2012/1/9 David L Wetzell <[email protected]> > ---------- Forwarded message ---------- >> From: Jameson Quinn <[email protected]> >> To: EM <[email protected]> >> Cc: >> Date: Sun, 8 Jan 2012 19:03:29 -0600 >> Subject: [EM] A problem with IRV3/AV3 >> Imagine a scenario of an ABCD one-dimensional continuum: >> >> 41: A>B>C >> 19: B>A>C >> 20: B>C>D >> 20: C>B>D >> >> If the A voters vote A>>D then A will win. By raising the turkey D over >> the true CW B, they have stolen the win. Even if their strategy fails to >> keep B out of the top 3, they lose nothing; B will still win. >> > > thanks for doing this. In the first stage wouldn't B and C tie for 3rd > place if only the first set of voters all voted strategically together in > the same way? > Right, though of course it would be easy to fix that by changing some fraction of the B>A>C voters to B>A.
> They'd both get rankings from 59 of the voters. So if it came down to > a coin-toss, there'd be a 50-50 chance of the CW winning vs the 2nd place > candidate given a massive coordinated strategic vote by only a subset of > the sample (We assume none of the 3rd or 4th set of voters decide to > strategically leave off D rankings)? > >> >> To be honest, it was harder to tune this scenario than I thought it would >> be. Thus, having taken the time to write this down, I am no longer opposed >> to IRV3/AV3. (For IRV2/AV2, it's easier to get this problem. It's also >> easier to get the problem if there are clones involved, but real-world >> clones beyond 3 candidates are unlikely.) >> > > Thank you again. > > The MSM+relevant portion of the Blogosphere shd be helpful in identifying > clones in real world. > >> >> Since I'm now not opposed to IRV3/AV3, I consider it one of the 3 reforms >> (along with SODA and IRV) that would be most acceptable to incumbents, >> because it avoids the weak Condorcet winner problem. >> > > remind me what is the weak Condorcet winner problem? > A polarized electorate, 49% A, 49%B. 2% support an unknown centrist X. Now, 25% each from A and B decide, "X couldn't possibly be worse than the other side", so add a second choice, without really looking into whether X really is better or worse. Most systems would then make X win, even if they would be crushed by either in an actual runoff where the voters actually took a serious look at them. > > >> Still, it is basically just as bad as IRV for nonmonotonicity and >> spoilers; all the spoiler scenarios I consider realistic are essentially >> 3-candidate anyway. As such, I see no reason to believe that it would not >> lead to lesser-evil voting and 2-party domination, as IRV does. Since I see >> 2-party domination (as opposed to just having 2 strongest parties, a >> logical necessity) as a source of the most-serious problems with Plurality, >> I still feel that SODA is a much better option than IRV3/AV3. >> > > dlw: And our difference is that I see the near exclusive use of Plurality > voting rules as the source of my country's current evils, since it's not > hard to imagine 2 party dominated system that is a lot better. All it > takes is for there to be better checks and balances between them and for > there to be two quite different major parties plus scope for > outsiders/dissenters to express themselves via minor parties and LTPs. > > dlw > ps, I'm going to repost this on my blog. > >> >> Jameson >> > > > ---- > Election-Methods mailing list - see http://electorama.com/em for list info > >
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