Ariel Colonomos is a Senior Research Fellow at the CNRS and a member of the Sciences Po Center for International Studies and Research (CERI). He is a co-ordinator (with Alain Dieckhoff) of the "Mondes" book series at the Presses de Sciences Po, a member of the editorial boards of International Political Sociology and Revue des deux mondes and a regular visiting scholar at Columbia University with the Institute of War and Peace. He is the author of several publications focusing on the emergence of norms in the post-cold war era and on the role of moral entrepreneurs, including a recent study on the preventive use of force and its justification. His new research project investigates the role of predictive ideas in international relations.