[EM] FBC, center squeeze, and CD

[Michael Ossipoff]

Because it's so brief, let me state the conditional(u) option, for
Approval, and for Bucklin:

Approval:

If a ballot conditionally approves a candidate, then it gives an approval
to that candidate only if that vote-receiving candidate has more
unconditional approvals than does any candidate unconditionally approved by
that ballot.

Bucklin:

1. At 1st rank:

In the 1st round, if a ballot gives conditional 1st ranking to a candidate,
that 1st ranking is given only if that vote-receiving candidate is
unconditionally 1st-ranked on more ballots than is any candidate
unconditionally 1st ranked on that ballot.

2. At any rank other than 1st:

In a round, at some non-1st rank, if a ballot gives a conditional vote to a
candidate, then that ballot gives that candidate a vote in that round only
if that vote-receiving candidate has a higher vote-total (as of just before
that round) than any candidate unconditionally 1st-ranked on that ballot.

Michael Ossipoff



On Sat, Nov 5, 2016 at 3:28 PM, Michael Ossipoff <email9648742 at gmail.com>
wrote:

> 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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>> info
>>
>>
>
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