Instant-runoff voting: Difference between revisions

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== Notes ==

IRV can rather simply be thought of as a modification to [[Choose-one FPTP voting|choose-one FPTP voting]] to pass the [[Mutual majority criterion|mutual majority criterion]] (and further, always elect from the [[Dominant mutual third set|dominant mutual third set]]). This is because when all but one of the candidates in the mutual majority-preferred set of candidates is eliminated, the remaining candidate will guaranteeably be the majority's 1st choice among the remaining candidates and thus win.

IRV can rather simply be thought of as a modification to [[Choose-one FPTP voting|choose-one FPTP voting]] to pass the [[Mutual majority criterion|mutual majority criterion]] (and further, always elect from the [[Dominant mutual third set|dominant mutual third set]]). This is because when all but one of the candidates in the mutual majority-preferred set of candidates is eliminated, the remaining candidate will guaranteeably be the majority's 1st choice among the remaining candidates and thus win. Example:

18 A>B>C

17 B>C>A

16 C>A>B

25 D>E>B

24 E>D>B

In normal [[runoff voting]], D and E are the two candidates with the most votes, preventing the majority's preferred candidates from entering the runoff. In FPTP, D has the most votes. But with IRV, first C is eliminated, and then E, and then B, resulting in A having 51 votes and winning. Note that though the 49 voter-minority preferred B to A, B didn't win; this is an example of IRV ignoring voter preferences in a way that can lead to some majorities (when looking at [[Head-to-head matchup|head-to-head matchups]]) having less power. However, the majority still got a better result than it would've had in some other methods.

One simple way to modify IRV to address many of the issues IRV opponents have without changing IRV fundamentally is to allow voters to approve candidates (using an [[approval threshold]]). If there are any majority-approved candidates, elect the most-approved of them, otherwise run IRV. Even if voters [[Favorite Betrayal|Favorite Betray]], they can still approve their honest favorite, giving that candidate a chance to still win. In addition, this allows voters to better avert the [[center squeeze effect]]. The standard argument made by IRV advocates against [[Approval voting]], that it fails [[later-no-harm]], has little to no relevance to this modification, since voters seeking to avoid hurting their favorite candidates' chances of winning in the approval round can simply refrain from approving anyone, forcing the election to run under IRV rules.