John Cook Wilson (b. 1849–d. 1915) was Wykeham Professor of Logic at the University of Oxford. He made a number of contributions in various areas of philosophy, including important work on knowledge, metaphysics, perception, logic, probability, and the interpretation of Plato and Aristotle. His most distinctive doctrines concerned knowledge. He held, first, that knowledge (or its exercises, in cases of what he called “apprehension”) is a primitive notion distinct from, and excluding, other mental states like belief or opinion. And he held, second, that what is known must obtain independently of its being known. The combination of those two doctrines formed the basis of what has come to be known as Oxford Realism, a family of views about knowledge and reality that builds on Cook Wilson’s articulation and defense of the two doctrines. Although Cook Wilson’s own work is no longer widely read, it has exerted an important influence on later work in epistemology via works in the broad Oxford Realist tradition, including works such as Prichard 1950 (cited under Knowledge) and Austin 1962, Hinton 1973, Snowdon 1980–1981 (cited under Legacy), McDowell 1982, Travis 1989, and Williamson 2000 (all cited under Legacy).