Every theory of modernity must at least presuppose an implicit ontology of the social-historical. Castoriadis is one of the few who makes these presuppositions explicit. Castoriadis’s socio-cultural ontology reveals that the essentially indeterminate nature of the social-historical entails ontological plurality, in the face of which monological or unilinear theories of modernity collapse — leaving us with a fragmented field of tensions. Castoriadis’s exposition of the ontological plurality of the social-historical is one of his most important contributions to social theory — (...) but when he turns his attention to modernity, he immediately polarizes the field. The aim here is to offer some correctives to Castoriadis’s polarized depiction, primarily by teasing out tensions in his work. (shrink)