Jon Elster is Professor of Rationalit� et sciences sociales at College de France, and Robert K. Merton Professor of Social Sciences at Columbia University. He is author of Closing the Books: Transitional Justice in Historical Perspective .
Peter Hedstr�m is Professor of Sociology and Fellow of Nuffield College, Oxford. He has published numerous articles in leading academic journals and is co-author of Social Mechanisms (CUP 1998) with R. Swedberg.