Gilbert Harman was born in 1938, graduated from Swarthmore College in 1960, and received his PhD from Harvard in 1963, where W. V. Quine was his dissertation advisor. He is distinctive in being a leading contributor across a broad range of subdisciplines of philosophy: epistemology, ethics, philosophy of language, philosophy of mind, and metaphysics. This entry reviews only a few of his many important contributions.

Harman has been perhaps the most significant contemporary defender of moral relativism. According to Harman, moral right and wrong are akin to motion: They are relative to a framework and no framework is privileged. Harman appeals effectively to two sorts of consideration in developing his position. First, like J. L. Mackie, he is impressed by the degree of moral diversity across and even within populations. Second, complementarily, Harman defends moral naturalism—the view, roughly, that morality is fundamentally continuous with the natural...