[EM] STAR

[Toby Pereira]

 On Monday, 14 August 2023 at 05:09:31 BST, C.Benham <cbenham at adam.com.au> wrote:
 
 
 >Toby wrote:

>>  I think this is an interesting point. We can ask at a philosophical level what makes a good voting method. Is it just one that ticks the most boxes, or is it one >>that most reliably gets the "best" result?


>Toby,

>How are those two counter-posed?  What do you think "the boxes" are about?

I mentioned that there could be multiple low-level failures versus a few high-level failures, but also that it was a fairly hypothetical discussion. I'm not of the view that because of Jameson Quinn's simulations, it must be the case that the only way to get the best results is to sacrifice the strict passing of criteria. However, if we do define best in terms of utility or the median voter, I'm agnostic as to what method would best get these results in practice. But it is still interesting that STAR does well in Jameson's simulations. As for what the boxes are about, they are about ensuring that voting methods have sensible behaviour in certain situations, so I wouldn't expect them to necessarily negatively correlate with a "good" result.

>> And that's partly because the premise of Condorcet is essentially built on a logical fallacy - basically that if A is preferred to B on more ballots that vice versa >>then electing A must
>> be a better result than electing B.

>I'd be interested in reading your explanation of why you think that is a 
>"logical fallacy".  What about if there are only two candidates?

It's what I just replied to Kristofer - the fact that there's no way that you can consistently define society's preference in a way that you can determine whether society prefers A or B by looking at the pairwise comparison. It also doesn't make any difference if there are only two candidates. It's just that with two candidates, you won't notice it. If A and B are the only two candidates, then A might pairwise beat B and get elected. But if C also stood, B might be the winner under any of the sensible Condorcet methods that people on this mailing list consider. So is A preferred to B or vice versa? And is it the same answer regardless of whether C stood? Also if C was unsure about standing but ultimately did, how would we view the creation of a cycle? Would we say that it's bad that it messed up our majoritarian ideals? Or would we say that it's good because it gave us more information overall, and with this extra information B was ultimately rightly selected over A?
One of the reasons I bring this up is that there are some people who think that only a Condorcet method could even be considered democratic. I would counter this by saying that it's based on this logical contradiction. I would also counter it by saying that someone could equally say (perhaps have a greater claim) that a method cannot be democratic if it fails participation. This isn't to say that I don't like Condorcet methods, but I don't think it's a good idea to have them on a pedestal when discussing the best method to use in a situation. They are not the last word in democracy.

>> I think generally while passing certain criteria is a good thing,..

>Which ones do you have in mind?

Two of the main ones I tend to look out for are monotonicity and independence of clones because they are obviously things we would want and they don't seem to be too restrictive in terms of methods they allow. But then with monotonicity, there is a family of criteria in addition to the "standard" one, some of which might be more restrictive than others. One criterion that I consider to be largely a box-ticking exercise is Local Independence of Irrelevant Alternatives. But other criteria such as participation and Independence of Irrelevant Alternatives look great in the abstract, but are very restrictive in terms of what they allow. Well, even methods that supposedly pass IIA in theory (e.g. approval, score) in no way pass them in practice.
>Chris B.

Toby



  
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