• chaogomu@lemmy.world
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    24 days ago

    https://medium.com/@Gbgrow/understanding-non-monotonicity-in-ranked-choice-voting-and-how-to-prevent-it-55ad54fdad06

    https://electionscience.org/research-hub/the-limits-of-ranked-choice-voting

    https://en.wikipedia.org/wiki/Negative_responsiveness_paradox#Specific_examples

    We’ve seen it happen in actual elections, as shown in the Wikipedia link.

    RCV is just a flawed system, which is expected for something created by a couple of guys 150+ years ago.

    • Sludgeyy@lemmy.world
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      23 days ago

      Disclaimer: I wrote this all for myself not to change your mind or argue. Helps if I write down my thoughts and I don’t see a problem sharing. Feel free to discuss if you like.

      35 voters: Alice > Carol > Bob

      35 voters: Bob > Carol > Alice

      30 voters: Carol > Alice > Bob

      Vs.

      41 voters: Alice > Carol > Bob

      29 voters: Bob > Carol > Alice

      30 voters: Carol > Alice > Bob

      Alice wins

      Vs.

      Carol wins

      Say you have:

      41 voters: Republican > Third-party > Democratic

      29 voters: Third-party > Democratic > Republican

      30 voters: Democratic > Third-party > Republican

      If those 29 voters couldn’t vote Third-party they would vote Democratic. So when the Third-party candidate is knocked out, their votes should favor their second pick. Democratic wins 59-41.

      If it was:

      41 voters: Republican > Third-party > Democratic

      29 voters: Third-party > Republican > Democratic

      30 voters: Democratic > Third-party > Republican

      Which makes more since on why the 6 votes moved to Republican because Republican was their second choice.

      Then Republicans win 70-30.

      In America you’d have 4 basic senarios

      25 voters: Republican > Third-party > Democratic

      25 voters: Third-party > Democratic > Republican

      25 voters: Third-party > Republican > Democratic

      25 voters: Democratic > Third-party > Republican

      In RCV, Third-party wins.

      Let’s say this

      30 voters: Republican > Third-party > Democratic

      25 voters: Third-party > Democratic > Republican

      20 voters: Third-party > Republican > Democratic

      25 voters: Democratic > Third-party > Republican

      Third-party still wins

      40 voters: Republican > Third-party > Democratic

      10 voters: Third-party > Democratic > Republican

      10 voters: Third-party > Republican > Democratic

      40 voters: Democratic > Third-party > Republican

      It would be a tie

      45 voters: Republican > Third-party > Democratic

      10 voters: Third-party > Democratic > Republican

      5 voters: Third-party > Republican > Democratic

      40 voters: Democratic > Third-party > Republican

      It would still be a tie

      45 voters: Republican > Third-party > Democratic

      5 voters: Third-party > Democratic > Republican

      10 voters: Third-party > Republican > Democratic

      40 voters: Democratic > Third-party > Republican

      Republicans win

      Let’s change it to this:

      35 voters: Alice > Carol > Bob

      35 voters: Bob > Alice > Carol

      30 voters: Carol > Alice > Bob

      Vs.

      41 voters: Alice > Carol > Bob

      29 voters: Bob > Alice > Carol

      30 voters: Carol > Alice > Bob

      Alice wins

      Vs.

      Alice wins

      They couldn’t make their whole point if you just switched Alice and Carol. And it makes much more sense that someone with Alice second would change it to Alice first.

      But when 29 votes still hold Alice as last, it does have some weight.

      Something just seems off about it and it’s because they cherry picked a senario that would work for their point.

      Alice > Carol > Bob

      Alice > Bob > Carol

      Bob > Alice > Carol

      Bob > Carol > Alice

      Carol > Alice > Bob

      Carol > Bob > Alice

      There are 6 ways to vote and they leave out half of them. Then they make Carol supporters favor Alice as their second choice.

      20 voters: Alice > Carol > Bob

      15 voters: Alice > Bob > Carol

      15 voters: Bob > Alice > Carol

      20 voters: Bob > Carol > Alice

      20 voters: Carol > Alice > Bob

      10 voters: Carol > Bob > Alice

      Carol eliminated, +10 Bob +20 Alice. Alice would win.

      If 5 voters from Bob > Alice > Carol were moved to Alice > Bob > Carol

      20 voters: Alice > Carol > Bob

      20 voters: Alice > Bob > Carol

      10 voters: Bob > Alice > Carol

      20 voters: Bob > Carol > Alice

      20 voters: Carol > Alice > Bob

      10 voters: Carol > Bob > Alice

      Alice would win

      What if everyone from Bob > Alice > Carol moved to vote for Alice > Bob > Carol

      20 voters: Alice > Carol > Bob

      30 voters: Alice > Bob > Carol

      0 voters: Bob > Alice > Carol

      20 voters: Bob > Carol > Alice

      20 voters: Carol > Alice > Bob

      10 voters: Carol > Bob > Alice

      It would be a tie.

      In bold are the three they selected:

      20 voters: Alice > Carol > Bob

      15 voters: Alice > Bob > Carol

      15 voters: Bob > Alice > Carol

      20 voters: Bob > Carol > Alice

      10 voters: Carol > Alice > Bob

      20 voters: Carol > Bob > Alice

      5 voters from Bob > Carol > Alice moved to Alice > Carol > Bob. Just like their example.

      26 voters: Alice > Carol > Bob

      15 voters: Alice > Bob > Carol

      15 voters: Bob > Alice > Carol

      14 voters: Bob > Carol > Alice

      10 voters: Carol > Alice > Bob

      20 voters: Carol > Bob > Alice

      Alice 41

      Bob 28

      Carol 30

      Bob is eliminated.

      15 votes goes to Alice. 14 goes to Carol.

      Alice still wins.

      But they set it up like:

      20 voters: Alice > Carol > Bob

      15 voters: Alice > Bob > Carol

      0 voters: Bob > Alice > Carol

      35 voters: Bob > Carol > Alice

      10 voters: Carol > Alice > Bob

      20 voters: Carol > Bob > Alice

      5 voters from Bob > Carol > Alice moved to Alice > Carol > Bob. Just like their example.

      26 voters: Alice > Carol > Bob

      15 voters: Alice > Bob > Carol

      0 voters: Bob > Alice > Carol

      29 voters: Bob > Carol > Alice

      10 voters: Carol > Alice > Bob

      20 voters: Carol > Bob > Alice

      Then when Bob is eliminated all 29 votes go to Carol.

      Then they say “It’s unfair that Carol wins”. When in reality those 29 people would prefer Carol over Alice.

      RCV might have some flaws but that article has some flaws.

      I haven’t looked at the others. I might later.

      Edit:Formatting

      • chaogomu@lemmy.world
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        23 days ago

        The first article is from someone who wants to save RCV, despite that one flaw that they’ve drilled into.

        The problem is that it’s a known attack vector, the Wikipedia article talks about how it was used intentionally by a political party in 2005 in Germany to effectively steal an additional seat in their parliament.

        My second link is a deeper dive into more of RCV’s many flaws. Because why stop at monotonicity? Seriously, the fact that increasing support can cause a candidate to lose, and not just lose but elect the worst choice, is insane.

        That fact that there are more flaws, just as game breaking, means we should all follow the example of the Marquis de Condorcet, the guy who invented RCV, abandoned it because he saw how broken it was.

        Then you have the lying liars at FairVote saying that the Condorcet criterion doesn’t matter in elections.

        The Condorcet criterion is that if you were to hold a series of one on one elections between all candidates, the winner of those should be the same winner of your election system. RCV fails this in most elections, which is why Condorcet abandoned it.

        It wasn’t until about 30 years after Condorcet’s death that an Englishman revived the voting method, but added a proportional twist. It still had all the flaws that Condorcet wrote about, but Condorcet was French, and lost the political games of the French Revolution, so he was mostly ignored.

        As a side note, the political writings of Condorcet should be required reading. The guy wrote this in 1790

        ‘The rights of men stem exclusively from the fact that they are sentient beings, capable of acquiring moral ideas and of reasoning upon them. Since women have the same qualities, they necessarily also have the same rights. Either no member of the human race has any true rights, or else they all have the same ones; and anyone who votes against the rights of another, whatever his religion, colour or sex, automatically forfeits his own.’

    • dan@upvote.au
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      23 days ago

      Thanks for the links. I appreciate it! Now I understand the issue.