The whole of the chapter on the Amphiboly, which follows this, is merely a criticism of the Leibnitzian philosophy, and as such is on the whole correct, though the form or pattern on which it is constructed is chosen merely for the sake of architectonic symmetry, which here also is the guiding clue. Thus, to carry out the analogy with the Aristotelian Organon, a transcendental Topic is set up, which consists in this, that every conception is to be considered from four points of view, in order to make out to which faculty of knowledge it belongs. But these four points of view are quite arbitrarily selected, and ten others might be added to them with just as much right; but their fourfold number corresponds to the titles of the categories, and therefore the chief doctrine of Leibnitz is divided among them as best it may be. By this critique, also, to some extent, certain errors are stamped as natural to the reason, whereas they were merely false abstractions of Leibnitz's, who, rather than learn from his great philosophical contemporaries, Spinoza and Locke, preferred to serve up his own strange inventions. In the chapter on the Amphiboly of Reflection it is finally said that there may possibly be a kind of perception entirely different from ours, to which, however, our categories are applicable; therefore the objects of that supposed perception would be noumena, things which can only be thought by us; but since the perception which would give that thought meaning is wanting to us, and indeed is altogether quite problematical, the object of that thought would also merely be a wholly indefinite possibility. I have shown above by quotations that Kant, in utter contradiction with himself, sets up the categories now as the condition of knowledge of perception, now as the function of merely abstract thought. Here they appear exclusively in the latter sense, and it seems quite as if he wished to attribute them merely to discursive thought. But if this is really his opinion, then necessarily at the beginning of the Transcendental Logic, before specifying the different functions of thought at such length, he was necessarily bound to characterise thought in general, and consequently to distinguish it from perception; he ought to have shown what knowledge is given by mere perception, and what that is new is added by thought. Then we would have known what he was really speaking about; or rather, he would then have spoken quite differently, first of perception, and then of thought; instead of which, as it is, he is always dealing with something between the two, which is a mere delusion. There would not then be that great gap between the transcendental Æsthetic and the transcendental Logic, where, after the exposition of the mere form of perception, he simply dismisses its content, all that is empirically apprehended, with the phrase “It is given,” and does not ask how it came about, whether with or without understanding; but, with one spring, passes over to abstract thought; and not even to thought in general, but at once to certain forms of thought, and does not say a word about what thought is, what the concept is, what is the relation of abstract and discursive to concrete and intuitive, what is the difference between the knowledge of men and that of brutes, and what is reason.
Yet it was just this distinction between abstract knowledge and knowledge of perception, entirely overlooked by Kant, which the ancients denoted by φαινομενα and νοουμενα,7 and whose opposition and incommensurability occupied them so much in the philosophemes of the Eleatics, in Plato's doctrine of Ideas, in the dialectic of the Megarics, and later the Scholastics in the controversy between Nominalism and Realism, the seed of which, so late in developing, was already contained in the opposite mental tendencies of Plato and Aristotle. But Kant, who, in an inexcusable manner, entirely neglected the thing to denote which the words φαινομενα and νοουμενα had already been taken, took possession of the words, as if they were still unappropriated, in order to denote by them his thing in itself and his phenomenon.
Since I have been obliged to reject Kant's doctrine of the categories, just as he rejected that of Aristotle, I wish here to indicate as a suggestion a third way of reaching what is aimed at. What both Kant and Aristotle sought for under the name of the categories were the most general conceptions under which all things, however different, must be subsumed, and through which therefore everything that exists would ultimately be thought. Just on this account Kant conceived them as the forms of all thought.
Grammar is related to logic as clothes to the body. Should not, therefore, these primary conceptions, the ground-bass of the reason, which is the foundation of all special thought, without whose application, therefore, no thought can take place, ultimately lie in those conceptions which just on account of their exceeding generality (transcendentalism) have their expression not in single words, but in whole classes of words, because one of them is thought along with every word whatever it may be, whose designation would therefore have to be looked for, not in the lexicon but in the grammar? In fact, should they not be those distinctions of conceptions on account of which the word which expresses them is either a substantive or an adjective, a verb or an adverb, a pronoun, a preposition, or some other particle – in short, the parts of speech? For undoubtedly these denote the forms which all thought primarily assumes, and in which it directly moves; accordingly they are the essential forms of speech, the fundamental constituent elements of every language, so that we cannot imagine any language which would not consist of at least substantives, adjectives, and verbs. These fundamental forms would then have subordinated to them those forms of thought which are expressed through their inflections, that is, through declension and conjugation, and it is unessential to the chief concern whether in denoting them we call in the assistance of the article and the pronoun. We will examine the thing, however, somewhat more closely, and ask the question anew: What are the forms of thought?
(1.) Thought consists throughout of judging; judgments are the threads of its whole web, for without making use of a verb our thought does not move, and as often as we use a verb we judge.
(2.) Every judgment consists in the recognition of the relation between subject and predicate, which it separates or unites with various restrictions. It unites them from the recognition of the actual identity of the two, which can only happen in the case of synonyms; then in the recognition that the one is always thought along with the other, though the converse does not hold – in the universal affirmative proposition; up to the recognition that the one is sometimes thought along with the other, in the particular affirmative proposition. The negative propositions take the opposite course. Accordingly in every judgment the subject, the predicate, and the copula, the latter affirmative or negative, must be to be found; even although each of these is not denoted by a word of its own, as is however generally the case. The predicate and the copula are often denoted by one word, as “Caius ages;” sometimes one word denotes all three, as concurritur, i. e., “the armies engage.” From this it is evident that the forms of thought are not to be sought for precisely and directly in words, nor even in the parts of speech, for even in the same language the same judgment may be expressed in different words, and indeed in different parts of speech, yet the thought remains the same, and consequently also its form; for the thought could not be the same if the form of thought itself were different. But with the same thought and the same form of thought the form of words may very well be different, for it is merely the outward clothing of the thought, which, on the other hand, is inseparable from its form. Thus grammar only explains the clothing of the forms of thought. The parts of speech can therefore be deduced from the original forms of thought themselves which are independent of all language; their work is to express these forms of thought in all their modifications. They are the instrument and the clothing of the forms of thought, and must be accurately adapted to the structure of the latter, so that it may be recognised in them.
(3.) These real, unalterable, original forms of thought are certainly those of Kant's logical table of judgments; only that in this table are to be found blind windows for the sake of symmetry and the table of the categories; these must all be omitted, and also a false arrangement. Thus: —
(a.) Quality: affirmation and negation, i. e., combination and separation of concepts: two forms. It depends on the copula.
(b.) Quantity: the subject-concept is taken either in whole or in part: totality or multiplicity. To the first belong also