But let us return to Kant. We are compelled to admit that he entirely lacks grand, classical simplicity, naïveté, ingénuité, candeur. His philosophy has no analogy with Grecian architecture, which presents large simple proportions revealing themselves at once to the glance; on the contrary, it reminds us strongly of the Gothic style of building. For a purely individual characteristic of Kant's mind is a remarkable love of symmetry, which delights in a varied multiplicity, so that it may reduce it to order, and repeat this order in subordinate orders, and so on indefinitely, just as happens in Gothic churches. Indeed, he sometimes carries this to the extent of trifling, and from love of this tendency he goes so far as to do open [pg 023] violence to truth, and to deal with it as Nature was dealt with by the old-fashioned gardeners, whose work we see in symmetrical alleys, squares, and triangles, trees shaped like pyramids and spheres, and hedges winding in regular curves. I will support this with facts.
After he has treated space and time isolated from everything else, and has then dismissed this whole world of perception which fills space and time, and in which we live and are, with the meaningless words “the empirical content of perception is given us,” he immediately arrives with one spring at the logical basis of his whole philosophy, the table of judgments. From this table he deduces an exact dozen of categories, symmetrically arranged under four heads, which afterwards become the fearful procrustean bed into which he violently forces all things in the world and all that goes on in man, shrinking from no violence and disdaining no sophistry if only he is able to repeat everywhere the symmetry of that table. The first that is symmetrically deduced from it is the pure physiological table of the general principles of natural science—the axioms of intuition, anticipations of perception, analogies of experience, and postulates of empirical thought in general. Of these fundamental principles, the first two are simple; but each of the last two sends out symmetrically three shoots. The mere categories were what he calls conceptions; but these principles of natural science are judgments. In accordance with his highest guide to all wisdom, symmetry, the series must now prove itself fruitful in the syllogisms, and this, indeed, is done symmetrically and regularly. For, as by the application of the categories to sensibility, experience with all its a priori principles arose for the understanding, so by the application of syllogisms to the categories, a task performed by the reason in accordance with its pretended principle of seeking the unconditioned, the Ideas of the reason arise. Now this takes place in the following manner: The three categories of relation supply to syllogistic reasoning the [pg 024] three only possible kinds of major premisses, and syllogistic reasoning accordingly falls into three kinds, each of which is to be regarded as an egg out of which the reason hatches an Idea; out of the categorical syllogism the Idea of the soul, out of the hypothetical the Idea of the world, and out of the disjunctive the Idea of God. In the second of these, the Idea of the world, the symmetry of the table of the categories now repeats itself again, for its four heads produce four theses, each of which has its antithesis as a symmetrical pendant.
We pay the tribute of our admiration to the really exceedingly acute combination which produced this elegant structure, but we shall none the less proceed to a thorough examination of its foundation and its parts. But the following remarks must come first.
It is astonishing how Kant, without further reflection, pursues his way, following his symmetry, ordering everything in accordance with it, without ever taking one of the subjects so handled into consideration on its own account. I will explain myself more fully. After he has considered intuitive knowledge in a mathematical reference only, he neglects altogether the rest of knowledge of perception in which the world lies before us, and confines himself entirely to abstract thinking, although this receives the whole of its significance and value from the world of perception alone, which is infinitely more significant, generally present, and rich in content than the abstract part of our knowledge. Indeed, and this is an important point, he has nowhere clearly distinguished perception from abstract knowledge, and just on this account, as we shall afterwards see, he becomes involved in irresolvable contradictions with himself. After he has disposed of the whole sensible world with the meaningless “it is given,” he makes, as we have said, the logical table of judgments the foundation-stone of his building. But here again he [pg 025] does not reflect for a moment upon that which really lies before him. These forms of judgment are indeed words and combinations of words; yet it ought first to have been asked what these directly denote: it would have been found that they denote conceptions. The next question would then have been as to the nature of conceptions. It would have appeared from the answer what relation these have to the ideas of perception in which the world exists; for perception and reflection would have been distinguished. It would now have become necessary to examine, not merely how pure and merely formal intuition or perception a priori, but also how its content, the empirical perception, comes into consciousness. But then it would have become apparent what part the understanding has in this, and thus also in general what the understanding is, and, on the other hand, what the reason properly is, the critique of which is being written. It is most remarkable that he does not once properly and adequately define the latter, but merely gives incidentally, and as the context in each case demands, incomplete and inaccurate explanations of it, in direct contradiction to the rule of Descartes given above.4 For example, at p. 11; V. 24, of the “Critique of Pure Reason,” it is the faculty of principles a priori; but at p. 299; V. 356, it is said that reason is the faculty of principles, and it is opposed to the understanding, which is the faculty of rules! One would now think that there must be a very wide difference between principles and rules, since it entitles us to assume a special faculty of knowledge for each of them. But this great distinction is made to lie merely in this, that what is known a priori through pure perception or through the forms of the understanding is a rule, and only what results from mere [pg 026] conceptions is a principle. We shall return to this arbitrary and inadmissible distinction later, when we come to the Dialectic. On p. 330; V. 386, reason is the faculty of inference; mere judging (p. 69; V. 94) he often explains as the work of the understanding. Now, this really amounts to saying: Judging is the work of the understanding so long as the ground of the judgment is empirical, transcendental, or metalogical (Essay on the Principle of Sufficient Reason, § 31, 32, 33); but if it is logical, as is the case with the syllogism, then we are here concerned with a quite special and much more important faculty of knowledge—the reason. Nay, what is more, on p. 303; V. 360, it is explained that what follows directly from a proposition is still a matter of the understanding, and that only those conclusions which are arrived at by the use of a mediating conception are the work of the reason, and the example given is this: From the proposition, “All men are mortal,” the inference, “Some mortals are men,” may be drawn by the mere understanding. On the other hand, to draw the conclusion, “All the learned are mortal,” demands an entirely different and far more important faculty—the reason. How was it possible for a great thinker to write the like of this! On p. 553; V. 581, reason is all at once the constant condition of all voluntary action. On p. 614; V. 642, it consists in the fact that we can give an account of our assertions; on pp. 643, 644; V. 671, 672, in the circumstance that it brings unity into the conceptions of the understanding by means of Ideas, as the understanding brings unity into the multiplicity of objects by means of conceptions. On p. 646; V. 674, it is nothing else than the faculty which deduces the particular from the general.
The understanding also is constantly being explained anew. In seven passages of the “Critique of Pure Reason” it is explained in the following terms. On p. 51; V. 75, it is the faculty which of itself produces ideas of perception. On p. 69; V. 94, it is the faculty of judging, [pg 027] i.e., of thinking, i.e., of knowing through conceptions. On p. 137 of the fifth edition, it is the faculty of knowledge generally. On p. 132; V. 171, it is the faculty of rules. On p. 158; V. 197, however, it is said: “It is not only the faculty of rules, but the source of principles (Grundsätze) according to which everything comes under rules;” and yet above it was opposed to the reason because the latter alone was the faculty of principles (Principien). On p. 160; V. 199, the understanding is the faculty of conceptions; but on p. 302; V. 359, it is the faculty of the unity of phenomena by means of rules.
Against such really confused and groundless language on the subject (even though it comes from Kant) I shall have no need to defend the explanation which I have given of these two faculties of knowledge—an explanation which is fixed, clearly defined, definite, simple, and in full agreement with the language of all nations and all ages. I have only quoted this language as a proof of my charge that Kant follows his symmetrical, logical system without sufficiently reflecting upon the subject he is thus handling.
Now, as I have said above, if Kant had seriously examined how far two such different faculties of knowledge, one of which is the specific difference of man, may be known, and what, in accordance with the language of all nations and all philosophers, reason and understanding are, he would never, without further authority than the intellectus theoreticus and practicus of the Schoolmen, which is used in an entirely different sense, have divided the reason into theoretical and practical, and made the latter the source of virtuous conduct. In the same way, before Kant separated so carefully conceptions of the understanding (by which he sometimes means his categories, sometimes all general conceptions) and conceptions of the reason (his so-called Ideas), and made them both the material of his philosophy, which for the most part deals only with the validity, application, and origin of all these conceptions;—first, I say, he ought to have really [pg 028] examined what in general a conception is. But this very necessary investigation has unfortunately been also neglected, and has contributed much to the irremediable confusion of intuitive and abstract knowledge which I shall soon refer to. The same want of adequate reflection with which he passed over the questions: what is perception? what is reflection? what is conception? what is reason? what is understanding? allowed him to pass over the following investigations, which were just as inevitably necessary: what is it that I call the object, which I distinguish from the idea? what is existence? what is object? what is subject? what is truth, illusion, error? But he follows his logical schema and his symmetry without reflecting or looking about him. The table of judgments ought to, and must, be the key to all wisdom.
I have given it above as the chief merit of Kant that he distinguished the phenomenon from the thing in itself, explained the whole visible world as phenomenon, and therefore denied all validity to its laws beyond the phenomenon. It is certainly remarkable that he did not deduce this merely relative existence of the phenomenon from the simple undeniable truth which lay so near him, “No object without a subject,” in order thus at the very root to show that the object, because it always exists merely in relation to a subject, is dependent upon it, conditioned by it, and therefore conditioned as mere phenomenon, which does not exist in itself nor unconditioned. Berkeley, to whose merits Kant did not do justice, had already made this important principle the foundation-stone of his philosophy, and thereby established an immortal reputation. Yet he himself did not draw the proper conclusions from this principle, and so he was both misunderstood and insufficiently attended to. In my first edition I explained Kant's avoidance of this Berkeleian principle as arising from an evident shrinking [pg 029] from decided idealism; while, on the other hand, I found idealism distinctly expressed in many passages of the “Critique of Pure Reason,” and accordingly I charged Kant with contradicting himself. And this charge was well founded, if, as was then my case, one only knew the “Critique of Pure Reason” in the second or any of the five subsequent editions printed from it. But when later I read Kant's great work in the first edition, which is already so rare, I saw, to my great pleasure, all these contradictions disappear, and found that although Kant does not use the formula, “No object without a subject,” he yet explains, with just as much decision as Berkeley and I do, the outer world lying before us in space and time as the mere idea of the subject that knows it. Therefore, for example, he says there without reserve (p. 383): “If I take away the thinking subject, the whole material world must disappear, for it is nothing but a phenomenon in the sensibility of our subject, and a class of its ideas.” But the whole passage from p. 348-392, in which Kant expounded his pronounced idealism with peculiar beauty and clearness, was suppressed by him in the second edition, and instead of it a number of remarks controverting it were introduced. In this way then the text of the “Critique of Pure Reason,” as it has circulated from the year 1787 to the year 1838, was disfigured and spoilt, and it became a self-contradictory book, the sense of which could not therefore be thoroughly clear and comprehensible to any one. The particulars about this, and also my conjectures as to the reasons and the weaknesses which may have influenced Kant so to disfigure his immortal work, I have given in a letter to Professor Rosenkranz, and he has quoted the principal passage of it in his preface to the second volume of the edition of Kant's collected works edited by him, to which I therefore refer. In consequence of my representations, Professor Rosenkranz was induced in the year 1838 to restore the “Critique of Pure Reason” to its original form, for in the second volume referred to [pg 030] he had it printed according to the first edition of 1781, by which he has rendered an inestimable service to philosophy; indeed, he has perhaps saved from destruction the most important work of German literature; and this should always be remembered to his credit. But let no one imagine that he knows the “Critique of Pure Reason” and has a distinct conception of Kant's teaching if he has only read the second or one of the later editions. That is altogether impossible, for he has only read a mutilated, spoilt, and to a certain extent ungenuine text. It is my duty to say this here decidedly and for every one's warning.
Yet the way in which Kant introduces the thing in itself stands in undeniable contradiction with the distinctly idealistic point of view so clearly expressed in the first edition of the “Critique of Pure Reason,” and without doubt this is the chief reason why, in the second edition, he suppressed the principal idealistic passage we have referred to, and directly declared himself opposed to the Berkeleian idealism, though by doing so he only introduced inconsistencies into his work, without being able to remedy its principal defect. This defect, as is known, is the introduction of the thing in itself in the way chosen by him, the inadmissibleness of which was exposed at length by G. E. Schulze in “Ænesidemus,” and was soon recognised as the untenable point of his system. The matter may be made clear in a very few words. Kant based the assumption of the thing in itself, though concealed under various modes of expression, upon an inference from the law of causality—an inference that the empirical perception, or more accurately the sensation, in our organs of sense, from which it proceeds, must have an external cause. But according to his own account, which is correct, the law of causality is known to us a priori, consequently is a function of our intellect, and is thus of subjective origin; further, sensation itself, to which we here apply the law of causality, is undeniably subjective; and finally, even space, in which, by means of this application, [pg 031] we place the cause of this sensation as object, is a form of our intellect given a priori, and is consequently subjective. Therefore the whole empirical perception remains always upon a subjective foundation, as a mere process in us, and nothing entirely different from it and independent of it can be brought in as a thing in itself, or shown to be a necessary assumption. The empirical perception actually is and remains merely our idea: it is the world as idea. An inner nature of this we can only arrive at on the entirely different path followed by me, by means of calling in the aid of self-consciousness, which proclaims the will as the inner nature of our own phenomenon; but then the thing in itself will be one which is toto genere different from the idea and its elements, as I have explained.
The great defect of the Kantian system in this point, which, as has been said, was soon pointed out, is an illustration of the truth of the beautiful Indian proverb: “No lotus without a stem.” The erroneous deduction of the thing in itself is here the stem; yet only the method of the deduction, not the recognition of a thing in itself belonging to the given phenomenon. But this last was Fichte's misunderstanding of it, which could only happen because he was not concerned with truth, but with making a sensation for the furtherance of his individual ends. Accordingly he was bold and thoughtless enough to deny the thing in itself altogether, and to set up a system in which, not, as with Kant, the mere form of the idea, but also the matter, its whole content, was professedly deduced a priori from the subject. In doing this, he counted with perfect correctness upon the want of judgment and the stupidity of the public, which accepted miserable sophisms, mere hocus-pocus and senseless babble, for proofs; so that he succeeded in turning its attention from Kant to himself, and gave the direction to German philosophy in which it was afterwards carried further by Schelling, and ultimately reached its goal in the mad sophistry of Hegel.
I now return to the great mistake of Kant, already [pg 032] touched on above, that he has not properly separated perceptible and abstract knowledge, whereby an inextricable confusion has arisen which we have now to consider more closely. If he had sharply separated ideas of perception from conceptions merely thought in abstracto, he would have held these two apart, and in every case would have known with which of the two he had to do. This, however, was unfortunately not the case, although this accusation has not yet been openly made, and may thus perhaps be unexpected. His “object of experience,” of which he is constantly speaking, the proper object of the categories, is not the idea of perception; neither is it the abstract conception, but it is different from both, and yet both at once, and is a perfect chimera. For, incredible as it may seem, he lacked either the wisdom or the honesty to come to an understanding with himself about this, and to explain distinctly to himself and others whether his “object of experience, i.e., the knowledge produced by the application of the categories,” is the idea of perception in space and time (my first class of ideas), or merely the abstract conception. Strange as it is, there always runs in his mind something between the two, and hence arises the unfortunate confusion which I must now bring to light. For this end I must go through the whole theory of elements in a general way.
The “Transcendental Æsthetic” is a work of such extraordinary merit that it alone would have been sufficient to immortalise the name of Kant. Its proofs carry such perfect conviction, that I number its propositions among incontestable truths, and without doubt they are also among those that are richest in results, and are, therefore, to be regarded as the rarest thing in the world, a real and great discovery in metaphysics. The fact, strictly proved by him, that a part of our knowledge is known to us a priori, admits of no other explanation than that this [pg 033] constitutes the forms of our intellect; indeed, this is less an explanation than merely the distinct expression of the fact itself. For a priori means nothing else than “not gained on the path of experience, thus not come into us from without.” But what is present in the intellect, and has not come from without, is just what belongs originally to the intellect itself, its own nature. Now if what is thus present in the intellect itself consists of the general mode or manner in which it must present all its objects to itself, this is just saying that what is thus present is the intellect's forms of knowing, i.e., the mode, fixed once for all, in which it fulfils this its function. Accordingly, “knowledge a priori” and “the intellect's own forms” are at bottom only two expressions for the same things thus to a certain extent synonyms.
Therefore from the doctrine of the Transcendental Æsthetic I knew of nothing to take away, only of something to add. Kant did not carry out his thought to the end, especially in this respect, that he did not reject Euclid's whole method of demonstration, even after having said on p. 87; V. 120, that all geometrical knowledge has direct evidence from perception. It is most remarkable that one of Kant's opponents, and indeed the acutest of them, G. E. Schulze (Kritik der theoretischen Philosophie, ii. 241), draws the conclusion that from his doctrine an entirely different treatment of geometry from that which is actually in use would arise; and thus he thought to bring an apagogical argument against Kant, but, in fact, without knowing it, he only began the war against the method of Euclid. Let me refer to § 15 of the first book of this work.
After the full exposition of the universal forms of perception given in the Transcendental Æsthetic, one necessarily expects to receive some explanation as to its content, as to the way in which the empirical perception comes into our consciousness, how the knowledge of this whole world, which is for us so real and so important, arises in [pg 034] us. But the whole teaching of Kant contains really nothing more about this than the oft-repeated meaningless expression: “The empirical element in perception is given from without.” Consequently here also from the pure forms of perception Kant arrives with one spring at thinking at the Transcendental Logic. Just at the beginning of the Transcendental Logic (Critique of Pure Reason, p. 50; V. 74), where Kant cannot avoid touching upon the content of the empirical perception, he takes the first false step; he is guilty of the πρωτον ψευδος. “Our knowledge,” he says, “has two sources, receptivity of impressions and spontaneity of conceptions: the first is the capacity for receiving ideas, the second that of knowing an object through these ideas: through the first an object is given us, through the second it is thought.” This is false; for according to it the impression, for which alone we have mere receptivity, which thus comes from without and alone is properly “given,” would be already an idea, and indeed an object. But it is nothing more than a mere sensation in the organ of sense, and only by the application of the understanding (i.e., of the law of causality) and the forms of perception, space and time, does our intellect change this mere sensation into an idea, which now exists as an object in space and time, and cannot be distinguished from the latter (the object) except in so far as we ask after the thing in itself, but apart from this is identical with it. I have explained this point fully in the essay on the principle of sufficient reason, § 21. With this, however, the work of the understanding and of the faculty of perception is completed, and no conceptions and no thinking are required in addition; therefore the brute also has these ideas. If conceptions are added, if thinking is added, to which spontaneity may certainly be attributed, then knowledge of perception is entirely abandoned, and a completely different class of ideas comes into consciousness, non-perceptible abstract conceptions. This is the activity of the reason, which yet obtains the whole [pg 035] content of its thinking only from the previous perception, and the comparison of it with other perceptions and conceptions. But thus Kant brings thinking into the perception, and lays the foundation for the inextricable confusion of intuitive and abstract knowledge which I am now engaged in condemning. He allows the perception, taken by itself, to be without understanding, purely sensuous, and thus quite passive, and only through thinking (category of the understanding) does he allow an object to be apprehended: thus he brings thought into the perception. But then, again, the object of thinking is an individual real object; and in this way thinking loses its essential character of universality and abstraction, and instead of general conceptions receives individual things as its object: thus again he brings perception into thinking. From this springs the inextricable confusion referred to, and the consequences of this first false step extend over his whole theory of knowledge. Through the whole of his theory the utter confusion of the idea of perception with the abstract idea tends towards a something between the two which he expounds as the object of knowledge through the understanding and its categories, and calls this knowledge experience. It is hard to believe that Kant really figured to himself something fully determined and really distinct in this object of the understanding; I shall now prove this through the tremendous contradiction which runs through the whole Transcendental Logic, and is the real source of the obscurity in which it is involved.
In the “Critique of Pure Reason,” p. 67-69; V. 92-94; p. 89, 90; V. 122, 123; further, V. 135, 139, 153, he repeats and insists: the understanding is no faculty of perception, its knowledge is not intuitive but discursive; the understanding is the faculty of judging (p. 69; V. 94), and a judgment is indirect knowledge, an idea of an idea (p. 68; V. 93); the understanding is the faculty of thinking, and thinking is knowledge through conceptions (p. 69; V. 94); the categories of the understanding are by no means [pg 036] the conditions under which objects are given in perception (p. 89; V. 122), and perception in no way requires the functions of thinking (p. 91; V. 123); our understanding can only think, not perceive (V. pp. 135, 139). Further, in the “Prolegomena,” § 20, he says that perception, sensation, perceptio, belongs merely to the senses; judgment to the understanding alone; and in § 22, that the work of the senses is to perceive, that of the understanding to think, i.e., to judge. Finally, in the “Critique of Practical Reason,” fourth edition, p. 247; Rosenkranz's edition, p. 281, he says that the understanding is discursive; its ideas are thoughts, not perceptions. All this is in Kant's own words.
From this it follows that this perceptible world would exist for us even if we had no understanding at all; that it comes into our head in a quite inexplicable manner, which he constantly indicates by his strange expression the perception is given, without ever explaining this indefinite and metaphorical expression further.
Now all that has been quoted is contradicted in the most glaring manner by the whole of the rest of his doctrine of the understanding, of its categories, and of the possibility of experience as he explains it in the Transcendental Logic. Thus (Critique of Pure Reason, p. 79; V. 105), the understanding through its categories brings unity into the manifold of perception, and the pure conceptions of the understanding refer a priori to objects of perception. P. 94; V. 126, the “categories are the condition of experience, whether of perception, which is found in it, or of thought.” V. p. 127, the understanding is the originator of experience. V. p. 128, the categories determine the perception of objects. V. p. 130, all that we present to ourselves as connected in the object (which is yet certainly something perceptible and not an abstraction), has been so connected by an act of the understanding. V. p. 135, the understanding is explained anew as the faculty of combining a priori, and of bringing the multiplicity of given [pg 037] ideas under the unity of apperception; but according to all ordinary use of words, apperception is not the thinking of a conception, but is perception. V. p. 136, we find a first principle of the possibility of all perception in connection with the understanding. V. p. 143, it stands as the heading, that all sense perception is conditioned by the categories. At the same place the logical function of the judgment also brings the manifold of given perceptions under an apperception in general, and the manifold of a given perception stands necessarily under the categories. V. p. 144, unity comes into perception, by means of the categories, through the understanding. V. p. 145, the thinking of the understanding is very strangely explained as synthetically combining, connecting, and arranging the manifold of perception. V. p. 161, experience is only possible through the categories, and consists in the connection of sensations, which, however, are just perceptions. V. p. 159, the categories are a priori knowledge of the objects of perception in general. Further, here and at V. p. 163 and 165, a chief doctrine of Kant's is given, this: that the understanding first makes Nature possible, because it prescribes laws for it a priori, and Nature adapts itself to the system of the understanding, and so on. Nature, however, is certainly perceptible and not an abstraction; therefore, the understanding must be a faculty of perception. V. p. 168, it is said, the conceptions of the understanding are the principles of the possibility of experience, and the latter is the condition of phenomena in space and time in general; phenomena which, however, certainly exist in perception. Finally, p. 189-211; V. 232-265, the long proof is given (the incorrectness of which is shown in detail in my essay on the principle of sufficient reason, § 23) that the objective succession and also the coexistence of objects of experience are not sensuously apprehended, but are only brought into Nature by the understanding, and that Nature itself first becomes possible in this way. Yet it is certain that Nature, the course of events, and the coexistence [pg 038] of states, is purely perceptible, and no mere abstract thought.
I challenge every one who shares my respect towards Kant to reconcile these contradictions and to show that in his doctrine of the object of experience and the way it is determined by the activity of the understanding and its twelve functions, Kant thought something quite distinct and definite. I am convinced that the contradiction I have pointed out, which extends through the whole Transcendental Logic, is the real reason of the great obscurity of its language. Kant himself, in fact, was dimly conscious of the contradiction, inwardly combated it, but yet either would not or could not bring it to distinct consciousness, and therefore veiled it from himself and others, and avoided it by all kinds of subterfuges. This is perhaps also the reason why he made out of the faculties of knowledge such a strange complicated machine, with so many wheels, as the twelve categories, the transcendental synthesis of imagination, of the inner sense, of the transcendental unity of apperception, also the schematism of the pure conceptions of the understanding, &c., &c. And notwithstanding this great apparatus, not even an attempt is made to explain the perception of the external world, which is after all the principal fact in our knowledge; but this pressing claim is very meanly rejected, always through the same meaningless metaphorical expression: “The empirical perception is given us.” On p. 145 of the fifth edition, we learn further that the perception is given through the object; therefore the object must be something different from the perception.
If, now, we endeavour to investigate Kant's inmost meaning, not clearly expressed by himself, we find that in reality such an object, different from the perception, but which is by no means a conception, is for him the proper object for the understanding; indeed that it must be by means of the strange assumption of such an object, which cannot be presented in perception, that the perception [pg 039] first becomes experience. I believe that an old deeply-rooted prejudice in Kant, dead to all investigation, is the ultimate reason of the assumption of such an absolute object, which is an object in itself, i.e., without a subject. It is certainly not the perceived object, but through the conception it is added to the perception by thought, as something corresponding to it; and now the perception is experience, and has value and truth, which it thus only receives through the relation to a conception (in diametrical opposition to my exposition, according to which the conception only receives value and truth from the perception). It is then the proper function of the categories to add on in thought to the perception this directly non-perceptible object. “The object is given only through perception, and is afterwards thought in accordance with the category” (Critique of Pure Reason, first edition, p. 399). This is made specially clear by a passage on p. 125 of the fifth edition: “Now the question arises whether conceptions a priori do not also come first as conditions under which alone a thing can be, not perceived certainly, but yet thought as an object in general,” which he answers in the affirmative. Here the source of the error and the confusion in which it is involved shows itself distinctly. For the object as such exists always only for perception and in it; it may now be completed through the senses, or, when it is absent, through the imagination. What is thought, on the contrary, is always an universal non-perceptible conception, which certainly can be the conception of an object in general; but only indirectly by means of conceptions does thought relate itself to objects, which always are and remain perceptible. For our thinking is not able to impart reality to perceptions; this they have, so far as they are capable of it (empirical reality) of themselves; but it serves to bring together the common element and the results of perceptions, in order to preserve them, and to be able to use them more easily. But Kant ascribes the objects themselves to thought, in order to make experience [pg 040] and the objective world dependent upon understanding, yet without allowing understanding to be a faculty of perception. In this relation he certainly distinguishes perception from thought, but he makes particular things sometimes the object of perception and sometimes the object of thought. In reality, however, they are only the object of the former; our empirical perception is at once objective, just because it proceeds from the causal nexus. Things, not ideas different from them, are directly its object. Particular things as such are perceived in the understanding and through the senses; the one-sided impression upon the latter is at once completed by the imagination. But, on the contrary, as soon as we pass over to thought, we leave the particular things, and have to do with general conceptions, which cannot be presented in perception, although we afterwards apply the results of our thought to particular things. If we hold firmly to this, the inadmissibleness of the assumption becomes evident that the perception of things only obtains reality and becomes experience through the thought of these very things applying its twelve categories. Rather in perception itself the empirical reality, and consequently experience, is already given; but the perception itself can only come into existence by the application to sensation of the knowledge of the causal nexus, which is the one function of the understanding. Perception is accordingly in reality intellectual, which is just what Kant denies.
Besides in the passages quoted, the assumption of Kant here criticised will be found expressed with admirable clearness in the “Critique of Judgment,” § 36, just at the beginning; also in the “Metaphysical Principles of Natural Science,” in the note to the first explanation of “Phenomenology.” But with a naïveté which Kant ventured upon least of all with reference to this doubtful point, it is to be found most distinctly laid down in the book of a Kantian, Kiesewetter's “Grundriss einer algemeinen Logik,” third edition, part i., p. 434 of the exposition, [pg 041] and part ii., § 52 and 53 of the exposition; similarly in Tieftrunk's “Denklehre in rein Deutschem Gewande” (1825). It there appears so clearly how those disciples who do not themselves think become a magnifying mirror of the errors of every thinker. Once having determined his doctrine of the categories, Kant was always cautious when expounding it, but his disciples on the contrary were quite bold, and thus exposed its falseness.
According to what has been said, the object of the categories is for Kant, not indeed the thing in itself, but yet most closely akin to it. It is the object in itself; it is an object that requires no subject; it is a particular thing, and yet not in space and time, because not perceptible; it is an object of thought, and yet not an abstract conception. Accordingly Kant really makes a triple division: (1.) the idea; (2.) the object of the idea; (3.) the thing in itself. The first belongs to the sensibility, which in its case, as in that of sensation, includes the pure forms of perception, space and time. The second belongs to the understanding, which thinks it through its twelve categories. The third lies beyond the possibility of all knowledge. (In support of this, cf. Critique of Pure Reason, first edition, p. 108 and 109.) The distinction of the idea from the object of the idea is however unfounded; this had already been proved by Berkeley, and it appears from my whole exposition in the first book, especially chap. i. of the supplements; nay, even from Kant's own completely idealistic point of view in the first edition. But if we should not wish to count the object of the idea as belonging to the idea and identify it with the idea, it would be necessary to attribute it to the thing in itself: this ultimately depends on the sense which is attached to the word object. This, however, always remains certain, that, when we think clearly, nothing more can be found than idea and thing in itself. The illicit introduction of that hybrid, the object of the idea, is the source of Kant's errors; yet when it is taken away, the doctrine of the categories as conceptions [pg 042] a priori also falls to the ground; for they bring nothing to the perception, and are not supposed to hold good of the thing in itself, but by means of them we only think those “objects of the ideas,” and thereby change ideas into experience. For every empirical perception is already experience; but every perception which proceeds from sensation is empirical: this sensation is related by the understanding, by means of its sole function (knowledge a priori of the law of causality), to its cause, which just on this account presents itself in space and time (forms of pure perception) as object of experience, material object, enduring in space through all time, yet as such always remains idea, as do space and time themselves. If we desire to go beyond this idea, then we arrive at the question as to the thing in itself, the answer to which is the theme of my whole work, as of all metaphysics in general. Kant's error here explained is connected with his mistake, which we condemned before, that he gives no theory of the origin of empirical perception, but, without saying more, treats it as given, identifying it with the mere sensation, to which he only adds the forms of intuition or perception, space and time, comprehending both under the name sensibility. But from these materials no objective idea arises: this absolutely demands the relation of the idea to its cause, thus the application of the law of causality, and thus understanding; for without this the sensation still remains always subjective, and does not take the form of an object in space, even if space is given with it. But according to Kant, the understanding must not be assigned to perception; it is supposed merely to think, so as to remain within the transcendental logic. With this again is connected another mistake of Kant's: that he left it to me to adduce the only valid proof of the a priori nature of the law of causality which he rightly recognised, the proof from the possibility of objective empirical perception itself, and instead of it gives a palpably false one, as I have already shown in my essay on the principle of [pg 043] sufficient reason, § 23. From the above it is clear that Kant's “object of the idea” (2) is made up of what he has stolen partly from the idea (1), and partly from the thing in itself (3). If, in reality, experience were only brought about by the understanding applying its twelve different functions in order to think through as many conceptions a priori, the objects which were previously merely perceived, then every real thing would necessarily as such have a number of determinations, which, as given a priori, absolutely could not be thought away, just like space and time, but would belong quite essentially to the existence of the thing, and yet could not be deduced from the properties of space and time. But only one such determination is to be found—that of causality. Upon this rests materiality, for the essence of matter consists in action, and it is through and through causality (cf. Bk. II. ch. iv.) But it is materiality alone that distinguishes the real thing from the picture of the imagination, which is then only idea. For matter, as permanent, gives to the thing permanence through all time, in respect of its matter, while the forms change in conformity with causality. Everything else in the thing consists either of determinations of space or of time, or of its empirical properties, which are all referable to its activity, and are thus fuller determinations of causality. But causality enters already as a condition into the empirical perception, and this is accordingly a thing of the understanding, which makes even perception possible, and yet apart from the law of causality contributes nothing to experience and its possibility. What fills the old ontologies is, with the exception of what is given here, nothing more than relations of things to each other, or to our reflection, and a farrago of nonsense.
The language in which the doctrine of the categories is expressed affords an evidence of its baselessness. What a difference in this respect between the Transcendental Æsthetic and the Transcendental Analytic! In the [pg 044] former, what clearness, definiteness, certainty, firm conviction which is freely expressed and infallibly communicates itself! All is full of light, no dark lurking-places are left: Kant knows what he wants and knows that he is right. In the latter, on the other hand, all is obscure, confused, indefinite, wavering, uncertain, the language anxious, full of excuses and appeals to what is coming, or indeed of suppression. Moreover, the whole second and third sections of the Deduction of the Pure Conceptions of the Understanding are completely changed in the second edition, because they did not satisfy Kant himself, and they have become quite different from the first edition, though not clearer. We actually see Kant in conflict with the truth in order to carry out his hypothesis which he has once fixed upon. In the Transcendental Æsthetic all his propositions are really proved from undeniable facts of consciousness, in the Transcendental Analytic, on the contrary, we find, if we consider it closely, mere assertions that thus it is and must be. Here, then, as everywhere, the language bears the stamp of the thought from which it has proceeded, for style is the physiognomy of the mind. We have still to remark, that whenever Kant wishes to give an example for the purpose of fuller explanation, he almost always takes for this end the category of causality, and then what he has said turns out correct; for the law of causality is indeed the real form of the understanding, but it is also its only form, and the remaining eleven categories are merely blind windows. The deduction of the categories is simpler and less involved in the first edition than in the second. He labours to explain how, according to the perception given by sensibility, the understanding produces experience by means of thinking the categories. In doing so, the words recognition, reproduction, association, apprehension, transcendental unity of apperception, are repeated to weariness, and yet no distinctness is attained. It is well worth noticing, however, that in this explanation [pg 045] he does not once touch upon what must nevertheless first occur to every one—the relation of the sensation to its external cause. If he did not intend this relation to hold good, he ought to have expressly denied it; but neither does he do this. Thus in this way he evades the point, and all the Kantians have in like manner evaded it. The secret motive of this is, that he reserves the causal nexus, under the name “ground of the phenomenon,” for his false deduction of the thing in itself; and also that perception would become intellectual through the relation to the cause, which he dare not admit. Besides this, he seems to have been afraid that if the causal nexus were allowed to hold good between sensation and object, the latter would at once become the thing in itself, and introduce the empiricism of Locke. But this difficulty is removed by reflection, which shows us that the law of causality is of subjective origin, as well as the sensation itself; and besides this, our own body also, inasmuch as it appears in space, already belongs to ideas. But Kant was hindered from confessing this by his fear of the Berkeleian idealism.
“The combination of the manifold of perception” is repeatedly given as the essential operation of the understanding, by means of its twelve categories. Yet this is never adequately explained, nor is it shown what this manifold of perception is before it is combined by the understanding. But time and space, the latter in all its three dimensions, are continua, i.e., all their parts are originally not separate but combined. Thus, then, everything that exhibits itself in them (is given) appears originally as a continuum, i.e., its parts appear already combined and require no adventitious combination of a manifold. If, however, some one should seek to interpret that combining of the manifold of perception by saying that I refer the different sense-impressions of one object to this one only—thus, for example, perceiving a bell, I recognise that what affects my eye as yellow, my hand as [pg 046] smooth and hard, my ear as sounding, is yet only one and the same body,—then I reply that this is rather a consequence of the knowledge a priori of the causal nexus (this actual and only function of the understanding), by virtue of which all those different effects upon my different organs of sense yet lead me only to one common cause of them, the nature of the body standing before me, so that my understanding, in spite of the difference and multiplicity of the effects, still apprehends the unity of the cause as a single object, which just on that account exhibits itself in perception. In the beautiful recapitulation of his doctrine which Kant gives at p. 719-726 or V. 747-754 of the “Critique of Pure Reason,” he explains the categories, perhaps more distinctly than anywhere else, as “the mere rule of the synthesis of that which empirical apprehension has given a posteriori.” It seems as if here he had something in his mind, such as that, in the construction of the triangle, the angles give the rule for the composition of the lines; at least by this image one can best explain to oneself what he says of the function of the categories. The preface to the “Metaphysical First Principles of Natural Science” contains a long note which likewise gives an explanation of the categories, and says that they “differ in no respect from the formal acts of the understanding in judging,” except that in the latter subject and predicate can always change places; then the judgment in general is defined in the same passage as “an act through which given ideas first become knowledge of an object.” According to this, the brutes, since they do not judge, must also have no knowledge of objects. In general, according to Kant, there are only conceptions of objects, no perceptions. I, on the contrary, say: Objects exist primarily only for perception, and conceptions are always abstractions from this perception. Therefore abstract thinking must be conducted exactly according to the world present in perception, for it is only their relation to this that gives content to conceptions; and we must [pg 047] assume for the conceptions no other a priori determined form than the faculty of reflection in general, the nature of which is the construction of conceptions, i.e., of abstract non-perceptible ideas, which constitutes the sole function of the reason, as I have shown in the first book. I therefore require that we should reject eleven of the categories, and only retain that of causality, and yet that we should see clearly that its activity is indeed the condition of empirical perception, which accordingly is not merely sensuous but intellectual, and that the object so perceived, the object of experience, is one with the idea, from which there remains nothing to distinguish except the thing in itself.
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.