After repeated study of the “Critique of Pure Reason” at different periods of my life, a conviction has forced itself upon me with regard to the origin of the Transcendental Logic, which I now impart as very helpful to an understanding of it. Kant's only discovery, which is based upon objective comprehension and the highest human thought, is the apperçu that time and space are known by us a priori. Gratified by this happy hit, he wished to pursue the same vein further, and his love of architectonic symmetry afforded him the clue. As he had found that a pure intuition or perception a priori underlay the empirical perception as its condition, he thought that in the same way certain pure conceptions as presuppositions in our faculty of knowledge must lie at the foundation of the empirically obtained conceptions, and that real empirical thought must be only possible through a pure thought a priori, which, however, would have no objects in itself, but would be obliged to take them from perception. So that as the Transcendental Æsthetic establishes an a priori basis of mathematics, there must, he supposed, also be a similar basis for logic; and thus, then for the sake of symmetry, the former received a pendant in a Transcendental Logic. From this point onwards Kant was no more free, no more in the position of purely, [pg 048] investigating and observing what is present in consciousness; but he was guided by an assumption and pursued a purpose—the purpose of finding what he assumed, in order to add to the Transcendental Æsthetic so happily discovered a Transcendental Logic analogous to it, and thus symmetrically corresponding to it, as a second storey. Now for this purpose he hit upon the table of judgments, out of which he constructed, as well as he could, the table of categories, the doctrine of twelve pure a priori conceptions, which are supposed to be the conditions of our thinking those very things the perception of which is conditioned by the two a priori forms of sensibility: thus a pure understanding now corresponded symmetrically to a pure sensibility. Then another consideration occurred to him, which offered a means of increasing the plausibility of the thing, by the assumption of the schematism of the pure conceptions of the understanding. But just through this the way in which his procedure had, unconsciously indeed, originated betrayed itself most distinctly. For because he aimed at finding something a priori analogous to every empirical function of the faculty of knowledge, he remarked that between our empirical perception and our empirical thinking, conducted in abstract non-perceptible conceptions, a connection very frequently, though not always, takes place, because every now and then we try to go back from abstract thinking to perception; but try to do so merely in order really to convince ourselves that our abstract thought has not strayed far from the safe ground of perception, and perhaps become exaggeration, or, it may be, mere empty talk; much in the same way as, when we are walking in the dark, we stretch out our hand every now and then to the guiding wall. We go back, then, to the perception only tentatively and for the moment, by calling up in imagination a perception corresponding to the conceptions which are occupying us at the time—a perception which can yet never be quite adequate to the conception, but is merely a temporary [pg 049] representative of it. I have already adduced what is needful on this point in my essay on the principle of sufficient reason, § 28. Kant calls a fleeting phantasy of this kind a schema, in opposition to the perfected picture of the imagination. He says it is like a monogram of the imagination, and asserts that just as such a schema stands midway between our abstract thinking of empirically obtained conceptions, and our clear perception which comes to us through the senses, so there are a priori schemata of the pure conceptions of the understanding between the faculty of perception a priori of pure sensibility and the faculty of thinking a priori of the pure understanding (thus the categories). These schemata, as monograms of the pure imagination a priori, he describes one by one, and assigns to each of them its corresponding category, in the wonderful “Chapter on the Schematism of the Pure Conceptions of the Understanding,” which is noted as exceedingly obscure, because no man has ever been able to make anything out of it. Its obscurity, however, vanishes if it is considered from the point of view here indicated, but there also comes out more clearly in it than anywhere else the intentional nature of Kant's procedure, and of the determination formed beforehand of finding what would correspond to the analogy, and could assist the architectonic symmetry; indeed this is here the case to such a degree as to be almost comical. For when he assumes schemata of the pure (empty) a priori conceptions of the understanding (categories) analogous to the empirical schemata (or representatives through the fancy of our actual conceptions), he overlooks the fact that the end of such schemata is here entirely wanting, For the end of the schemata in the case of empirical (real) thinking is entirely connected with the material content of such conceptions. For since these conceptions are drawn from empirical perception, we assist and guide ourselves when engaged in abstract thinking by now and then casting a momentary glance back at [pg 050] the perception out of which the conceptions are framed, in order to assure ourselves that our thought has still real content. This, however, necessarily presupposes that the conceptions which occupy us are sprung from perception, and it is merely a glance back at their material content, indeed a mere aid to our weakness. But in the case of a priori conceptions which as yet have no content at all, clearly this is necessarily omitted. For these conceptions are not sprung from perception, but come to it from within, in order to receive a content first from it. Thus they have as yet nothing on which they could look back. I speak fully upon this point, because it is just this that throws light upon the secret origin of the Kantian philosophising, which accordingly consists in this, that Kant, after the happy discovery of the two forms of intuition or perception a priori, exerted himself, under the guidance of the analogy, to prove that for every determination of our empirical knowledge there is an a priori analogue, and this finally extended, in the schemata, even to a mere psychological fact. Here the apparent depth and the difficulty of the exposition just serve to conceal from the reader that its content remains a wholly undemonstrable and merely arbitrary assumption. But he who has penetrated at last to the meaning of such an exposition is then easily induced to mistake this understanding so painfully attained for a conviction of the truth of the matter. If, on the contrary, Kant had kept himself here as unprejudiced and purely observant as in the discovery of a priori intuition or perception, he must have found that what is added to the pure intuition or perception of space and time, if an empirical perception arises from it, is on the one hand the sensation, and on the other hand the knowledge of causality, which changes the mere sensation into objective empirical perception, but just on this account is not first derived and learned from sensation, but exists a priori, and is indeed the form and function of the pure understanding. It is also, however, [pg 051] its sole form and function, yet one so rich in results that all our empirical knowledge rests upon it. If, as has often been said, the refutation of an error is only complete when the way it originated has been psychologically demonstrated, I believe I have achieved this, with regard to Kant's doctrine of the categories and their schemata, in what I have said above.
After Kant had thus introduced such great errors into the first simple outlines of a theory of the faculty of perception, he adopted a variety of very complicated assumptions. To these belongs first of all the synthetic unity of apperception: a very strange thing, very strangely explained. “The I think must be able to accompany all my ideas.” Must—be able: this is a problematic-apodictic enunciation; in plain English, a proposition which takes with one hand what it gives with the other. And what is the meaning of this carefully balanced proposition? That all knowledge of ideas is thinking? That is not the case: and it would be dreadful; there would then be nothing but abstract conceptions, or at any rate a pure perception free from reflection and will, such as that of the beautiful, the deepest comprehension of the true nature of things, i.e., of their Platonic Ideas. And besides, the brutes would then either think also, or else they would not even have ideas. Or is the proposition perhaps intended to mean: no object without a subject? That would be very badly expressed by it, and would come too late. If we collect Kant's utterances on the subject, we shall find that what he understands by the synthetic unity of apperception is, as it were, the extensionless centre of the sphere of all our ideas, whose radii converge to it. It is what I call the subject of knowing, the correlative of all ideas, and it is also that which I have fully described and explained in the 22d chapter of the Supplements, as the focus in which the rays of the activity [pg 052] of the brain converge. Therefore, to avoid repetition, I now refer to that chapter.
That I reject the whole doctrine of the categories, and reckon it among the groundless assumptions with which Kant burdened the theory of knowledge, results from the criticism given above; and also from the proof of the contradictions in the Transcendental Logic, which had their ground in the confusion of perception and abstract knowledge; also further from the proof of the want of a distinct and definite conception of the nature of the understanding and of the reason, instead of which we found in Kant's writings only incoherent, inconsistent, insufficient, and incorrect utterances with regard to these two faculties of the mind. Finally, it results from the explanations which I myself have given of these faculties of the mind in the first book and its Supplements, and more fully in the essay on the principle of sufficient reason, § 21, 26, and 34,—explanations which are very definite and distinct, which clearly follow from the consideration of the nature of our knowledge, and which completely agree with the conceptions of those two faculties of knowledge that appear in the language and writings of all ages and all nations, but were not brought to distinctness. Their defence against the very different exposition of Kant has, for the most part, been given already along with the exposure of the errors of that exposition. Since, however, the table of judgments, which Kant makes the foundation of his theory of thinking, and indeed of his whole philosophy, has, in itself, as a whole, its correctness, it is still incumbent upon me to show how these universal forms of all judgment arise in our faculty of knowledge, and to reconcile them with my exposition of it. In this discussion I shall always attach to the concepts understanding and reason the sense given them in my explanation, which I therefore assume the reader is familiar with.
An essential difference between Kant's method and that which I follow lies in this, that he starts from indirect, reflected knowledge, while I start from direct or intuitive knowledge. He may be compared to a man who measures the height of a tower by its shadow, while I am like him who applies the measuring-rule directly to the tower itself. Therefore, for him philosophy is a science of conceptions, but for me it is a science in conceptions, drawn from knowledge of perception, the one source of all evidence, and comprehended and made permanent in general conceptions. He passes over this whole world of perception which surrounds us, so multifarious and rich in significance, and confines himself to the forms of abstract thinking; and, although he never expressly says so, this procedure is founded on the assumption that reflection is the ectype of all perception, that, therefore, all that is essential in perception must be expressed in reflection, and expressed in very contracted forms and outlines, which are thus easily surveyed. According to this, what is essential and conformable to law in abstract knowledge would, as it were, place in our hands all the threads by which the varied puppet-show of the world of perception is set in motion before our eyes. If Kant had only distinctly expressed this first principle of his method, and then followed it consistently, he would at least have been obliged to separate clearly the intuitive from the abstract, and we would not have had to contend with inextricable contradictions and confusions. But from the way in which he solves his problem we see that that fundamental principle of his method was only very indistinctly present to his mind, and thus we have still to arrive at it by conjecture even after a thorough study of his philosophy.
Now as concerns the specified method and fundamental maxim itself, there is much to be said for it, and it is a brilliant thought. The nature of all science indeed consists in this, that we comprehend the endless manifold of [pg 054] perceptible phenomena under comparatively few abstract conceptions, and out of these construct a system by means of which we have all those phenomena completely in the power of our knowledge, can explain the past and determine the future. The sciences, however, divide the wide sphere of phenomena among them according to the special and manifold classes of the latter. Now it was a bold and happy thought to isolate what is absolutely essential to the conceptions as such and apart from their content, in order to discover from these forms of all thought found in this way what is essential to all intuitive knowledge also, and consequently to the world as phenomenon in general; and because this would be found a priori on account of the necessity of those forms of thought, it would be of subjective origin, and would just lead to the ends Kant had in view. Here, however, before going further, the relation of reflection to knowledge of perception ought to have been investigated (which certainly presupposes the clear separation of the two, which was neglected by Kant). He ought to have inquired in what way the former really repeats and represents the latter, whether quite pure, or changed and to some extent disguised by being taken up into its special forms (forms of reflection); whether the form of abstract reflective knowledge becomes more determined through the form of knowledge of perception, or through the nature or constitution which unalterably belongs to itself, i.e., to reflective knowledge, so that even what is very heterogeneous in intuitive knowledge can no longer be distinguished when it has entered reflective knowledge, and conversely many distinctions of which we are conscious in the reflective method of knowledge have also sprung from this knowledge itself, and by no means point to corresponding differences in intuitive knowledge. As the result of this investigation, however, it would have appeared that knowledge of perception suffers very nearly as much change when it is taken up into reflection as food when it is taken into the animal organism whose [pg 055] forms and compounds are determined by itself, so that the nature of the food can no longer be recognised from the result they produce. Or (for this is going a little too far) at least it would have appeared that reflection is by no means related to knowledge of perception as the reflection in water is related to the reflected objects, but scarcely even as the mere shadow of these objects stands to the objects themselves; which shadow repeats only a few external outlines, but also unites the most manifold in the same form and presents the most diverse through the same outline; so that it is by no means possible, starting from it, to construe the forms of things with completeness and certainty.
The whole of reflective knowledge, or the reason, has only one chief form, and that is the abstract conception. It is proper to the reason itself, and has no direct necessary connection with the world of perception, which therefore exists for the brutes entirely without conceptions, and indeed, even if it were quite another world from what it is, that form of reflection would suit it just as well. But the combination of conceptions for the purpose of judging has certain definite and normal forms, which have been found by induction, and constitute the table of judgments. These forms are for the most part deducible from the nature of reflective knowledge itself, thus directly from the reason, because they spring from the four laws of thought (called by me metalogical truths) and the dictum de omni et nullo. Certain others of these forms, however, have their ground in the nature of knowledge of perception, thus in the understanding; yet they by no means point to a like number of special forms of the understanding, but can all be fully deduced from the sole function which the understanding has—the direct knowledge of cause and effect. Lastly, still others of these forms have sprung from the concurrence and combination of the reflective and intuitive modes of knowledge, or more properly from the assumption of the latter into the [pg 056] former. I shall now go through the moments of the judgment one by one, and point out the origin of each of them in the sources referred to; and from this it follows of itself that a deduction of categories from them is wanting, and the assumption of this is just as groundless as its exposition was found to be entangled and self-conflicting.
1. The so-called Quantity of judgments springs from the nature of concepts as such. It thus has its ground in the reason alone, and has absolutely no direct connection with the understanding and with knowledge of perception. It is indeed, as is explained at length in the first book, essential to concepts, as such, that they should have an extent, a sphere, and the wider, less determined concept includes the narrower and more determined. The latter can therefore be separated from the former, and this may happen in two ways,—either the narrower concept may be indicated as an indefinite part of the wider concept in general, or it may be defined and completely separated by means of the addition of a special name. The judgment which carries out this operation is in the first case called a particular, and in the second case an universal judgment. For example, one and the same part of the sphere of the concept tree may be isolated through a particular and through an universal judgment, thus—“Some trees bear gall-nuts,” or “All oaks bear gall-nuts.” One sees that the difference of the two operations is very slight; indeed, that the possibility of it depends upon the richness of the language. Nevertheless, Kant has explained this difference as disclosing two fundamentally different actions, functions, categories of the pure understanding which determines experience a priori through them.
Finally, a concept may also be used in order to arrive by means of it at a definite particular idea of perception, from which, as well as from many others, this concept itself is drawn; this happens in the singular judgment. Such a judgment merely indicates the boundary-line [pg 057] between abstract knowledge and knowledge of perception, and passes directly to the latter, “This tree here bears gall-nuts.” Kant has made of this also a special category.