Hilary Putnam (born July 31, 1926, Chicago, Illinois, U.S.—died March 13, 2016, Arlington, Massachusetts, U.S.) leading American philosopher who made major contributions to metaphysics, epistemology, the philosophy of mind, the philosophy of language, the philosophy of science, the philosophy of mathematics, and the philosophy of logic. He is best known for his semantic externalism, according to which linguistic meanings are not purely mental entities but reach out to external reality; his antireductionist philosophy of mind; and his persistent defense of realism, the view that truth and knowledge are objective. In his later years he became increasingly sensitive to the moral aspects of epistemology and metaphysics and, more generally, to philosophy’s moral calling.