Mutual majority criterion
The mutual majority criterion is a criterion used to compare voting systems. It is also known as the majority criterion for solid coalitions and the generalized majority criterion. The criterion says that if a majority of voters like a group of candidates more than all of the other candidates, then one of the candidates in the group must win.[1] This is similar to, but more broad than, the majority criterion, where the group of candidates can only have one candidate in it. [2]The Droop proportionality criterion is a more broad form of the mutual majority criterion, which also applies to multi-winner elections.
The Schulze method, ranked pairs, instant-runoff voting, Nanson's method, and Bucklin voting pass this criterion. All Smith-efficient Condorcet methods pass the mutual majority criterion.[3]
The plurality vote, approval voting, range voting, the Borda count, and minimax fail this criterion.
Voting methods which pass the majority criterion but fail mutual majority can have a spoiler effect, since if a minority-preferred candidate wins, and all of the candidates preferred by the majority, except for one, leave the election, then the remaining majority-preferred candidate will win instead.
References
- ↑ Weak Mutual Majority Criterion for Voting Rules.
- ↑ Tideman, Nicolaus. Collective Decisions and Voting: The Potential for Public Choice (2006)Ashgate Publishing. ISBN 9780754647171.
- ↑ Four Condorcet-Hare Hybrid Methods for Single-Winner Elections (2011).