The principle of the Synthetical Unity of Apperception is the
highest principle of all exercise of the Understanding.
SS 13.
The supreme principle of the possibility of all intuition in
relation to sensibility was, according to our transcendental
æsthetic, that all the manifold in intuition be subject to the formal
conditions of space and time. The supreme principle of the possibility
of it in relation to the understanding is that all the manifold in
it be subject to conditions of the originally synthetical Unity or
Apperception.* To the former of these two principles are subject all
the various representations of intuition, in so far as they are
given to us; to the latter, in so far as they must be capable of
conjunction in one consciousness; for without this nothing can be
thought or cognized, because the given representations would not
have in common the act Of the apperception I think; and therefore
could not be connected in one self—consciousness.
[*]
Space and time, and all portions thereof, are Intuitions;
consequently are, with a manifold for their content, single
representations. (See the Transcendental Aesthetic.) Consequently,
they are not pure conceptions, by means of which the same
consciousness is found in a great number of representations; but, on
the contrary, they are many representations contained in one, the
consciousness of which is, so to speak, compounded. The unity of
consciousness is nevertheless synthetical and, therefore, primitive.
From this peculiar character of consciousness follow many important
consequences. (See SS 21.)
Understanding is, to speak generally, the faculty of Cognitions.
These consist in the determined relation of given representation to an
object. But an object is that, in the conception of which the manifold
in a given intuition is united. Now all union of representations
requires unity of consciousness in the synthesis of them.
Consequently, it is the unity of consciousness alone that
constitutes the possibility of representations relating to an
object, and therefore of their objective validity, and of their
becoming cognitions, and consequently,
the possibility of the
existence of the understanding itself.
The first pure cognition of understanding, then, upon which is
founded all its other exercise, and which is at the same time
perfectly independent of all conditions of mere sensuous intuition, is
the principle of the original synthetical unity of apperception.
Thus the mere form of external sensuous intuition, namely, space,
affords us, per se, no cognition; it merely contributes the manifold
in a priori intuition to a possible cognition. But, in order to
cognize something in space (for example, a line), I must draw it,
and thus produce synthetically a determined conjunction of the given
manifold, so that the unity of this act is at the same time the
unity of consciousness (in the conception of a line), and by this
means alone is an object (a determinate space) cognized. The
synthetical unity of consciousness is, therefore, an objective
condition of all cognition, which I do not merely require in order
to cognize an object, but to which every intuition must necessarily be
subject, in order to become an object for me; because in any other
way, and without this synthesis, the manifold in intuition could not
be united in one consciousness.
This proposition is, as already said, itself analytical, although it
constitutes the synthetical unity, the condition of all thought; for
it states nothing more than that all my representations in any given
intuition must be subject to the condition which alone enables me to
connect them, as my representation with the identical self, and so
to unite them synthetically in one apperception, by means of the
general expression, I think.
But this principle is not to be regarded as a principle for every
possible understanding, but only for the understanding by means of
whose pure apperception in the thought I am, no manifold content is
given. The understanding or mind which contained the manifold in
intuition, in and through the act itself of its own
self—consciousness, in other words, an understanding by and in the
representation of which the objects of the representation should at
the same time exist, would not require a special act of synthesis of
the manifold as the condition of the unity of its consciousness, an
act of which the human understanding, which thinks only and cannot
intuite, has absolute need. But this principle is the first
principle of all the operations of our understanding, so that we
cannot form the least conception of any other possible
understanding, either of one such as should be itself intuition, or
possess a sensuous intuition, but with forms different from those of
space and time.