This book proposes a new interpretation of Claude Lefort thought focusing on his phenomenological method. Although all scholars recognize the influence of Merleau-Ponty, so far no one has demonstrated the fundamental coherence between Merleau-Ponty theory and the main concepts proposed by Lefort; in particular between the concept of institution and the definitions of social and democracy. If Merleau-Ponty uses the idea of institution to think beyond the division between subject and object, to think together continuity and difference, permanence and change, this same concept allows Lefort to understand society as both conflict and unity. From this starting point, this study will attempt to clarify Lefort concept of the political and his interpretations of modernity, humanism, and the work of Niccolò Machiavelli. These very concepts will show the difference from structuralism, Michel Foucault contemporary theory and theories of immanence. At the same time this study highlightsan internal tension in Lefort own thinking: between autonomy and experience, institution and insurgence.