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 shouldnīt win.
[end of SFC definition]
Russ continued:
Here's my comment:
Mike considers this criterion critical and uses it as evidence that certain Condorcet variations are less vulnerable to insincere strategy
I reply:
Iīve repeatedly said that emphasis on vulnerability to insincere strategy is barking up the wrong tree. The problem is the need for defensive strategy that conceals oneīs genuine preferences. Yes I admit that offensive insincere strategy in Margins Condorcet can cause serious problems, but the problems that it causes has to do with creating a need for defensive strategy that falsifies oneīs preferences or buries oneīs favorite.
Russ continued:
...when they base defeat strength on "winning votes" rather than "margins."
Forget for now all the disputes about Mike's definition of preferences. Even if Mike's definition of preferences is clear and unambiguous (and I realize that's a big "if")...
I reply:
A few days ago, Russ posted a statement that SFC is well-defined, even though Russ claimed that he believes that SFC isnīt useful.
Russ continues:
, what is the significance of SFC?
I reply:
Itīs as Iīve 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 doesnīt mention winning-votes.
SFC is about a majority not not needing strategy to accomplish the familiar goal of ensuring that some greater-evil wonīt 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 itīs 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 SFCīs premise doesnīt need any strategy in the plausible situation of that premise.
Russ continues:
When you get right down to the basics, Mike's SFC is simply an arbitrary criterion
I reply:
It isnīt 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 youīre saying that youīve 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 IRVīs winner.Thatīs essentionally what your "Margins SFC" is.
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, youīre going to add something new? Good, when will you start? But perhaps "worth" isnīt the right word for what you add.
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:
Thatīs been answered many times. Youīve shown that a pairwise defeat that is better by winning-votes can look not as good by margins. Amazing. Itīs because wv and margins are different.
Russ wants us to count those 49 voters who voted against the 51-49 defeat. Some like to do that, saying that itīs 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 arenīt symmetrically related. Why?
The Y voters lost.
If every candidate has a pairwise defeat, then, to elect someone, we have to disregard their pairwise defeat, we have to overrule the publicīs statement that someone else would be better, if weīre to appoint that person the winner.
When we do that, weīre overruling the people who voted for the X>Y defeat. As I said, we shouldnīt do that lightly. So donīt avoidably overrule more voters than necessary, by using a count rule that doesnīt distinguish the voters who won from the voters who lost.
You see, Russ, if we keep the X>Y defeat, we arenīt 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.
Why does margins violate majority rule so readily? Because, when it subtracts to calculate the margins, it destroys information about majorities.
Aside from those reasons, another reason why I advocate wv instead of margins is because wv meets the defensive strategy criteria that I chose because they measure for the goal of getting rid of need for defensive strategy that conceals preferences or buries oneīs favorite.
Russ continued:
Just for fun, let's frame this in terms of Mike's definitions of preferences and sincere voting. I don't feel like searching for it now, but Mike recently wrote something to the effect that a sincere vote is one in which the voter does not falsify any preferences and votes every preference that the particular method allows.
I reply:
Thatīs not it, but maybe youīre just trying to sound roughly like it.
Russ continues:
That means that a "sincere" vote cannot be truncated unless the voter truly rates all the unranked candidates *exactly* equal.
I reply:
Yes, with a method that allows the ranking of all the candidates, and counts those rankings in a way such that ranking X over Y means voting X over Y, by my definition of voting X over Y, a sincere ballot would only be one that ranks all of the candidates in accord with the voterīs preferences.
So if you donīt rate anyone equal, then yes, you have to rank them all if you want to vote a sincere ballot.
Russ continues:
Well, what does that mean? As I tried to explain previously, it requires a model of voter preferences
I reply:
But it isnīt enough to try to explain it. You need to try to show it. In fact, you need to successfully show it.
I told why my criteria are well-defined no matter what "prefer" means, even if it has only been defined imprecisely, even if the meaning of "·prefer" is unknown, and even if "prefer" doesnīt mean anything.
If you want to deny that, then you need to tell which sentence you claim is incorrect in my discussion about that.
I refer you to my posting whose subject title was "Four approaches to the meaning of preference", or something like that. It was posted some days ago.
But, for those who prefer having a defintiion of preferences, I included on in that posting. Itīs a simple definition, and so it doesnīt correspond perfectly to what we usually mean by preference. But that doesnīt matter:
A person prefers X to Y if, given the choice between X and Y, that person would choose X instead of Y. By my definition, if you would choose pepperoni pizza over some other kind, except that someone says that theyīll beat you up if you choose pepperoni, and so as a result youīd choose some other kind if given the choice, you then prefer some other kind to pepperoni. Well, it could be argued that, in a sense you do, since, taken with all the consequences of the choice, you prefer the results of choosing something other than pepperoni. Sure, that definition could be improved by stipulating the condition that your choice isnīt influenced by anything other than the intrinsic qualities of the things between which youīre choosing. That loses some definiteness of meaning, but thatīs ok, since a precise definition of preference is not needed for my criteria. So, take your pick: My simple preference definition, or my enhanced one, both of which are stated in this paragraph. But remember that no defintiion of preference is needed for my criteria. I refer you to my posting about that.
Russ continues:
What do I mean by a "model" of voter preferences?
I reply:
Iīm sure youīll tell us. Feel free to define it as you please. But donīt say that everyone must use your definition or "model".
Russ continues:
The very concept of preferences implies that the voter either explicitly or implicitly rates the candidates on a one-dimensional scale. Suppose I claim that the scale is continuous rather than discrete. Well, it's as good a model as any. That means that the voter's ratings of the candidates fall essentially randomly on a continuous real-valued scale. It also means the the probability of two candidates being rated exactly equal is zero.
I reply:
But not in practice. Donīt believe in your model so much that you want to use it to replace actual-world facts.
Russ continues:
If the probability of exactly equal ratings is zero, that means that Mike's definition of a "sincere" vote has zero probability of being truncated.
I reply:
So far, so good. Congratulations, Russ.
Russ continues:
It also means that no equal rankings will occur.
I reply:
No it doesnīt. It only means that a particular voter wonīt vote equal rankings if his/her ballot is sincre, in a voting system that allows all candidates to be ranked, and counts ranking X over Y in such a way that doing so means voting X over Y, by my defintion of voting X over Y. (Most or all seriously-proposed rank methods do so).
Russ builds on that incorrect statement:
And what
does that all mean? Your [you're] jumping the gun! Yes, that's right! It means
that winning votes and margins are equivalent, given that continuous
model of voter preferences.
I reply:
Russ has confused "A particular voter wonīt vote equal rankings if s/he votes sincerely in a rank-method" with "No one will vote equal rankings".
Indeed, if no one would equal rank or truncate, then margins would be the same as wv. But nothing in my definitions implies that no one will rank equally or truncate.
Every rank balloting election that Iīve conducted or participated in, and probably every rank balloting election that Iīve heard of, except those that explicitly require complete rankings, have truncation. In one case, the truncator specifically said that he was doing so as an offensive strategy, though he didnīt use those words.
Russ continues:
As Blake pointed out, we can think of truncated votes as more or less equivalent to the same votes completed with random rankings.
I reply:
Certainly Russ can think of anything any way that he wants to. But when it comes to counting a truncated ranking, I wouldnīt add to it preferences that the voter didnīt vote.
Aside from demonstrating Russīs 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. Iīd asked Russ if he was going to become a margins advocate now. And a few days later, Russ becomes a magins advocate :-)
Mike Ossipoff
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