‘The research laboratory for world destruction’ was what, in 1914, the journalist Karl Kraus presciently called Vienna. At various times in the early 20th century, its inhabitants included Adolf Hitler, Theodor Herzl (founder of modern Zionism), Sigmund Freud, Leon Trotsky, the modernists Arnold Schoenberg, Egon Schiele and Oskar Kokoschka, and Ludwig Wittgenstein, whose diary in 1931 recorded his fear of being remembered merely as the endpoint of Western philosophy. In fact, he is celebrated for transforming and rejuvenating philosophy, and Anthony Gottlieb’s Ludwig Wittgenstein: Philosophy in the Age of Airplanes is a moving portrait of his tortured, passionate and exuberant life.

Born in 1889, Wittgenstein was the ninth and last child in a family that epitomised one of the paradoxes of Vienna. In the Palais Wittgenstein, Gustav Klimt’s painting of a knight in gold armour, ramrod straight in his horse’s stirrups, dominated the marble staircase, and the Wittgensteins, according to Johannes Brahms, who frequented their musical salons, moved about ‘as if at court’. But, like 12 per cent of Vienna’s population in the late 19th century, Wittgenstein’s father and maternal grandfather were Jews – Wittgenstein’s great-­grandfather, a land agent’s son, had adopted the grand surname and, later, Christianity. The Wittgensteins were,