[EM] Votes-only criteria vs preference criteria. IRV squeeze-effect. Divulge IRV election specifics?

[MIKE OSSIPOFF]

(If it seems as if I'm posting a lot today, I emphasize that only these two most recent postings were sent
today)

Votes-only criteria vs preference criteria:
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Kevin, you objected to my preference-mentioning criteria on the grounds that no one knows what the voters'
true preferences really are. But so what?

As I said before, my criteria indirectly stipulate votes. They do that when they stipulate that people have
a certain preference and vote sincerely; or have a certain preference and don't vote anyone equal to or over
their favorite. Etc.

Are you saying that methods meeting my preference-mentioning criteria can act wrongly when the preferences aren't
as stipulated? If so, then say so explicitly, and show how that can happen.

As a matter of fact, that _can_ happen with some votes-only criteria, such as the Plurality Criterion:

The Approval bad-example is an example of that. I'll give it again here:

Sincere preferences:

49: C
27: AB
24: BA

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: AB
24: B

Now, in MDDTR and MMPO, A wins. According to the Plurality Criterion, that's wrong.

But it's only wrong if the B voters aren't voting for A because they don't prefer A to C
as much as the A voters prefer B to C.

Given the preferences, and the explanation for the actual votes, the Plurality Criterion is wrong
when it calls the election of A a wrong result.

So yes: A criterion can rule wrongly, based on an incorrect built-in assumption about true preferences.

But the Plurality Criterion is a votes-only criterion. So that problem certainly isn't peculiar to 
my preference-mentioning criteria.

And I'll repeat something that I said before in this discussion:

Votes-only criteria tend to be unintendedly met by Plurality. 

Votes-only Condorcet's Criterion is met by Plurality.
]
The votes-only criterion called "Minimal Defense" is met by Plurality.

The votes-only criterion called "Majority for Solid Coalitions"is met by Plurality.

Of course you could avoid that by saying "This criterion doesn't apply to Plurality or Approval"

Do you know how inelegant that is?

My preference-mentioning criteria apply seamlessly to all methods.

(An exception is my SFC for 3-Slot Methods (SFC3). I couldn't find a way to evaluate or describe
the SFC-like benefit of 3-Slot methods that doesn't stipulate a 3-slot method)
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IRV squeeze-effect:
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I mentioned this before, but there was a recent post claiming that IRV has no problems :-)

If, as very often the case, the favoriteness of candidates tapers gradually, by distance from the middle CW,
then it's pretty much a sure thing, especially with a (at least nearly) 1-dimensional political spectrum,
that middle CW will be eliminated, even if s/he's the Plurality-winner. That will happen because the
eliminations will begin at the extremes, and votes will transfer inward, and snowball and build up, till
the candidates flanking that middle CW will thereby accumulate enough votes to eliminate that middle CW.

The CW is the candidate who is the best you can get. S/he can get a majority against anyone. Riker showed that
informed strategic voting will always elect the Condorcet Candidate. That's the goal of non-offensive strategic
voting, even when voters don't think of it in those terms.

The fact is that IRV will, nor rarely, but often, make people regret that they didn't vote someone over their
favorite.

Oh...I take that back: They won't regret it if the fact is concealed from them by the limited information divulged
when IRV election results are reported.

How about this: Let's write to the IRv opposition, and to the newspapers, in the cities where IRV is in use, 
and make the following suggestion:

"I suggest that the election results reported after IRV elections include a file containing the rankings. 
Confidentially won't be violated, because no one will tell(or know) who voted what ranking.

"Then anyone can look at the results and determine if IRV failed. IRV's failures can't be detected by
the limited information typically revealed after IRV elections.

"In fact, e-mail that file to the EM mailing list. There are people there who'd be glad to examine
the rankings, to detect the serious failures that IRV is so prone to.

"Or would you rather conceal those failures, by concealing the rankings from public scrutiny.
...as if IRV, like some movie vampire, can't survive exposure to the light of day."

Mike Ossipoff