[EM] Re: equal rankings IRV

[Kevin Venzke]

Bart,

The simplest FBC failure scenario I can think of looks like this:

6 A
3 C>B
2 C=B  <<< (sincere is C>B)
2 B

A and B are the lesser evils.

B is eliminated and A beats C, when the two voters vote C=B.  However, this
only happens because the 3 voters buried their support for B.  If the lesser
evil candidates are always promoted to (equal) first place, on everyone's
ballots, then I don't see how there would be any FBC failures.

Reasoning: If lesser evils never have lower preferences, only first preferences,
then A is either going to have more votes than B or he isn't.  Eliminating
other candidates isn't going to change that.

I think for the C=B voters to vote B>C, they would have to believe that C
can't beat A, and that despite this, more voters will vote C>B than B.

I think the voters risking the election are those who DON'T use approval
strategy.

--- Bart Ingles <bartman at netgate.net> a écrit : > 
> What would convince me otherwise would be a set of strategy equations
> comparable to those used for calculating optimal strategy in approval
> voting, or possibly simulations with ER-IRV(whole) showing that
> "lesser-evil or better" strategy is as good or better than
> "lesser-evil-only" in terms of social utility efficiency.

Well, I can't produce these, at least not at the moment...  But my thoughts
would be:

"Lesser-evil-only" will only elect lesser evils.
"Lesser-evil or better" could elect a more broadly appealing candidate, just
as in Approval.

Again, if people are using "lesser-evil or better" strategy, I don't know
where the FBC failures come in.

Kevin Venzke
stepjak at yahoo.fr


	

	
		
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