[EM] [ESF #1100] Re: [RangeVoting] Scenario where IRV and Asset outperform Condorcet, Range, Bucklin, Approval.

[Jameson Quinn]

2010/5/13 Abd ul-Rahman Lomax <abd at lomaxdesign.com>

> At 10:37 PM 5/12/2010, Jameson Quinn wrote:
>
>> Look. It's a scenario. It's not totally implausible. We are blowing hot
>> air if we argue too much about how plausible it is.
>>
>
> No, I showed some aspects of the scenario that were highly implausible as
> supposed "sincere" ratings. First, what was implausible was apparent
> discontinuity in the political spectrum, so that any voter who preferred one
> of the two centrists had no preference for the extremists. That indicated
> three basic groupings, with a large gap between them. Real voters are not
> distributed like that, when an election is large-scale.
>

I repeat: "The equal-bottom of the centrists is solely to save typing. Of
course in real life the centrists would be somewhat to one side or the
other. The point is that the two centrist candidates are equally centrist,
but differ on some other dimension." In other words, each centrist voter
group would actually be two equal subgroups, a center-right and a
center-left.

Please read my responses.


> The second problem was a problem, but not so implausible. Each of the two
> extremist groups were almost evenly divided on which of the two centrist
> candidates was preferred. Yet they all had a preference. The centrists were
> shown as equal-ranking the left and right candidates, equal bottom.
>
> That indicates, from the centrist view, that the left and right are far
> away from them. The only way we identify this as a centrist party is the
> uniformity of left in ranking them above right, and right in ranking them
> above left.
>
>
>   A system that deals with it well is better than a system which doesn't,
>> all other things being equal. All other things are never equal, so it's just
>> one factor among many.
>>
>
> I'm not sure what "it" is, that's my point. From the preferences, there is
> no clear winner that is intrinsic. It seems that the best winner, though,
> would be one of the centrists, because a centrist is everyone's first or
> second choice. The question devolves, then, on which of the two centrists is
> the best choice. If they totally bullet vote, high partisan feeling is
> implied between them. Thus they are centrists only by relation to the other
> two parties. That's odd in itself.
>
> There is really only one clear problem shown by the scenario. If the
> centrists bullet vote -- which would be very odd, since neither one of them
> is a frontrunner -- one of the extremists could win. If it's a top two
> runoff (FPTP primary), the runoff could be the two extremists. That's a
> known (and real) flaw of TTR with sincere voting in the primary. But that
> flaw seems highly unlikely to surface in Bucklin, where everyone gets to
> express their sincere first preference and then add approvals queued for
> voting in the second or third round. The centrists, given their equal bottom
> rating for the left and right, would very much dislike seeing the election
> go to the extremists, so pure bullet voting seems very, very unlikely. And
> since left and right get no support from anyone else, but will clearly
> support a center candidate over the other extreme, one or the other centrist
> will likely get a majority (or both), and I showed the range of votes
> consistent with the setup. If it were top-two runoff, the most-feared
> outcome for the centrists would be for neither centrist to make it to the
> runoff, so pure bullet voting becomes very, very unlikely.
>
>
>  I am planning to one day make a program which explores how likely and how
>> severe strategic opportunities are in each system. Typifying such strategic
>> opportunities is useful prior work.
>>
>
> You could tweak Warren's simulator, IEVS is it called? It was designed to
> be heavily configurable. What "strategic opportunity" was there in this
> election that is not depending upon high knowledge? The election setup is
> extremely close. Left and right are in balance. The center candidates are
> close to each other, and every move toward bullet voting risks a very bad
> outcome.
>

"Risks a very bad outcome"... yes, that's the problem with strategy, isn't
it? But actually, in this case, there is a total amount of strategy that M
and RC can get away with. As long as fewer than half of the total of both
groups are strategic, one of them wins. And whichever of the two groups is
more strategic, will win. That's pretty close to a prisoner's dillemma
(actually, a stag hunt), and it's collective. If you've got some way that
humans can reliably avoid falling on the horns of the prisoners' dilemma,
you might have a Nobel prize there.


>
> A "strategic opportunity" is not one where it is merely *possible* that it
> improves the outcome, truly, but where it will *likely* improve the outcome.
> In order to use such an opportunity, one must know that the election can be
> moved in a desired direction without risking a larger loss.
>

Prisoners' dilemma. Actions can improve individual outcomes locally but
collectively lead to a bad outcome.

....

> This is the paradox of the "strategic" analysis of Approval Voting: it is
> often asserted that a voter "really" approves of both A and B but only votes
> for one of them for "selfish" strategic gain. However, if there is a gain,
> that must mean that the voter *really* has a preference, so, *of course* the
> voter will vote to elect one over the other! The reverse is sometimes
> asserted, that Approval fails the majority criterion because a voter may
> approve of more than one candidate while, supposedly, preferring one to
> another.
>
...

Approval strategy is always semi-honest (except in super-bizarre cases. For
instance, if there's an perfectly balanced circular tie between 3
husband/wife clone pairs, then the only feminist voter might vote for the
three women, so that her vote has a very high chance of breaking a clonal
tie, even though she actually prefers the man from her favorite clone group
over the woman from her least-favorite). But where you put your cutoff is
still strategic. And it still has the disadvantages of strategy in terms of
legitimacy, expressiveness, divisiveness, and even utility; though these
disadvantages are definitely less severe than with dishonest strategies.

JQ
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