DP13316 Equitable Voting Rules

Author(s):	Laurent Bartholdi, Wade Hann-Caruthers, Maya Josyula, Omer Tamuz, Leeat Yariv
Publication Date:	November 2018
Keyword(s):	equity, Finite Groups, May's Theorem, Social Choice, Voting rules
JEL(s):	C60, D71, D72
Programme Areas:	Public Economics, Industrial Organization
Link to this Page:	cepr.org/active/publications/discussion_papers/dp.php?dpno=13316

A celebrated result in social choice is May's Theorem (May, 1952), providing the foundation for majority rule. May's crucial assumption of symmetry, often thought of as a procedural equity requirement, is violated by many choice procedures that grant voters identical roles. We show that a modification of May's symmetry assumption allows for a far richer set of rules that still treat voters equally, but have minimal winning coalitions comprising a vanishing fraction of the population. We conclude that procedural fairness can coexist with the empowerment of a small minority of individuals. Methodologically, we introduce techniques from discrete mathematics and illustrate their usefulness for the analysis of social choice questions.