Nondictatorial & Nonmanipulable axioms (was Re: York's version o

[Mike Ossipoff]

In a May 2 letter (I've been away from e-mail for a while), Bruce
stated that Condorcet's method fails the non-manipulability criterion.

So let me remind everyone that every non-dictatorial single-winner
method fails that criterion. Certainly Copeland's method &
Regular-Champion fail it.

Since no method is un-manipulable, as Gibbard & Satterthwaite
use the term in their mysterious, un-posted theorem, what's the
point for Bruce to say in his May 2 letter that Condorcet's
method isn't un-manipulable by that un-stated definition?

The meaning of "manipulable" subject to misunderstanding.
For instance, is Plurality subject to manipulation? Sure, because
I can improve the outcome, as I judge it, by voting for Clinton
instead of voting sincerely for Nader.

Excuse me, but the fact that Plurality is manipulable, in that
sense, isn't the problem. The problem is that voters _have_ to
strategize in a drastic way to get their best outcome.

That's what I mean by "defensive strategy". I've defined it
more precisely in previous letters to this list, along with
"drastic defensive strategy".

So it's meaningless that Plurality, & all other methods
are "manipulable"; the important thing is: What do you have
to do to optimize the outcome for yourself? What does a
majority have to do to elect someone that it wants to elect,
or deny election to 1 or more candidates that they don't want
to elect?

Condorcet's method doesn't require strategic manipulations,
and the attendant strategy dilemma under all reasonable &
plausible conditions. That can't be said for Copeland or
Regular Champion. So even though all methods are
"manipulable", or whatever that's worth, Condorcet's method
is the one that doesn't force strategic manipulation dilemmas
on the voter under ordinary conditions. In fact, even under
unfavorable devious conditions, Condorcet's method doesn't
require the degree of manipulation that Copeland &
Regular-Champion do--Condorcet, unlike those other 2 methods,
doesn't require drastic defensive strategy (voting a less-
liked alternative equal to or over a more-liked one).


Mike



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