[EM] RE : Re: A few concluding points about SFC, CC, method choice, etc.

[Kevin Venzke]

Hi,

This post is just about criteria generally.

--- Abd ul-Rahman Lomax <abd at lomaxdesign.com> a écrit :
> At 10:52 AM 2/19/2007, Kevin Venzke wrote:
> >--- Abd ul-Rahman Lomax <abd at lomaxdesign.com> a écrit :
> > > Election criteria sometimes presume omniscience. For example, the
> > > Majority Criterion is based upon voter preferences that may not be
> > > expressed, or even expressable, in the votes. "Prefer," as it was
> > > clearly interpreted here, refers to a mental state of the voter.....
> >
> >Well, I wouldn't define MF that way. But I can go with this. We can
> >say that MF says that if there is a majority favorite on sincere
> >preferences, and voting is sincere, the MF wins.
> 
> If you use actual votes rather than unexpressed 
> but sincere preferences, then Approval satisfies 
> Majority Favorite. But when I pointed that out 
> here, I was told, quite clearly and with nobody 
> chiming in with support for my position, that the 
> Majority Criterion -- which I think is the same 
> as MF -- was about sincere preferences, not about actual votes.

I'm pretty sure I expressed my stance during that discussion. For me
MF is not about sincere preferences, and neither does Approval satisfy
it.

My scheme requires methods to be interpreted as rank methods (allowing
equal ranking and truncation). Methods are not barred from having other
components that affect the result, though. If the ballot format doesn't
allow equal ranking and truncation, the voter is still imagined to be
able to submit them, but when finding the result these should be fixed
arbitrarily to conform to the ballot requirements. (This is important
for instance when a criterion intends that truncation be effective for
defensive strategy. Disallowing truncation on the ballot shouldn't allow
the method to satisfy the criterion merely because no scenario appears
to apply to it.)

I know of three ways to evaluate Approval under this scheme: That the
voter is only submitting first preferences, that the voter is submitting
non-last preferences, and that the voter submits only the position of
an approval cutoff and no rankings. Of these three, the only one that
allows Approval to satisfy MF is the first one, which I find to be the
least intuitive.

As far as I can see, Range would have to be interpreted in the last way.
Rating data exists with the rank data and can probably be assumed to
be consistent with it.

It's true that it's a disadvantage that non-rank methods require special
interpretations and more than one may be possible.

(Although, incidentally, Mike's criticism that my scheme can't be used to
show that Approval and Range fail SFC is quite strange. SFC is defined on
sincere preferences. If Mike means "what I use in place of SFC" then I
believe it's at least true that there is no way to interpret Approval or
Range such that they satisfy the criterion under my scheme.)

I'll reply to the rest later. I'm short time...

Kevin Venzke


	

	
		
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