Fuzzy social choice: a selective retrospect

One of the founders of social choice theory, Marquis de Condorcet, assigned truth degrees to propositions expressing preferences over options. Although his work is often discussed in terms of probability theory, it is arguable that his truth degree lends itself to a more natural interpretation as a fuzzy preference. We shall review some of Condorcet’s results in the light of this interpretation. The first twentieth century applications of fuzzy concepts to social choice appeared rather shortly after the introduction by L. A. Zadeh of the concept of fuzzy binary relation in early 1970s. The early applications dealt with experimental anomalies and their accountability with the aid of fuzzy preference relations and fuzzy goal states. Considerable literature now exists on various solution concepts in fuzzy voting games and many important theorems of traditional social choice theory have found their counterpart in fuzzy social choice. The natural next step would seem to be the design of fuzzy mechanisms and institutions.