[EM] C/D is persistent. Another Approval C/D mitigation. IRV and sincerity.

MIKE OSSIPOFF nkklrp at hotmail.com
Tue Feb 28 11:47:21 PST 2012


It seems to me that the co-operation/defection (C/D) problem is more difficult to truly eliminate
than I'd believed. Hugely reducible, but maybe not eliminatable.

The methods that I've been suggesting, to get rid of the C/D problem--I'll refer to those as 
"defection-resistant" methods. They include AOC, MTAOC, MCAOC, AOCBucklin, AC, MTAC,
MCAC, ACBudklin, MMT, GMAT, and ICT.

It seems to me that all of the defection-resistant methods that I know of which meet FBC 
still allow another C/D problem, with burial. Of course the mechanism differs with different
methods, but they all seem to have that burial C/D problem.

For example, with the conditional methods, the burial takes the form that Jameson described.

But, for one thing, as I said, the burial can backfire, in the conditional methods, just as it
can in the pairwise-count methods. 

Besides, unlike pairwise-count methods, the conditional methods have no such thing as 
truncation offensive strategy.

I don't know, but it may well be that, in principle, strictly-speaking the new C/D problem,
with the defection, is the same as the old one. But there's a big and important difference:

It requires the drastic offensive strategy of burial. Burial is much less likely, more culpable, and
better-deterred than mere truncation or non-support.

So I still claim that the defection-resistant methods are a big improvement. I still claim that
they're the only significant improvement over Approval, and that there's no point proposing
or using something more complicated than ordinary Approval, unless it's defection-

Maybe someone could show that the C/D problem can't be entirely eliminated with a
FBC-complying nonprobalistic ballots-only method. Defection-resistant, yes. Defection-proof,

Another Approval C/D mitigation:

This isn't anything new, but I just haven't mentioned it before:

Actual elections are different from examples, such as the Approval bad-example (ABE). When there's going to be an actual
Approval election (ordinary non-conditional Approval), people will know what the supporters of other
candidates are saying about their candidate. You'll know if they're going to vote for hir. In fact that
matter could be made explicit during a campaign. There could be an agreement that the supporters
of 2 candidates, or members of 2 factions, will vote for eachothers' candidate. Or it could be declared
that they won't.

So Approval's C/D problem is exaggerated by the Approval bad-example.

But I still claim that AOC would be better, and that, in general, the defection-resistant methods would
be better.

Still, Approval looks quite adequate and merit-possessing, as a first proposal. I don't think that there's any
reason to propose anything other than Approval, as a first proposal. For me, there's no question about what
voting system should be proposed: Approval.

IRV with sincere voting:

Though I don't like FairVote's dishonesty, I must agree with something that they've claimed:

Sincere voting is an ok strategy in IRV. But that doesn't mean that people will vote sincerely.
I hasten to add that we know that voters are overly 
compromise-prone, and that they _won't_ vote sincerely. We can't not take that into consideration when
proposing a voting system. At least if the method is Approval, no one will fail to fully support for their
favorite. I'm not saying that IRV would be as good a proposal as Approval.

But, for sincere voters, IRV wouldn't be so bad. As you know, it meets the Mutual Majority Criterion (MMC). 
A mutual majority has nothing to fear when voting sincerely. One of their candidates will win.

Maybe you're not in a mutual majority, and the supporters of your needed compromise will bottom-rank your
favorite, and so, when Compromise gets eliminated, due to your not top-ranking hir, Worst will win.

That's why I earlier suggested, and still suggest for that situation, ranking the _acceptable_ candidates
in order of their winnability. The key word is _acceptable_. The problem is that voters who are resigned to
compromise tend to be willing to compromise their hopes away too readily.

So, in IRV, advise people to rank sincerely, because a mutual majority can't lose that way.

And advise them that if they're not in a mutual majority, even then, they should reserve their compromise-
high-ranking only for acceptable candidates. And they should be very particular what they deem acceptable.
They shouldn't give up their hopes. They should rank the genuinely acceptable candidates over all the others.
...no matter what they think the winnabilities are. Do that, and IRV would be ok.

Mike Ossipoff

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