The Critique of Pure Reason | Page 7

metaphysics, if we assume that the objects
must conform to our cognition. This appears, at all events, to accord
better with the possibility of our gaining the end we have in view, that
is to say, of arriving at the cognition of objects a priori, of determining
something with respect to these objects, before they are given to us. We
here propose to do just what Copernicus did in attempting to explain
the celestial movements. When he found that he could make no
progress by assuming that all the heavenly bodies revolved round the
spectator, he reversed the process, and tried the experiment of assuming
that the spectator revolved, while the stars remained at rest. We may
make the same experiment with regard to the intuition of objects. If the
intuition must conform to the nature of the objects, I do not see how we
can know anything of them a priori. If, on the other hand, the object
conforms to the nature of our faculty of intuition, I can then easily
conceive the possibility of such an a priori knowledge. Now as I cannot
rest in the mere intuitions, but--if they are to become cognitions--must
refer them, as representations, to something, as object, and must
determine the latter by means of the former, here again there are two
courses open to me. Either, first, I may assume that the conceptions, by
which I effect this determination, conform to the object--and in this
case I am reduced to the same perplexity as before; or secondly, I may
assume that the objects, or, which is the same thing, that experience, in
which alone as given objects they are cognized, conform to my
conceptions--and then I am at no loss how to proceed. For experience
itself is a mode of cognition which requires understanding. Before
objects, are given to me, that is, a priori, I must presuppose in myself

laws of the understanding which are expressed in conceptions a priori.
To these conceptions, then, all the objects of experience must
necessarily conform. Now there are objects which reason thinks, and
that necessarily, but which cannot be given in experience, or, at least,
cannot be given so as reason thinks them. The attempt to think these
objects will hereafter furnish an excellent test of the new method of
thought which we have adopted, and which is based on the principle
that we only cognize in things a priori that which we ourselves place in
them.*
[*Footnote: This method, accordingly, which we have borrowed from
the natural philosopher, consists in seeking for the elements of pure
reason in that which admits of confirmation or refutation by experiment.
Now the propositions of pure reason, especially when they transcend
the limits of possible experience, do not admit of our making any
experiment with their objects, as in natural science. Hence, with regard
to those conceptions and principles which we assume a priori, our only
course ill be to view them from two different sides. We must regard
one and the same conception, on the one hand, in relation to experience
as an object of the senses and of the understanding, on the other hand,
in relation to reason, isolated and transcending the limits of experience,
as an object of mere thought. Now if we find that, when we regard
things from this double point of view, the result is in harmony with the
principle of pure reason, but that, when we regard them from a single
point of view, reason is involved in self-contradiction, then the
experiment will establish the correctness of this distinction.]
This attempt succeeds as well as we could desire, and promises to
metaphysics, in its first part--that is, where it is occupied with
conceptions a priori, of which the corresponding objects may be given
in experience--the certain course of science. For by this new method we
are enabled perfectly to explain the possibility of a priori cognition, and,
what is more, to demonstrate satisfactorily the laws which lie a priori at
the foundation of nature, as the sum of the objects of
experience--neither of which was possible according to the procedure
hitherto followed. But from this deduction of the faculty of a priori
cognition in the first part of metaphysics, we derive a surprising result,

and one which, to all appearance, militates against the great end of
metaphysics, as treated in the second part. For we come to the
conclusion that our faculty of cognition is unable to transcend the limits
of possible experience; and yet this is precisely the most essential
object of this science. The estimate of our rational cognition a priori at
which we arrive is that it has only to do with phenomena, and that
things in themselves, while possessing a real existence, lie beyond its
sphere. Here we are