PROLEGOMENA TOANYFUTUREMETAPHYSICS 817
understanding, which are however undetermined with respect to any object. I finally
referred these functions of judging to objects in general, or rather to the condition of
determining judgments as objectively valid; and so there arose the pure concepts of the
understanding, concerning which I could make certain that these, and this exact number
only, constitute our whole knowledge of things by pure understanding. I was justified in
calling them by their old name “categories,” while I reserved for myself the liberty of
adding, under the title of “predicables,” a complete list of all the concepts deducible
from them by combinations, whether among themselves, or with the pure form of the
appearance, that is, space or time, or with its matter, so far as it is not yet empirically
determined (namely, the object of sensation in general), as soon as a system of tran-
scendental philosophy should be completed, with the construction of which I was
engaged in the Critique of Pure Reasonitself.
Now the essential point in this system of categories, which distinguishes it from
the old rhapsody which proceeded without any principle and for which alone it
deserves to be considered as philosophy, consists in this: that, by means of it, the true
significance of the pure concepts of the understanding and the condition of their use
could be precisely determined. For here it became obvious that they are themselves
nothing but logical functions, and as such do not produce the least concept of an
object, but require sensuous intuition as a basis. These concepts, therefore, only serve
to determine empirical judgments (which are otherwise undetermined and indifferent
as regards all functions of judging) with respect to the functions of judging, thereby
procuring them universal validity and, by means of them, making judgments of experi-
ence in general possible.
Such an insight into the nature of the categories, which limits them at the same
time to use merely in experience, never occurred either to their first author or to any
of his successors; but without this insight (which immediately depends upon their
derivation or deduction), they are quite useless and only a miserable list of names,
without explanation or rule for their use. Had the ancients ever conceived such a
notion, doubtless the whole study of pure rational knowledge, which under the name
of metaphysics has for centuries spoiled many a sound mind, would have reached us
in quite another shape and would have enlightened the human understanding, instead
of actually exhausting it in obscure and vain speculations and rendering it unfit for
true science.
This system of categories makes all treatment of every object of pure reason itself
systematic, and affords a direction or clue how and through what points of inquiry every
metaphysical consideration must proceed in order to be complete; for it exhausts all the
possible functions of the understanding, among which every concept must be classed.
In like manner the table of principles has been formulated, the completeness of which
we can only vouch for by the system of the categories. Even in the division of the
concepts,* which must go beyond the physical application of the understanding, it is
always the very same clue, which, as it must always be determined a prioriby the same
fixed points of the human understanding, always forms a closed circle. There is no
doubt that the object of a pure concept, either of the understanding or of reason, so far
as it is to be estimated philosophically and on a prioriprinciples, can in this way be
completely known. I could not therefore omit to make use of this clue with regard to
one of the most abstract ontological divisions, namely, the various distinctions of the
325*Cf. the tables in the Critique of Pure Reasonin the chapters on “The Paralogisms of Pure Reason”
and the “System of Cosmological Ideas.”
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