[EM] Probabilistic criteria. Participation & no-show.

MIKE OSSIPOFF nkklrp at hotmail.com
Fri May 5 20:48:17 PDT 2000

 > I've only heard of one person advocating such a
 > method, and he didn't have a proposal, only the suggestion
 > that maybe a good method of that type could someday be found.

Markus said--

I guess that you are talking about Albert Langer. But remember
e.g. that Lucien Saumur promotes Smith//RandomCandidate.

I comment:

True. And so it could be of some interest how his method does
by criteria generalized to cover random methods.
But Smith//RandomCandidate isn't a proposal that we reform
advocates are ever going to have to deal with as a competitor
or a serious rival, if only because random selection would never
be accepted by the public, or by the people who write media
articles. It seems to me that RandomBallot did worse in Norman's
simulation than any other method. RandomCandidate seems like it
would surely do worse. Simulation results like that further clinch
the public unacceptability of random methods. I personally don't
have much objection to trying such a method, because eventually
we'd get lucky and get a good President, and the public might
find out that they like his policies. But as a proposal, it's
out of the question.


Markus said:

The participation criterion says that the participation in the
election by a same-voting group of voters should never worsen
(due to the opinion of this group) the result of the elections.

Of course, the participation criterion presumes sincere voting
because (1) if this additional group of voters votes insincerely
then -as we know only the reported opinion and not the sincere
opinion of this group- we cannot check whether it worsens the
result of the elections due to its sincere opinion. and (2) if

I reply:

Yes, but, whether we can check it or not, it's still meaningful
& useful to talk about what they can do to themselves, without
assuming sincere voting. Because, whether we can check it or not,
people surely will (and do) vote insincerely in Pluality, and
surely will in Borda.

In fact, as I discussed when I mentioned Myerson-Weber equilibrium,
the fact that we can't check on that giveaway is what makes
it particularly dangerous, and a bad result that the electorate
can get mistakenly stuck in.

For instance, using the familiar example of Plurality, the
notoriously common insincere voting people do in Plurality
, and the obvious incentive for it, makes Plurality fail SARC.

Whether the vote-totals reveal it or not, it still is undesirable
for someone who prefers Nader to defeat Nader by voting for Gore.

So, instead of sincere voting, I prefer to assume only reasonable
voting, voting in a way that could conceivably be the voter's
best strategy, with some configuration of the other people's votes.

Markus continued:

And (2):

This additional group of voters voted insincerely and worsened
the result of the elections due to its sincere opinion then this
wouldn't be considered as a problem because this fact would deter
this group from voting insincerely.

I reply:

Of course it's a problem, because, though dumping one's favorite
can and often will worsen the voter's result, it regrettably
_doesn't_ deter the insincere voting. Voters will give their
support away to someone whom they believe they need as a compromise,
and routinely dump their favorite in order to do so.

And if Nader had a win, but his voters gave it away by
voting for Gore, the election count results wouldn't show what
happened. Voters wouldn't be deterred from giving the election
away again & again, because the count results don't show that it
happened. The count results will merely show that Gore is a big
votegetter, and that very few voted for Nader, confirming what
the Nader-to-Gore giveaway voters believed. That's the
voting equilibrium that Myerson & Weber wrote about.

Now, with Approval it would be different, and a giveaway wouldn't
escape notice, as I spoke of when I wrote about Myerson's & Weber's
discussion. Aside from that,  Approval will never have the kind
of giveaways that happen with Plurality, and will happen with
IRV & Borda. And, with Approval, voters who vote in a way that
could conceivably be their best strategy, as spelled out in SARC,
will never defeat their sincere favorite or elect their sincere
last choice.

Yes, the academics mostly seem to ignore the possibility of
defensive order-reversal, and the fact that the need for it
creates a problem.

By the way, I should add that, under the conditions that
authors quoted by Tideman consider plausible and worth
considering, something stronger than SARC compliance can be
said for Approval: A group of same-voting voters who share the
same preferences, and vote in a way that could, with some
configuration of the other people's votes, gain an outcome that
they like better than all the outcomes that they could get by
other ways of voting, will never worsen their result, compared
to what it would have been had they not showed up & voted.

The above is true unless there are improbably inconsistent
frontrunner probabilities, a condition that could cause voters
to "skip" someone in their preference ordering.

For one thing, such conditions aren't considered worth
considering. For another thing, they wouldn't cause Approval
voters to defeat their favorite or elect their last choice,
if that wouldn't have happened had they stayed home.

Mike Ossipoff

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