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...

I Preliminaries: Introduction -- Abstract Social Choiuce Problems and Concrete Resource Allocation Problems -- Describing an Allocation Problem: a Checklist -- II Axiom Types: Axiom Format -- Axiom Content: Delineating Broad Categories -- Axiom Content: Punctual Requirements on Welfare...