[EM] FBC, center squeeze, and CD

Sat Nov 5 12:28:49 PDT 2016

Hi Jameson--

The choice among the 3 goals you name is a subjective choice, with no wrong
choice of goal.

So we can amicably prefer differfent goal-choices & different solutions to
achieve them.

To me, FBC is essential.

 ...because...

1.  Many people won't consider not fully helping some compromise (maybe a
really odious "compromise" like Hillary).  At least let them also fully
support their favorite, and other better candidates when doing so.

2. Because of the importance of the strong top-set, and maybe the ordinary
top-set too, it's important to always allow the option of fkully-effective
strategically optimal approval-votilng, equal top rating or ranking.

#1 applies mostly just to current conditions. #2 applies in any conditions.

As you said, reliably electing the CWs (& in rank-methods, the CWv) is
incompatible with FBC. Therefore I reject the Condorcet Crirerion (CC) as a
goal. As you or Chris mentioned, the center-squeeze concern is closely
related to CC.

It's possible to get CD & FBC. Therefore, a genuinely _best_ method should
have both.

Because MMPO must reluctantly be abandoned (Chris finally convinced me)
because of its "Hitler with 2 votes" problem, then:

The best methods are Conditional Approval & Conditional(u) Bucklin.

...But I repeat that the choice among your 3 goals is subjective and
individual, and that there's no wrong choice. I'm just stating my own
choice.

Of course, for a first proposal, for a first reform from Plurality, brief
definition is essential. Also, the easiest possible implementation, without
any new balloting-equipment or software, might be advantageous, making
Approval the best first proposal.

But, if people want rankings (and many do, and many likely need them, to
soften their voting-errors), then Bucklin has the advantage of relative
brevity, and use-precedence.

Or, if new balloting & software is feasible (as would be necessary for
Bucklin, then Conditional Approval could be considered.

Conditional(u) Bucklin, adding some to the definition-length of Bucklin,
might or might not be publicly acceptable, by the public's brevity-standard.

Michael Ossipoff

On Sat, Nov 5, 2016 at 2:32 PM, Jameson Quinn <jameson.quinn at gmail.com>
wrote:

> We've had some productive discussions recently about methods that attempt
> to deal with FBC, center squeeze, and chicken dilemma. (Note that "deal
> with chicken dilemma" could mean one of two things: punish betrayal, or
> avoid a slippery slope. There are differing opinions as to which of these
> is better.)
>
> But there is a fundamental tension between these three characteristics.
> After all, center squeeze is really just a special case of the Condorcet
> criterion; and FBC and Condorcet are well-known to be incompatible.
>
> Why are those two things incompatible? Because in a Condorcet cycle, with
> a Condorcet-compliant voting system, if the other two groups vote honestly,
> then your faction can guarantee electing your second choice by betraying
> your favorite. So if you expect your least-favorite to win, betrayal is
> strategically forced.
>
> Essentially, in a cycle of 3, sticking with your favorite is a signal for
> the group who likes your second favorite and hates your favorite that your
> favorite is a threat, and they'd better compromise because you're unwilling
> to.
>
> My various recent proposals have tried to thread this needle in different
> ways:
>
> MAS gets FBC, no-slippery-slope CD, and (with some explicit strategy)
> center squeeze, by having two middle ranks: an upper level to signal
> willingness to compromise even with a smaller faction (as in center
> squeeze), and a lower level to signal the idea that you expect the larger
> faction to be correct (as in chicken dilemma).
>
> PAR gets no-slippery-slope CD, strategy-free center squeeze, and comes
> close to (but fails to reach) FBC, by automating the strategic choice for
> middle votes. Unfortunately, that makes it too close to
> Condorcet-compliant, so that FBC breaks.
>
> PAR-prime is basically the same compromise as PAR, but slightly extends
> the cases where center squeeze works, at the cost of a bit more complexity
> of description.
>
> QQQ gets FBC, no-slippery-slope CD, and handles the more clear-cut cases
> of center squeeze, at the cost of EXTREME complexity of description, by
> barely sipping the strategic information from other votes, so that the
> drops of strategic information that your vote leaks to opposing factions
> can be equalled by an ideal FBC-compliant ballot.
>
> Other proposals (ICT, IBIFA, conditional approval, etc.) have other
> interesting attempts to resolve this trilemma.
>
> Essentially, if you have a method that deals with center squeeze and
> no-slippery-slope CD, then there are two possibilities. Either it will be
> using some kind of hard threshold to decide which is which, in which case
> it's possible to make scenarios which will fall on the wrong side of the
> threshold naturally, and in which there could be subgroups whose only way
> to fix things would be favorite betrayal; or it will be resolving things by
> placing the strategic burden on the voters.
>
> One idea which I'd like to explore, but haven't managed to make work
> (yet?), is that of "patching FBC". For instance: take a sysem like PAR or
> PAR-prime, and restore FBC by making some way to cast a ballot that
> essentially says "these are my true preferences, but I realize that in
> order to get the best outcome I may have to help deep-six my true
> favorite". Since the true favorite would still be at the top, and since the
> "help eliminate my favorite" would only kick in if it actually helped, this
> would technically restore FBC.
>
> Another avenue that might be useful is to develop some weakened FBC
> criterion. For instance: "If the other ballots combined with your true
> preferences do not include a Condorcet cycle, there is always a
> strategically-optimal semi-honest ballot". In other words, if there isn't
> an honest CC, there's no motive to create a false one. I'd call this
> criterion "non-paradoxical semi-honesty". This is not exactly strictly
> weaker than FBC, but in practice it mostly is; most FBC-compliant methods
> would pass this criterion. But are there any non-FBC methods which meet it?
>
> ....
>
> OK, here's a proposal. It's PAR-like, it solves the same problem as
> PAR-prime does, but it may be technically FBC compliant:
>
>
>    1. Voters can Prefer, Accept, or Reject each candidate. Default is
>    Accept. For each candidate they prefer, they may also check a "secret"
>    checkbox.
>    2. Candidates with a majority of Reject, or with under 25% Prefer, are
>    eliminated, unless that would eliminate all candidates.
>    3. Candidates with a majority of (public reject plus secret prefer),
>    or with under 25% public prefer are given the label "supposedly
>    eliminated", unless all candidates would be "supposedly eliminated".
>    4. Each candidate gets a point for each ballot where they don't fall
>    below any non-supposedly-eliminated candidates. Most points wins.
>
>
> I think this may meet FBC, if you count secret preference as a kind of
> preference. Basically secret preference is a way of saying "I think I may
> be on the losing wing of a center-squeeze situation, but that the opposite
> wing may not be eliminated. Thus, I want the other voters on my wing to be
> ready to compromise, even if our candidate is apparently viable."
>
> This has all the good characteristics of PAR, except for the additional
> complexity it brings.
>
> Secret preference would not be a favored strategy in any simple 3-faction
> scenario; in fact, I think that it requires a minimum of 4 factions AND 4
> "meaningful" candidates (candidates without whom some ballots would not be
> using the full ratings range). If no candidate can be alone at bottom-rank
> unless they're alone at top rank for some faction, it may even take at
> least 5 factions before "secret" is ever a factor.
>
> In other words: secret preference is only a hacked-up patch to restore
> FBC, and not something that I think would be strategically useful in real
> life.
>
> ...
>
>
>
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