[EM] Chicken Dilemma--To whom is it a problem?

[Michael Ossipoff]

Just a few more words about a previous topic. Maybe a few things I've
already said, but with additional things, and different emphasis:

When I first proposed SDSC, I did so because it's something that the
best wv Condorcet methods offer, and i wanted to name that desirable
property, so that I could say which methods have it.

Beatpath and Ranked-Pairs meet SDSC. Kevin, your 2nd example shows
that IRV, Benham and Woodall don't meet SDSC.

It's a desirabe property, but it can't be called a _necessary_
property. A failure of SDSC isn't an _outrage_.  A failure of the
harder-to-fail, easier-to-meet Mutual Majority Criteion is an outrage.
Here is a majority of the voters, all supporting eachother's
candidates...and they lose?

As for why SDSC-failure isn't an outrage, look at candidate B's
win-qualifications, in your 2nd example:

The B voters want B to be elected by a majority coalition that they
don't support. They have no right to expect anything from that
non-existent majority coalition.

B isn't CW. There is no voted CW. If the B voters are sincere in their
truncation, there's no sincere CW either.

Maybe SDSC can be advocated for the rights of the A voters to support
B to defeat C.

Sure, and that's SDSC's justification. Probably, ideally, even a
1-sided "coalition", like the one in your 2nd example, should have the
power to defeat C. When I introduced SDSC, it was because I considered
the defeat of the despised to be the important thing. That's why you
ike SDSC too.

But a 1-sided coalition is a questionable thing. It can and will be
abused. A _mutual_ majority coalition is solid and fully legitimate.
That's why Woodall called his votes-only MMC "Majority for Solid
Coalitions".

Sure, ideally, on paper, SDSC looks good. Regrettablly, human nature
spoils its on-paper merit...and thereby spoils the on-paper perfection
of Ranked-Pairs and Beatpath for the Green scenario.

And that is regrettable, because I like Ranked-Pairs and Beatpath for
their elegant pairwise-based choice, and for SDSC. When something is
so good theoretically, it's natural to want to ignore what would
actually happen in real elections. (I acknowledge that Beatpath has
proven its adequacy for organizations that don't have favorite-burial
need or chicken dilemma).

I don't know if MMC,CD, CC and SDSC are compatible. Probably not,
because I don't know of a method that meets them all.

I don't know of a method that meets MMC, CD and FBC either. That
combination, too, is probably incopatible.

Your 2nd example shows that CD, SDSC and Plurality are incompatible. I
don't consider Plurality to be important, except maybe as a somethng
that could be use by heavily-funded opponents, making it into
something that it isn't.

Michael Ossipoff










On Thu, Oct 17, 2013 at 10:36 PM, Kevin Venzke <stepjak at yahoo.fr> wrote:
> Hi Mike,
>
> First, regarding the CD criterion and SDSC: They are, it seems
> to me, almost totally incompatible. Not just incidentally but
> even in their philosophical approach to the situation. This is
> why CD makes me skittish.
>
> CD says that when the votes look like this, and A is the winner:
>
> 26 A>B
> 25 B>A
> 49 C
>
> Then in this election, B cannot be the winner:
>
> 26 A>B
> 25 B
> 49 C
>
> "Votes-only" versions of SDSC say that C can't win. So if we
> were to satisfy both CD and SDSC we would only be able to
>
> elect A (and I wouldn't see that as viable for a proposal
>
> personally).
>
>
> In the scenario where B voters truncate, SDSC essentially
>
> wants to find a majority (even hidden beneath the unviable
> A preferences) and count it if possible. This is similar in
> spirit to FBC because it means that the A voters can defeat
> C while still expressing their support for A. It doesn't
>
> harm B.
>
> But CD looks at this scenario and concludes that somebody
> deserves a beating, and the only way to do it is to punish both
> A and B voters.
>
> My concern is that I think scenario #2 is likely in the
> "near term" (given adoption of a rank method), and that it is
> likely sincere, or at least not intentionally insincere.
>
>
>
>
> ----- Mail original -----
>> De : Michael Ossipoff <email9648742 at gmail.com>
>>>  Sure. If they can enact a system that ensures they always have
>>>  incentive to vote as a mutual majority, then they don't have any
>>>  need of e.g. SDSC.
>>>
>>>  But this is a long ways off.
>>
>>>  Isn't there a sense in which it's
>>>  "more realistic," as you say above, to be concerned about whether
>>>  methods satisfy SDSC, or other criteria which could be useful to
>>>  parties that can't win in the short term but want to at least
>>>  collect their share of the votes?
>>
>> I haven't evaluated by SDSC for quite a while. I used to apply it to
>> compare some wv Condorcet methods to other methods, but I don't know
>> how Benham & Woodall do by it.
>>
>> I'm not saying that I have a monopoly on saying what's practical.
>> You're referring to a time before there is a progressive majority,
>> right?
>>
>
> Yes.
>
>>
>> Before there's a progressive majority, there isn't any good outcome
>> that we can hope for, and I feel that Plurality is the only voting
>> system that we'll have.  And are you assuming that we can enact a new
>> voting system under Republocrat rule? If we could, then, for current
>> conditions, it would be best to have one that meets FBC. I just feel
>> that if we could ever get a better voting system, it would probably be
>> _after_ electing a progressive govt, via Plurality strategy.
>>
>> I'm in the odd position of having to ask how my own criterion (SDSC)
>> applies.  ..for which conditions (current, or Green scenaio) it
>> usefully measures merit...and in what way.  I remember the definition
>> of SDSC, and that it shows some benefits of wv Condorcet. But wv
>> Condorcet would undeniably give favorite-burial need, under current
>> conditions. For Green scenario conditions then?
>>
>
> No, I meant near-term conditions.
>
> SDSC is satisfied by WV methods, yes, but it's not incompatible with
> FBC. Examples are MDDA, MAMPO, ICA, ER-Bucklin(whole). None are
> Condorcet methods though (but ICA is quite close).
>
> I suspect that you, at some point, ruled out MDDA etc. due to the
> chicken dilemma. Assuming we might agree that SDSC is useful for near-
> term elections (and maybe we can't), I guess that there isn't going to
> be one method that is both a good "near term" method and also a good
> Green scenario method.
>
> Kevin Venzke
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