826 IMMANUELKANT
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there arises an unexpected conflict which never can be removed in the common dogmatic
way; because the thesis, as well as the antithesis, can be shown by equally clear, evident,
and irresistible proofs—for I pledge myself as to the correctness of all these proofs—and
reason therefore perceives that it is divided against itself, a state at which the skeptic
rejoices, but which must make the critical philosopher pause and feel ill at ease.
§ 52b.We may blunder in various ways in metaphysics without any fear of being
detected in falsehood. If we but avoid self-contradiction, which in synthetical though
purely fictitious propositions is quite possible, then whenever the concepts which we con-
nect are mere Ideas that cannot be given (with respect to their whole content) in experience,
we cannot be refuted by experience. For how can we make out by experience whether the
world is from eternity or had a beginning, whether matter is infinitely divisible or consists
of simple parts? Such concepts cannot be given in any experience, however extensive, and
consequently the falsehood either of the affirmative or the negative proposition cannot be
discovered by this touchstone.
The only possible way in which reason could have revealed unintentionally its secret
dialectic, falsely announced as its dogmatics, would be when it were made to ground an
assertion upon a universally admitted principle and to deduce the exact contrary with the
greatest accuracy of inference from another which is equally granted. This is actually here
the case with regard to four natural Ideas of reason, whence four assertions on the one side
and as many counterassertions on the other arise, each consistently following from univer-
sally acknowledged principles. Thus they reveal, by the use of these principles, the dialec-
tical illusion of pure reason, which would otherwise forever remain concealed.
This is therefore a decisive experiment, which must necessarily expose any error
lying hidden in the assumptions of reason.* Contradictory propositions cannot both be
false, except the concept on which each is founded is self-contradictory; for example,
the propositions, “A square circle is round,” and “A square circle is not round,” are both
false. For, as to the former, it is false that the circle is round because it is quadrangular;
and it is likewise false that it is not round, that is, angular, because it is a circle. For the
logical criterion of the impossibility of a concept consists in this that, if we presuppose
it, two contradictory propositions both become false; consequently, as no middle
between them is conceivable, nothing at all is thought by that concept.
§ 52c.The first two antinomies, which I call mathematical because they are
concerned with the addition or division of the homogeneous, are founded on such a
contradictory concept; and hence I explain how it happens that both the thesis and
antithesis of the two are false.
When I speak of objects in time and in space, it is not of things in themselves, of
which I know nothing, but of things in appearance, that is, of experience, as the particu-
lar way of knowing objects which is afforded to man. I must not say of what I think in
time or in space, that in itself, and independent of these my thoughts, it exists in space
and in time, for in that case I should contradict myself; because space and time, together
with the appearances in them, are nothing existing in themselves and outside of my
representations, but are themselves only modes of representation, and it is palpably
contradictory to say that a mere mode of representation exists without our representation.340
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*I therefore would be pleased to have the critical reader to devote to this antinomy of pure reason
his chief attention, because nature itself seems to have established it with a view to stagger reason in its
daring pretensions and to force it to self-examination. For every proof which I have given of both thesis and
antithesis I undertake to be responsible, and thereby to show the certainty of the inevitable antinomy of
reason. When the reader is brought by this curious phenomenon to fall back upon the proof of the
presumption upon which it rests, he will feel himself obliged to investigate the ultimate foundation of all
knowledge by pure reason with me more thoroughly.