Somebody said: >>At the risk of repeating myself, my argument against Condorcet can be >> summarised as follows: >> >>I do not support Condorcet because I believe that in practice, >> regardless of the theoretical and conceptual advantages it may >> possess, it would be too favourable towards parties who succeed in >> positioning themselves in the centre and correspondingly >> discriminatory against wing parties.
Suppose that we have 3 candidates, and voters and candidates mostly fall along a 1D left-right spectrum. Let's call the candidates Left, Right, and Middle. Let's also assume (I'll justify this momentarily) that the 3 candidates will always maintain their relative positions. Assume (for the purposes of this model) that if somebody suddenly went to the other side, he'd lose credibility. People would compare his track record with his new stances and he'd be regarded as a liar. Given the assumption of no role-reversal, Left and Right can guarantee that Middle won't win an IRV race moving toward the middle. They don't have to land right on top of Middle, they just have to get close enough to him so they can steal first-place votes. If I'm slightly left of center, and Left is also slightly left of center, even if he's to the left of me I might prefer him to Middle as long as he isn't TOO far from Middle. This analysis suggests that, as long as most voters/issues/candidates fall along a 1D spectrum, IRV will maintain a 2-party duopoly with a weak center trying but failing to win elections. The "weak center" will have to take a very different position and make the issue space 2D. Maybe go to the left on social issues and to the right on economic issues. Or maybe turn "moderation" into its own issue: "We're the reasonable people who try to do what's right, the others are just stuck in an ideological vendetta." In any case, going 2D is the only hope for the center if we use IRV. Only then can the "third party" hope to pick up more first-place votes. By contrast, with Condorcet the middle will ALWAYS win if the issues are 1D, unless either the left or right happens to have an outright first place majority. There will always be 4 types of voters in a 3-way race: Middle>Left>Right Middle>Right>Left Left>Middle>Right Right>Middle>Left Unless Left or Right has an outright majority, the 2 Middle factions can always join with one of the "wings" to defeat the other "wing" pairwise. Left and Right desperately need to go 2D so they can persuade some people to vote Left>Right>Middle or Right>Left>Middle (at that point the labels become less meaningful, but I think everybody knows what I mean). So Condorcet gives 2 of the 3 parties an incentive to "go 2D" in this example, while IRV only gives 1 party an incentive to "go 2D" in this model. What interests me is that, based on what I hear of politics in other countries (which is admittedly not a lot), it seems like most countries have some sort of left-right division. The factions may not have the same respective stances as the American left and right, but that sort of division still seems to stand. Even PR doesn't seem to do much to cure this problem. Of course, I am quite willing (and EAGER!) to be corrected on this, to be told that my gloomy assessment is false. If in fact humans get easily trapped in 1D political molds, then maybe IRV is almost more desirable than Condorcet (commence flaming now). As long as we're 1D, there will be 2 competitive parties in IRV but Condorcet might yield single-party monopoly. So, in summary: If it's possible for cultures to break out of the 1D political stalemate then I'm enthusiastically pro-Condorcet. If it isn't possible for the most part, if fiscally conservative/socially liberal mold-breaking is impossible, then I may actually be more sympathetic to IRV than I was previously. (Commence flaming now.) Alex ---- Election-methods mailing list - see http://electorama.com/em for list info
