Plato's Later Dialogues: Metaphysics, Cosmology, and Politics

Central to Plato's middle-period epistemology, especially in Republic Book V, is a sharp distinction between episteme, genuine knowledge, and doxa, mere opinion. Because knowledge requires an object that is stable and unchanging, only the eternal Forms can be objects of episteme; the ever-shifting particulars of the sensible world, by contrast, can only ever be objects of doxa, belief that may happen to be true but lacks the certainty and justification of real knowledge. This distinction underwrites Plato's low estimate of ordinary sense-based judgment and his insistence that philosophers, who pursue the Forms through reason, are alone capable of true understanding.