Majority favorite criterion

The majority favorite criterion is a winner-takes-all voting system criterion that says that, if only one candidate is ranked first by a over 50% of voters, that candidate must win.^[1]

Some methods that comply with this criterion include any Condorcet method, instant-runoff voting, Bucklin voting, plurality voting, and approval voting.

The criterion was originally defined only for methods based on ranked ballots, so while ranked systems such as Borda fail the criterion under any definition, its application to methods that give weight to preference strength is disputed, as is the desirability of satisfying such a criterion (see tyranny of the majority).^[2]^[3]^[4]

The mutual majority criterion is a generalized form of the criterion meant to account for when the majority prefers multiple candidates above all others; voting methods which pass majority but fail mutual majority can encourage all but one of the majority's preferred candidates to drop out in order to ensure one of the majority-preferred candidates wins, creating a spoiler effect.^[5]

^ Pennock, Ronald; Chapman, John W. (1977). Due Process: Nomos XVIII. NYU Press. p. 266. ISBN 9780814765692. if there is some single alternative which is ranked first by a majority of voters, we shall say there exists a majority will in favor of that alternative, according to the absolute majority (AM) criterion.
^ Beatty, Harry (1973). "Voting Rules and Coordination Problems". The Methodological Unity of Science. Theory and Decision Library. Springer, Dordrecht. pp. 155–189. doi:10.1007/978-94-010-2667-3_9. ISBN 9789027704047. This is true even if the members of the majority are relatively indifferent among a, b and c while the members of the minority have an intense preference for b over a. So the objection can be made that plurality or majority voting allows a diffident majority to have its way against an intense minority.
^ Hillinger, Claude (2006-05-15). "The Case for Utilitarian Voting". Homo Oeconomicus. Rochester, NY: Social Science Research Network. SSRN 878008.
^ Lippman, David. "Voting Theory" (PDF). Math in Society. Borda count is sometimes described as a consensus-based voting system, since it can sometimes choose a more broadly acceptable option over the one with majority support.
^ Kondratev, Aleksei Y.; Nesterov, Alexander S. (2020). "Measuring Majority Power and Veto Power of Voting Rules". Public Choice. 183 (1–2): 187–210. arXiv:1811.06739. doi:10.1007/s11127-019-00697-1. S2CID 53670198.

[1] Pennock, Ronald; Chapman, John W. (1977). Due Process: Nomos XVIII. NYU Press. p. 266. ISBN 9780814765692. if there is some single alternative which is ranked first by a majority of voters, we shall say there exists a majority will in favor of that alternative, according to the absolute majority (AM) criterion.

[2] Beatty, Harry (1973). "Voting Rules and Coordination Problems". The Methodological Unity of Science. Theory and Decision Library. Springer, Dordrecht. pp. 155–189. doi:10.1007/978-94-010-2667-3_9. ISBN 9789027704047. This is true even if the members of the majority are relatively indifferent among a, b and c while the members of the minority have an intense preference for b over a. So the objection can be made that plurality or majority voting allows a diffident majority to have its way against an intense minority.

[3] Hillinger, Claude (2006-05-15). "The Case for Utilitarian Voting". Homo Oeconomicus. Rochester, NY: Social Science Research Network. SSRN 878008.

[4] Lippman, David. "Voting Theory" (PDF). Math in Society. Borda count is sometimes described as a consensus-based voting system, since it can sometimes choose a more broadly acceptable option over the one with majority support.

[5] Kondratev, Aleksei Y.; Nesterov, Alexander S. (2020). "Measuring Majority Power and Veto Power of Voting Rules". Public Choice. 183 (1–2): 187–210. arXiv:1811.06739. doi:10.1007/s11127-019-00697-1. S2CID 53670198.

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