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

The foregoing proposition is of the greatest importance, for it determines the limits of the employment of the pure concepts of the understanding with reference to objects, in the same manner as the transcendental Esthetic determined the limits of the employment of the pure form of our sensuous intuition. Space and time are conditions of the possibility of how objects can be given to us, so far only as objects of the senses, therefore of experience, are concerned. Beyond these limits they represent nothing, for they belong only to the senses, and have no reahty beyond them. Pure concepts of the understanding are free from

756 Supplement XIV this limitation, and extend to objects of intuition in general, whether that intuition be like our own or not, if only it is sensuous and not intellectual. This further extension, however, of concepts beyond our sensuous intuition, is of no avail to us ; for they are in that case empty concepts of objects, and the concepts do not even enable us to say, whether such objects be possible or not. They are mere forms of thought, without objective reality : because we have no intuition at hand to which the synthetical unity of apperception, which is contained in the concepts alone, could be appUed, so that they might determine an object. Nothing can give them sense and meaning, except our sensuous and empirical intuition.

If, therefore, we assume an object of a non-sensuous intuition as given, we may, no doubt, determine it through all the predicates, which follow from the supposition that nothing belonging to sensuous intuition belongs to it, that, therefore, it is not extended, or not in space, that its duration is not time, that no change (succession of determinations in time) is to be met in it, etc. But we can hardly call this knowledge, if we only indicate how the intuition of an object is not, without being able to say what is contained in it, for, in that case, I have not represented the possibility of an object, corresponding to my pure concept of the understanding, because I could give no intuition corresponding to it, but could only say that our intuition did not apply to it. But what is the most important is this, that not even a single category could be applied to such a thing ; as, for instance, the concept of substance, that is, of something that can exist as a subject only, but never as a mere predicate. For I do not know whether there can be anything corresponding to such a determination of thought, unless empirical intuition supplies the case for its application. Of this more hereafter.

§ 24

Of the Application of the Categories to Objects of the Senses in

General

The pure concepts of the understanding refer, through the mere understanding, to objects of intuition, whether it be our own, or any

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other, if only sensuous intuition, but they are, for that very reason, n\txt forfus of thought, by which no definite object can be known. The synthesis, or connection of the manifold in them, referred only to the unity of apperception, and became thus the ground of the possibility of knowledge a priori, so far as it rests on the understanding, and is therefore not only transcendental, but also purely intellectual. Now as there exists in us a certain form of sensuous intuition a prioii, which rests on the receptivity of the faculty of representation (sensibility), the understanding, as spontaneity, is able to determine the internal sense through the manifold of given representations, according to the synthetical unity of apperception, and can thus think synthetical unity of the apperception of the manifold oi sensuous intuitioji a priori, as the condition to which all objects of our (human) intuition must necessarily be subject. Thus the categories, though pure forms of thought, receive objective reality, that is, application to objects which can be given to us in intuition, but as phenomena only ; for it is with reference to them alone that we are capable of intuition a priori.

This synthesis of the manifold of sensuous intuition, which is possible and necessary a priori, may be called figurative {synthesis speciosd), in order to distinguish it from that which is thought in the mere category, with reference to the manifold of an intuition in general, and is called intellectual synthesis (synthesis intellectualis). Both are transcendental, not only because they themselves are carried out a priori, but because they establish also the possibility of other knowledge a priori.