The Vienna of the late 1920s and early 1930s was in many ways a depressed and unsettled place. Once the centre of the Austro-Hungarian empire, it became, after the First World War, the capital of a small and poor clerical republic, racked by religious and political conflict. A few days before Ayer and his new wife, Renee Lees, left the city in March 1933, the Austrian Chancellor, Engelbert Dollfuss, dissolved parliament, threw his lot in with Mussolini and set about constructing a Catholic-Fascist state. Ayer himself sometimes arrived at the university to find it closed due to political disturbance.
Nevertheless the city remained, as it had been before the war, an intellectual and artistic hotbed. The municipal elections of 1919 had put Vienna's powerful government into the hands of the Socialists, who embarked on a programme of radical reform. Freud was still practising in the city, as was Alfred Adler, who ran an influential education institute where the young Karl Popper had studied. The economist Friedrich von Hayek, who taught at the university in the early 1930s, remembered it as a place of "great intellectual excitement" - the result of an unusual degree of interaction between the various departments.
The Vienna Circle itself evolved in the mid 1920s from a discussion group founded by Moritz Schlick, who was appointed Professor of the Philosophy of Science at Vienna University in 1922. In addition to Schlick and his assistant Friedrich Waismann, its other leading participants were Rudolf Carnap and Otto Neurath, two idealistic radicals with contacts in the socialist municipal government as well as with the Bauhaus. Wittgenstein, who was in Vienna from 1925 to 1929, was never a member of the circle, but he often met with Schlick and Waismann and influenced its development as well as being influenced by it in turn. The Viennese positivists inevitably disagreed among themselves, but, like positivists everywhere, they shared a fundamental belief in progress, in fact and science. They argued, indeed, that science alone, stretched to encompass common-sense observation, is the only source of real knowledge.
Ayer spoke little German and spent his first weeks in the city studying the language. After Christmas he introduced himself to Schlick, who invited him not only to attend his lectures but join the meeting of Vienna Circle itself - a rare privilege. As Ayer admitted in letters to Isaiah Berlin and Gilbert Ryle back in Oxford, he got "very little" from the circle's meetings because of his poor German. Nevertheless, he was infected by its spirit and ambition - its desire to eradicate the superstitions of the past and refound science and society on rational principles.
It would not quite be true to say that Ayer was converted by his visit to Vienna. His encounter with the Viennese positivists, however, gave him a mission and nine months after returning from Vienna he began work on his masterpiece, Language, Truth and Logic. Here was an organised movement that thought like him and which seemed to have the future on its side. He would be its English-language apostle.
That logical positivism was a foreign movement added to its allure. Ayer, half Dutch-Jewish, half French-Swiss, felt - had been made to feel - a foreigner. It was only fitting that he should spearhead the invasion of foreign ideas.
Ben Rogers is the author of `A. J. Ayer, A Life' (Chatto and Windus, pounds 20)Reuse content