The life and politics of Martin Heidegger raise a serious question: How was one of the most important philosophers of the twentieth century willing to ally himself with Nazism and what does this mean for philosophy? Because the influence of Heidegger's thought continues to spread, we must confront him at the core of his philosophy, using the concepts of autonomy, temporality and freedom. The most important philosophical challenge to Heideggerian thought has been expressed by Cornelius Castoriadis. This vital new study outlines the Castoriadian philosophy of time in contrast to the Heideggerian and highlights the main points of their opposition. It deals with both philosophers? concepts and arguments around human existence, the individual, society, and temporality, extending to consider transformative contemporary phenomena like space exploration, cyberspace and online communications. The book revives the public debate around philosophy and politics, illuminating the importance of critical philosophical and political thinking.