ar principles involved being
attributed to the imagination; and so, when he comes to consider the
part played in knowledge by the understanding, he is apt to ignore the
need of particular principles.[88] Hence, Kant's proof that the
categories are the principles of synthesis can at best be taken only
as a proof that the categories, though not sufficient for the
synthesis, are involved in it.

[85] Cf. p. 177, note 2, and p. 185.

[86] Cf. pp. 215-17.

[87] Cf. pp. 181-2.

[88] Cf. p. 217.

The proof runs thus:

"I could never satisfy myself with the definition which logicians
give of a judgement in general. It is, according to them, the
representation of a relation between two conceptions...."

"But if I examine more closely the relation of given
representations[89] in every judgement, and distinguish it, as
belonging to the understanding, from their relation according to the
laws of the reproductive imagination (which has only subjective
validity), I find that a judgement is nothing but the mode of bringing
given representations under the _objective_ unity of apperception.
This is what is intended by the term of relation 'is' in judgements,
which is meant to distinguish the objective unity of given
representations from the subjective. For this term indicates the
relation of these representations to the original apperception, and
also their _necessary unity_, even though the judgement itself is
empirical, and therefore contingent, e. g. 'Bodies are heavy.' By this
I do not mean that these representations _necessarily_ belong _to each
other_ in empirical perception, but that they belong to each other _by
means of the necessary unity_ of apperception in the synthesis of
perceptions, that is, according to principles of the objective
determination of all our representations, in so far as knowledge can
arise from them, these principles being all derived from the principle
of the transcendental unity of apperception. In this way alone can
there arise from this relation _a judgement_, that is, a relation
which is _objectively valid_, and is adequately distinguished from the
relation of the very same representations which would be only
subjectively valid, e. g. according to laws of association. According
to these laws, I could only say, 'If I carry a body, I feel an
impression of weight', but not 'It, the body, _is_ heavy'; for this is
tantamount to saying, 'These two representations are connected in t