[EM] Markus & Manipulability

[MIKE OSSIPOFF]

Markus, we went over this a long time ago on this list.

Markus wrote:

Due to Nurmi and Bartholdi, the more information you need about the
opinions of the voters resp. the more accurate this information must
be to be able to calculate a strategy, the less vulnerable to strategies
the used election method is. To my opinion, this argument by Nurmi and
Bartholdi is plausible.

I reply:

Markus, there's nothing wrong with copying & repeating what you've
heard from academic authors, but it would be good to also question
a what you read from them.

When academic authors write about methods with regard to strategy,
they tend to speak of vulnerability to strategy. Strategy is
taken to mean offensive strategy, by which someone is manipulating
the method.

It's (almost) common knowledge on this list that strategy is important
as an undesirable _need_ for voters, rather than as a manipulation
opportunity. However that's something that most academic authors
, and those who worship them, remain ignorant of.

When there's a problem with offensive strategy, the problem is
the problem that that offensive strategy causes for others, the
defensive strategy dilemma that it causes for them.

I'm almost certain that it was Nurmi who, in one of his books or
articles, rated the methods on their vulnerability to strategy.
IRV rated best or near best in that regard, because offensive
strategy is difficult in IRV. But what good does that do, when
defensive strategy is necessary in IRV, regardless of whether or
not anyone is using offensive strategy?

Is it possible that the academics & their loyal are unaware that
Plurality has a strategy problem not because someone can offensively
manipulate it, but because Plurality forces voters to use a drastic
defensive strategy, a kind of strategy needed to protect a sincere
CW, or to enfore majority rule?

With any non-probabilistic voting system, a majority can get their
way about something that they all agree on. If there's an alternative
that they all want to win, they can make it win. If there's an
alternative that they all want to lose, they can make it lose.
The former is usually easy, but the latter, with most methods,
can require members of that majority to vote something else over
their favorite.

Strategy that's needed to protect the win of a sincere CW, or to
enforce majority rule--I call that "defensive" strategy. It's the
old "lesser-of-2-evils problem", and it's the reason why most of
us want a better voting. And still the academics & their obedient
copiers don't seem to understand that, and still consider
"strategy problem" to mean vulnerability to manipulation.

Markus once said that Plurality's strategy problem is a vulnerability
to manipulation, because if Bush ought to win by 1st choices, then
the Nader preferrers who vote for Gore are manipulating the
voting system when they elect Gore. That sort of thing is why
I sometimes say that the academics have their heads up their ass.

(Markus, you know that doesn't strictly apply to you, if you aren't
an academic, but merely an academic loyalist).

Plurality's problem is not that Nader preferrers can make Gore win
even though Bush is favorite of most. It's problem is that Nader
preferrers need to dump Nader & vote for Gore to enforce the
majority against Bush.

Mike Ossipoff





_________________________________________________________________
Join the world’s largest e-mail service with MSN Hotmail. 
http://www.hotmail.com