 Analytic propositions are thought to be true in virtue of their meaning alone, while "a posteriori" propositions are thought to be true in virtue of their meaning "and" certain facts about the world.According to the analytic explanation of the "a priori", all "a priori" knowledge is analytic; so "a priori" knowledge need not require a special faculty of pure intuition, since it can be accounted for simply by one's ability to understand the meaning of the proposition in question.More simply, proponents of this explanation claimed to have reduced a dubious metaphysical faculty of pure reason to a legitimate linguistic notion of analyticity.