[EM] Introducing "Insanity Voting" - the only voting system which meets the Insanity Criterion

Kevin Venzke stepjak at yahoo.fr
Fri Jun 3 19:12:56 PDT 2005


--- Scott Ritchie <scott at open-vote.org> a écrit :
> Plurality criterion: "If the number of ballots ranking A as the first
> preference is greater than the number of ballots on which another
> candidate B is given any preference, then A's probability of election
> must be no less than B's.": Passed.  Since all candidates always have an
> equal chance of winning, this criterion holds.

Since your method is actually deterministic, and doesn't return ties, it's
actually never true that every candidate has an equal chance of winning.
So I'm sure Plurality must be failed.

But interestingly, Random Candidate actually would satisfy Plurality.

> Favorite Betrayal Criterion: "For any voter who has a unique favorite,
> there should be no possible set of votes cast by the other voters such
> that the voter can optimize the outcome (from his own perspective) only
> by voting someone over his favorite.":  Passed, for two reasons.  If we
> assume the voter is voting strategically, then for any and all sets of
> votes by others, he can elect his favored candidate.  If, on the other
> hand, the voter isn't voting strategically, it should be noted that he
> cannot alter the probability of his candidate winning anyway, and thus
> can't possibly betray him.

I'm afraid I don't understand this. Suppose several voters, with a common
favorite candidate, know how every other voter will vote. Is it guaranteed
that they can put this favorite candidate in the top position and get at
least as good a result as if they don't?

> Participation Criterion: Depending on the definition used, this one is
> either passed or failed.  Mike Ossipoff's overly restrictive definition,
> "Adding one or more ballots that vote X over Y should never change the
> winner from X to Y" is not met. However, Douglas Woodall's definition,
> "The addition of a further ballot should not, for any positive whole
> number k, reduce the probability that at least one candidate is elected
> out of the first k candidates listed on that ballot" is met.  It should
> also be noted that an inverse of the participation criterion, that
> choosing to vote and rank your candidate can cause him to win, is always
> true regardless of the makeup of the electorate - in other words, one
> always has a complete incentive to vote, no matter how unpopular his
> candidate is.

That's an "inverse" of Participation? It sounds like an extreme strengthening
of it.

I get the impression that you've misunderstood what "probability" means
in criteria definitions. It refers to probability after all the ballots
have been counted. And as above, your method doesn't return ties; a
candidate always wins with 100% probability.

> Later-no-harm Criterion: Passed.  All candidates have the same
> probability of winning regardless of what you put on your ballot, so
> adding him later will do him no harm.

Same issue here.

> Condorcet and Generalized Condorcet Criterion: Failed, however we could
> modify the method to select a Condorcet winner if one exists, then
> default to insanity voting.  That seems to be all the rage these days.

I guess you may be referring to the variant of Condorcet//Approval that
I suggested. I'm limited in what I can put on the front end. It doesn't
seem possible to modify Schwartz or Smith to be FBC-friendly.

> Strategy-Free Criterion: Failed, but that's ok because strategic voting
> is important to have in an election system.

Must be a joke about the name of the criterion.

> Impossibility of Ties Criterion:  The voting system should never rank
> two candidates equally or resort to nondeterministic methods to resolve
> ambiguity.

Never? I guess you could make most methods pass by privileging a voter
or candidate selected non-randomly.

Kevin Venzke


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