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

[C.Benham]

>  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.