knowledge

a priori of objects, that is to say, the answer to the following

questions:



How is pure mathematical science possible?



How is pure natural science possible?



Respecting these sciences, as they do certainly exist, it may with

propriety be asked, how they are possible?--for that they must be

possible is shown by the fact of their really existing.* But as to

metaphysics, the miserable progress it has hitherto made, and the fact

that of no one system yet brought forward, far as regards its true

aim, can it be said that this science really exists, leaves anyone at

liberty to doubt with reason the very possibility of its existence.





Yet, in a certain sense, this kind of knowledge must unquestionably be

looked upon as given; in other words, metaphysics must be considered

as really existing, if not as a science, nevertheless as a natural

disposition of the human mind (metaphysica naturalis). For human

reason, without any instigations imputable to the mere vanity of great

knowledge, unceasingly progresses, urged on by its own feeling of

need, towards such questions as cannot be answered by any empirical

application of reason, or principles derived therefrom; and so there

has ever really existed in every man some system of metaphysics. It will

always exist, so soon as reason awakes to the exercise of its power

of speculation. And now the question arises: "How is metaphysics, as a

natural disposition, possible?" In other words, how, from the nature

of universal human reason, do those questions arise which pure reason

proposes to itself, and which it is impelled by its own feeling of need

to answer as well as it can?



But as in all the attempts hitherto made to answer the questions which

reason is prompted by its very nature to propose to itself, for example,

whether the world had a beginning, or has existed from eternity, it has

always met with unavoidable contradictions, we must not rest satisfied

with the mere natural disposition of the mind to metaphysics, that is,

with the existence of the faculty of pure reason, whence, indeed, some

sort of metaphysical system always arises; but it must be possible to

arrive at certainty in regard to the question whether we know or do not

know the things of which metaphysics treats. We must be able to arrive

at a decision on the subjects of its questions, or on the ability or

inability of reason to form any judgement respecting them; and therefore

either to extend with confidence the bounds of our pure reason, or to

set strictly defined and safe limits to its action.