[EM] SARC definition improvement

[Markus Schulze]

Dear Mike,

you wrote (12 Sep 2000):
> Markus wrote (12 Sep 2000):
> > Mike wrote (10 Sep 2000):
> > > Markus wrote (10 Sep 2000):
> > > > In the website http://home.pacbell.net/paielli/voting you introduce
> > > > 7 criteria. 2 of the 7 criteria are violated by Condorcet methods.
> > > >
> > > > 4 of the 5 remaining criteria are motivated by the opinion that
> > > > if a majority of the voters strictly prefers candidate A to candidate
> > > > B then rather candidate A than candidate B should be elected resp.
> > > > then there should be a way of voting with certain properties that
> > > > will ensure that B cannot win.
> > > >
> > > > The problem is that these 4 criteria (SFC, GSFC, WDSC, SDSC) are so
> > > > similar that a reader either considers all 4 to be important or all
> > > > 4 to be unimportant.
> > > >
> > > > A reader who thinks that the fact that a majority of the voters
> > > > strictly prefers A to B has no important meaning will simply reject
> > > > all 4 criteria simultaneously.
> > >
> > > Sure, but you'd be surprised how many people value majority rule.
> >
> > And you would be surprised how many people value majority rule
> > without valueing the Condorcet criterion.
>
> No, I don't think that would surprise me, since most people have
> never heard of the Condorcet Criterion. I'm not sure what your point
> is in the above-quoted sentence.

Your comment ("You'd be surprised how many people value majority rule.")
makes sense only when you presume that everybody who values majority rule
also values SFC, GSFC, WDSC and SDSC. My comment ("You would be surprised
how many people value majority rule without valueing the Condorcet
criterion.") says that I don't agree that everybody who values majority
rule also values SFC, GSFC, WDSC and SDSC.

******

You wrote (12 Sep 2000):
> Markus wrote (12 Sep 2000):
> > Suppose that you were a very pessimistic voter. Suppose that you
> > believed that whenever you do something then the worst possible
> > will happen. Then -if PC was used- you would divide the candidates
> > into two groups and approve (i.e. give a "1" to) all the candidates
> > of the one group and disapprove (i.e. give a "2" to) all the
> > candidates of the other group. Since this voting behaviour
> > guarantees that the winner cannot be changed from an approved to
> > a disapproved candidate, this voting behaviour guarantees that
> > you cannot be punished for showing up. Therefore the same voting
> > behaviour that guarantees that you cannot be punished for showing
> > up under Approval Voting also guarantees that you cannot be
> > punished for showing up under PC. Therefore -although Approval
> > Voting meets SARC and PC violates SARC- it isn't feasible to
> > conclude that Approval Voting deters less from showing up than PC.
> > To my opinion, this demonstrates that SARC doesn't do what it
> > was designed for.
>
> It was designed to find out with which methods undominated voting
> can defeat favorites or elect last choices. It does what it's
> designed for. The fact that you can devise some way of voting
> in PC or Plurality that won't do that doesn't matter unless you
> can promise that everyone will vote as you suggest.  Because,
> otherwise, you haven't shown that the violation won't happen.

But why was SARC designed to find out with which methods undominated
voting can defeat favorites or elect last choices? If the aim is to
make the voters be not deterred from showing up, then I have to answer
that my example above demonstrates that SARC doesn't do what it was
designed to do. If the aim of SARC is to guarantee that a voter isn't
punished for showing up and using a certain kind of strategy, then I
have to answer that if you show up and vote strategically then it is
your own fault when you are punished.

******

You wrote (12 Sep 2000):
> You're making the error of feeling as if a method meets a criterion
> because you can find some case where it doesn't fail the criterion.

In so far as I wrote in my last mail that Approval Voting meets SARC
and PC violates SARC, I don't understand your comment.

******

You wrote (12 Sep 2000):
> Actually it might be possible to write a wording of SDSC that
> refers to actual votes instead of sincere preferences, and
> is about a specific way of voting rather than speaking of
> people having a way of voting, a wording that means the same
> as my SDSC wording.
>
> But I doubt that it would be simpler. And I doubt very much
> that it would be as clear in its purpose. WDSC & SDSC are about
> a majority being able to keep someone from winning without
> a specified degree of insincere voting. I don't think you could
> say it more directly or simply than the current wordings.
>
> But I wish Markus would write the new WDSC & SDSC wordings that
> he suggests. Then Blake won't say that all of the defensive
> strategy criteria were written by me. Actuall, even now, one
> of them, GSFC, was written by Steve, who also wrote a wording
> for SDSC, but that doesn't stop Blake from making that claim.

I suggest beat-path GMC as an alternative to SFC, GSFC, WDSC and
SDSC. (In so far as you consider beat-path GMC to be too strict,
you can also use BC.)

******

You wrote (12 Sep 2000):
> In a reply to Markus I spoke of minimizing need for insincerity.
> When I say that I want criteria that measure how well a method
> minimizes need for insincerity, I mean that I'd like to
> minimize the degree of insincerity needed, and it would be good
> for that protection to extend to as many voters in as many
> situations as possible.

I consider the way you measure the need for insincerity to be
unrealistic. You ask about the needed insincerity when a majority
of the voters strictly prefers candidate A to candidate B and
this majority wants to prevent candidate B from winning. I consider
this way to measure the need for insincerity to be unrealistic
because when someone votes strategically then he does so to
maximize his own utility expectations and not because he wants
some "rightful" candidate to win.

******

You wrote (12 Sep 2000):
> Bruce sent me an objection to it by individual e-mail,
> and I answered his objection. Then, at least some months later, Bruce
> repeated the exact same objection on EM, making no reference to my
> reply that I'd sent him. I questioned the sincerity of that intentional
> re-use of an answered objection without reference to the answer.
> That tactic by Bruce was in violation of the stated guidelines for EM.
>
> Anyway, now it looks as if it's necessary for me to answer that same
> objection yet again, just like I did on EM before (Markus, why didn't
> you posts that too), and just like I did when Bruce sent it to me
> individually. I suppose I could look it up in the archives and
> re-post my reply, but that would be even more time consuming. But
> I suggest that we ask ourselves why Markus re-posted Bruce's old
> objection, without re-posting my reply to it. By so doing, Markus
> is wasting your time & mine, and, it seems to me, is violating the
> EM guideline against recycling old arguments without replying to
> the answers that were already given to those arguments.
>
> Why is Markus posting this outdated message from Bruce?

I don't agree with you that Bruce message is "outdated." Bruce wrote
in great detail where he had problems understanding the wordings of
your "lesser-of-two-evils" criteria. It is true that in a reply to
Bruce you explained in great detail the wordings of your "lesser-of-
two-evils" criteria. But nevertheless you still use the same
wordings. Therefore someone who reads today's wordings of your
criteria will still have the same problems like Bruce.

Markus Schulze
schulze at sol.physik.tu-berlin.de
schulze at math.tu-berlin.de
markusschulze at planet-interkom.de