[EM] Kevin reply 2/9/04 0945 GMT

[MIKE OSSIPOFF]

Kevin--

You said:

ROC is indeed a rank method.  It's just one that fails anonymity.

I reply:

Or nondictatorship. It depends on whether I'm considered a voter. I was 
assuming that I wasn't a voter. (There'd be no need for me to vote in that 
method).

Of course failing nondictatorship is more extreme than just failing 
anonymity.

You continued:

What's the point of making exceptions for methods that don't accept a
full ranking, when the omitted rankings wouldn't even make a difference
in the result?

I reply:

That's exactly my point.

My criteria make no exceptions for any type of method. They apply uniformly 
to all proposable methods, without specifying anything about rules, and 
without any ridiculous fictions about any method's rules.

The person who's making an exception for Pluralty & Approval is the person 
who claims that it's necessary to pretend that their rules are different 
from what they are.

You can call Plurality's & Approval's nonranked rules "an exception", but it 
isn't an exception that I make. It's just the actual rules of those methods. 
To pretend that their rules are different from what they are, that would be 
"making an exception" for those methods.

You continued:

The methods that pose problems are those that require some input from the
voter other than a ranking.  Consider Approval, which arguably requires
a cutoff in addition to the ranking.

I reply:

No, if you're going to pretend that Plurality allows ranking all the 
candidates, you can pretend the same thing about Approval. Approval simply 
differs by allowing a voter to equal-rank. Sure, and let voters equal rank 
at all rank positions--why not. Or rather _say_ that Approval allows that.

You continued:

Is it possible to say whether Approval meets Clone-Winner?

I reply:

Yes.

When ICC is defined in terms of sincere preference and stipulates sincere 
voting, like my CC, then Approval doesn't pass ICC. But Approval passes the 
ICC that Markus posted. I don't know if Approval would fail Markus's ICC  if 
we used the ridiculous fiction that Approval allows the ranking of all the 
candidates. Maybe. I haven't checked.

You continued:

Unless we have specific rules about how the cutoff may move in response
to the introduction of clones, I suppose we have to assume that Approval
fails this criterion.

I reply:

I once asked what ICC assumes about how people vote. I asked, does ICC 
assume sincere voting, or that voting is undominated strategy, or that 
voting maximizes utility expectation by some possible set of utilities and 
probability estimates. Or does it just require that no ballot is changed 
when a clone is deleted from the election? It turned out that the assumption 
of sincere voting comes closest to the way that ICC is intended.

You continued:

For a more abstract example, suppose the method requires the voter to
label each candidate "red," "green," or "blue."  Unless we have rules about 
how
and why labels may adjust in coordination with the rankings, we have to 
assume
that the method fails every criterion.

I reply:

Are you sure? A method meets the Majority Criterion if a candidate wins if 
more than half of the voters vote hir over all the other candidates.

No matter what color they vote hir, if s/he always wins if more than half of 
the voters vote hir over everyone else, then the method meets the Majority 
Criterion. If s/he can lose even though everyone votes hir over everyone 
else, then the method fails MC.

Those things are true regardless of what color people vote hir. Colors 
aren't part of the requirement or premise of MC. The failure-example-writer 
can configure color votes anyway s/he wants to, since they aren't mentioned 
in MC's premise.

But MC's requirement doesn't mention colors either. Of course the method's 
count rule might be strongly affected by color votes. If so, the 
failure-example-writer, being able to configure the color votes however s/he 
wants to, because they aren't mentioned in MC's premise, can try to find a 
combination of color votes, and whatever other kind of voting the method 
uses, in which a candidate loses even though everyone votes hir over 
everyone else.

And, by the way, in that hypothetical method, for all we know, your color 
assignments could have something to do with whether you're voting X over Y. 
If so, then the voters' color-assignments would have to be part of what the 
failure-example writer would have to configure. Even if there's a way to 
vote X over Y regardless of  how you color anyone, the matter of whether you 
vote X over Y could still be affected by your color votes under some 
conditions.  Aside from that, it could still be necessary, by the method's 
rules, to configure the coloring in a certain way in order to make a 
candidate lose when more than half of the voters vote hir over everyone 
else.

But if someone can show an example in which more than half of the voters 
vote a candidate over everyone else, and that candidate loses, then that 
person has shown that the method fails MC. And if it can be shown that 
there's no such example, then it's been shown that the method passes MC.

That's true regardless of the method's color votes.

Mike Ossipoff

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