He was educated at Eton College and Oxford University, after which he studied the philosophy of logical positivism at the University of Vienna. From 1933 to 1940 he lectured on philosophy at Christ Church, Oxford.
During the Second World War Ayer was a Special Operations Executive and MI6 agent.
He was Grote Professor of the Philosophy of Mind and Logic at University College London from 1946 until 1959, after which he returned to Oxford to become Wykeham Professor of Logic at New College. He was president of the Aristotelian Society from 1951 to 1952 and knighted in 1970.
Ayer was born in St John's Wood, in north west London, to a wealthy family from continental Europe. His mother, Reine Citroën, was from the Dutch-Jewish family who founded the Citroën car company in France. His father, Jules Ayer, was a Swiss Calvinist financier who worked for the Rothschild family.
Ayer was educated at Ascham St Vincent's School, a former boarding preparatory school for boys in the seaside town of Eastbourne in Sussex, in which he started boarding at the comparatively early age of seven for reasons to do with the First World War, and Eton College, a boarding school in Eton (near Windsor) in Berkshire. It was at Eton that Ayer first became known for his characteristic bravado and precocity. Although primarily interested in furthering his intellectual pursuits, he was very keen on sports, particularly rugby, and reputedly played the Eton Wall Game very well. In the final examinations at Eton, Ayer came second in his year, and first in classics. In his final year, as a member of Eton's senior council, he unsuccessfully campaigned for the abolition of corporal punishment at the school. He won a classics scholarship to Christ Church, Oxford.
After graduation from Oxford University Ayer spent a year in Vienna, returned to England and published his first book, Language, Truth and Logic in 1936. The first exposition in English of Logical Positivism as newly developed by the Vienna Circle, this made Ayer at age 26 the 'enfant terrible' of British philosophy. In the Second World War he served as an officer in the Welsh Guards, chiefly in intelligence (Special Operations Executive (SOE) and MI6). Ayer was commissioned second lieutenant into the Welsh Guards from Officer Cadet Training Unit on 21 September 1940.
After the war he briefly returned to Oxford University where he became a fellow and Dean of Wadham College. He thereafter taught philosophy at London University from 1946 until 1959, when he also started to appear on radio and television. He was an extrovert and social mixer who liked dancing and attending the clubs in London and New York. He was also obsessed with sport: he had played rugby for Eton, and was a noted cricketer and a keen supporter of the Tottenham Hotspur football team. For an academic, Ayer was an unusually well-connected figure in his time, with close links to 'high society' and the establishment. Presiding over Oxford high-tables, he is often described as charming, but at times he could also be intimidating.
Ayer was married four times to three women. His first marriage was from 1932–1941 to (Grace Isabel) Renée (d. 1980), who subsequently married philosopher Stuart Hampshire, Ayer's friend and colleague. In 1960 he married Alberta Constance (Dee) Wells, with whom he had one son. Ayer's marriage to Wells was dissolved in 1983 and that same year he married Vanessa Salmon, former wife of politician Nigel Lawson. She died in 1985 and in 1989 he remarried Dee Wells, who survived him. Ayer also had a daughter with Hollywood columnist Sheilah Graham Westbrook.
From 1959 to his retirement in 1978, Sir Alfred held the Wykeham Chair, Professor of Logic at Oxford. He was knighted in 1970.
Ayer died on 27 June 1989. From 1980 to 1989, Ayer lived at 51 York Street, Marylebone, where a memorial plaque was unveiled on 19 November 1995.
In Language, Truth and Logic (1936), Ayer presents the verification principle as the only valid basis for philosophy. Unless logical or empirical verification is possible, statements like "God exists" or "charity is good" are not true or untrue but meaningless, and may thus be excluded or ignored. Religious language in particular was unverifiable and as such literally nonsense. He also criticises C. A. Mace's opinion that metaphysics is a form of intellectual poetry. The stance of a person who believes "God" denotes no verifiable hypothesis is sometimes referred to as igtheism (for example, by Paul Kurtz). In later years Ayer reiterated that he did not believe in God and began to refer to himself as an atheist. He followed in the footsteps of Bertrand Russell by debating with the Jesuit scholar Frederick Copleston on the topic of religion.
Ayer's version of emotivism divides "the ordinary system of ethics" into four classes:
- "Propositions that express definitions of ethical terms, or judgements about the legitimacy or possibility of certain definitions"
- "Propositions describing the phenomena of moral experience, and their causes"
- "Exhortations to moral virtue"
- "Actual ethical judgments"
He focuses on propositions of the first class—moral judgments—saying that those of the second class belong to science, those of the third are mere commands, and those of the fourth (which are considered in normative ethics as opposed to meta-ethics) are too concrete for ethical philosophy.
Ayer argues that moral judgments cannot be translated into non-ethical, empirical terms and thus cannot be verified; in this he agrees with ethical intuitionists. But he differs from intuitionists by discarding appeals to intuition of non-empirical moral truths as "worthless" since the intuition of one person often contradicts that of another. Instead, Ayer concludes that ethical concepts are "mere pseudo-concepts":
The presence of an ethical symbol in a proposition adds nothing to its factual content. Thus if I say to someone, "You acted wrongly in stealing that money," I am not stating anything more than if I had simply said, "You stole that money." In adding that this action is wrong I am not making any further statement about it. I am simply evincing my moral disapproval of it. It is as if I had said, "You stole that money," in a peculiar tone of horror, or written it with the addition of some special exclamation marks. … If now I generalise my previous statement and say, "Stealing money is wrong," I produce a sentence that has no factual meaning—that is, expresses no proposition that can be either true or false. … I am merely expressing certain moral sentiments.
Between 1945 and 1947, together with Russell and George Orwell, he contributed a series of articles to Polemic, a short-lived British "Magazine of Philosophy, Psychology, and Aesthetics" edited by the ex-Communist Humphrey Slater.
Ayer was closely associated with the British humanist movement. He was an Honorary Associate of the Rationalist Press Association from 1947 until his death. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1963. In 1965, he became the first president of the Agnostics' Adoption Society and in the same year succeeded Julian Huxley as president of the British Humanist Association, a post he held until 1970. In 1968 he edited The Humanist Outlook, a collection of essays on the meaning of humanism. In addition he was one of the signers of the Humanist Manifesto.
He taught or lectured several times in the United States, including serving as a visiting professor at Bard College in the fall of 1987. At a party that same year held by fashion designer Fernando Sanchez, Ayer, then 77, confronted Mike Tyson who was forcing himself upon the (then) little-known model Naomi Campbell. When Ayer demanded that Tyson stop, the boxer said: "Do you know who the fuck I am? I'm the heavyweight champion of the world," to which Ayer replied: "And I am the former Wykeham Professor of Logic. We are both pre-eminent in our field. I suggest that we talk about this like rational men". Ayer and Tyson then began to talk, while Naomi Campbell slipped out.
In 1988, shortly before his death, Ayer wrote an article entitled, "What I saw when I was dead", describing an unusual near-death experience. Of the experience, Ayer first said that it "slightly weakened my conviction that my genuine death ... will be the end of me, though I continue to hope that it will be." However, a few days later he revised this, saying "what I should have said is that my experiences have weakened, not my belief that there is no life after death, but my inflexible attitude towards that belief".
In 2001 Dr Jeremy George, the attending physician, claimed that Ayer had confided to him: "I saw a Divine Being. I'm afraid I'm going to have to revise all my books and opinions." Ayer's son Nick, however, said that he had never mentioned this to him though he did find his father's words to be extraordinary, and said he had long felt there was something possibly suspect about his father's version of his near death experience.
Ayer is best known for popularising the verification principle, in particular through his presentation of it in Language, Truth, and Logic (1936). The principle was at the time at the heart of the debates of the so-called Vienna Circle which Ayer visited as a young guest. Others, including the leading light of the circle, Moritz Schlick, were already offering their own papers on the issue. Ayer's own formulation was that a sentence can only be meaningful if it has verifiable empirical import, otherwise it is either "analytical" if tautologous, or "metaphysical" (i.e. meaningless, or "literally senseless"). He started to work on the book at the age of 23 and it was published when he was 26. Ayer's philosophical ideas were deeply influenced by those of the Vienna Circle and David Hume. His clear, vibrant and polemical exposition of them makes Language, Truth and Logic essential reading on the tenets of logical empiricism– the book is regarded as a classic of 20th century analytic philosophy, and is widely read in philosophy courses around the world. In it, Ayer also proposed that the distinction between a conscious man and an unconscious machine resolves itself into a distinction between 'different types of perceptible behaviour', an argument which anticipates the Turing test published in 1950 to test a machine's capability to demonstrate intelligence.
Ayer wrote two books on the philosopher Bertrand Russell, Russell and Moore: The Analytic Heritage (1971) and Russell (1972). He also wrote an introductory book on the philosophy of David Hume and a short biography of Voltaire.
Ayer was a strong critic of the German philosopher Martin Heidegger. As a logical positivist Ayer was in conflict with Heidegger's proposed vast, overarching theories regarding existence. These he felt were completely unverifiable through empirical demonstration and logical analysis. This sort of philosophy was an unfortunate strain in modern thought. He considered Heidegger to be the worst example of such philosophy, which Ayer believed to be entirely useless.
In 1972–1973 Ayer gave the Gifford Lectures at University of St Andrews, later published as The Central Questions of Philosophy. In the preface to the book, 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 "philosophy"– including the whole of metaphysics, theology and aesthetics– were not matters that could be judged as being 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 to this in the essay "Has Austin Refuted the Sense-data Theory?", which can be found in his Metaphysics and Common Sense (1969).
He was awarded a Knighthood as Knight Bachelor in the London Gazette on 1 January 1970.1936, Language, Truth, and Logic, London: Gollancz. (2nd edition, 1946.) OCLC 416788667 Reprinted 2001 with a new introduction, London: Penguin. ISBN 978-0-14-118604-7
1940, The Foundations of Empirical Knowledge, London: Macmillan. OCLC 2028651
1954, Philosophical Essays, London: Macmillan. (Essays on freedom, phenomenalism, basic propositions, utilitarianism, other minds, the past, ontology.) OCLC 186636305
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. OCLC 557578816
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.) OCLC 3573935
1967, "Has Austin Refuted the Sense-Data Theory?" Synthese vol. XVIII, pp. 117–140. (Reprinted in Ayer 1969).
1968, The Origins of Pragmatism, London: Macmillan. OCLC 641463982
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].) ISBN 978-0-333-10517-7
1971, Russell and Moore: The Analytical Heritage, London: Macmillan. OCLC 464766212
1972, Probability and Evidence, London: Macmillan. ISBN 978-0-333-12756-8
1972, Russell, London: Fontana Modern Masters. OCLC 186128708
1973, The Central Questions of Philosophy, London: Weidenfeld. ISBN 978-0-297-76634-6
1977, Part of My Life, London: Collins. ISBN 978-0-00-216017-9
1979, "Replies", in G. Macdonald, ed., Perception and Identity: Essays Presented to A. J. Ayer, With His Replies, London: Macmillan; Ithaca, N.Y.: Cornell University Press.
1980, Hume, Oxford: Oxford University Press
1982, Philosophy in the Twentieth Century, London: Weidenfeld.
1984, Freedom and Morality and Other Essays, Oxford: Clarendon Press.
1986, Ludwig Wittgenstein, London: Penguin.
1984, More of My Life, London: Collins.
1988, Thomas Paine, London: Secker & Warburg.
1989, "That undiscovered country", New Humanist, Vol. 104 (1), May, pp. 10–13.
1990, The Meaning of Life and Other Essays, Weidenfeld & Nicolson.
1992, The Philosophy of A.J. Ayer (The Library of Living Philosophers Volume XXI), edited by Lewis Edwin Hahn, Open Court Publishing Co.