Alain Badiou

Badiou was born in Rabat in French Morocco; his father was a mathematics teacher, a Resistance member and after the war socialist mayor of Toulouse, his mother a teacher of literature. He studied philosophy at the École Normale Supérieure under Althusser, also attending Canguilhem and Lacan, passed the agrégation in 1960, was a Sartrean in youth, wrote novels, and took part in the campaign against the Algerian war.

May 1968 made him a Maoist; he founded and led the Union des communistes de France marxiste-léniniste and for twenty years gave much of his time to organising and pamphleteering, clashing fiercely with Deleuze and Lyotard while teaching at Vincennes. Theory of the Subject (1982) tried to join Lacanian psychoanalysis with Hegelian dialectic. Being and Event (1988) is his major work; he said it turned him 'from a militant into a philosopher'.

Its thesis is 'mathematics is ontology': being as such is pure multiplicity without the One, set theory is the science of pure multiplicity, and the discourse of ontology is the Zermelo–Fraenkel axioms. But being is not all: at the edge of every situation an 'event' may occur that cannot be deduced from the situation's knowledge but can only be 'named' and 'decided'; a subject is fidelity to an event, and a truth is the 'generic' procedure that fidelity builds point by point within the situation. Truths occur in four domains, science, art, politics and love; philosophy produces no truths of its own but thinks the compossibility of the four.

In 1999 he returned to the École Normale as professor, and Logics of Worlds (2006) used category theory to explain how events appear in concrete worlds. The Meaning of Sarkozy (2007) became a best-seller and introduced the 'communist hypothesis', after which he became one of France's best-known public philosophers, attacked for defending Stalin and Mao and for his critique of 'democratic materialism'. He is also a playwright and novelist and an ally of Žižek. He continues to write and lecture.