Collective decision-making is studied from a theoretical perspective by Jean-François Laslier and Antonin Macé. The enquiry includes the study of voting rules in small groups (committees) as well as in large and very large groups, and thus involves political theory. The purely theoretical aspects are accompanied by experiments. Recent studies developed at PSE treat approval voting and evaluation voting, storable votes and proportional representation.
A particularly interesting case is that of a collective reduced to just two people. There, the question is about two-person bargaining and the resolution of conflict, such as during divorce.
The formal theory of deliberation is Franz Dietrich’s speciality: how can we model mathematically the ways in which opinions change during arguments? From a more applied perspective, a PSE team comprising Bénédicte Apouey, Thomas Douenne, Adrien Fabre, Fanny Henriet, Jean-François Laslier, Antonin Macé and Katheline Schubert, analyse the French Citizens’ Convention on Climate.
The notion of economic justice is used in current research into criteria for making collective choices, to be applied to long-term problems such as climate change. These delicate questions are linked on the one hand to the uncertainty of the future and on the other to the rights of absent people (i.e. future generations). Marc Fleurbaey and Stéphane Zuber are specialists in this field and in questions that touch on economic and social philosophy.