presented and the aid furnished by experience.
So much for the completeness and thoroughness necessary in the
execution of the present task. The aims set before us are not
arbitrarily proposed, but are imposed upon us by the nature of
cognition itself.
The above remarks relate to the matter of our critical inquiry. As
regards the form, there are two indispensable conditions, which any
one who undertakes so difficult a task as that of a critique of pure
reason, is bound to fulfil. These conditions are certitude and
clearness.
As regards certitude, I have fully convinced myself that, in this
sphere of thought, opinion is perfectly inadmissible, and that
everything which bears the least semblance of an hypothesis must be
excluded, as of no value in such discussions. For it is a necessary
condition of every cognition that is to be established upon a priori
grounds that it shall be held to be absolutely necessary; much more is
this the case with an attempt to determine all pure a priori
cognition, and to furnish the standard- and consequently an example-
of all apodeictic (philosophical) certitude. Whether I have
succeeded in what I professed to do, it is for the reader to
determine; it is the author's business merely to adduce grounds and
reasons, without determining what influence these ought to have on the
mind of his judges. But, lest anything he may have said may become the
innocent cause of doubt in their minds, or tend to weaken the effect
which his arguments might otherwise produce- he may be allowed to
point out those passages which may occasion mistrust or difficulty,
although these do not concern the main purpose of the present work. He
does this solely with the view of removing from the mind of the reader
any doubts which might affect his judgement of the work as a whole,
and in regard to its ultimate aim.
I know no investigations more necessary for a full insight into
the nature of the faculty which we call understanding, and at the same
time for the determination of the rules and limits of its use, than
those undertaken in the second chapter of the "Transcendental
Analytic," under the title of "Deduction of the Pure Conceptions of
the Understanding"; and they have also cost me by far the greatest
labour- labour which, I hope, will not remain uncompensated. The
view there taken, which goes somewhat deeply into the subject, has two
sides, The one relates to the objects of the pure understanding, and
is intended to demonstrate and to render comprehensible the
objective validity of its a priori conceptions; and it forms for
this reason an essential part of the Critique. The other considers the
pure understanding itself, its possibility and its powers of
cognition- that is, from a subjective point of view; and, although
this exposition is of great importance, it does not belong essentially
to the main purpose of the work, because the grand question is what
and how much can reason and understanding, apart from experience,
cognize, and not, how is the faculty of thought itself possible? As
the latter is an, inquiry into the cause of a given effect, and has
thus in it some semblance of an hypothesis (although, as I shall
