# [EM] : Chicken problem (was: SODA and the Condorcet

Jameson Quinn jameson.quinn at gmail.com
Sun Aug 7 15:28:01 PDT 2011

```2011/8/7 <fsimmons at pcc.edu>

> To sum up my point of view suppose that the candidates publicly announce
> the respective preferences
> (with levels of support shown):
>
> 48 A
> 27 C>B
> 25 B
>
>
I'm going to cut you off right there. Although the rest of what you say
includes interesting points, I'd like to tell you how I envisioned solving
this.

C has some way of saying to B, before voting occurs: "Either include me in
your preference order, or I won't include you." At that point, whether B and
C are bluffing is obvious before voters have to vote.

> We cannot tell from these ballots alone if B is bluffing or if B really
> despises A and C equally.
>
> If the decision is made only on the basis of these ballots, then the right
> decision for the case when B is
> bluffing will be the wrong decision for the case when B is not bluffing, so
> no method that relies on the
> ballots alone will solve the problem.
>
> But if C is allowed to play before B, and C strongly believes that B is
> bluffing, then C can "bullet."
>
> If C is right, then B will approve C also, and C will win.  If C is wrong,
> then A will win.
>
> Under actual conditions it is very unlikely that C is going to guess
> wrongly as to whether or not B is
> bluffing.
>
> SODA allows C to play before B, so the problem is basically solved, as long
> as B is allowed to approve
> someone that she did not rank on her ballot, or else as long as there is a
> very strong incentive for B to
> rank significant preferences.
>

Despite the fix above, this situation could still conceivably happen (if C
backed down from the "you'd better approve me or else" bluff). It might be
nice if there were some way to complete B's preference rankings so that they
can approve C. But I don't want to make it possible for any candidate to
approve anyone unapproved; I think that is too likely to lead to candidates
just not declaring any preferences, and also significantly weakens the "your
vote won't elect someone you despise" guarantee.

So, how to do it? My previous proposal would allow A to approve C (and thus
resolve the chicken problem, if they cared to), but would only allow B to
approve A.

Hmmm... I think I like my fixes better than Forest's, but I'm not sure that
there isn't some other possible fix that beats them both. Maybe, only allow
C full kingmaker powers between unapproved candidates, if C has already
lost? That would still keep A from non-chicken-related meddling...

I'll sleep on it.

JQ

>
> I've been thinking that perhaps we should allow candidtes to approve
> candidates that they did not rank
> ahead of time, as long as they also approve all candidates that they did
> rank in that case.
>
> This would allow a candidate to back down when their bluff was called.
>
> Would the candidates then just rank themselves in the pre-election public
> rankings so that they would
> have free reign when it came to approval designations?
>
> I don't thnk so, because there are other dynamics that make it advantageous
> for them to commit to
> ranking their significant preferences ahead of time, especially when there
> is no chicken standoff, but
> even in that case as well.
>
> Am I misjudging this orI over-looking a worse problem?
>
>
>
> ----- Original Message -----
> From: Jameson Quinn
> Date: Saturday, August 6, 2011 4:04 pm
> Subject: Re: [EM] : Chicken problem (was: SODA and the Condorcet
> To: fsimmons at pcc.edu
> Cc: election-methods at lists.electorama.com
>
> > 2011/8/6
> >
> > > Jan,
> > >
> > > IRV elects C like all of the other methods if the B faction doesn't
> > > truncate. But IRV elects A when the B
> > > faction truncates. Of course, with this knowledge, the B
> > faction isn't
> > > likely to truncate, and as you say C
> > > will be elected.
> > >
> > > The trouble with IRV is that in the other scenario when the B
> > faction> truncates sincerely because of
> > > detesting both A and C, IRV still elects A instead of B.
> > >
> >
> > Also, if the A faction votes A>B, then B clearly should win, but
> > does not
> > under IRV. So yes, IRV solves the chicken dilemma, but in so
> > doing causes
> > other problems. (This same argument, as it happens, works
> > against tree-based
> > methods.)
> >
> > I still claim that SODA is the only system I know of that can
> > solve the
> > chicken dilemma without over-solving it and making other problems.
> >
>
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