Hybrid Invariance and Oligarchic Structures

摘要

This study addresses the problem of Arrovian preference aggregation. Social rationality plays a crucial rolernin the standard Arrovian framework. However, no assumptions on social rationality are imposed here. Socialrnpreferences are allowed to be any binary relation (possibly incomplete and intransitive). We introduce the axiomrnof hybrid invariance, which requires that if social preferences under two preference profiles make the samernjudgment, then a social preference under a “hybrid” of the two profiles must extend the original judgment inrna certain way. Then, we characterize the structure of decisive coalitions under hybrid invariance.