[EM] Election-Methods Digest, Vol 234, Issue 13

[Sass]

I think you're overcomplicating it. The question to ask is about
incentives. In public elections, voters (and candidates) will follow the
incentives. For public elections under a Condorcet method, by far the
strongest incentive is to vote honestly.

On Fri, Jan 12, 2024 at 2:06 PM Kristofer Munsterhjelm <km_elmet at t-online.de>
wrote:

> On 2024-01-12 19:45, Sass wrote:
> >  > as of now I don't think anyone has much evidence for what will happen
> > in practice.
> >
> > I think we do. We have the full ballot data on 448 RCV elections in the
> > US from this century. Only one did not have a Condorcet Winner. Even if
> > you reduce the set to elections with three competitive candidates
> > (defined as elections where the candidate with the third most first
> > choices has at least half as many as the candidate with the most), it's
> > still only 1 in 88, which could easily become 1 in 880 over time. If
> > elections with no Condorcet Winner are that unlikely, then by far the
> > strongest incentive for voters is to vote honestly as a rule. And we
> > know from RCV that voters are inclined to vote honestly under new
> > systems until the system backfires on them.
>
> I think the problem is one of predicting how voters may alter their
> behavior when the circumstances change. Consider these possible
> descriptions:
>
> - Voters always vote in a way that there's a majority candidate. If so,
> FPTP is sufficient.
>
> - Voters always vote in a way that there's a number of no-hope fringe
> candidates as well as a mutual majority set containing clones of what
> would otherwise be a majority candidate. If so, IRV is sufficient.
>
> - Voters always vote in a way that there's a Condorcet winner, possibly
> with spurious cycles from noise. If so, any Condorcet method will
> suffice, and Condorcet cycles can be handled like ordinary ties, by a
> coin toss or whatnot.
>
> - Voters' honest distributions will always have a Condorcet winner but
> they may strategize, or be told to strategize by the candidates. If so,
> strategy resistance is more important.
>
> - Voters will vote for multiple viable candidates if the method doesn't
> have too strong incentives to exit, and politics may evolve to be
> multidimensional, in which case honest cycles would appear. Then just
> how the Condorcet method deals with cycles would be important, as would
> robust clone independence (i.e. clone independence that generalizes to
> JGA's incentives to exit and entry).
>
> - Voters have an absolute utility scale and would use it if they can,
> making distinctions beyond ranking. If so, we may need rated methods.
> (Or if a relative scale, something that normalizes rated ballots and treats
>
> etc.
>
> It's difficult to say ahead of time which of these are right. An
> argument to the extent that "we have n elections and none of these have
> shown behavior beyond the kth of these descriptions" has a flaw in that
> they are all under the context of the current method.
>
> But we at least know that the first two descriptions are false. It *is*
> possible to say "ah, those two instances of center squeeze are just
> flukes" and keep going for IRV, but that seems rather iffy.
>
> I suppose my position has been a combination of trying to get things
> right the first time (hence advanced/cloneproof Condorcet methods) and
> going by my own intuition (which finds the ambiguity of honest votes in
> a non-normalized rated system a real problem that burdens even honest
> voters with tactical decisions).
>
> But I can't prove that "minmax and be there" would fail.
>
> -km
>
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