True preferences: 49: C>B 27: A>C 24: B>C
Clearly, C is the correct winner here, by a lot. And A is worst, again, by a lot. Actual votes under MMPO or MDDTR: 49: C (Truncating out of overconfident laziness, not strategy) 27: A>B (strategy) 24: B A wins. Bad result. And please don't tell me I'm not allowed to talk about this scenario because it doesn't meet your criterion. Jameson 2011/11/17 MIKE OSSIPOFF <[email protected]> > > Chris said: > > Mike refers to this scenario: > > > The Approval bad-example is an example of that. I'll give it again here: > > > > Sincere preferences: > > > > 49: C > > 27: A>B > > > 24: B>A > > > > A majority _equally strongly_ prefer A and B to C. > > > > > > Actual votes: > > > > The A voters defect, in order to take advantage of the > > co-operativeness and > > > responsibility of the A voters: > > > > 49: C > > 27: A>B > > 24: B > > > > I agree that *if* the sincere preferences are as Mike specifies then a > just interventionist mind-reading God > > should award the election to A. > > [endquote] > > Fine. But can Chris say what's wrong with that outcome in other instances? > > Chris continued: > > But a voting method's decisions and philosophical justification should > > be based on information that is actually > on the ballots, not on some guess or arbitrary assumption about some > maybe-existing "information" that isn't. > > [endquote] > > Why? Why shouldn't a voting system avoid a worst-case, if, by so doing, > > it hasn't been shown to act seriously wrongly in other cases? > > And MMPO & MDDTR don't just bring improvement in the Approval bad-example. > They, > in general, get rid of any strategy dilemma regarding whether you should > middle-rate > > a lesser-evil instead of bottom-rating hir. For instance, consider the > A 100, B 15, C 0 utility example. > > In MCA, there's a question about whether you should middle-rate or > bottom-rate B. In > MDDTR and MMPO, that dilemma is completely eliminated. > > In those methods, middle rating someone can never help hir against your > favorite(s). > > Chris continues: > > I think a very reasonable tenet is that if, based on the information on > the ballots, candidate X utterly dominates > > candidate Y then we should not elect Y. > > [endquote] > > Yes, there are many reasonable tenets among the aesthetic criteria. > > Chris continues: > > For several reasons (for those who can pooh-pooh this as "merely > > aesthetic"): electing Y gives the supporters > of X a very strong post-election complaint with no common-sense or > philosophically cogent answer, X is highly > likely to be higher Social Utility (SU), Y's victory will have > > compromised legitimacy. > > [endquote] > > Wait a minute. These candidates in this example are A, B, and C. > > How does A lack legitimacy? Among the candidates not majority-defeated, A > has more favoriteness-supporters than any other candidate. > > Chris continues: > > The Plurality criterion is one very reasonable criterion that says that > C is so much stronger than A that the election > of A can't be justified. . > > [endquote] > > There are lots of aesthetic criteria that say things like that, and they all > sound > > aesthetically reasonable. How great is their practical strategic importance? > > > Chris continued: > > There are other criteria I find reasonable > that say the same thing: > > "Strong Minimal Defense": If the number of ballots on which both X is > > voted above bottom and Y isn't is greater than > the total number of ballots on which Y is voted above bottom, then don't > elect Y. > > [endquote] > > But can you word that in such a way that it isn't met by Plurality? > > What sort of strategic guarantees are protected by the criteria > that you propose in this posting? > > Chis continues: > > The election of A is unacceptable because C's domination of A is > vastly more impressive than A's pairwise win over > > B. The Plurality criterion plus the three other criteria I define above > all loudly say "not A". > > [endquote] > > In other words, it looks bad from those perspectives. > > The election of A is justified by its being consistent with FBC, SFC or SFC3, > > freedom from dilemma about middle-rating a compromise, and either > Later-No-Harm or non"failure" in Kevin's MMPO bad-example. --things that are > guaranteed by MMPO and MDDTR. > > Additionally, as I was showing to Jameson, electing A in these methods > > isn't really wrong. > > > > > The A voters defect, in order to take advantage of the > > co-operativeness and > > responsibility of the A voters: > > Chris replies: > > The plausibility of arbitrary claims about the voters' sincere > > preferences and motivations > > [endquote] > > More a matter of "what if", rather than claims. > > Chris continued: > > can weighed in the light of the > used election method's incentives. How is it so "co-operative and > > responsible" of the A voters to rank B when doing > so (versus truncating) can only help their favourite? > > [endquote] > > It's co-operative because it defeats the candidate commonly disliked by A > voters and B voters, in MCA, MDDTR and MMPO. > > If neither did that, C would win. > > If the A voters refused to, and, instead, the B voters co-operated, then it > would > be B would win, by being the defectors. > > Chris continues: > > And why would the > > B voters be insincerely truncating ("defecting") > when doing so can only harm their favourite? > > [endquote] > > In MCA that defection could give their favorite the win, if the A voters have > co-operated, in spite of the A voters being more numerous. > > In MPPO or MDDTR, the problem doesn't exist. The A voters can co-operate or > defect, and A will still win, having more top ratings. Hardly a controversial > result. > > Chris continues: > > Given the incentives of the MDD,TR method that Mike is advocating, it is > > only reasonable to assume that the truncators > are all sincere > > [endquote] > > Wait a minute: I'm not saying that B truncation is a problem in MDDTR or > MMPO. In fact, > my point is that it is _not_. But co-operaton/defection is indeed a problem > in MCA. > > Hency my advocacy of MDDTR and MMPO. > > > ---- > Election-Methods mailing list - see http://electorama.com/em for list info > >
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