[EM] (3) MJ -- The easiest method to 'tolerate'

[Brian Olson]

Could someone add a writeup of Majority Judgement to the wiki?
http://wiki.electorama.com/wiki/Category:Single-winner_voting_systems

On Thu, Sep 22, 2016 at 5:23 AM, Kristofer Munsterhjelm <
km_elmet at t-online.de> wrote:

> On 09/22/2016 03:38 AM, Jameson Quinn wrote:
> >
> >
> > 2016-09-21 18:59 GMT-04:00 Kristofer Munsterhjelm <km_elmet at t-online.de
> > <mailto:km_elmet at t-online.de>>:
> >
> >     On 09/06/2016 01:29 AM, Jameson Quinn wrote:
> >     >     ...
> >     >     If that's true, then there's some kind of threshold of number
> of grades,
> >     >     below which there aren't enough grades for the ballot format to
> >     >     encourage grading against a common standard. So three-slot
> methods would
> >     >     have to be tested to see if voters would vote grading-style or
> >     >     relative-rank style with three grades, or if three grades are
> still
> >     >     too few.
> >     >
> >     >
> >     > Personally, I'd guess that three would be enough. I think the four
> most
> >     > common voting heuristics, in descending order, would be:
> >     >
> >     > First, as I've said: approve of one, disqualify greater evil among
> the
> >     > frontrunners and any evils greater still.
> >     >
> >     > Second: Approve of one, disqualify both frontrunners.
> >     >
> >     > Third: if one side of the left-right divide got used to habitually
> >     > losing, the centrists among them might begin to extend approval
> all the
> >     > way to the most-centrist on the other side.
> >     >
> >     > Fourth: Approve of one, disqualify unqualified/unserious
> candidates.
> >     >
> >     > Any of the heuristics above would tend to lead to a "successful"
> >     > resolution of the Chicken Dilemma.
> >
> >     That's kind of going into the domain of "manual DSV", though, which
> I'm
> >     not as much a fan of. MJ has this going for it that there are ways
> for
> >     honest voters to vote as long as the categories are well-defined.
> >     Approval is a *lot* muddier, because it's much less certain that
> honest
> >     voters can divide the candidates into "I like these" and "I
> definitely
> >     don't like these". Three-slot methods could work if the heuristics
> are
> >     common and intuitive enough, but they're kind of in-between MJ's
> >     expressiveness and having Approval's manual DSV needs.
> >
> >
> > Median-based methods, especially those which break ties using
> > above-median votes, can do well with chicken dilemma scenarios. The
> > flipside of this is that in order to handle center-squeeze scenarios,
> > they require the voters who favor the centrist CW to put all other
> > candidates below the winning median; for safety, at bottom-rating.
> >
> > I think that's somewhat plausible as a naive strategy ("Since I'm
> > Center, I think Left and Right are equally bad, so even though I don't
> > hate them as much as they hate each other, I might as well put both of
> > them at bottom rank"). I also think that when Center voters don't so
> > strategize, the outcome is not too bad; generally, that will tend to be
> > in cases where Center might even have lost a score election, and the
> > candidate who beats Center might even be the utility winner or at least
> > close to it.
> >
> > But yes, there is this much "manual" strategy necessary, and I don't see
> > any way around it. I think a system can't be robust to strategy in both
> > Chicken and Center Squeeze scenarios, and I'd rather get Chicken right
> > in spite of some strategy (and thus not encourage strategies which, when
> > over-applied, can end up electing the CL) instead of getting Center
> > Squeeze right without any strategy.
>
> Do you think there's a way to formalize vulnerability to center squeeze?
> I imagine there would be two criteria:
>
> - No center squeeze outright (e.g. IRV)
> - No center squeeze with strategy
>
> And I suppose for the latter, you *could* make a rather heavyhanded
> criterion saying something like: if C is center and strategy can make
> not-C win but not make C win, then it's vulnerable to strategic center
> squeeze...
>
> but that doesn't feel very elegant. Any ideas? Perhaps something
> involving votes being drawn from a spatial model so that the idea of
> "center" is relatively apparent?
>
> The point is that if we had a formal model, I could check what methods
> pass the criterion (or often pass it), and then see if there's anything
> that both passes CD and whatever it ends up being.
>
> Do you think hybrids that use both Condorcet and positional data (like
> my fpA-fpC stub method or Benham/Woodall methods) pass both CD and
> center squeeze? They do at least elect the centrist when there is a CW.
> I guess the question would be how badly they degrade when there is no CW.
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