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

fsimmons at pcc.edu fsimmons at pcc.edu
Sun Aug 7 14:57:58 PDT 2011

```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

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.

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.
>

```