[EM] Re : Re : Toy election model: 2D IQ (ideology/quality) model

[Kevin Venzke]

Hi Jameson,
 
 
De : Jameson Quinn <jameson.quinn at gmail.com>
>>À : Kevin Venzke <stepjak at yahoo.fr>
>>Cc : em <election-methods at electorama.com>
>>Envoyé le : Mercredi 9 Novembre 2011 2h06
>>Objet : Re: [EM] Re : Toy election model: 2D IQ (ideology/quality) model
>>
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>>2011/11/8 Kevin Venzke <stepjak at yahoo.fr>
>>
>>Speaking of quoting messages, I have to admit I don't understand how it is even supposed to be done under Yahoo. I can indent the message, and I used to be able to correctly quote plain text messages. But usually when I try to quote an html message I just end up destroying the formatting somehow.
>>> 
>>>Anyway, to Jameson:
>>> 
>>>
>>>De : Jameson Quinn <jameson.quinn at gmail.com>
>>>À : kathy.dopp at gmail.com
>>>Cc : EM <election-methods at lists.electorama.com>
>>>Envoyé le : Dimanche 6 Novembre 2011 20h23
>>>Objet : Re: [EM] Toy election model: 2D IQ (ideology/quality) model
>>>
>>>
>>>
>>>
>>>> 3. It is therefore reasonable to hope for a voting system that tends to
>>>>> elect centrists, but slightly less so than a Condorcet system.
>>>>
>>>>Why would utility be considered more important than centrist?  Or would it?
>>>>
>>>>
>>>>
>>>Utility is the goal, almost tautologically. I mean yeah, there's plenty of ways you could criticize the model, or even the idea that the votes have anything at all to do with the utility that the voters will gain from a given candidate winning; but until someone comes up with something better, for democracy at least, utility is the best paradigm we have.
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>>>I don't think I agree. Utilities are everpresent in simulations because they are a convenient way to represent the priorities of the voters. They can easily be generated from distances in space. But, it's not obvious that these priorities need to be aggregable (we could use a system where the "addition" of different voters' priorities isn't even a straightforward task) and it's not obvious that maximizing the aggregation should even be a goal. You don't need to do it. 
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>>I know there are proofs for a single agent that something equivalent to utility is the only way to have consistent priorities and avoid being "money pumped". ("You have A? OK, will you trade that and $1 for B? Now will you trade that and $1 for C? OK, now will you trade that and $1 for A? Heh heh heh, you just gave me $3 for nothing, fool.") I suspect you could prove something similar for aggregate agents (societies). Basically, utilities are the only way to avoid the Condorcet paradox.
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I understand what you're saying about being money pumped, though I don't see how a similar thing would work for societies. Utility does give you a result when Condorcet doesn't, but I'm not sure this is a huge problem unless your scenario is mostly generating scenarios where Condorcet or say Schwartz isn't making any distinctions.

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>>I do not think that this means that utilities are somehow real. I do think that it is a pretty good argument for using a utility-based model.
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>>I've said before that I prefer to look at sincere Condorcet efficiency and strategic incentives. 
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>>While I'm advocating using utilities, I must say that we could do a lot worse than your plan. In particular, as I've said elsewhere, using utilities is no substitute for looking at strategic incentives.
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>>So you don't get one clean number from me, sorry. But I think it may be less artificial than aggregated utility.
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>>>Furthermore I doubt that aggregate utility is likely to get you anywhere unique. Electorates in practice try to get sincere CWs elected. If someone ever pointed to a simulation and a scenario and a rule and said, "here is a concrete method by which we can favor higher utility candidates over sincere Condorcet efficiency" my intuition would be that their tools are underestimating the voters. When the sincere CW loses, it represents an error from the standpoint of what the electorate was trying to do. I think it would take some genius work to capitalize consistently on such errors, and gain more than is lost.
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>>I suspect that Majority Judgment does exactly that. My evidence? B+L's study that shows that MJ is the only system which does not elect almost solely centrists nor almost solely extremists, in a model based on 2007 France. That is to say, where Condorcet elected centrists, MJ sometimes elected extremists. And in my toy model, that is sometimes the right answer.

Well, I believe you that you have read this study and that's what it said. That result of the study doesn't make a lot of sense to me though. As I suggested, I would guess that if I read what their model was, I would feel that it's underestimating the voters' motivation or ability to strategize.

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>>>All that said, I would be interested to hear if someone has made an argument that majority rule, as a sensible principle, depends on some other more fundamental principle.
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>>OK, here goes: utility is happiness and is the true goal. Majority rule is just the most strategy-proof principle which tends to agree with maximum utility. 
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>>That wasn't too hard.
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Well, for this to work your model has to include happiness as a concept. It's not enough to define voter priorities using utilities, because that doesn't allow you to presume aggregability. Priorities only *need* to be defined in terms of the other priorites of the same voter only.

What I'm saying above is that I wonder whether majority rule can be argued to be a nonsensical principle when, let's say, happiness isn't in the model.

Here is a great doubt I have. When your model tells you we predictably have a situation where the utility maximizer isn't the sincere CW, and we are able to capitalize on this... How do you know the model is realistic? All you would have to do is adjust the "scales" of the utilities of some voters and you could almost certainly make the CW into the utility maximizer. Can we hope to show that this revised scenario (where the sincere CW is the maximizer) is less likely to occur in real life? (This even gets into questions of nomination strategy that are currently hard to answer.) Basically, I think that majority rule is more resistent to inaccuracies in the model that establishes what the absolute utilities are.

Kevin
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