Ayer A(lfred) J(ules) (1910–89), British philosopher, one of the most important of the British logical positivists. He continued to occupy a dominant place in analytic philosophy as he gradually modified his adherence to central tenets of the view. He was educated at Eton and Oxford, and, after a brief period at the University of Vienna, became a lecturer in philosophy at Christ Church in 1933. After the war he returned to Oxford as fellow and dean of Wadham College. He was Grote Professor of the Philosophy of Mind and Logic at the University of London (1946–59), Wykeham Professor of Logic in the University of Oxford and a fellow of New College (1959–78), and a fellow of Wolfson College, Oxford (1978–83). Ayer was knighted in 1973 and was a Chevalier de la Légion d’Honneur. His early work clearly and forcefully developed the implications of the positivists’ doctrines that all cognitive statements are either analytic and a priori, or synthetic, contingent, and a posteriori, and that empirically meaningful statements must be verifiable (must admit of confirmation or disconfirmation). In doing so he defended reductionist analyses of the self, the external world, and other minds. Value statements that fail the empiricist’s criterion of meaning but defy naturalistic analysis were denied truth-value and assigned emotive meaning. Throughout his writings he maintained a foundationalist perspective in epistemology in which sense-data (later more neutrally described) occupied not only a privileged epistemic position but constituted the subject matter of the most basic statements to be used in reductive analyses. Although in later works he significantly modified many of his early views and abandoned much of their strict reductionism, he remained faithful to an empiricist’s version of foundationalism and the basic idea behind the verifiability criterion of meaning. His books include Language, Truth and Logic; The Foundations of Empirical Knowledge; The Problems of Knowledge; Philosophical Essays; The Concept of a Person; The Origins of Pragmatism; Metaphysics and Common Sense; Russell and Moore: The Analytical Heritage; The Central Questions of Philosophy; Probability and Evidence; Philosophy in the Twentieth Century; Russell; Hume; Freedom and Morality, Ludwig Wittgenstein; and Voltaire. See also EMOTIVISM , LOGICAL POSITIVIS. R.A.F.