ON THE DIFFICULTY OF MAKING SOCIAL CHOICES

The difficulty of making social choices seems to take on two forms: on e that is related to both preferences and the method used in aggregati ng them and one which is related to the preferences only. In the forme r type the difficulty has to do with the discrepancies of outcomes res ulting from various preference aggregation methods and the computation of winners in elections. Some approaches and results which take their motivation from the computability theory are discussed. The latter 'i nstitution-free' type of difficulty pertains to solution theory of the voting games. We discuss the relationships between various solution c oncepts, e.g, uncovered set, Banks set, Copeland winners. Finally roug h sets are utilized in an effort to measure the difficulty of making s ocial choices.