On Mon, 23 Aug 2004, James Green-Armytage wrote: > Has anyone clearly advanced this pro-Condorcet argument? I think that it > is devastating to methods which are not Condorcet efficient. If someone > else has made this same argument already, please let me know, so that I > can cite it in the paper I’m trying to write on weighted pairwise. > > BASIC STATEMENT: > If there is a Condorcet winner with regard to the sincere preference > rankings of voters, and the voting method is plurality, then the Vote is > only at equilibrium when the Condorcet winner is selected. > changing their vote.
Your argument implicitly relies on the assumption that half the population can coordinate a change their votes, which is very difficult, especially with secret balloting. That is why the stability of the 2-party duopoly in US presidential elections does not contradict your theorem. (I suspect that McCain pairwises beats Bush and Kerry, but he is not elected under plurality because the current scenario is stable against any small number of voters changing their votes.) I don't think this is a good argument for Condorcet since its consequences are at variance with common knowledge, because of the assumption mentioned above. Unfortunately, I'm not sure what a better definition of a voting equilibrium would be. However, I will point out that others have published about voting equilibria in some detail. Here's a reference for an article that develops an interesting definition of a voting equilibrium: Myerson, Roger B. and Robert J. Weber. 1993. "A Theory of Voting Equilibria." American Political Science Review. 87:102-114. There's also a more readable webpage (by one of the authors of the above paper) that cites that paper: http://www.kellogg.nwu.edu/faculty/weber/papers/approval.htm -wjs /-----------------------------------------\ | Warren Schudy | | WPI Class of 2005 | | Physics and computer science major | | AIM: WJSchudy email: [EMAIL PROTECTED] | | http://users.wpi.edu/~wschudy/ | \-----------------------------------------/ ---- Election-methods mailing list - see http://electorama.com/em for list info