Plurality criterion: Difference between revisions
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It is difficult to imagine that a method could have a good reason to elect ''B'' over ''A'' when the voters giving ''B'' any ranking at all are outnumbered by the voters who ranked ''A'' as being the best candidate. The Plurality criterion is about avoiding such unintuitive results. |
It is difficult to imagine that a method could have a good reason to elect ''B'' over ''A'' when the voters giving ''B'' any ranking at all are outnumbered by the voters who ranked ''A'' as being the best candidate. The Plurality criterion is about avoiding such unintuitive results. |
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[[Category:Voting system criteria]] |
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Revision as of 08:38, 27 March 2005
Statement of Criterion
If the number of ballots ranking A as the first preference is greater than the number of ballots on which another candidate B is given any preference, then A's probability of election must be greater than B's.
Complying Methods
First-Preference Plurality, Approval voting, IRV, and many Condorcet methods (using winning votes as defeat strength) satisfy the Plurality criterion. Condorcet methods using margins as the measure of defeat strength fail it, as does Raynaud (using either winning votes or margins as the measure of defeat strength), and also Minmax(pairwise opposition).
Commentary
It is difficult to imagine that a method could have a good reason to elect B over A when the voters giving B any ranking at all are outnumbered by the voters who ranked A as being the best candidate. The Plurality criterion is about avoiding such unintuitive results.