[EM] Reply to Chris regarding the Approval bad-example

[Jameson Quinn]

I agree with Chris.

But mostly, I'm writing to say that I would really like someone to fill in:

http://wiki.electorama.com/wiki/MDDTR
http://wiki.electorama.com/wiki/MTA

Of course, redirects are fine. And you don't have to put in all sorts of
sections for compliances and such if you don't know them, just a few
sentences explaining the method itself is plenty.

Thanks,
Jameson

2011/11/17 C.Benham <cbenhamau at yahoo.com.au>

>
>   49: C
>>  27: A>B
>>  24: B
>>
>>  I agree that *if* the sincere preferences are as Mike specifies then a
>> just interventionist mind-reading God
>> should award the election to A.
>>
>> [endquote]
>>
>> Fine. But can Chris say what's wrong with that outcome in other instances?
>>
>
>
> Yes. If the method used meets Later-no-Harm but fails Later-no-Help, i.e
> has
> a strong random-fill incentive like the MDD,TR method that Mike is
> advocating, there
> isn't any good reason to assume that the Middle ratings are sincere.
>
> So it could be that all the voters really have no interest in any
> candidate except their favourites
> and sincere is
>
> 49: C
> 27: A
> 24: B
>
> in which case C is the strong sincere Condorcet winner, or as Jameson
> pointed out it could
> be worse still and the A voters were Burying against C so sincere is
>
> 49: C
> 27: A>C
> 24: B
>
>
>  Chris continues:
>>
>> Given the incentives of the MDD,TR method that Mike is advocating, it is
>> only reasonable to assume that the truncators
>> are all sincere
>>
>> [endquote]
>>
>> Wait a minute: I'm not saying that B truncation is a problem in MDDTR or
>> MMPO. In fact,
>> my point is that it is _not_.
>>
>
>
> Truncation isn't a "problem" (for the full-rankers) as an  "offensive
> strategy". The problem is that it
> isn't fair to the sincere truncators.
>
>
>  Wait a minute. These candidates in this example are A, B, and C.
>>
>> How does A lack legitimacy? Among the candidates not majority-defeated, A
>> has more favoriteness-supporters than any other candidate.
>>
>
>
> Translation: "I love this arbitrary algorithm, so any winner it produces
> is by definition legitimate."
>
> A's win lacks legitimacy simply because there is another candidate that
> was vastly better supported on
> the ballots.
>
> If we add between 2 and 21 ballots that plump for A, then C's
> "majority-defeatedness" goes away and
> the winner changes from A to C, another failure of  Mono-add-Plump.
>
> If we nonetheless accept that C but not A should be immediately
> disqualified, electing the undisqualified
> candidate with the most top-ratings is just another arbitrary feature of
> the algorithm.
>
> Why that candidate and not the one that is most approved?  Based on the
> information actually on the ballots,
> no faction of voters has a very strong post-election complaint against B.
>
> Chris Benham
>
>
> 49: C
> 27: A>B
> 21: A   (new voters, whose ballots change the MDD,TR winner from A to C)
> 24: B
>
>
>
>
> Mike Ossipoff wrote (17 Nov 2011):
>
> Chris said:
>
> Mike refers to this scenario:
>
> > The Approval bad-example is an example of that. I'll give it again here:
> >
> > Sincere preferences:
> >
> > 49: C
> > 27: A>B
> > 24: B>A
> >
> > A majority _equally strongly_ prefer A and B to C.
> >
> >
> > Actual votes:
> >
> > The A voters defect, in order to take advantage of the
> > co-operativeness and
> > responsibility of the A voters:
> >
> > 49: C
> > 27: A>B
> > 24: B
> >
>
> I agree that *if* the sincere preferences are as Mike specifies then a
> just interventionist mind-reading God
> should award the election to A.
>
> [endquote]
>
> Fine. But can Chris say what's wrong with that outcome in other instances?
>
> Chris continued:
>
> But a voting method's decisions and philosophical justification should
> be based on  information that is actually
> on the ballots, not on some guess or  arbitrary assumption about some
> maybe-existing "information" that isn't.
>
> [endquote]
>
> Why? Why shouldn't a voting system avoid a worst-case, if, by so doing,
> it hasn't been shown to act seriously wrongly in other cases?
>
> And MMPO & MDDTR don't just bring improvement in the Approval bad-example.
> They,
> in general, get rid of any strategy dilemma regarding whether you should
> middle-rate
> a lesser-evil instead of bottom-rating hir. For instance, consider the
> A 100, B 15, C 0 utility example.
>
> In MCA, there's a question about whether you should middle-rate or
> bottom-rate B. In
> MDDTR and MMPO, that dilemma is completely eliminated.
>
> In those methods, middle rating someone can never help hir against your
> favorite(s).
>
> Chris continues:
>
> I think a very reasonable tenet is that if, based on the information on
> the ballots, candidate X utterly dominates
> candidate Y then we should not elect Y.
>
> [endquote]
>
> Yes, there are many reasonable tenets among the aesthetic criteria.
>
> Chris continues:
>
> For several reasons (for those who can pooh-pooh this as "merely
> aesthetic"): electing Y gives the supporters
> of X a  very strong post-election complaint with no common-sense or
> philosophically cogent answer, X is highly
> likely to be higher Social Utility (SU),  Y's victory will have
> compromised legitimacy.
>
> [endquote]
>
> Wait a minute. These candidates in this example are A, B, and C.
>
> How does A lack legitimacy? Among the candidates not majority-defeated, A
> has more favoriteness-supporters than any other candidate.
>
> Chris continues:
>
> The Plurality criterion is one very reasonable criterion that says that
> C  is so much stronger than A that the election
> of  A can't be justified. .
>
> [endquote]
>
> There are lots of aesthetic criteria that say things like that, and they
> all sound
> aesthetically reasonable. How great is their practical strategic
> importance?
>
>
> Chris continued:
>
> There are other criteria I find reasonable
> that say the same thing:
>
> "Strong Minimal Defense": If the number of ballots on which both X is
> voted above bottom and Y isn't is greater than
> the total number of ballots on which Y is voted above bottom, then don't
> elect Y.
>
> [endquote]
>
> But can you word that in such a way that it isn't met by Plurality?
>
> What sort of strategic guarantees are protected by the criteria
> that you propose in this posting?
>
> Chis continues:
>
> The election of  A is unacceptable because C's domination of  A is
> vastly more impressive than A's pairwise win over
> B.  The Plurality criterion plus the three other criteria I define above
> all loudly say "not A".
>
> [endquote]
>
> In other words, it looks bad from those perspectives.
>
> The election of A is justified by its being consistent with FBC, SFC or
> SFC3,
> freedom from dilemma about middle-rating a compromise, and either
> Later-No-Harm or non"failure" in Kevin's MMPO bad-example.  --things that
> are
> guaranteed by MMPO and MDDTR.
>
> Additionally, as I was showing to Jameson, electing A in these methods
> isn't really wrong.
>
>
>
> > The A voters defect, in order to take advantage of the
> > co-operativeness and
> > responsibility of the A voters:
>
> Chris replies:
>
> The plausibility of  arbitrary claims about the voters' sincere
> preferences and motivations
>
> [endquote]
>
> More a matter of "what if", rather than claims.
>
> Chris continued:
>
> can weighed in the light of the
> used election method's incentives. How is it so "co-operative and
> responsible" of the A voters to rank B when doing
> so (versus truncating) can only help their favourite?
>
> [endquote]
>
> It's co-operative because it defeats the candidate commonly disliked by A
> voters and B voters, in MCA, MDDTR and MMPO.
>
> If neither did that, C would win.
>
> If the A voters refused to, and, instead, the B voters co-operated, then
> it would
> be B would win, by being the defectors.
>
> Chris continues:
>
> And why would the
> B voters be insincerely truncating ("defecting")
> when doing so can only harm their favourite?
>
> [endquote]
>
> In MCA that defection could give their favorite the win, if the A voters
> have
> co-operated, in spite of the A voters being more numerous.
>
> In MPPO or MDDTR, the problem doesn't exist. The A voters can co-operate or
> defect, and A will still win, having more top ratings. Hardly a
> controversial
> result.
>
> Chris continues:
>
> Given the incentives of the MDD,TR method that Mike is advocating, it is
> only reasonable to assume that the truncators
> are all sincere
>
> [endquote]
>
> Wait a minute: I'm not saying that B truncation is a problem in MDDTR or
> MMPO. In fact,
> my point is that it is _not_.  But co-operaton/defection is indeed a
> problem in MCA.
> Hency my advocacy of MDDTR and MMPO.
>
>
> ----
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>
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