By Immanuel Kant.
THE A PRIORI GROUNDS OF THE POSSIBILITY OF
EXPERIENCE
THAT a concept, although itself neither contained in the concept of possible experience nor consisting of elements of a possible experience, should be produced completely a priori and should relate to an object, is altogether contradictory and impossible. For it would then have no content, since no intuition corresponds to it; and intuitions in general, through which objects can be given to us, constitute the field, the whole object, of possible experience. An a priori concept which did not relate to experience would be only the logical form of a concept, not the concept itself through which something is thought.
Pure a priori concepts, if such exist, cannot indeed contain anything empirical; yet, none the less, they can serve solely as a priori conditions of a possible experience. Upon this ground alone can their objective reality rest. If, therefore, we seek to discover how pure concepts of understanding are possible, we must enquire what are the a priori conditions upon which the possibility of experience A96 rests, and which remain as its underlying grounds when everything empirical is abstracted from appearances. A concept which universally and adequately expresses such a normal and P 130
objective condition of experience would be entitled a pure concept of understanding. Certainly, once I am in possession of pure concepts of understanding, I can think objects which may be impossible, or which, though perhaps in themselves possible, cannot be given in any experience. For in the connecting of these concepts something may be omitted which yet necessarily belongs to the condition of a possible experience (as in the concept of a spirit). Or, it may be, pure concepts are extended further than experience can follow (as with the concept of God). But the elements of all modes of a priori knowledge, even of capricious and incongruous fictions, though they cannot, indeed, be derived from experience, since in that case they would not be knowledge a priori, must none the less always contain the pure a priori conditions of a possible experience and of an empirical object. Otherwise nothing would be thought through them, and they themselves, being without data, could never arise even in thought.