Alain Badiou (French: [alɛ̃ badju] (listen) ; born 17 January 1937) is a French philosopher, formerly chair of Philosophy at the École Normale Supérieure (ENS) and founder of the faculty of Philosophy of the Université de Paris VIII with Gilles Deleuze, Michel Foucault and Jean-François Lyotard. Badiou has written about the concepts of being, truth, event and the subject in a way that, he claims, is neither postmodern nor simply a repetition of modernity. Badiou has been involved in a number of political organisations, and regularly comments on political events. Badiou argues for resurrecting the idea of communism.
Badiou was a student at the Lycée Louis-Le-Grand and then the École Normale Supérieure (1957–1961). He taught at the lycée in Reims from 1963 where he became a close friend of fellow playwright (and philosopher) François Regnault, and published a couple of novels before moving to the University of Paris VIII (Vincennes-Saint Denis) in 1969. Badiou was politically active very early on, and was one of the founding members of the Unified Socialist Party (PSU). The PSU was particularly active in the struggle for the decolonization of Algeria. He wrote his first novel, Almagestes, in 1964. In 1967 he joined a study group organized by Louis Althusser, became increasingly influenced by Jacques Lacan and became a member of the editorial board of Cahiers pour l'Analyse. By then he "already had a solid grounding in mathematics and logic (along with Lacanian theory)", and his own two contributions to the pages of Cahiers "anticipate many of the distinctive concerns of his later philosophy".