[EM] What Approval guarantees to those uninterestred in strategy

[MIKE OSSIPOFF]

Chris Benham asked me that question, and I pointed asked him what strategy 
guarantees he wants for people uninterested in strategy. Of course there are 
other kinds of guarantees too, and Approval does offer those, even to people 
uninterested in strategy.

Say that, instead of voting strategically, people just vote for the 
candidates who are acceptable, or deserving. Then Approval guarantees that 
the winner will be the candidate who is acceptable or deserving to the most 
people. What other kind of guarantee do you want for someone uninterested in 
strategy, presumably because s/he is uninterested in maximizing hir 
expectation. For hir, that overall social optimization is enough.

But Approval offers social opimization guarantees to voters uninterested in 
strategy (and to voters who are interested in strategy) even if the other 
voters are strategizing to maximize expectation:

Then, if it's 0-info, Approval guarantees that the winner will be the 
candidate who is above the mean for the most voters. If it isn't 0-info, 
then Approval guarantees (with some reasonable approximations) that the 
winner will be the candidate whom the most voters consider so good that 
they'd rather have hir in office than hold the election.  These social 
optimizations are demonstrated at our website, 
http://www.electionmethods.org  at the Approval Strategy pages.

The first of those 2 guarantees is actually a special case of the 2nd one.

Approval also does much better by social utility than IRV does.

These considerations, along with FBC, are the reasons why some say that 
Approval is better than the best rank methods. That of course is an 
individual judgement, and I agree with the importance and desirability of 
those considerations, though I personally prefer SFC, GSFC, & SDSC, 
available with the best Condorcet versions, or at least SFC, available with 
PC. Or SFC & SDSC., available with PC with AERLO.

As for Approval vs ERIRV(fractional), I don't  have a very strong opinion on 
that issue, because, as I said, SFC is the criterion that I like the most, 
and it isn't met by ERIRV.

Unlike unmitigated IRV, ERIRV's MMC & ICC compliance are usable in 
comparisons with Approval. And ERIRV avoids the co-operation/defection 
dilemma that James described. I don't think that dilemma is as important as 
he does, but it's still somewhat important. And, with AERLO, ERIRV meets 
SDSC.

I'm not saying that's conclusive proof that ERIRV is better than Approval. 
There's no definite answer to that, of course. They're both good. It depends 
on what you want. It's a question of FBC & the social oiptimizations vs the  
ERIRV advantages stated above. I like the criteria that ERIRV brings, though 
it isn't nearly as good as PC, it seems to me. I tend to prefer ERIRV's 
advantages to those of Approval, but that's just a personal subjective 
opiniion.

Mike Ossipoff



Mike Ossipoff

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