A biographical itinerary of political activism and social research during the last thirty years influences the ways politics and social sciences are carried out. The times are changing. We saw the end of modern forms of politics, the exhaustion of forms of representation and mediation. Social sciences which were born in this environment cannot survive this upheaval without being transformed. The author approached the 1980s through the lens of Marxism and of partisanship. Today, he makes the choice of an applied and political anthropology, and of an ethics of public accountability for the scientists.