A priori ('from the earlier') and a posteriori ('from the later') are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on experience.
Both terms appear in Euclid's Elements and were popularized by Immanuel Kant's Critique of Pure Reason, an influential work in the history of philosophy.
"[3] One theory, popular among the logical positivists of the early 20th century, is what Boghossian calls the "analytic explanation of the a priori".
More simply, proponents of this explanation claimed to have reduced a dubious metaphysical faculty of pure reason to a legitimate linguistic notion of analyticity.
Most notably, Quine argues that the analytic–synthetic distinction is illegitimate:[5]But for all its a priori reasonableness, a boundary between analytic and synthetic statements simply has not been drawn.
That there is such a distinction to be drawn at all is an unempirical dogma of empiricists, a metaphysical article of faith.Although the soundness of Quine's proposition remains uncertain, it had a powerful effect on the project of explaining the a priori in terms of the analytic.
American philosopher Saul Kripke (1972), for example, provides strong arguments against this position, whereby he contends that there are necessary a posteriori truths.
Following such considerations of Kripke and others (see Hilary Putnam), philosophers tend to distinguish the notion of aprioricity more clearly from that of necessity and analyticity.
Taking these differences into account, Kripke's controversial analysis of naming as contingent and a priori would, according to Stephen Palmquist, best fit into Kant's epistemological framework by calling it "analytic a posteriori.
They appear in Latin translations of Euclid's Elements, a work widely considered during the early European modern period as the model for precise thinking.
[11] The early modern Thomistic philosopher John Sergeant differentiates the terms by the direction of inference regarding proper causes and effects.
G. W. Leibniz introduced a distinction between a priori and a posteriori criteria for the possibility of a notion in his (1684) short treatise "Meditations on Knowledge, Truth, and Ideas".
Unlike the rationalists, Kant thinks that a priori cognition, in its pure form, that is without the admixture of any empirical content, is limited to the deduction of the conditions of possible experience.
The claim is more formally known as Kant's transcendental deduction and it is the central argument of his major work, the Critique of Pure Reason.
For he declared everything to be a priori, naturally without any evidence for such a monstrous assertion; instead of these, he gave sophisms and even crazy sham demonstrations whose absurdity was concealed under the mask of profundity and of the incomprehensibility ostensibly arising therefrom.