[EM] Sincere methods

Sun Apr 17 11:58:00 PDT 2005

Hi Juho,

 --- Juho Laatu <juho at bluebottle.com> a écrit : 
> >> From this explanation it sounds like you think the only people who can
> > really revolt are those not matched by the opposition numbers; i.e., 
> > the
> > voters constituting the margin. In other words you suppose that when A
> > is elected, only 2 B>A voters can cause any trouble, since the other 49
> > can be restrained by corresponding A>B voters. I think that is a little
> > silly.
> 
> Yes, a bit silly from one viewpoint. That is maybe the most obvious 
> problem of my reasoning. One alternative (maybe more natural) 
> explanation would be to count the total number of people who think that 
> the winner is not the best possible. This explanation actually points 
> out that plurality can be seen as a SVM. (The candidate with most first 
> positions in ranked ballots meets that requirement.)

That doesn't work unless you count the total number of people "who think
that the winner is not the first choice of the most voters." Otherwise
you have everyone revolting who doesn't get their first choice.

> If one wants to see that "weakest pairwise opposition margin" 
> explanation in a positive light, then one may think that each candidate 
> corresponds to some alternative policy. There are thus as many policies 
> as there were candidates. In this situation one would compare these 
> policies every day in a similar manner as one compared candidates on 
> the election day.

I didn't understand this paragraph...

> > No, since all three of those candidates are in the Smith set. I'm 
> > talking
> > about the principle which says (among other things) that if there is 
> > only
> > one majority-strength decision, such as B>A, then you can't elect A.
> 
> Ok, now I understand which rule we are talking about. I think 
> majority-strength decision could be a requirement in some SVM, but I 
> think there are also SVMs that do not respect this criterion. I guess 
> it depends on what kind of solution the society is looking for.

Well, for me this is a very basic component of the purpose of asking the
voters for their opinion. You don't have to use (and explain) WV to satisfy
this.

> > Ok. My view is that Smith is important for clone reasons. It seems like
> > a problem that in MinMax methods, votes for similar candidates, by the 
> > same
> > voters, can cause all of those candidates to lose, and cause a 
> > candidate to
> > win who pairwise didn't win any contests.
> 
> Interesting comments. Do you refer to the case where e.g. one party 
> members intentionally vote a loop for the candidates of  competing 
> party. This is in my mind one of the worst threats against minmax. This 
> is because individual voters can do that quite autonomously (only 
> direction of loop agreed by all) and it doesn't include risks, it just 
> makes the position of the competing party worse. The latter part of 
> your comment is also interesting although I don't agree. I think it is 
> ok to elect e.g. the Condorcet loser if all the other alternatives are 
> even worse (typically a very strongly looped Smith set).

But the other alternatives are only "even worse" according to MinMax.
If the voters preferring Smith members to the Condorcet loser were
given the chance to change their votes, they would do so, to change your
perception that all of the Smith members were worse.

> > I don't know what you mean by "true clones." A method that chokes on 
> > "fake
> > clones" will also choke on "true clones" since it can't tell the 
> > difference.
> 
> With true clones I meant situation where one party has set several 
> candidates (that appear next to each others in all votes) and it would 
> have had also the possibility of setting only one candidate. Fake 
> clones would be ones that are always grouped but just by accident.

It still makes no difference, since a method can't tell the two types of
clones apart.

> > The thing that would change this, is if you want to argue that 
> > sometimes
> > Smith or clone independence causes a worse candidate to be elected. 
> > But I
> > don't think that's what you're saying.
> 
> Actually I do. I don't know the clone world well enough to say anything 
> on that but I can make a claim on the Smith set. My claim is that 
> minmax (margins) is a SVM. It may choose a candidate outside the Smith 
> set. And I claim that in line with the "sincere minmax (margins) 
> philosophy" it makes the right choice. And the reasoning is that if the 
> defeats between the Smith set candidates are worse than the defeats of 
> the candidate outside of the Smith set (to the Smith set candidates), 
> then the non Smith set candidate is the least bad of the mentioned 
> candidates. In this case the non Smith set candidate needs least 
> additional votes to become a Condorcet winner.
> 
> The claim above thus says that Smith + minmax (margins) sometimes makes 
> worse decisions than minmax (margins).
> 
> (Hmm, I feel happy that we got at least one claim that hopefully has a 
> good grip in the sense that it is easy to force people to either agree 
> or disagree with it :-). Too many of my earlier comments were just 
> viewpoints etc.)

Yes, there's that.

But I don't find your reasoning persuasive, since if there were hypothetically
the ability to obtain "additional votes" to create a Condorcet winner, then
why couldn't there be the ability for voters to alter their votes so as to
avoid the election of the Condorcet loser?

I can't remember if you and James used this scenario:

20 A>B>C>D
20 B>C>A>D
20 C>A>B>D
13 D>A>B>C
13 D>B>C>A
13 D>C>A>B

You could imagine that it would be slightly easier for the D voters to get
the additional voters necessary to make D the CW. But it seems to me easier 
to imagine that the voters solidly committed to {a,b,c} would just compress
their rankings.

Kevin Venzke

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