On 04/09/2012 11:31 PM, MIKE OSSIPOFF wrote:
I've said seemingly contradictory things about IRV. It's particularly flagrant FBC failure makes it entirely inadequate for public political elections, more so than Condorcet, which, too, is inadequate due to FBC failure.
You keep saying anything without FBC is automatically a no-go. How do you know that? Condorcet elections seem to work well where they're used: in the Pirate Parties, in Debian, on Wikimedia, and in smaller organizations (see the Wikipedia article on the Schulze method for more).
IRV's compromise problem is particularly bad. In a Burlington scenario, the voters (and/or parties) immediately know they didn't compromise well enough. In contrast, that doesn't happen in Condorcet, because it picks the CW.
I suppose you could argue I'm making the same mistake as the IRVists. The IRVists say "oh, we need a way of not making small third parties get in the way of the major parties - here's a fix". You might argue I'm saying "oh, we need a way of the method not messing up when third parties get reasonably large - here's a fix, in the form of Condorcet compliance". But if I'm just proposing a fix and the fix isn't substantial, then we should be seeing backsliding from Condorcet where it's used, and I don't know of any such.
And I also said that IRV would be a fine method, were it not for the public's inclination towards resigned, cowed overcompromise, and their very sad and disastrous lowering of standards for acceptability. "Vote for the least bad of the corrupt candidates, because they're the winnable ones".
I disagree. Look at Burlington with its center squeeze again. The Burlington voters didn't strategize (much or effectively). Yet instead of picking the candidate closest to the median voter, IRV threw that one away because it didn't have enough first-place votes and picked the largest wing instead.
Sure, it's better than Plurality. It's not as polarizing as Plurality, either, but it does have some element of polarization in picking the largest wing.
But how could IRV be alright, even with better voting? Wouldn't people wanting to maximize their expectation still favorite-bury sometimes? Sure. But if their judgement was at all reasonable, they wouldn't do so in a way that would bother me. It comes down to what one calls "acceptable". IRV's strategy in non-u/a elections would be especially complicated to describe, but it's a sure thing that it would often involve favorite-burial, to maximize a voter's expectation. Without knowing the details on how to vote (no method matches Approval's clearly-defined simple strategy, for any kind of election), voters would still do favorite-burial. As with Approval, and probably all methods, IRV's expectation-maximizing strategy is simpler in a u/a election. But that doesn't mean that it's simple enough for anyone to know what it is, exactly.
How about this zero-info: Rank all the acceptables in alphabetical order. Rank the unacceptables in random order after the acceptables. By ranking the acceptables in the same order, you focus the first preference votes on a few candidates so that compromise is maximized; by ranking the unacceptables randomly, you discourage strategy that attempts to compromise with your pattern (because there is no pattern).
If you have information, then rank the acceptables in order of first preference votes, then the unacceptables in reverse order of first preference votes. There might be better strategies that would make use of later-round data, but I think that data would be hard to come by.
If you can poll ranking data, you could in any case just do so and then use a computer to find your optimal ballot (or the optimal ballot for your coalition). For IRV, the strategy algorithm is worst-case exponential time with respect to the number of candidates, but in practice that doesn't matter. When there are loads of candidates, some will have no chance and so not contribute to making strategy harder.
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