This entry highlights the contribution to sociological theory of the work of Cornelius Castoriadis (1922–1997), the Greco‐French philosopher, economist, psychoanalyst, and post‐Marxist revolutionary. After growing up amid dictatorship and war in Greece, Castoriadis went to study philosophy in Paris, cofounding the libertarian‐socialist group and journal
Socialisme ou Barbarie
(1949–1967), many of whose ideas influenced the 1968 worker‐student uprising. As the journal's editor, Castoriadis initiated a series of thoroughgoing internal critiques of Marxist orthodoxy, advocating worker's self‐management, which he expanded into the radically democratic “project of human autonomy.” Castoriadis's mature work (exemplified in
The Imaginary Institution of Society
), propounds an original ontology of indeterminate creativity to anchor his interdisciplinary and revolutionary critique of contemporary capitalist societies, offering a coherent alternative to both foundationalist social science and poststructural relativism. The interdisciplinary and political activist character of Castoriadis's writing has meant a slow reception in sociology but his conception of society as the contested institution of collective imaginaries in action has much to offer sociology's interpretive social action perspectives and critical theory. More recently, it has informed critical research in fields as diverse as sexual assault, civilizational analysis, urban social movements, aged care and mental health, disability, and the sociology of education.