820 IMMANUELKANT
the transcendent cognitions of reason cannot either, as Ideas, appear in experience or, as
propositions, ever be confirmed or refuted by it. Hence whatever errors may slip in
unawares can only be discovered by pure reason itself—a discovery of much difficulty,
because this very reason naturally becomes dialectical by means of its Ideas; and this
unavoidable illusion cannot be limited by any objective and dogmatic researches into
things, but only by a subjective investigation of reason itself as a source of ideas.
§ 43. In the Critique of Pure Reasonit was always my greatest care to endeavor,
not only carefully to distinguish the several species of knowledge, but to derive concepts
belonging to each one of them from their common source. I did this in order that, by
knowing whence they originated, I might determine their use with safety and also have
the unanticipated but invaluable advantage of knowing, according to principles, the
completeness of my enumeration, classification, and specification of concepts a priori.
Without this, metaphysics is mere rhapsody, in which no one knows whether he has
enough or whether and where something is still wanting. We can indeed have this
advantage only in pure philosophy, but of this philosophy it constitutes the very essence.
As I had found the origin of the categories in the four logical forms of all the judg-
ments of the understanding, it was quite natural to seek the origin of the Ideas in the three
forms of syllogisms. For as soon as these pure concepts of reason (the transcendental
Ideas) are given, they could hardly, except they be held innate, be found anywhere else
than in the same activity of reason, which, so far as it regards mere form, constitutes the
logical element of syllogisms; but, so far as it represents judgments of the understanding
as determined a prioriwith respect to one or another form, constitutes transcendental
concepts of pure reason.
The formal distinction of syllogisms renders necessary their division into
categorical, hypothetical, and disjunctive. The concepts of reason founded on them
contain therefore, first, the Idea of the complete subject (the substantial); secondly, the
Idea of the complete series of conditions; thirdly, the determination of all concepts in
the Idea of a complete complex of that which is possible.* The first idea is psycho-
logical, the second cosmological, the third theological; and, as all three give occasion
to dialectic, yet each in its own way, the division of the whole dialectic of pure reason
into its paralogism, its antinomy, and its Ideal was arranged accordingly. Through this
deduction we may feel assured that all the claims of pure reason are completely repre-
sented and that none can be wanting, because the faculty of reason itself, whence they
all take their origin, is thereby completely surveyed.
§ 44. In these general considerations it is also remarkable that the Ideas of reason,
unlike the categories, are of no service to the use of our understanding in experience,
but quite dispensable, and become even an impediment to the maxims of a rational
knowledge of nature. Yet in another aspect still to be determined they are necessary.
Whether the soul is or is not a simple substance is of no consequence to us in the expla-
nation of its phenomena. For we cannot render the concept of a simple being sensuous
and thus concretely intelligible by any possible experience. The concept is therefore330
*In disjunctive judgments, we consider all possibility as divided in respect to a particular concept. By
the ontological principle of the universal determination of a thing in general, I understand the principle that
either the one or the other of all possible contradictory predicates must be assigned to any object. This is, at
the same time, the principle of all disjunctive judgments, constituting the foundation of a complete whole of
possibility, and in it the possibility of every object in general is considered as determined. This may serve as
a slight explanation of the above propositions: that the activity of reason in disjunctive syllogisms is formally
the same as that by which it fashions the idea of a complete whole of all reality, containing in itself that which
is positive in all pairs of contradictory predicates.331