But, with the exception of space, there is no representation, subjective and ref erring to something external to us, which could be called objective a priori.For there are no other subjective representations from which we can deduce synthetical propositions a priori, as we can from the intuition of space.(See SS 3.)Therefore, to speak accurately, no ideality whatever belongs to these, although they agree in this respect with the representation of space, that they belong merely to the subjective nature of the mode of sensuous perception; such a mode, for example, as that of sight, of hearing, and of feeling, by means of the sensations of colour, sound, and heat, but which, because they are only sensations and not intuitions, do not of themselves give us the cognition of any object, least of all, an a priori cognition.My purpose, in the above remark, is merely this: to guard any one against illustrating the asserted ideality of space by examples quite insufficient, for example, by colour, taste, etc.; for these must be contemplated not as properties of things, but only as changes in the subject, changes which may be different in different men.For, in such a case, that which is originally a mere phenomenon, a rose, for example, is taken by the empirical understanding for a thing in itself, though to every different eye, in respect of its colour, it may appear different.On the contrary, the transcendental conception of phenomena in space is a critical admonition, that, in general, nothing which is intuited in space is a thing in itself, and that space is not a form which belongs as a property to things; but that objects are quite unknown to us in themselves, and what we call outward objects, are nothing else but mere representations of our sensibility, whose form is space, but whose real correlate, the thing in itself, is not known by means of these representations, nor ever can be, but respecting which, in experience, no inquiry is ever made.
SECTION II.Of Time.
SS 5 Metaphysical Exposition of this Conception.
1.Time is not an empirical conception.For neither coexistence nor succession would be perceived by us, if the representation of time did not exist as a foundation a priori.Without this presupposition we could not represent to ourselves that things exist together at one and the same time, or at different times, that is, contemporaneously, or in succession.
2.Time is a necessary representation, lying at the foundation of all our intuitions.With regard to phenomena in general, we cannot think away time from them, and represent them to ourselves as out of and unconnected with time, but we can quite well represent to ourselves time void of phenomena.Time is therefore given a priori.In it alone is all reality of phenomena possible.These may all be annihilated in thought, but time itself, as the universal condition of their possibility, cannot be so annulled.
3.On this necessity a priori is also founded the possibility of apodeictic principles of the relations of time, or axioms of time in general, such as: "Time has only one dimension," "Different times are not coexistent but successive" (as different spaces are not successive but coexistent).These principles cannot be derived from experience, for it would give neither strict universality, nor apodeictic certainty.We should only be able to say, "so common experience teaches us," but not "it must be so." They are valid as rules, through which, in general, experience is possible; and they instruct us respecting experience, and not by means of it.
4.Time is not a discursive, or as it is called, general conception, but a pure form of the sensuous intuition.Different times are merely parts of one and the same time.But the representation which can only be given by a single object is an intuition.Besides, the proposition that different times cannot be coexistent could not be derived from a general conception.For this proposition is synthetical, and therefore cannot spring out of conceptions alone.
It is therefore contained immediately in the intuition and representation of time.
5.The infinity of time signifies nothing more than that every determined quantity of time is possible only through limitations of one time lying at the foundation.Consequently, the original representation, time, must be given as unlimited.But as the determinate representation of the parts of time and of every quantity of an object can only be obtained by limitation, the complete representation of time must not be furnished by means of conceptions, for these contain only partial representations.
Conceptions, on the contrary, must have immediate intuition for their basis.
SS 6 Transcendental Exposition of the Conception of Time.
I may here refer to what is said above (SS 5, 3), where, for or sake of brevity, I have placed under the head of metaphysical exposition, that which is properly transcendental.Here I shall add that the conception of change, and with it the conception of motion, as change of place, is possible only through and in the representation of time; that if this representation were not an intuition (internal) a priori, no conception, of whatever kind, could render comprehensible the possibility of change, in other words, of a conjunction of contradictorily opposed predicates in one and the same object, for example, the presence of a thing in a place and the non-presence of the same thing in the same place.It is only in time that it is possible to meet with two contradictorily opposed determinations in one thing, that is, after each other.thus our conception of time explains the possibility of so much synthetical knowledge a priori, as is exhibited in the general doctrine of motion, which is not a little fruitful.
SS 7 Conclusions from the above Conceptions.