. For it seems to seize upon the whole world, and indeed upon everything that is around the earth, though not upon the earth itself.... As the heavens, which contain and cover everything, are the common locus of things, it is not at all evident why it should be to the containing rather than to the contained, to the located rather than to the locating, that a motion is to be ascribed.”[138]

The apparently objective movements of the fixed stars and of the sun are mere appearances, due to the projection of our own motion into the heavens.

“The first and highest of all the spheres is that of the fixed stars, self-containing and all-containing, and consequently immobile, in short the locus of the universe, by relation to which the motion and position of all the other heavenly bodies have to be reckoned.”[139]

Now it is this doctrine, and this doctrine alone, to which Kant is referring in the passages before us, namely, Copernicus’ hypothesis of a subjective explanation of apparently objective motions. And further, in thus comparing his Critical procedure to that of Copernicus, he is concerned more with the positive than with the negative consequences of their common hypothesis. For it is chiefly from the point of view of the constructive parts of the Aesthetic, Analytic, and Dialectic that the comparison is formulated. By means of the Critical hypothesis Kant professes on the one hand to account for our scientific knowledge, and on the other to safeguard our legitimate metaphysical aspirations. The spectator projects his own motion into the heavens; human reason legislates for the domain of natural science. The sphere of the fixed stars is proved to be motionless; things in themselves are freed from the limitations of space and time. “Copernicus dared, in a manner contradictory of the senses but yet true, to seek the observed movements, not in the heavenly bodies, but in the spectator.”[140]

In view of Kant’s explicit elimination of all hypotheses from the Critique[141] the employment of that term would seem to be illegitimate. He accordingly here states that though in the Preface his Critical theory is formulated as an hypothesis only, in the Critique itself its truth is demonstrated a priori.

Distinction between knowing and thinking.[142]—Since according to Critical teaching the limits of sense-experience are the limits of knowledge, the term knowledge has for Kant a very limited denotation, and leaves open a proportionately wide field for what he entitles thought. Though things in themselves are unknowable, their existence may still be recognised in thought.