Kevin had said:
> Hi, By the way, you can also ensure a method satisfies SFC by having it
> comply with this votes-only criterion: "If more than half of the voters
> rank > A over B, but there is no majority of the voters ranking some
third > candidate over A, then B doesn't win." > >
I replied
> First, does Kevins criterion apply only to rank methods? My criteria >
apply to all methods.
Kevin replies:
I wrote the above to help clarify the implications of SFC on at least rank
ballot methods.
I reply now:
Ok, so you were just offering a pedagogical help for Warren. Warren had
offered your definition as a better wording for SFC.
Kevin continues:
I won't get into again how I interpret criteria so that they apply to all
methods
I reply:
Yes, its probably best that you dont. Because, last time you did, posted
your rough sketch of what sort of criteria system you proposed, and then I
asked you for:
1. A precise definition of your proposed criteria system
2. A demonstration that uses that definition to show that Approval and
another RV version pass or fail SFC.
And your answer?:
.silence
Your proposed criteria system was a sketch that never took precise form that
could be used to show that Approval or RV meet or fail SFC.
When asked why he feels that SFC isnt about a strategy guarantee, Kevin
says:
I've told you why in the past actually. I don't think it is a very *useful*
guarantee, since you can't know in advance whether you qualify for it
I reply:
That seems an odd objection, because the whole reason why there can be
strategy dilemma, and the reason why we need a better method than Plurality,
is because one _doesnt_ have complete information, doesnt know what the
situation is. Are there criteria with which a voter knows for sure that the
criterions premise applies in a particular election, and that s/he is one
of the voters to whom the criterion makes its guarantee?
Anyway, you do know that, if there is a CW, you prefer that CW to the
candidates to whom you prefer the CW. All thats additionally needed is a
majority who prefer the CW to those same candidates. But its hardly unusual
for the CW to be preferred to other candidates by a majority. So if you
prefer the CW to Y, then most likely a majority does too--because thats the
CW.
So I guess you arent being entirely clear with us about in what sense you
feel that the voter doesnt know if s/he qualifies for SFCs guarantee.
Note that it isnt necessary to know who the CW is. Whoever the CW is, no
one worse (in your estimation) will win, if (as is typically the case) a
majority prefer the CW to him/her. For that, you and the rest of that
majority need do nothing other than vote sincerely.
Its true that you dont know for sure that falsification wont occur on a
scale sufficient to change the election outcome--but thats unlikely to
happen, for reasons that I went over in a posting within the past week.
Someone could object: Youre saying that most likely there wont be enough
indifference to keep the CW from having a majority over Y, but if, elsewhere
too, theres no truncation, Pairwise-count methods dont need SFC. But the
benefit of SFC is for a majority. That isnt an unreasonable premise
stipulation. A group smaller than a majority typically, with any method,
cant really expect to get its way. For instance, if its Nader, Hillary
Clinton and McCain, and Nader + Clinton dont have a majority--so McCain has
a majority--theres not a lot that you can expect. The Lesser-of-2-Evils
problem is about what has to be done to enforce majority wishes.
And, as I said, for some other candidate Y, there typically is a majority
preferring the CW to Y.
Kevin continues:
, and if you did know that you qualify for it, you'd also know that you
don't need to use it, since your candidate should win no matter what you do
with your lower rankings.
I reply:
Here I must admit that I have no idea what Kevin means. My candidate? SFC
isnt about my candidate or your candidate winning. Its about some
candidate Y _not_ winning, when a majority prefer the CW to him/her and vote
sincerely, when no one falsifies (or at least falsification doesnt occur on
a scale sufficient to change the election outcome).
If you know you qualify for [SFCs guarantee]
Does that mean If you know
the CW is preferred by a majority to the candidates whom you like less than
the CW
? If so, then Kevin is mistaken, because even if you know that,
there is no guarantee that one of those less-preferred candidates wont win,
if the method doesnt meet SFC. With non-complying methods, truncation by
voters outside that majority can cause one of the less-preferred candidates
to win. With IRV, Borda, etc., it doesnt even require truncation.
Kevin continues:
Well, the way I understand CC and "pairwise count method," MMPO and MDDA are
pairwise count methods that satisfy SFC but fail CC.
I reply:
Any kind of method would do. Thank you. If those methods meet SFC and fail
CC, that means that it isnt possible to say with assurance that SFC is
stronger than CC. I much prefer SFCs guarantee to that of CC because CC
only gives its guarantee if everyone votes sincerely, whereas with SFC only
that beneficiary majority need vote sincerely, and everyone else is only
stipulated to not falsify.
Mike Ossipoff
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