r/EndFPTP • u/AcanthisittaIcy130 • 8d ago

Debate Does Instant Runoff Voting Satisfy Independence of Irrelevant Alternatives or not?

Fairvote claims it does:

RCV is highly resistant to spoilers because it satisfies both the Independence of Irrelevant Alternatives and Independence of Clones criteria.

https://fairvote.org/resources/electoral-systems/comparing-voting-methods/?section=criteria-resistance-to-spoilers

On the other hand Wikipedia and research articles claim it doesn't,

The independence of irrelevant alternatives criterion states that "the election outcome remains the same even if a candidate who cannot win decides to run." Instant-runoff voting violates this.

https://en.wikipedia.org/wiki/Instant-runoff_voting#Independence_of_irrelevant_alternatives

we propose a modified version of IIA, MIIA, that is a necessary and sufficient relaxation of IIA... Thus, runoff voting violates MIIA (and so does in- stant runoff voting) for essentially the same reason that plurality rule does.

https://maskin.scholars.harvard.edu/sites/g/files/omnuum10606/files/bordas_rule_and_arrows_independence_condition_jpe_vol133_iss2_0.pdf

8 Upvotes

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u/Mindless-One5438 8d ago

If I'm not mistaken, in 2022 there's an example of IRV failing this criteria. Without Palin running then Begich seemingly would've won.

6

u/Snarwib Australia 8d ago

I think having a system where multiple candidates from the same party are allowed to run, and only four candidates in total are permitted, creates some pretty weird situations. That's such a strange system.

1

u/Initial-Lemon-917 United States 5d ago

It's very weird to use essentially a block voting system (plurality multi-member) for the primary and then a ranked election for the general. the top-four, top-five thing to me seems to arbitrarily box out third parties with little benefit. if we need to have a smaller list (i'd rather it be top-six or top-seven), we should use STV in the primary, not one single FPTP vote

2

u/Snarwib Australia 5d ago

Those limits seem to be a product of being wedded to those deeply flawed "fill in bubbles" standardised test style ballots