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

Thinking, taken by itself, is a logical function only, and therefore pure spontaneity, in connecting the manifold of a merely possible intuition. It does not represent the subject of consciousness, as phenomenal, for the simple reason, that it takes no account whatsoever of the manner of intuition, whether it be sensuous or intellectual. I do not thereby represent myself to myself, either as I am, or as I appear to myself, but I only conceive of ni) self,

8o6 Supplement XXVII as of any other object, without taking account of the manner of intuition. If thereby I represent myself as the subject of my thoughts, or as the ground of thinking, these modes of representation are not the categories of substance or cause, because these are functions of thought (judgment) as apphed already to our sensuous intuition, such sensuous intuition being necessary, if I wish to know myself. But I only wish to become conscious of myself as thinking, and as I take no account of what my own self may be as a phenomenon, it is quite possible that it might be a phenomenon only to me, who thinks, but not to me, so far as I am thinking. In the consciousness of myself in mere thinking I am the substance itself^ but of that substance nothing is thus given me for thinking.

The proposition I think, if it means / exist thinking, is not merely logical function, but determines the subject (which then is at the same time object) with reference to its existence, and is impossible without the internal sense, the intuition of which always supplies the object, not as a thing by itself, but as phenomenal only. Here, therefore, we have no longer mere spontaneity of thinking, but also receptivity of intuition, that is, the thinking of myself applied to the empirical intuition of the same subject. In that empirical intuition the thinking self would have to look for the conditions under which its logical functions can be employed as categories of substance, cause, etc., in order not only to distinguish itself as an object by itself, through the Ego, but to determine the mode of its existence also, that is, to know itself as a noumenon. This, as we know, is impossible, because the internal empirical intuition is sensuous, and supplies us with phenomenal data only, which furnish nothing to the object of the pure consciousness for the knowledge of its own separate existence, but can serve the purpose of experience only.

Supposing, however, that we should hereafter discover, not indeed in experience, but in certain (not only logical rules, but) a priori established laws of pure reason, concerning our existence, some ground for admitting ourselves, entirely a priori, as determining and ruling our own existence, there would then be a spontaneity by which our reality would be determinable without the

Supplement XXVII 807

conditions of empirical intuition, and we should then perceive that in the consciousness of our existing there is contained a priori something which may serve to determine with respect to some inner faculty, our existence, which otherwise can be determined sensuously only with reference to an intelligible, though, of course, an ideal world only.