[EM] My summary of the recent discussion

[Juho Laatu]

As promised, here's a short summary of my findings in the recent lengthy email chain that discussed Approval, Condorecet and Plurality reform.

1) There was a proposal to replace the Plurality method with a compromise seeking single-winner method (e.g. Approval, Condorcet) in a two-party country. The reform would keep the single-member districts to elect representatives of the representative bodies. This proposal is unorthodox in the sense that it does not fall into the two traditional categories, two-party systems and proportional representation. The proposal is simple and therefore maybe an easy start. Time would tell how this kind of a "centrist representation oriented" system would change the dynamics of the political system.

2) Approval method and its strategies were once more discussed. My understanding is simply that Approval works quite fine as long as there are only one or two winnable candidates, but when there are three or more, the method pretty much fails since voters will have very hard time trying to find any reasonable way to vote. I made one case study of a problematic situation in http://lists.electorama.com/pipermail/election-methods-electorama.com/2012-May/030437.html.

3) Mike Ossipoff presented a Condorcet strategy that is supposed to work in all Condorcet elections. The best description of the strategy that I got is: "if there are winnable unacceptable candidates and winnable acceptable candidates, find that winnable acceptable candidate that is most likely to win all the unacceptable candidates, and rank him alone at top". Terms "acceptable" and "unacceptable" refer simply to a larger than marginal preference gap between those candidate groups. In theory voters might be happy to bury their favourites if they have no chance to win in this election. And in theory not burying one's favourite might in some situations lead to a loop that would make the outcome worse from the voter's point of view. I analyzed this problem in one example case and concluded that in practical elections this strategy does not seem to pay off and therefore should not be followed. Further proposals of working Condorcet strategies that regular voters could implement and that are beneficial to them are welcome. As long as nobody presents such working strategies, sIncere strategy should be considered to be the best and recommended strategy for practical Condorcet elections. http://lists.electorama.com/pipermail/election-methods-electorama.com/2012-May/030482.html

In the discussions I wanted to make a clear distinction between theoretical vulnerabilities and practical vulnerabilities. A theoretical vulnerability means that there exists a set of sincere votes that can be modified (by one strategist with access to all the votes) so that the winner will change to a candidate that the strategic voters prefer to the sincere winner. This concept is still very far from a practical vulnerability, that requires a clear description of a strategy that can be implemented successfully in typical real life elections by normal voters, based on incomplete and conflicting poll information, continuously changing opinions, with possible other competing strategies, and that is likely to improve the outcome, and not be too risky.

I also presented one additional strategy for Approval elections. That was just a sidetrack, but in case anyone is interested in how major parties could/should defend their strong position in Approval elections, here is a link. http://lists.electorama.com/pipermail/election-methods-electorama.com/2012-May/030472.html

Juho




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