This book is a critical exploration of the philosophical underpinnings and implications of Cornelius Castoriadis’ reflections on Being, society and the self. The book introduces the reader to the main concepts of Castoriadis’ work, but goes further to uncover the fundamental philosophical issues addressed by Castoriadis, and to critically examine the issues his work opens up, assessing and, where necessary, offering suggested amendments to the answers Castoriadis himself puts forward. Key conceptual problems addressed include the distinction between autonomy and heteronomy, the nature of the self and self-creation, and the nature of determination in a fundamentally indeterminate universe.