How should (political) candidates be elected? What are good ways of merging individual judgments into collective judgments? Social Choice Theory is the systematic study and comparison of how groups and societies can come to collective decisions.

The course offers a rigorous and comprehensive treatment of judgment and preference aggregation as well as voting theory. It is divided into two parts. The first part deals with (general binary) aggregation theory and builds towards a general impossibility result that has the famous Arrow theorem as a corollary. The second part treats voting theory. Among other things, it includes prooving the Gibbard-Satterthwaite theorem.

Main texts:

• Hervé Moulin: Axioms of Cooperative Decision Making, Cambridge University Press, 1988
• Christian List and Clemens Puppe: Judgement Aggregation. A survey, in: Handbook of rational & social choice, P.Anand,P.Pattanaik, C.Puppe (Eds.), Oxford University Press 2009.

Secondary texts:

• Amartya Sen: Collective Choice and Social Welfare, Holden-Day, 1970
• Wulf Gaertner: A Primer in Social Choice Theory, revised edition, Oxford University Press, 2009
• Wulf Gaertner: Domain Conditions in Social Choice Theory, Oxford University Press, 2001