Monotonicity criterion: Difference between revisions
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:''If an alternative X loses, and the ballots are changed only by placing X in lower positions, without changing the relative position of other candidates, then X must still lose.'' |
:''If an alternative X loses, and the ballots are changed only by placing X in lower positions, without changing the relative position of other candidates, then X must still lose.'' |
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This criterion is also called '''Mono-raise'''. |
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A looser way of phrasing this is that in a non-monotonic system, voting for a candidate can cause that candidate to lose. Systems which fail the monotonicity criterion suffer a form of [[tactical voting]] where voters might try to elect their candidate by voting against that candidate. |
A looser way of phrasing this is that in a non-monotonic system, voting for a candidate can cause that candidate to lose. Systems which fail the monotonicity criterion suffer a form of [[tactical voting]] where voters might try to elect their candidate by voting against that candidate. |
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[[Plurality voting]], [[Majority Choice Approval]], [[Borda count]], [[Cloneproof Schwartz Sequential Dropping]], |
[[Plurality voting]], [[Majority Choice Approval]], [[Borda count]], [[Cloneproof Schwartz Sequential Dropping]], [[Maximize Affirmed Majorities]], and [[Descending Solid Coalitions]] are monotonic, while [[Coombs' method]] and [[Instant-runoff voting]] are not. [[Approval voting]] is monotonic, using a slightly different definition, because it is not a preferential system: you can never help a candidate by not voting for them. |
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''Some parts of this article are derived from text at http://condorcet.org/emr/criteria.shtml'' |
''Some parts of this article are derived from text at http://condorcet.org/emr/criteria.shtml'' |
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