§ 40.
Pure mathematics and pure science of nature had no occasion for such a
deduction, as we have made of both, for their own safety and
certainty. For the former rests upon its own evidence; and the latter
(though sprung from pure sources of the understanding) upon experience
and its thorough confirmation. Physics cannot altogether refuse and
dispense with the testimony of the latter; because with all its
certainty, it can never, as philosophy, rival mathematics. Both
sciences therefore stood in need of this inquiry, not for themselves,
but for the sake of another science, metaphysics.
Metaphysics has to do not only with concepts of nature, which always
find their application in experience, but also with pure rational
concepts, which never can be given in any possible experience.
Consequently the objective reality of these concepts (viz., that they
are not mere chimeras), and the truth or falsity of metaphysical
assertions, cannot be discovered or confirmed by any experience. This
part of metaphysics however is precisely what constitutes its
essential end, to which the rest is only a means, and thus this
science is in need of such a deduction for its own sake. The third
question now proposed relates therefore as it were to the root and
essential difference of metaphysics, i.e., the occupation of Reason
with itself, and the supposed knowledge of objects arising immediately
from this incubation of its own concepts, without requiring, or indeed
being able to reach that knowledge through, experience.{28}
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{28} If we can say, that a science is actual at least in the ideas of
all men, as soon as it appears that the problems which lead to it are
proposed to everybody by the nature of human reason, and that
therefore many (though faulty) endeavors are unavoidably made in its
behalf, then we are bound to say that metaphysics is subjectively (and
indeed necessarily) actual, and therefore we justly ask, how is it
(objectively) possible.
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Without solving this problem reason never is justified. The empirical
use to which reason limits the pure understanding, does not fully
satisfy the proper destination of the latter. Every single experience
is only a part of the whole sphere of its domain, but the absolute
totality of all possible experience is itself not experience. Yet it
is a necessary [concrete] problem for reason, the mere representation
of which requires concepts quite different from the categories, whose
use is only immanent, or refers to experience, so far as it can be
given. Whereas the concepts of reason aim at the completeness, i.e.,
the collective unity of all possible experience, and thereby transcend
every given experience. Thus they become transcendent.
As the understanding stands in need of categories for experience,
reason contains in itself the source of ideas, by which I mean
necessary concepts, whose object cannot be given in any experience.
The latter are inherent in the nature of reason, as the former are in
that of the understanding. While the former carry with them an
illusion likely to mislead, the illusion of the latter is inevitable,
though it certainly can be kept from misleading us.
Since all illusion consists in holding the subjective ground of our
judgments to be objective, a self-knowledge of pure reason in its
transcendent (exaggerated) use is the sole preservative from the
aberrations into which reason falls when it mistakes its destination,
and refers that to the object transcendently, which only regards its
own subject and its guidance in all immanent use.
§ 41. The distinction of ideas, that is, of pure concepts of reason,
from categories, or pure concepts of the understanding, as cognitions
of a quite distinct species, origin and use, is so important a point
in founding a science which is to contain the system of all these a
priori cognitions, that without this distinction metaphysics is
absolutely impossible, or is at best a random, bungling attempt to
build a castle in the air without a knowledge of the materials or of
their fitness for any purpose. Had the Critique of Pure Reason done
nothing but first point out this distinction, it had thereby
contributed more to clear up our conception of, and to guide our
inquiry in, the field of metaphysics, than all the vain efforts which
have hitherto been made to satisfy the transcendent problems of pure
reason, without ever surmising that we were in quite another field
than that of the understanding, and hence classing concepts of the
understanding and those of reason together, as if they were of the
same kind.
§ 42. All pure cognitions of the understanding have this feature,
that their concepts present themselves in experience, and their
principles can be confirmed by it; whereas 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 dogmatical researches
into things, but by a subjective investigation of reason itself as a
source of ideas.
§ 43. In the Critique of Pure Reason it was always my greatest care
to endeavor not only carefully to distinguish the several species of
cognition, 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 the completeness of
my enumeration, classification and specification of concepts a priori,
and therefore according to principles. 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
functions of all the judgments of the understanding, it was quite
natural to seek the origin of the ideas in the three functions of the
syllogisms of reason. 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 the syllogisms of reason; but, so far as it represents
judgments of the understanding with respect to the one or to the other
form a priori, constitutes transcendental concepts of pure reason.
The formal distinction of syllogisms renders their division into
categorical, hypothetical, and disjunctive necessary. The concepts of
reason founded on them contained 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.{29} The first
idea is psychological, the second cosmological, the third theological,
and, as all three give occasion to Dialectics, yet each in its own
way, the division of the whole Dialects 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 represented, and that none can be wanting;
because the faculty of reason itself, whence they all take their
origin, is thereby completely surveyed.
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{29} 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 our conception 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 proposition: that
the activity of reason in disjunctive syllogisms is formally the same
as that by which it fashions the idea of a universal conception of all
reality, containing in itself that which is positive in all
contradictory predicates.
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§ 44. In these general considerations it is also remarkable that the
ideas of reason are unlike the categories, 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 cognition 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 explanation of its phenomena. For we cannot render the
notion of a simple being intelligible by any possible experience that
is sensuous or concrete. The notion is therefore quite void as regards
all hoped-for insight into the cause of phenomena, and cannot at all
serve as a principle of the explanation of that which internal or
external experience supplies. So the cosmological ideas of the
beginning of the world or of its eternity (a parte ante) cannot be of
any greater service to us for the explanation of any event in the
world itself. And finally we must, according to a right maxim of the
philosophy of nature, refrain from all explanations of the design of
nature, drawn from the will of a Supreme Being; because this would not
be natural philosophy, but an acknowledgment that we have come to the
end of it. The use of these ideas, therefore, is quite different from
that of those categories by which (and by the principles built upon
which) experience itself first becomes possible. But our laborious
analytics of the understanding would be superfluous if we had nothing
else in view than the mere cognition of nature as it can be given in
experience; for reason does its work, both in mathematics and in the
science of nature, quite safely and well without any of this subtle
deduction. Therefore our Critique of the Understanding combines with
the ideas of pure reason for a purpose which lies beyond the empirical
use of the understanding; but this we have above declared to be in
this aspect totally inadmissible, and without any object or meaning.
Yet there must be a harmony between that of the nature of reason and
that of the understanding, and the former must contribute to the
perfection of the latter, and cannot possibly upset it.
The solution of this question is as follows: Pure reason does not in
its ideas point to particular objects, which lie beyond the field of
experience, but only requires completeness of the use of the
understanding in the system of experience. But this completeness can
be a completeness of principles only, not of intuitions (i.e.,
concrete atsights or Anschauungen) and of objects. In order however to
represent the ideas definitely, reason conceives them after the
fashion of the cognition of an object. The cognition is as far as
these rules are concerned completely determined, but the object is
only an idea invented for the purpose of bringing the cognition of the
understanding as near as possible to the completeness represented by
that idea.
Prefatory Remark to the Dialectics of Pure Reason.
§ 45. We have above shown in §§ 33 and 34 that the purity of the
categories from all admixture of sensuous determinations may mislead
reason into extending their use, quite beyond all experience, to
things in themselves; though as these categories themselves find no
intuition which can give them meaning or sense in concreto, they, as
mere logical functions, can represent a thing in general, but not give
by themselves alone a determinate concept of anything. Such
hyperbolical objects are distinguised by the appellation of Noümena,
or pure beings of the understanding (or better, beings of thought),
such as, for example, "substance," but conceived without permanence in
time, or "cause," but not acting in time, etc. Here predicates, that
only serve to make the conformity-to-law of experience possible, are
applied to these concepts, and yet they are deprived of all the
conditions of intuition, on which alone experience is possible, and so
these concepts lose all significance.
There is no danger, however, of the understanding spontaneously making
an excursion so very wantonly beyond its own bounds into the field of
the mere creatures of thought, without being impelled by foreign laws.
But when reason, which cannot be fully satisfied with any empirical
use of the rules of the understanding, as being always conditioned,
requires a completion of this chain of conditions, then the
understanding is forced out of its sphere. And then it partly
represents objects of experience in a series so extended that no
experience can grasp, partly even (with a view to complete the series)
it seeks entirely beyond it noumena, to which it can attach that
chain, and so, having at last escaped from the conditions of
experience, make its attitude as it were final. These are then the
transcendental ideas, which, though according to the true but hidden
ends of the natural determination of our reason, they may aim not at
extravagant concepts, but at an unbounded extension of their empirical
use, yet seduce the understanding by an unavoidable illusion to a
transcendent use, which, though deceitful, cannot be restrained within
the bounds of experience by any resolution, but only by scientific
instruction and with much difficulty.