[EM] SFC and "margins vs. winning votes"

[Russ Paielli]

MIKE OSSIPOFF nkklrp-at-hotmail.com |EMlist| wrote:

 >
 > Russ quoted my definition of SFC:
 >
 > SFC:
 >
 > If no one falsifies a preference, and if a majority prefer the CW to
 > candidate Y, and vote sincerely, then Y shouldn´t win.
 >
 > [end of SFC definition]


 > A few days ago, Russ posted a statement that SFC is well-defined, 
even though Russ claimed that he believes that SFC isn´t useful.


IIRC, I said SFC could be well-defined if it were based on a clearly 
specified model of "true" voter preferences. But then it is only as good 
as that model. Mike doesn't see a need for such a model because he 
doesn't understand the underlying problem of basing his criteria on 
"true" voter preferences.

 > Russ continues:
 >
 > , what is the significance of SFC?
 >
 > I reply:
 >
 > It´s as I´ve been explaining it all this time.
 >
 > Russ continues:
 >
 > Well, since Mike feels that he can write his own version of the
 > Condorcet criterion, I'll write my own version of SFC, and I'll call it
 > the margins SFC:
 >
 > If no one falsifies a preference, and if the margin of the victory of
 > the CW over candidate Y is larger than any other margin of victory, then
 > Y shouldn't win.
 >
 > [end of margins SFC definition]
 >
 > Does it now appear that margins is less vulnerable to strategy than
 > winning votes?
 >
 > I reply:
 >
 > Is that criterion of yours supposed to be in some way a counterpart 
of SFC? Your criterion is a method-dedicated criterion, of course, 
mentioning margins.  SFC doesn´t mention winning-votes.


No, SFC doesn't explicitly mention winning votes, but it implies it. 
That was my main point.

 > SFC is about a majority not not needing strategy to accomplish the 
familiar goal of ensuring that some greater-evil won´t win.
 >
 > By the way, Plurality meets "Margins SFC", though Plurality is far 
from free from strategy for members of a majority who prefer the CW to 
Y, when the members of that majority have different favorites. So it´s 
odd that you call your criterion SFC. Or do you now believe that 
Plurality is strategy-free under those conditions?
 >
 > SFC stands for Strategy-Free Criterion, because, with complying 
methods, the majority described in SFC´s premise doesn´t need any 
strategy in the plausible situation of that premise.


What is it about a majority of voters that is so special? Suppose we 
have a proposition on the ballot, and the result is 47% to 44%? Do we 
say it didn't pass because a majority of the voters did not approve it? 
Of course not. It passes. Why? Because a majority of the voters WHO 
VOTED ON IT approved it -- and that's all that matters.

But Mike thinks that if voters abstain from voting on a particular 
Condorcet pairwise race, then their opinion should still matter in terms 
of setting some significant threshold. If that's true, then why not 
count the registered voters who didn't bother to vote at all (either for 
that particular office or for the entire election)? If only half of the 
registered voters even bother to show up, why isn't the "majority" 
threshold for your SFC the majority of all the registered voters? Or all 
the eligible voters even if they aren't registered?

I think your criterion is inconsistent. It defines a majority in terms 
that include voters who didn't see fit to vote on a particular pairwise 
race, but it doesn't account for voters who didn't vote at all for that 
office or for the entire election.

 >
 > Russ continues:
 >
 >
 > When you get right down to the basics, Mike's SFC is simply an arbitrary
 > criterion
 >
 > I reply:
 >
 > It isn´t entirely clear what Russ means by an arbitrary criterion. If 
"arbitrary" means not wanting  majorities to need defensive strategy 
that conceals their preferences and surrenders their aspirations, , then 
call me arbitrary. :-)


 > Russ continues:
 >
 > that happens to favor winning votes, but an equally arbitrary
 > criterion can be written to favor margins.
 >
 > I reply:
 >
 > Well, you certainly have proven that an arbitrary criterion can be 
written.
 >
 > Russ continued:
 >
 > Hence, Mike's SFC criterion
 > is completely irrelevant to the debate over winning votes vs. margins.
 > In fact, it's completely irrelevant, period. And so is its generalized
 > version, GSFC, of course. They're both really just pedantic tricks.
 >
 > I reply:
 >
 > And people should take your word for those things? Or is it that 
you´re saying that you´ve proven it by your explicitly margins-dedicated 
criterion that Plurality passes?
 >
 > Anyone can write a criterion such as the IRV criterion that says that 
a method passes the IRV criterion if it chooses IRV´s winner.That´s 
essentionally what your "Margins SFC" is.


And that is essentially what your SFC criterion is too, except that it 
is written for wv Condorcet.

 > Russ continues:
 >
 > I realize that "margins vs. winning votes" is an old topic here, but I
 > would just like to add my two cents worth.
 >
 > I reply:
 >
 > Ok, you´re going to add something new? Good, when will you start? But 
perhaps "worth" isn´t the right word for what you add.


Mike, I suspect that you will promptly ignore or misinterpret anything 
"new" that I add just as you have done with all the "old" stuff in the past.

 > Russ continues:
 >
 > If you argue for wv, you are claiming that a 51-49 victory is "stronger"
 > than a 49-0 victory. Common sense tells us that's nonsense. Some of us
 > still have common sense.
 >
 > I reply:
 >
 > That´s been answered many times. You´ve shown that a pairwise defeat 
that is better by winning-votes can look not as good by margins. 
Amazing. It´s because wv and margins are different.


Yes, I'm sure it's been "answered" many times. What does that prove, 
Mike? Does the truth of a proposition depend on how many times it's been 
asserted? Apparently you think so.

 > Russ wants us to count those 49 voters who voted against the 51-49 
defeat. Some like to do that, saying that it´s more "symmetrical" if we 
count them as we count the winning-votes.
 >
 > But, if X pairwise-beats Y, the X>Y voters and the Y>X voters aren´t 
symmetrically related. Why?
 >
 > The Y voters lost.


But we're trying to resolve an ambiguity here, Mike. We *must* 
ultimately choose a winner who "lost" to another candidate. The question 
is not *whether* something needs to give but rather *what* needs to 
give. According to your impeccable "logic", nobody should win.

 > If every candidate has a pairwise defeat, then, to elect someone, we 
have to disregard their pairwise defeat, we have to overrule the 
public´s statement that someone else would be better, if we´re to 
appoint that person the winner.
 >
 > When we do that, we´re overruling the people who voted for the X>Y 
defeat. As I said, we shouldn´t do that lightly. So don´t avoidably 
overrule more voters than necessary, by using a count rule that doesn´t 
distinguish the voters who won from the voters who lost.
 >
 > You see, Russ, if we keep the X>Y defeat, we aren´t overruleing the 
Y>X voters. The Y>X voters were overruled when they were defeated in the 
public vote between X and Y, when the public said that they collectively 
prefer X to Y.


I know the whole song and dance, Mike. And it's nothing more than your 
arbitrary "logic" about what should and shouldn't be "overruled." But 
the bottom line is that, while you are perfectly willing to overrule a 
49-0 defeat, you consider a 51-49 defeat sacrosanct. That's arbitrary 
whether you are willing to recognize it or not.

<cut>

 > Certainly Russ can think of anything any way that he wants to. But 
when it comes to counting a truncated ranking, I wouldn´t add to it 
preferences that the voter didn´t vote.


But you somehow think that the "majority" should be defined in terms of 
voters who didn't vote for a particular pairwise race. Once again, Mike, 
why don't you at least be consistent and also count the voters who 
didn't vote at all, either for that particular office or for the entire 
election?

 > Aside from demonstrating Russ´s usual confusion, this posting 
well-expemplifies what I was saying about how what Russ says has little 
if anything to do with what Russ actually believes.
 >
 > A few days after I told Russ why he would stop advocating wv, Russ 
predictably stopped advocating wv. I´d asked Russ if he was going to 
become a margins advocate now. And a few days later, Russ becomes a 
magins advocate :-)


This statement is no more accurate than the rest of Mike's reply. I 
advocate neither "margins" nor "winning votes." My point was that either 
can be considered valid -- Mike's intolerant dogmatism notwithstanding.