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La Mettrie is best known as the author of the eighteenth-century materialist manifesto, L’Homme machine (1747). His interest in philosophical issues grew out of his preoccupation with medicine, and he developed a tradition of medical materialism within the French Enlightenment. Born in St Malo, into the family of a prosperous textile merchant, La Mettrie pursued a medical career in Paris. He also studied for two years with the renowned Hermann Boerhaave in Leiden. After a brief period of medical practice, La Mettrie devoted his efforts to his translations and commentaries on Boerhaave’s medical works. He also began to publish the works that made him a pariah to both the Faculty of Medicine of Paris and to the orthodox – that is, his medical satires and his first work of materialist philosophy, L’Histoire naturelle de l’aˆme (1745). Because of the outrage provoked by these works, he was exiled to Holland in 1745. But L’Homme machine, the text in which he applied his materialism thoroughly and explicitly to human beings, was too radical even for the unusually tolerant Dutch, and La Mettrie was forced to seek asylum at the court of Frederick the Great where he later died. His willingness to publish ideas his contemporaries considered too dangerous led the philosophes to repudiate him. See also: Enlightenment, Continental

Antonio Labriola was the founder of Italian theoretical Marxism. Generally situated in the Marxism of the Second International, he was more questioning than others in that movement. He profoundly influenced the development of Italian thought, constantly challenging the influential idealism of Benedetto Croce and Giovanni

Gentile. His attempt to maintain a place for human creativity within a deterministic Marxist view of history influenced Antonio Gramsci and helped give Italian Eurocommunism its distinctive flexibility. His concepts of ‘genetic method’, ‘social morphology’, ‘philosophy of praxis’ and ‘social pedagogy’ are indications of this attempt. See also: Marxism, Western

Jacques Lacan was a French psychoanalyst and philosopher whose contribution to philosophy derives from his consistent and thoroughgoing reinterpretation of Freud’s writings in the light of Heidegger and Hegel as well as structuralist linguistics and anthropology. Whereas Freud himself had disparaged philosophical speculation, claiming for himself the mantle of the natural scientist, Lacan demonstrates psychoanalysis to be a rigorous philosophical position. Specifically, Lacan suggests that the Freudian unconscious is best understood as the effect of language (what he calls ‘the symbolic’) upon human behaviour. See also: Freud, S.; Psychoanalysis, postFreudian; Structuralism; Structuralism in social science

Imre Lakatos made important contributions to the philosophy of mathematics and of science. His ‘Proofs and Refutations’ (1963-4) develops a novel account of mathematical discovery. It shows that counterexamples (‘refutations’) play an important role in mathematics as well as in science and argues that both proofs and theorems are gradually improved by searching for counterexamples and by systematic ‘proof analysis’. His ‘methodology of scientific research programmes’ (which he presented as a ‘synthesis’ of the accounts of science given by

Popper and by Kuhn) is based on the idea that

science is best analysed, not in terms of single

theories, but in terms of broader units called

research programmes. Such programmes issue in

particular theories, but in a way again governed by

clear-cut heuristic principles. Lakatos claimed that

his account supplies the sharp criteria of ‘progress’

and ‘degeneration’ missing from Kuhn’s account,

and hence captures the ‘rationality’ of scientific

development. Lakatos also articulated a ‘meta-

methodology’ for appraising rival methodologies

of science in terms of the ‘rational reconstructions’

of history they provide.