[EM] Steve Eppley's Just-In-Time Withdrawal (JITW)

[Raph Frank]

On Fri, Jan 11, 2013 at 5:19 AM, Michael Ossipoff
<email9648742 at gmail.com> wrote:
> In a 3-candidate Condorcet cycle, for any pair of candidates, only one
> of those could elect the other by withdrawing. If the other withdrew,
> that would elect the 3rd candidate.

Fair enough, I was thinking of IRV (or Asset), but looks like it
doesn't apply to IRV.

> Suppose the method is IRV, with JITW. Say the candidates are a Green,
> a Democrat, and a Republican.
>
> Most or all Dem preferrers would rank Repub 2nd, because Dem & Repub
> are incomparably closer to eachother than either is to Green.

If you assume that a majority prefer both major parties to the 3rd
party, then obviously one should win.

> There's no chicken dilemma there either.

You are assuming centre squeeze.  That pretty much only happens to a
minor party.

Anyway, you make a good point, the chicken dilemma doesn't seem to
apply to IRV.  Maybe it might still happen in more complex situations,
but not with 3 candidates.

>> However, I am not entirely convinced that candidates would put their
>> voters first in such a situation.
>
> If not, then they could kiss their political career goodbye.

I was thinking of the chicken situation, so if that doesn't apply,
withdrawal would have no disadvantages to candidate.

The only reason would be that they want an easier shot at the seat
next time.  They don't want an incumbent with similar views, but that
would be harder to explain to the voters.

>> This is also a problem with Asset voting.
>
> Well, with Asset, or (better) with Approval or Score with optional
> delegation, there could, and often would, be negotiation among the
> candidates, to decide the placement of delegated votes. It might work
> well.

Chicken can definitely happen with Asset, especially if the voters
vote directly for candidates (or more accurately, if proxies can vote
for themselves).

>> Maybe the withdrawal decision could be taken by someone other than the
>> candidate themselves.
>
> Maybe, but the candidate would be responsive to hir voters' wishes,
> and would, in fact, likely share them.

If there is no chicken, then no big deal.

> If someone wins by 1st-count majority, then there'd be no need for
> anyone to withdraw.

Right.