In advancing the political project of autonomy, Castoriadis raises the fundamental question: what ought we to think? Following an interpretation of his elucidation of the connections between time, history, and the groundlessness of the world and society, this study argues for a broadening of Castoriadis's question, something which enables attention, not just to the subject matter of thinking, but also its form and the thinker's situatedness. While Castoriadis's insights may be usefully deployed both to expose the limits of inherited thought, which privileges the power of receiving meaning and value over creation and creativity, and to explore the interaction between politics and philosophy, his own approach may well represent the other equally problematic side of the Platonic tradition he criticizes. Consequently, Castoriadis's notions of radical democratic subjectivity and autonomous thinking, both of which respond to the 'ought' question, may inadvertently conform to a mode of being that can do no more than protest the dominant formalism characterising the modern Western world. At the core of this limitation lies a decisive issue for philosophy: whether the enactment of thinking is informed by the historical irruption and retreat of the visionary collective.