It deals with the evolution of philosophical problems in contemporary times, that is, from the crisis opened by the emergence of the masses in politics in 1848. He studies four critical moments and the thought they generate. 1. The crisis of 1848 and the bourgeois hopes. 2. The Crisis of 1871 and Mass Industrialization 3. The Crisis of the Interwar: An Open World 4. Post-war thinking: an inflection not yet closed.