[EM] SSD vs Tideman

[MIKE OSSIPOFF]

Another thing that I didn't mention, that results from differences in
how much the 2 methods overrule voters, is their difference in social
utility. In SU simulations, SSD does noticibly better than Tideman,
because SSD does less overruling of voters. Because SSD tries to
minimize how defeated the winner is more than Tideman does. Tideman
has its other goals of making a transitive ordering, while minimizing
how many defeats it drops in order to do so, and those goals conflict
with the goal of minimizing how defeated the winner is. I'm not saying
that SSD puts that goal absolutely first, but SSD is less distracted
from it than Tideman is.

Social utility, then, is a compelling advantage of SSD over Tideman.

Then there's the fact that, in small committee votes, Tideman will
sometimes embarrass us by choosing outside the Schwartz set. Not
a serious problem, but definitely an aesthetic gaffe.

Anyway, I don't think it's possible to say that there's a candidate
who's the best, in an absolute sense. You're assuming that there
is such a candidate, and that the candidates all have some genuine
absolute merit ordering, and that the method should try to say what
it is. I don't agree that there's such a thing as absolute merit, for
the purpose of voting systems. Sure, by my standards there's absolute
merit. Nader was incomparably better than Gore or Bush in 2000, absolutely. 
Though I claim that's true, others might disagree, and
so, when it comes to voting systems, if someone says "best", we have
to say "best for whom". Maybe different candidates are genuinely best
for different people. Maybe voters believe in absolute merit, but
they disagree on ordering the candidates by it. Then how can the
voting system be expected to do right in terms of absolute merit, when
absolute merit is radically different from different people's points
of view. There _is_ no absolute best or absolute merit ranking from
the larger electionwide point of view, even though there absolute merit
for you or for me.

And a point that I was making last year was that, if you want to
measure for merit, judged by how liked the candidates are, then
it would be better to measure that by Borda, instead of by a method
that can have a cycle of betterness. Borda's absolute score of how
many individual preference votes vote a particular candidate over
other candidates is more direct.

I'm not suggesting Borda for public elections.

Mike Ossipoff


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