In 2002, he created the group «The Republic of Ideas», which he chairs. In 1978, he took charge of the Sociology department at the Travail et Societé centre created by Jacques Delors at the University of Paris-Dauphine. Since 1978, he has been Professor at the École des Hautes Etudes en Science Sociales and Director of Studies, a position he still holds. Since the 1990s, he has devoted himself to documenting the intellectual history of democracy in France. In 2001, he was appointed Professor at the Collège de France.