[EM] Strategic voting in Condorcet & Range N-canddt elections

[Kevin Venzke]

Hi Warren,

--- En date de : Mar 9.6.09, Warren Smith <warren.wds at gmail.com> a écrit :
> >> So for the rest let us assume voters will cast
> votes with
> > A,B top &
> > bottom (or reverse)
> > only, due to them being strategically wise and also
> due to
> > them
> > wanting to simplify
> > their lives if they can (and they can, here).
> 
> >Venzke:But the "strategically wise" characterization,
> as well as the assumption
> >that only A or B can win, go out the window as soon as
> neither A nor B
> >has an outright majority. This happens already in
> Plurality elections.
> >I am pretty sure that third party supporters will
> analyze this situation
> >and find that the odds of C>A>B votes creating a
> harmful cycle are small
> >compared to the odds of C being the (voted) Condorcet
> winner.
> 
> --No.  Remember.  We agreed at an earlier stage
> of the argument, that
> strategic votes were going to be intended to influence who
> wins among
> {A,B}, for only
> TWO candidates A,B... because we could regard 3-way
> near-ties
> [where that your vote had a chance of electing any of THREE
> canddts]
> as a neglectibly unlikely scenario.
> 
> OK?  That is stipulated. Only A or B can
> win.   I do not give a damn
> about anybody possibly having an outright majority. 
> Or any cycle
> maybe existing in the minds of third parties.  It is
> unnecessary to
> let those concepts enter our minds.  Expunge them from
> consideration;
> they serve no purpose except to confuse.  When things
> are very simple
> don't make them complicated.  This argument needs very
> few axioms.
> Keep it that way.
> All we need to know is
> 1. only A or B can win.  Others neglectibly unlikely,
> so neglect them,
> dammit.  Be utterly convinced that no matter what,
> nobody besides A &
> B can win.
> 2. method is monotone.
> Period.
> 
> Now.  In that case, in any monotone method, an A-top
> B-bottom vote
> is always maximally strategic, in the sense that if ANY
> vote you can
> cast will make A win (and remember, only A or B can win -
> we agreed on
> that earlier)  then a vote
> of this form will always do the job.
> 
> OK? So, assuming strategic voters know that theorem, why
> would they do
> anything else?  They would not, unless they have an
> insane desire to
> complicate their lives
> (and maybe not even then).  I put it to you: 99% of
> people smart
> enough to know this theorem, are also smart enough not to
> have insane
> desires to complicate their lives and live on the edge.
> 
> It's kind of like if we agreed a best way to drive was in
> your lane.
> Perhaps under some circumstances, it might be equal-best to
> swerve way
> the hell off the road thru a field
> for 5 loop-the-loops...   by why would
> anybody do that if they were
> sure that just
> staying in their lane could not possibly be a worse
> strategy, but
> could be better?

Ok. It seems I misunderstood the point of your arguments 1-3. I thought
that when you made these points:

1. your vote will rarely matter
2. usually your vote can only determine between two frontrunners
3. it is so unlikely that you can break a three-way tie that it need
not be considered

that you were attempting to be comprehensive and discuss all or most
elections. It is pretty clear to me that given that point 5 is correct,
then points 1-3 are not even close to all-encompassing for Condorcet
methods. You never explicitly argued that they were meant to be. Although,
you did make comments like:

"My old (1999-2000) Bayesian Regret simulations, when considering
strategic voters,
made as their first move, the decision to rank the two frontrunners
top and bottom.
As we've seen, that decision was wholy justifiable..."

Kevin Venzke