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

[Kevin Venzke]

Hi,

--- Abd ul-Rahman Lomax <abd at lomaxdesign.com> a écrit :
> At 06:15 PM 2/16/2007, Kevin Venzke wrote:
> >Hm? "Maximum utility" meaning "matches the SU winner perfectly" or
> >"matches the SU winner the best among methods that actually exist"?
> >
> >In the former case it's not clear this method actually exists. In the
> >latter case I'd guess that you shouldn't guarantee this.
> 
> 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.

> So we can state that if a method elects the candidate who maximizes 
> voter expected utility, summed across the electorate, it satisfies 
> the Expected Utility Criterion. And we know, without doubt, that the 
> Expected Utility Criterion and the Majority Criterion are not 
> mutually compatible.

Presumably the EUC would also have to require sincerity in the votes.
Yes, I agree that EUC and MF aren't compatible given this.

> What we are limited to, however, is what voters actually express. 
> Condorcet methods purport to elect the pairwise preference winner. 
> But if voters vote "strategically," that is, they don't express their 
> actual preferences, the method can fail to select the actual preference
> winner.

We could define Condorcet on sincere preferences also.

> Range, of sufficient resolution, *is* precisely a method which 
> explicitly selects the utility winner, if voters vote sincere 
> utilities. So Range satisfies the EUC. Got any other methods which do
> this?

Nope. But you see that your criticism of Condorcet also applies to EUC.

> If voters don't vote strategically, then it can fail to find the 
> utility winner. Garbage in, garbage out.
> 
> But the real practical question is whether or not it fails 
> gracefully. And it appears that it does.

I do think it is interesting to consider whether a method fails 
"gracefully." The worst result under Condorcet methods is probably
worse than the worst result under IRV. You have to ask also how much
to worry about this relative to other concerns.

> For me, the only question about SU is the best way to measure it. The 
> Condorcet Criterion has *nothing* to do with measuring SU. It's just 
> a guess at a beneficial method, an intuititively satisfying one that 
> turns out to miss something extremely important.

In simulations it seems to be quite a good guess, assuming sincerity.

Also, I can substitute "EUC" for "Condorcet" in that paragraph and
really have the same criticism.

> > > It is obvious that MF has a utility. It is unlikely to choose a truly
> > > bad candidate.
> 
> It can and has, so I don't know about "unlikely." Think Ruanda. (Now, 
> I don't know the full details of the election involved, but it was 
> won by the leader of the majority Hutu tribe. I'm guessing that he 
> was a majority victor.)

Well, you're replying to yourself here. I didn't say this.

> > > But methods which specifically optimize utility are
> > > going to fail MF. That's the point.
> >
> >As far as I'm aware, there is no way at this point to conclude that
> there
> >is a method failing MF that optimizes utility better than every method
> >that satisfies MF. Or vice versa for that matter.
> >
> >If you want to posit sincerity, though, then never mind this comment.
> 
> There is no real alternative to positing sincerity. *No* method can 
> guarantee good results if the voters don't disclose their opinions!

Ok. I just want to know that you're positing sincerity when you say that
methods which specifically optimize utility fail MF.

But when you posit sincerity it isn't clear that this is an interesting
point. It is hard for me to take this as an argument that MF is not
desirable for real elections.

> > > If you really think B is quite good -- and 80% is quite good -- then
> > > why would you rate B at zero, merely in order to get a slight
> > > improvement in personal utility, while at the same time knowing that
> > > you are going to be seriously disappointing half the society?
> >
> >If you're saying that
> >1. electing A seriously disappoints half of society, and
> >2. I do not want to seriously disappoint half of society
> >
> >Then I don't see how it can possibly be that I rate A higher than B.
> 
> Yes. However, that is post-facto information. How would I know that I 
> will seriously disappoint half of society? *The poll is the 
> information.* I have argued again and again that single-step election 
> methods are doomed to be inferior to more complex, essentially 
> deliberative, process.

Well, I would argue that public elections actually are multi-step and
complex. Since in public elections there should already have been
polls.

I believe in this scenario I really would be likely to know that almost
half of the voters will be seriously disappointed by A.

> Here is a way in which a Range method satisfies the Majority 
> Criterion: A Range poll is taken and the winner is presented for a 
> second vote to the electorate, "Shall the Range Winner be elected?"
> 
> If the majority votes Yes, we have, with the overall method, 
> satisfied the Majority Criterion.

What happens if the majority votes No? If it's "elect the range winner
or have a new election" I wouldn't say that satisfies MF.

> We could also do the same thing by presenting the Range Winner 
> together with the best winner by any other method, in which case, the 
> question would be a runoff between two candidates.

I think Range winner vs. MF runoff would at least not fail MF in a
meaningful way.

> While methods, in my opinion, should optimize utility, the majority 
> should retain the right of decision. I'm claiming only that the 
> majority should be informed when it makes that decision.

Again, I'm not very worried about this in public elections.

> > > This is a basic question, a different view of human nature than is
> > > being expressed by some. Are people generally out only for
> > > themselves? Will they impoverish their neighbors for a small gain?
> > >
> > > We know that people can be selfish. But *how* selfish? If you
> > > discover that burning your neighbor's house down, and you are sure
> > > you can get away with it, will somehow raise your own property value
> > > by a few thousand dollars, would you do it? How would most people
> > > answer this question, and how would they act if actually faced with
> > > the situation.
> >
> >The answer to the house-burning question is that it doesn't matter,
> >because we can set up laws and institutions to handle the case that
> >people do think it is worth burning each other's houses down.
> 
> The question is about human nature, not about how to prevent houses 
> being burned down.

But what are the practical implications of the answer? I guess you want
to guess that people actually won't burn houses down for profit, so that
we can have a society that doesn't worry about this possibility.

I think it is more cautious, and not that expensive, to have a society
that can handle it if people actually do want to burn houses down.

Kevin Venzke


	

	
		
___________________________________________________________________________ 
Découvrez une nouvelle façon d'obtenir des réponses à toutes vos questions ! 
Profitez des connaissances, des opinions et des expériences des internautes sur Yahoo! Questions/Réponses 
http://fr.answers.yahoo.com