The chief intellectual influence on the philosopher Antony Flew, who has died aged 87, was the leading Enlightenment figure David Hume, whom he followed both in his empiricist critique of natural theology and also, to some extent, his political sympathies. His second book, Hume's Philosophy of Belief (1961), was a major contribution to Hume scholarship.
It was preceded by A New Approach to Psychical Research (1953). For Flew, the language and logic approach of the analytical philosopher did not preclude examination of the most speculative questions. However, his last book, There Is a God: How the World's Most Notorious Atheist Changed His Mind (with Roy Abraham Varghese, 2007), pointed to the change in his outlook over the last decade, undercutting the position he had maintained while holding university posts in England, Scotland and North America.
Flew had become well known to a generation of students as an official atheist philosopher, much to the chagrin of his father, a Methodist minister, who is said to have prayed for him every day. In an early, seminal essay, Theology and Falsification (1950), Flew tried to show that the hypothesis of an almighty and loving God was unfalsifiable and therefore empty. He claimed the "endemic evil" in theology was that, however terrible the world, religious folk continued to believe in an all-powerful, benevolent deity. For them, no horror was, even in principle, allowed to count against this. But then, how could there be meaningful evidence for God's existence? Thus, theism suffered a "death by a thousand qualifications".
These ideas were developed in God and Philosophy (1966), which contained an attempted demolition of revelation, and particularly miracles. Nevertheless, Flew seemed fascinated by the possibility of empirical evidence for theological claims, and maintained a sceptical interest not only in alleged miracles but paranormal phenomena in general. He was especially known as a sustained critic of the belief in life after death, arguing in many works that post-mortem survival was impossible.
Thus, it came as shock to some of his humanist friends when in 2004, he confessed to a change of mind concerning God. He announced in a video entitled Has Science Discovered God? that aspects of biological order, especially in DNA, had led him to believe in intelligent design after all. Commentators seized on this, but the revelation was less dramatic than it appeared. He still disbelieved in revealed religion and immortality. He did, however, express concern about the damage his writings on the subject could have done.
Flew wrote prolifically, producing both scholarly and general works, including his Introduction to Western Philosophy: Ideas and Argument from Plato to Popper (1971), two shorter books on critical thinking and many other works that often combined a polemical with a philosophical style. Among the last of these were Crime or Disease? (1973), an attack on fashionable conceptions of crime, and The Politics of Procrustes (1981), a trenchant critique of egalitarian political theory. He adamantly defended human free agency, though he eventually gave up his earlier Humean conviction that free will was compatible with determinism.
Born in London, Flew was educated at St Faith's school, Cambridge, and Kingswood school, Bath. During the second world war, he studied Japanese at the School of Oriental and African Studies in London and did intelligence work with the RAF. His study of classics at St John's College, Oxford, included classical philosophy, and contact with the Christian apologist CS Lewis helped him maintain his interest in the philosophy of religion, despite the loss of his own faith during his teens. He taught briefly at Christ Church (1949-50), and, after a stint at Aberdeen (1950-54), was one of the pioneers who went to the University College of North Staffordshire (now Keele), staying as professor of philosophy until 1971. After a year at the University of Calgary, Alberta (1972-73), he became professor at Reading University, with part-time appointments at York University, Toronto, and Bowling Green State University, Ohio, after his retirement as emeritus professor in 1983.
Flew's work was partly influenced by his early teachers, in particular Gilbert Ryle. His longstanding humanism was reflected in his involvement with organisations such as the Rationalist Press Association. He had various hobbyhorses, and many found him obsessional. He detested the progressive, egalitarian ethos of the late 1960s and 70s, supported the cold war and lamented the state of education.
A former colleague at Keele described how he was once expressly forbidden from turning his seminars into political rallies. In the 1970s he wrote in defence of an American psychologist, Arthur Jensen, who had been accused of racism for claiming that genetic factors might partially account for IQ differences between black and white people. Flew opposed racism but often wrote condemning the intolerant and illogical features that he saw in much anti-racist and multicultural ideology. Paradoxically, much of what he courageously said then has now become fairly respectable.
Many former colleagues and students remembered him with great respect. One acknowledged him as having high principles and high standards, always following arguments where they led him. Another, then a novice lecturer at Keele, noted his helpfulness, in spite of political differences. A former student recalled how, in 1962, he boomed at a bemused philosophy class that "sex ... is a very dangerous thing", fearing that it would interfere with studying. But his views on abortion and homosexual law reform were liberal, and he was a trenchant critic of the Roman Catholic church's teaching on contraception.
Indeed his conservatism had a strongly libertarian streak, though perhaps he later regretted some of the resulting social effects. He was also a passionate opponent of European integration, proudly declaring himself a "subject of Her Majesty, not a citizen of Europe".
His dogged pursuit of reason to reach truth, and his willingness to change his mind (as well as altering his beliefs about God, in his early youth he had briefly been a communist sympathiser before becoming a Conservative) marked him out as having a deep integrity and innocence. Moreover, he had an excellent reputation as a teacher. Old-fashioned to the last, he was one of a generation at odds with the climate of bureaucracy, managerialism, "research assessment" and audits now besetting the university world.
Flew was fond of walking, climbing and, according to Who's Who, house maintenance. He is survived by his wife, Annis, whom he married in 1952, and two daughters.
Francis Beckett writes: For students brought up to accept without question the assertions of ministers of religion, or inclined to be taken in by the mystics of the 1960s or 70s, or tempted by Marxist historicism, a session with Tony Flew was always a little like having a bucket of ice-cold water thrown over you. He had a grand contempt for vague, metaphysical statements, and loved stripping arguments down to their skeletons. "Can you hit it with a hammer?" he would ask when confronted with a particularly nebulous concept.