[EM] Can someone point me at an example of the nonmonotonicityof IRV?

[Stéphane Rouillon]

I agree IRV can rarely make your vote work against you (about 1 chance on 
1000).
How about a system that can make a candidate wanted by a majority lose 
(about 1 chance on 5)!!
That's what FPTP can do when political strategists present a clone of the 
favourite candidate to split the votes...
Clearly FPTP is worst than all other single-winner systems.

>From: "rob brown" <rob at karmatics.com>
>To: EM <election-methods at lists.electorama.com>
>Subject: Re: [EM] Can someone point me at an example of the 
>nonmonotonicityof IRV?
>Date: Sat, 9 Aug 2008 13:15:16 -0700
>
>On Sat, Aug 9, 2008 at 11:55 AM, Kathy Dopp <kathy.dopp at gmail.com> wrote:
>
> > Can you imagine knowingly supporting a voting system where voters have
> > no idea how to rank their first choice candidate (first or last or in
> > between) in order to help their first choice candidate win?!
> >
> > I.e. ranking one's first choice candidate LAST, may help one's first
> > choice candidate win, whereas ranking one's first choice candidate
> > FIRST will not.
>
>
>Don't you think you are being a bit over dramatic, Kathy?
>
>Are you aware that in going to a doctor to treat an injury, you can get in 
>a
>car accident and get injured some more?  Why would anyone go to a doctor if
>doing so can actually make your health WORSE?
>
>Just because there is a non-zero chance of harm resulting from your choice
>does not mean that you should be paralyzed from making a decision.  The
>potential harm (and good) needs to be balanced with the probability of the
>various outcomes.  We do this sort of balancing every day, usually
>subconsciously, on just about every decision we make.  By your logic, 
>people
>should have "no idea" whether to do anything.
>
>I also think you are putting far too much emphasis on people's first choice
>candidate, as if all results other than the first choice candidate winning
>are equally bad.  This way of thinking seems to be a common symptom of 
>being
>accustomed to plurality and the two party system that results from it.  In
>an election with many candidates, if you hurt your first choice candidate's
>chances, but you help your second choice beat your least favorite, is that
>really so bad?
>
>-rob


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