English

Axioms for Defeat in Democratic Elections

Theoretical Economics 2023-10-16 v4 Computer Science and Game Theory Multiagent Systems

Abstract

We propose six axioms concerning when one candidate should defeat another in a democratic election involving two or more candidates. Five of the axioms are widely satisfied by known voting procedures. The sixth axiom is a weakening of Kenneth Arrow's famous condition of the Independence of Irrelevant Alternatives (IIA). We call this weakening Coherent IIA. We prove that the five axioms plus Coherent IIA single out a method of determining defeats studied in our recent work: Split Cycle. In particular, Split Cycle provides the most resolute definition of defeat among any satisfying the six axioms for democratic defeat. In addition, we analyze how Split Cycle escapes Arrow's Impossibility Theorem and related impossibility results.

Keywords

Cite

@article{arxiv.2008.08451,
  title  = {Axioms for Defeat in Democratic Elections},
  author = {Wesley H. Holliday and Eric Pacuit},
  journal= {arXiv preprint arXiv:2008.08451},
  year   = {2023}
}

Comments

Added missing edges in first graph in Remark 4.10