Talk:Participation criterion

Mono-add-plump

User:BetterVotingAdvocacy, the restricted version of Participation that you claim IRV and Condorcet fail, "A can't be harmed by adding a vote that bullet-votes for A", is called mono-add-plump. Here's a link that shows that at least one Condorcet method passes it: [1]. I think the Minmax-y ones also do (Schulze, RP, etc). IRV passes mono-add-top, which is a stronger (more general) version of mono-add-plump, and thus also passes mono-add-plump. I don't know about STAR, but you should probably find a source given that the other two claims were wrong. I've removed the section for now. Kristomun (talk) 11:12, 13 May 2020 (UTC)

Thanks for catching this. Edit: Actually, I didn't say "A can't be hurt by adding bullet votes for A", I said the voter can't be hurt by bullet voting. So consider that in IRV and STAR, adding a bullet vote could help a voter's favorite eliminate their lesser evil, and then their favorite loses later rounds. For Condorcet, while I am not admittedly not being rigorous there, I'm sure that adding bullet votes for Favorite could similarly start a Condorcet cycle that helps elect a Greater evil. BetterVotingAdvocacy (talk) 18:37, 13 May 2020 (UTC)

Then that criterion is not a variant of Participation. Participation says "if you show up and cast a ballot that ranks X over Y, then that shouldn't change the winner from X to Y". A bullet vote for X ranks X above everybody else, so there's only a Participation violation if the outcome changes from X to someone who isn't X. Kristomun (talk) 13:38, 14 May 2020 (UTC)

Thinking about it a bit more, it seems your criterion is closer to "If a voter shows up and equal-ranks a set S of candidates at the bottom, then that shouldn't change the outcome from someone in S to someone else in S". It's a sort of "reverse no favorite betrayal". Kristomun (talk) 13:46, 14 May 2020 (UTC)

I came up with this variation because I wanted to point out that not only do many voting reforms fail Favorite Betrayal, just like FPTP, but they fail Participation even in the case where you limit your expressiveness to an FPTP-style vote, unlike FPTP. So with such methods, a plausible argument could be made that they're actually worse than FPTP (though I'm not saying that is actually true). Also, the thinking you just did is basically Irrelevance of Independent Ballots, which has been discussed at forum.electionscience.org as IIB. BetterVotingAdvocacy (talk) 18:15, 14 May 2020 (UTC)