[EM] [CES #4445] Re: Looking at Condorcet

[Kevin Venzke]

Hi Robert,


De : robert bristow-johnson <rbj at audioimagination.com>
>>À : election-methods at lists.electorama.com 
>>Envoyé le : Jeudi 9 février 2012 10h07
>>Objet : Re: [EM] [CES #4445] Re: Looking at Condorcet
>>
>>On 2/8/12 1:25 PM, Juho Laatu wrote:
>>> On 8.2.2012, at 7.33, robert bristow-johnson wrote:
>>> 
>>> ...
>>>> if it's not the majority that rule, what's the alternative?
>>> I'm not aware of any good alternatives to majority rule in competitive two-candidate elections (with some extra assumptions that rule out random ballot etc.).
>>> 
>>> Juho
>>
>>thank you Juho, for stipulating to the obvious.  i will confess that i am astonished at the resistance displayed here at the EM list to this obvious fact.
>>
Nobody on EM said anything contrary to Juho's statement. I agree with Juho. And Bryan said something similar at the end of his post.

With two candidates, most of us agree that you have to use majority rule. That doesn't mean it gives perfect answers according to some ideal. If your ideal is maximum utility, then it's pretty clear majority rule isn't always giving the correct answer. Not because the ballots make it clear that this is happening, but because almost any model of voter preferences will lead to this conclusion. It would be frankly bizarre, if "fairness" and utility always gave the same answers.

(Your idea of all the utilities being 0 or 1 can't even be made to work as a model, I don't think, unless voters really only have two stances toward candidates. Because what happens when you introduce a third candidate that some people like even better? Utilities don't change based on who else is in the race, they are supposed to represent in absolute terms the benefit from a candidate being elected.)

When you try to make an argument for Condorcet and 3+ candidate scenarios, based on the inevitability of using majority rule with two candidates, you will fail to convince an advocate of utility, because an advocate of utility probably doesn't think the method options are as limited anymore, once you have 3+ candidates. The majority rule procedure with two candidates may be necessary (Clay may even disagree with that though), but that doesn't mean it was always doing the right thing.

Is this clear enough? I understand you want to make a fairness argument in favor of majority rule with two candidates, and then build off of that. But a utility advocate may reject fairness and prefer utility, even without offering a different method that could be used with two candidates. (He may perceive that there is no utility improvement to be had by doing something else.) So even if you attack Range as silly in the two-candidate case, you're not making the point that fairness is paramount over utility.

I'd note also that utility goes far beyond the question of whether Range is a workable method. A utility advocate is free to leave Range in the trash-bin while seeking to maximize utility under other methods that you might recognize as less prone to exaggeration strategies.
 
And from your last mail to me:
 
>> It could be true if it so happens that nobody wants to vote truthfully under
>> Condorcet methods, while Approval in practice never has any bad outcomes, etc.
>
>it could be true that hundreds of people who have testified to such have actually been abducted by extraterrestrial aliens who poked needles into them 
>and did experiments on human subjects.  but it's an extraordinary claim that requires extraordinary evidence.
 
Yes, you're right. However, the important point here is just that it could be true. "More Condorcet than Condorcet" isn't inherently nonsense. You just have to read it as "better sincere Condorcet efficiency than under Condorcet methods." Such a thing is possible.

Kevin
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