Sylvain Lazarus (born 1943) is a French sociologist, anthropologist and political theorist. He has also written under the pseudonym Paul Sandevince. Lazarus is a Professor at the Paris 8 University.

Sylvain Lazarus worked out a theory of the social function of political categorizations (cf. The Anthropology of the Name, 1996), exploring in the anthropological field what his Lacanian friends Alain Badiou (Being and Event, 1988) and Jean-Claude Milner (The Indistinct Names, 1983) worked out, respectively, in the fields of philosophy, of linguistics and of psychoanalytic theory.

Lazarus's 1996 book 'Anthropologie du nom' (The Anthropology of the Name) has not yet been translated into English. It was discussed at length by Alain Badiou in his Abrégé de Métapolitique (1998), now translated into English as Metapolitics (2005).

Following the student uprisings of May 1968 in France, Lazarus was a founding member of the Union des communistes de France marxiste-léniniste (UCFml). To quote Badiou himself, the UCFml is "the Maoist organization established in late 1969 by Natacha Michel, Sylvain Lazarus, myself and a fair number of young people". Fifteen year's later, Lazarus was a founding member (along with Badiou and Michel) of the militant French political organisation "L'Organisation Politique" which called itself a post-party organization concerned with direct popular intervention in a wide range of issues (including immigration, labor, and housing). In addition to numerous writings and interventions since the 1980s, L'Organisation Politique has stressed the importance of developing political prescriptions concerning undocumented migrants (in France referred to as les sans papiers) and stresses that they must be conceived primarily as workers and not immigrants.

Alain Badiou (French pronunciation: [alɛ̃ badju]  (listen) (help·info); born 17 January 1937 in Rabat, Morocco) is a French philosopher, professor at European Graduate School, formerly chair of Philosophy at the École Normale Supérieure (ENS).

Badiou has written about the concepts of being, truth and the subject in a way that, he claims, is neither postmodern nor simply a repetition of modernity. Politically, Badiou is committed to the far left, and to the communist tradition.

Slavoj Žižek has written of Badiou that he is "a figure like Plato or Hegel walk[ing] here among us".

Badiou was a student at the Lycée Louis-Le-Grand and then the Ecole 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".