Immanuel Kant's Critique of Pure Reason — trans. F. Max Müller

We are met here by an illusion which is difficult to avoid. The categories do not depend in their origin on sensibiUty, like the forms of intuition, space, and time, and seem, therefore, to admit of an appHcation extending beyond the objects of the senses. But, on the other side, they are nothing but /^r;;^i- of thought, containing the logical faculty only of comprehending a priori in one consciousness the manifold that is given in intuition, and they would therefore, if we take away the only intuition which is possible to us, have still less significance than those pure sensuous forms by which at least an object is given, while a peculiar mode of our understanding of connecting the manifold (unless that intuition, in which the manifold alone can be given, is added), signifies nothing at all.

Nevertheless, it seems to follow from our very concept, if we call certain objects, as phenomena, beings of the senses, by distinguishing between the mode of our intuition and the nature of those objects by themselves, that we may take either the same objects in that latter capacity, though they cannot as such come before our intuition, or other possible things, which are not objects of our senses at all, and place them, as objects thought only by the understanding, in opposition to the former, calling them beings of the understanding {noumena). The question then arises, whether our pure concepts of the understanding do not possess some significance with regard to these so-called beings of the understanding, and constitute a mode of knowing them ?

At the very outset, however, we meet with an ambiguity which may cause great misapprehension. The understanding, by calling

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an object in one aspect a phenomenon only, makes to itself, apart from that aspect, another representation of an object by itself, and imagines itself able to form concepts of such an object. As, then, the understanding yields no other concepts but the categories, it supposes that the object in the latter aspect can be thought at least by those pure concepts of the understanding, and is thus induced to take the entirely indefinite concept of a being of the understanding, as of a something in general outside our sensibility, as a definite concept of a being which we might know to a certain extent through the understanding.

If by noumenon we mean a thing so far as it is not an object of our sensuous intuition, and make abstraction of our mode of intuition, it may be called a noumenon in a negative sense. If, however, we mean by it an object of a non-sensuous intuition, we admit thereby a peculiar mode of intuition, namely, the intellectual, which, however, is not our own, nor one of which we can understand even the possibihty. This would be the noumenon in 2^ positive sense.

The doctrine of sensibiHty is at the same time the doctrine of noumena in their negative sense ; that is, of things which the understanding must think without reference to our mode of intuition, and therefore, not as phenomena only, but as things by themselves, but to which, after it has thus separated them, the understanding knows that it must not, in this new aspect, apply its categories ; because these categories have significance only with reference to the unity of intuitions in space and time, and can therefore a priori determine that unity, on account of the mere ideality of space and time only, by means of general connecting concepts. Where that unity in time cannot be found, i.e. in the noumenon, the whole use, nay, the whole significance of categories comes to an end : because even the possibility of things that should correspond to the categories, would be uninteUigible. On this point I may refer the reader to what I have said at the very beginning of the general note to the previous chapter (Suppl. XXII). The possibility of a thing can never be proved from the fact that its concept is not self-contradictory, but only by being authenticated by an intuition corresponding to it.

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Supplement XXIV