An intuition is a noninferential awareness of something: a concept, a proposition, space or time, a physical object, our own existence, or God. While sometimes people talk of sensory intuitions of perceptual objects, by which they mean an immediate awareness of how they appear, this use of "intuition" is becoming more rare. Nowadays philosophers use the term primarily to mean a nonsensory and nonintrospective awareness of a proposition or concept. Some philosophers hold that an intuition must be of a proposition that seems necessarily, or possibly, true. But people who lack the concepts of necessity and possibility are able to have something very like what philosophers call intuitions. So a more plausible view is that a person has an intuition that P if and only if P seems true, or possibly or necessarily true, where that appearance is intellectual—that is, based on the understanding, not...