Working Paper: CEPR ID: DP13316
Authors: Laurent Bartholdi; Wade Hann-Caruthers; Maya Josyula; Omer Tamuz; Leeat Yariv
Abstract: 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.
Keywords: voting rules; May's theorem; equity; social choice; finite groups
JEL Codes: C60; D71; D72
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| Modification of May's symmetry assumption (C62) | New voting rules (K16) |
| New voting rules (K16) | Smaller winning coalitions (D79) |
| Equitable voting rules (D72) | Smaller winning coalitions (D79) |
| No equitable voting rule (D72) | Winning coalitions of size less than n (D79) |