[EM] full rankings, voter desire for

Rob Lanphier robla at robla.net
Sat Oct 15 12:27:16 PDT 2005


On Sat, 2005-10-15 at 10:58 -0400, Warren Smith wrote:
> I did not say voters always want full rankings.
> 
> What I said was, I think there is a substantial SUBCLASS of elections,
> in which, all voters (except perhaps for a few who are insane or writing
> illegible ballots or something random like that) will want to provide full rankings.
> 
> If your voting method  misbehaves badly commonly when confronted with elections from within
> that subclass, then it is not a good voting method.
> 
> That was all I claimed.  Now since I am asked for supporting evidence, I respond
> that many books and many authors, simply refuse to consider truncated ballots.
> Also some countries make them illegal.  I suggest to you, that much as you may
> dislike this, there is a reason they did that, and it is not a good idea to
> ignore it and pretend it does not exist when we design voting methods.

I agree with Warren that a system that doesn't break down in the face of
full rankings is highly desirable, for many of the reasons that he
cites.

I think his argument could be reworded slightly to be less
controversial.  It's not that there's a universal or near-universal
desire to provide full rankings.  It's that there's a strong sense that
asking voters to provide full rankings is the "right" (i.e.
civically-minded) thing to do.  A system that violates later-no-harm
therefore has a serious political liability in that regard.  You may
disagree as to whether or not it's "right", but I think Warren presents
a reasonable anecdotal case that there's widespread belief in full
rankings (though I like others am interested in the specifics).

My personal belief is that satisfying later-no-harm (or at least
minimizing violation to rare instances) is highly desirable.  I
personally believe that getting people to think deeply about compromises
is how we get to a more civil state in politics.  If people can be
jostled out of their comfort zone and consider the relative merits of
candidates who they might at first blush consider "evil", then perhaps
we'll truly get less evil candidates than the current batch who foment
partisan rancor.

Here's a related set of questions I've been meaning to ask:

1.  Are the Later No Harm (LNH) criterion and the Sincere Favorite
Criterion (SFC) mutually incompatible?

2.  Are LNH and the Favorite Betrayal Criterion (FBC) mutually
incompatible?

3.  Are LNH, SFC and FBC mutually incompatible?

If the answer to #3 is "no", I'm very interested in figuring out a
system that satisfies those three.

Rob

p.s. can we please please please rename the "Sincere Favorite Criterion
(SFC)" to "Majority Pairwise Winner criterion (MPW)" or something else
more accurate?





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