(a) The Theoretical Faculty. Cognition qua cognition. The specific ground of the categories is declared by the Critical system to lie in the primary identity of the 'I' in thought what Kant calls the 'transcendental unity of self−consciousness'. The impressions from feeling and perception are, if we look to their contents, a multiplicity or miscellany of elements: and the multiplicity is equally conspicuous in their form. For sense is marked by a mutual exclusion of members; and that under two aspects, namely space and time, which, being the forms, that is to say, the universal type of perception, are themselves a priori. This congeries, afforded by sensation and perception, must however be reduced to an identity or primary synthesis. To accomplish this the 'I' brings it in relation to itself and unites it there in one consciousness which Kant calls 'pure apperception'. The specific modes in which the Ego refers to itself the multiplicity of sense are the pure concepts of the understanding, the Categories.
Kant, it is well known, did not put himself to much trouble in discovering the categories. 'I', the unity of selfconsciousness, being quite abstract and completely indeterminate, the question arises, how are we to get at the specialised forms of the 'I', the categories? Fortunately, the common logic offers to our hand an empirical classification of the kinds of judgment. Now, to judge is the same as to think of a determinate object. Hence the various modes of judgment, as enumerated to our hand, provide us with the several categories of thought. To the philosophy of Fichte belongs the great merit of having called attention to the need of exhibiting the necessity of these categories and giving a genuine deduction of them. Fichte ought to have produced at least one effect on the method of logic. One might have expected that the general laws of thought, the usual stock−in−trade of logicians, or the classification of notions, judgments, and syllogisms, would be no longer taken merely from observation and so only empirically treated, but be deduced from thought itself. If thought is to be capable of proving anything at all, if logic must insist upon the necessity of proofs, and if it proposes to teach the theory of demonstration, its first care should be to give a reason for its own subject.
(1) Kant therefore holds that the categories have their source in the 'Ego' and that the 'Ego' consequently supplies the characteristics of universality and necessity. If we observe what we have before us primarily, we may describe it as a congeries or diversity: and in the categories we find the simple points or units, to which this congeries is made to converge. The world of sense is a scene of mutual exclusion: its being is outside itself. That is the fundamental feature of the sensible. 'Now' has no meaning except in reference to a before and a hereafter. Red, in the same way, only subsists by being opposed to yellow and blue. Now this other thing is outside the sensible; which latter is, only in so far as it is not the other, and only in so far as that other is. But thought, or the 'Ego', occupies a position the very reverse of the sensible, with its mutual exclusions, and its being outside itself. The 'I' is the primary identity −− at one with itself and all at home in itself. The word 'I' expresses the mere act of bringing−to−bear−upon−self: and whatever is placed in this unit or focus is affected by it and transformed into it. The 'I' is as it were the crucible and the fire which consumes the loose
plurality of sense and reduces it to unity. This is the process which Kant calls pure apperception in distinction from the common apperception, to which the plurality it receives is a plurality still; whereas pure apperception is rather an act by which the 'I' makes the materials 'mine'.
This view has at least the merit of giving a correct expression to the nature of all consciousness. The tendency of all man's endeavours is to understand the world, to appropriate and subdue it to himself: and to this end the positive reality of the world must be as it were crushed and pounded, in other words, idealised. At the same time we must note that it is not the mere act of our personal self−consciousness which introduces an absolute unity into the variety of sense. Rather, this identity is itself the absolute. The absolute is, as it were, so kind as to leave individual things to their own enjoyment, and it again drives them back to the absolute unity.
(2) Expressions like 'transcendental unity of self−consciousness' have an ugly look about them, and suggest a monster in the background: but their meaning is not so abstruse as it looks. Kant's meaning of transcendental may be gathered by the way he distinguishes it from transcendent. The transcendent may be said to be what steps out beyond the categories of the understanding: a sense in which the term is first employed in mathematics. Thus in geometry you are told to conceive the circumference of a circle as formed of an infinite number of infinitely small straight lines. In other words, characteristics which the understanding holds to be totally different, the straight line and the curve, are expressly invested with identity. Another transcendent of the same kind is the self−consciousness which is identical with itself and infinite in itself, as distinguished from the ordinary consciousness which derives its form and tone from finite materials. That unity of self−consciousness, however, Kant called transcendental only; and he meant thereby that the unity was only in our minds and did not attach to the objects apart from our knowledge of them.
(3) To regard the categories as subjective only, i.e. as a part of ourselves, must seem very odd to the natural mind; and no doubt there is something queer about it. It is quite true however that the categories are not contained in the sensation as it is given us. When, for instance, we look at a piece of sugar, we find it is hard, white, sweet, etc. All these properties we say are united in one object. Now it is this unity that is not found in the sensation. The same thing happens if we conceive two events to stand in the relation of cause and effect. The senses only inform us of the two several occurrences which follow each other in time. But that the one is cause, the other effect −− in other words, the causal nexus between the two −− is not perceived by sense; it is only evident to thought. Still, though the categories, such as unity, or cause and effect, are strictly the property of thought, it by no means follows that they must be ours merely and not also characteristics of the objects. Kant however confines them to the subject−mind, and his philosophy may be styled subjective idealism: for he holds that both the form and the matter of knowledge are supplied by the Ego −− or knowing subject −− the form by our intellectual, the matter by our sentient ego.
So far as regards the content of this subjective idealism, not a word need be wasted. It might perhaps at first sight be imagined, that objects would lose their reality when their unity was transferred to the subject. But neither we nor the objects would have anything to gain by the mere fact that they possessed being.
The main point is not, that they are, but what they are, and whether or not their content is true. It does no good to the things to say merely that they have being. What has being, will also cease to be when time creeps over it. It might also be alleged that subjective idealism tended to promote self−conceit. But surely if a man's world be the sum of his sensible perceptions, he has no reason to be vain of such a world. Laying aside therefore as unimportant this distinction between subjective and objective, we are chiefly interested in knowing what a thing is: i.e. its content, which is no more objective than it is subjective. If mere existence be enough to make objectivity, even a crime is objective: but it is an existence which is nullity at the core, as is definitely made apparent when the day of punishment comes.