Philosophy. In the book's preface, he defends his selection to hold the lectureship on the basis that Lord Gifford wished to promote "natural theology, in the widest sense of that term", and that non-believers are allowed to give the lectures if they are "able reverent men, true thinkers, sincere lovers of and earnest inquirers after truth". He still believed in the viewpoint he shared with the logical positivists: that large parts of what was traditionally called philosophyincluding metaphysics, theology and aestheticswere not matters that could be judged true or false, and that it was thus meaningless to discuss them. In The Concept of a Person and Other Essays (1963), Ayer heavily criticized Wittgenstein's private language argument. Ayer's sense-data theory in Foundations of Empirical Knowledge was famously criticised by fellow Oxonian J. L. Austin in Sense and Sensibilia, a landmark 1950s work of common language philosophy. Ayer responded in the essay "Has Austin Refuted the Sense-datum Theory?", which can be found in his Metaphysics and Common Sense (1969). Awards Ayer was awarded a Knighthood as Knight Bachelor in the London Gazette on 1 January 1970. Selected publications 1936, Language, Truth, and Logic, London: Gollancz., 2nd ed., with new introduction (1946) 1936, "Causation and free will," The Aryan Path. 1940, The Foundations of Empirical Knowledge, London: Macmillan. 1954, Philosophical Essays, London: Macmillan. (Essays on freedom, phenomenalism, basic propositions, utilitarianism, other minds, the past, ontology.) 1957, "The conception of probability as a logical relation", in S. Korner, ed., Observation and Interpretation in the Philosophy of Physics, New York, N.Y.: Dover Publications. 1956, The Problem of Knowledge, London: Macmillan. 1957, "Logical Positivism - A Debate" (with F. C. Copleston) in: Edwards, Paul, Pap, Arthur (eds.), A Modern Introduction to Philosophy; readings from classical and contemporary sources 1963, The Concept of a Person and Other Essays, London: Macmillan. (Essays on truth, privacy and private languages, laws of nature, the concept of a person, probability.) 1967, "Has Austin Refuted the Sense-Datum Theory?" Synthese vol. XVIII, pp. 117–140. (Reprinted in Ayer 1969). 1968, The Origins of Pragmatism, London: Macmillan. 1969, Metaphysics and Common Sense, London: Macmillan. (Essays on knowledge, man as a subject for science, chance, philosophy and politics, existentialism, metaphysics, and a reply to Austin on sense-data theory [Ayer 1967].) 1971, Russell and Moore: The Analytical Heritage, London: Macmillan. 1972, Probability and Evidence, London: Macmillan. 1972, Russell, London: Fontana Modern Masters. 1973, The Central Questions of