On Apr 13, 2005, at 18:44, Kevin Venzke wrote:
I don't see a difference. What you call "majority defending modifications"
in e.g. winning votes is nothing more, nothing less than the use of a
defeat strength measure that inherently views majority-strength defeats
as being stronger than sub-majority-strength defeats.
Suppose I think it's important to have peanut butter rather than jelly
on my toast, so I decide that instead of using jelly, I will use peanut
butter. Based on this discussion, I might expect you to claim that peanut
butter toast is a form of jelly toast, but with strategic modifications
designed to defend people who prefer peanut butter.
Whatever you say is your true wish is a sincere opinion to me. It seems that peanut butter is your sincere target. Saying that you want jelly could be strategic if you think that the one who makes the toasts becomes jealous, reserves all the jelly for himself and leaves all the peanut butter for you.
Should I read this so that for you some wv method is a sincere method. That is ok to me and in line with the SVM definition. The fact that I tend to see wv as a strategy defence mechanism should not influence your sincere opinions. I.e. any method that someone claims to be sincere and is able to convince himself of the "correctness" of the method (and hopefully make also others understand the reasoning) is a SVM to that person and probably a good SVM candidate for anyone.
The example used below: 49 A 24 B 27 C>B
WV and Approval elect B, and this isn't a coincidence: both methods consider the actual number of voters voting a certain way.
If approval is chosen as the SVM => B should win. If margins is chosen as the SVM => A should win. If wv is chosen as the SVM => B should win.
Well, I'm afraid I don't understand either how margins is "natural" or how being "natural" suggests that something could be used as an SVM.
My justification for the naturalness of margins includes the following explanation: "winner requires least additional votes to become a Condorcet winner". Does this sound like a natural explanation to you like it does to me?
The latter part of your comment is more tricky. You use expression "used as an SVM". I don't say that SVMs should always be used in practical elections. That is possible but if e.g. strategy threats are considered serious enough, one should use some other practical voting methods (that probably are close to the SVM but offer better defence against strategies) and leave the SVM only as a "theoretical construction". But SVMs are natural by definition.
Do you have a favorite example in which, when all abstention in pairwise contests is informed and deliberate, margins produces a "more ideal" result than WV?
I don't have any such favourite at hand. I guess I would favour margins
in any example where the results differ. Maybe you have some
interesting example in mind.
The 49 24 27 scenario is good enough.
Ok. If I try to defend margins as the sincere voting method, then my explanation could be that A needs only 3 additional votes to become a Condorcet winner. B needs 4 additional votes and is therefore slightly worse than A. A can be said to be strongest in defending her policy when in office because the difference between her supporters and supporters of any other candidate is always positive or only slightly negative. Although the supporters of A are neutral with respect to battle between B and C and are likely to remain neutral also after B would be elected, the C (with her supporters) would still cause more serious opposition to B than anyone is able to cause to A.
What I mean is that sincere criteria almost always have a strategic justification.
The only thing that comes into my mind (on how sincere methods could be linked to strategies) is that a sincere criterion can be said to defend the correct winner. This could be called a strategy to defend the best candidate, but I have used word strategy only in the sense of trying to elect someone else than the best candidate that SVM would elect. I.e. strategies in SVMs are designed to change the intended/wanted/ideal outcome of an election. (Counter strategies could aim at electing the correct sincere winner, but that is another story.)
P.S. I'm not familiar with "Majority criterion for solid coalitions"
That is the one that says if more than half of the voters prefer every
candidate in some set of candidates to every other candidate, then the winner
must come from that set.
Ok, sounds like Smith set. Correct? (Or is the intention to say that the _same_ group would prefer one candidate (or all candidates?) of the set over all other candidates?) (And my answer to this part is the same as the previous generic answer above.)
If that's what "ideal winner" means, then your statement above that you
"believe many of [Schulze(wv)'s] features are related to fighting against
strategies, not to electing the ideal winner" doesn't make any sense,
since my claim is that Schulze(wv) is a good SVM.
I note again that I accept that some people find different methods sincere than others.
For me finding a natural (SVM) explanation for Schulze(wv) has not been easy. I start my search from thinking what the winning paths might mean in real life, and I have failed to find a good explanation. There is nome naturalness in the paths but not enough that I would be able to convince myself that it is just the Schulze(wv) winner that is the obvious best candidate.
Maybe you think "SVM" is already well-defined, but you've suggested that
approval and margins could be used, and those aren't similar.
There can be many SVMs. This is because 1) people expressing their sincere opinions on SVMs are different, 2) the targets of the election may be different (sometimes we want to elect a compromise candidate, sometimes one that has many eager supporters etc.), 3) the available information may be different (rankings or ratings or just one candidate pointed out by each voter or maybe e.g. rankings+approval)
The more I talk with you, the more I am convinced that there is no way to
justify a method except in strategic terms. The only justifications you have
used so far are "naturalness" and a kind of "immunity to mutiny" (which I
don't think counts).
"Naturalness" is to me an essential part of SVM. "Immunity to mutiny" I used only to give rationale why margins could be claimed to be a SVM.
I think I lost you here since the difference between sincere methods and strategies is so clear to me that I find it hard to see why all methods would be linked to strategic considerations. Maybe your definition of strategy is different than mine. As explained above, I see strategies pretty much as attempts to deviate from the ideal/sincere voting results.
Justifying SVMs follows different logic than justifying PVMs. => Explanation why something is natural and wanted in theory vs. explanation why some method is most useful in real life (including also strategic considerations).
49 A 24 B 27 C>B
I see B as a sincere winner. A can't win because this would be contrary
to majority rule (in any way I've defined it). C can't win because by any
measure, C seems to have done worse than A.
You haven't offered an SVM choice that would preserve majority rule, in my
sense.
True. I guess we are talking about the Smith set. To me electing someone outside the Smith set is ok in some extreme cases. This is a violation against majority opinion in the sense that majority prefers someone to this candidate. But electing someone from the Smith set violates also the same majority rule. (To me Smith set does not represent any new additional strong majority rule but is just a collection of smaller majority preferences in the spirit described above.)
I understand that many people see Smith set as a natural sincere criterion. And as a result Smith set based methods are SVMs to many. (I have criticized use of Smith set in some other mails because of its links to trying to linearize group opinions.)
If you think "Minimize voter regret" is not a strategy concern, then I note
that in the above scenario, if A is elected, then the C>B voters will regret
that they ranked C, since surely if they had just voted "B," B would have
been elected.
Ok. This sounds like linked to strategies.
If you really are not convinced that a sincere method should be independent
of clones, I won't argue with you, but that makes me doubt how "good" the
method is, even given sincere voters.
I agree that independence of clones is a nice idea but I'm not familiar enough and not convinced enough of the available definitions (if they always refer to true clones) and need to respect these criteria over other voter preferences to give my final opinion on what criteria are sincere to me. Hoping to come back as I said. Smith set sounded natural to me first but after some thinking I now find it just a criterion that should apply in 99% of the elections. I'm not sure about the clones yet.
I'm saying that strategy defense mechanisms don't operate by detecting insincere votes.
I agree. That would be too difficult.
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