"All-Crushing" Critic of Metaphysics 245peculiar character that it [the principle] makes possible the very experi¬
ence which is its own ground of proof" ^737=6765), and this implies not
only that experience would not be possible without these categories, but
also that we cannot establish the objective validity of the categories with¬
out relating them to possible experience, which, per se, is "something en¬
tirely contingent."
Before moving on to the ideas, Kant discusses the universal principles of
knowledge, which are based on the categories (Analytic of Principles). The
so-called Schematism of the Pure Concepts of the Understanding, which
introduces this part of the Critique, is easily its second-most-difficult chap¬
ter (after the Transcendental Deduction). In the Schematism chapter, Kant
argues that a merely logical discussion of the categories is insufficient.
Such a discussion abstracts from the fact that we always employ the cate¬
gories in thinking and thus in time. We must therefore explain how these
pure concepts enter into our thinking. "We must be able to show how pure
concepts can be applicable to appearances" (Ai38=Bi77). Kant thinks
that "obviously there must be some third thing, which is homogeneous
on the one hand with the category, and on the other hand with the ap¬
pearance.. ." (Ai33=Bi77). These are what he calls "the transcendental
schema" or the schemata of the categories. These schemata are rules that
relate the pure to what is given through the senses. There are accordingly
schemata for quantity, quality, relation, and modality. What all these rules
have in common is that they are given in time. Indeed, the "schemata
are ... nothing but a priori determinations of time in accordance with
rules" (Ai45=Bi84). These rules concern the time-series (quantity), the
time-content (quality), the time-order (relation), and the scope of time
(modality).
The Principles of the Understanding are the judgments that the un¬
derstanding actually achieves, given these general schemata. Again, Kant
thinks that the table of the categories "is the natural and the safe guide"
(Ai48=Bi87). There are accordingly Axioms of Intuition (quantity),
Anticipations of Perception (quality), Analogies of Experience (relation),
and Postulates of Empirical Thought (modality). It is under these headings
that Kant tries to solve some of the most important problems of traditional
metaphysics and gives them a place in his system, along with the problems
of substance, causality, and reality in general.
Yet one of the most important consequences of this part of Kant's view
is drawn only later in the Dialectic, where he tries to show that the tradi¬
tional proofs about the nature of the soul, about the world as a whole, and