priori

is a truth, like mathematics, which derives its necessary character not from experience, but from the inherent structure of our minds, from the natural and inevitable manner in which our minds must operate.

But whence do we get this character of absoluteness and necessity? Not from experience; for experience gives us nothing but separate sensations and events, which may alter their sequence in the future. 2 These truths derive their necessary character from the inherent structure of our minds, from the natural and inevitable manner in which our minds must operate.

is a general truth which must be independent of experience; clear and certain in themselves.

General truths, which at the same time bear the character of an inward necessity, must be independent of experience,—clear and certain in themselves."

is exemplified in mathematical knowledge which is necessary and certain; we cannot conceive of future experience violating it.

How far we can advance independently of all experience, in a priori knowledge, is shown by the brilliant example of mathematics. 1 Mathematical knowledge is necessary and certain; we cannot conceive of future experience violating it. We may believe that the sun will "rise" in the west to-morrow, or that some day, in some conceivable asbestos world, fire will not burn stick; but we cannot for the life of us believe that two times two will ever make anything else than four. Such truths are true before experience; they do not depend on experience past, present, or to come. Therefore they are absolute and necessary truths; it is inconceivable that they should ever become untrue.

is important because it makes absolute truth, and absolute science, possible.

Let us grant that absolute certainty of knowledge is impossible if all knowledge comes from sensation, from an independent external world which owes us no promise of regularity of behavior. But what if we have knowledge that is independent of sense-experience, knowledge whose truth is certain to us even before experience — a priori? Then absolute truth, and absolute science, would become possible, would it not? Is there such absolute knowledge?

is knowledge that is independent of sense-experience, whose truth is certain to us even before experience.

is a truth that must be true no matter what our later experience may be; true even before experience.

That is to say, they must be true no matter what our later experience may be; true even before experience; true a priori.

priori, n.Definitions

priori