Ever since Sen crystallized the logical conflict between the welfaristic value of the Pareto principle and the nonwelfaristic value of individual libertarian rights into what he christened the impossibility of a Paretian liberal , there have been many attempts in social choice theory to...

Fuzzy set theory has been explicitly introduced to deal with vagueness and ambiguity. One can also use probability theory or techniques borrowed from philosophical logic. In this chapter, we consider fuzzy preferences and we survey the literature on aggregation of fuzzy preferences. We restrict...

A competitive market mechanism is a prominent example of a nonbinary social choice rule, typically defined for a special class of economic environments in which each social state is an economic allocation of private goods, and individuals’ preferences concern only their own personal...

Any procedure of social choice makes use of some types of information and ignores others. For example, the method of majority decision concentrates on people's votes, but pays no direct attention to, say, their social standings, or their prosperity or penury, or even the intensities of their...