are heavy, and, consequently, that they fall when their supports are
taken away, must have been known to him previously, by means of
experience.

By the term "knowledge a priori," therefore, we shall in the
sequel understand, not such as is independent of this or that kind
of experience, but such as is absolutely so of all experience. Opposed
to this is empirical knowledge, or that which is possible only a
posteriori, that is, through experience. Knowledge a priori is
either pure or impure. Pure knowledge a priori is that with which no
empirical element is mixed up. For example, the proposition, "Every
change has a cause," is a proposition a priori, but impure, because
change is a conception which can only be derived from experience.



II. The Human Intellect, even in an Unphilosophical State,
is in Possession of Certain Cognitions "a priori".

The question now is as to a criterion, by which we may securely
distinguish a pure from an empirical cognition. Experience no doubt
teaches us that this or that object is constituted in such and such
a manner, but not that it could not possibly exist otherwise. Now,
in the first place, if we have a proposition which contains the idea
of necessity in its very conception, it is a if, moreover, it is not
derived from any other proposition, unless from one equally
involving the idea of necessity, it is absolutely priori. Secondly,
an empirical judgement never exhibits strict and absolute, but only
assumed and comparative universality (by induction); therefore, the
most we can say is--so far as we have hitherto observed, there is no