[EM] Re: Issues, Condorcet, and IRV (was: IRV vs. plurality)

[Alex Small]

At some point Dave Ketchum wrote:
>Except for cases involving IRV spoilers, winners are
>IDENTICAL - repeat IDENTICAL!!!

So, Dave seemed to be asserting that it will be very rare that IRV and
Condorcet give different results in real elections.

How about this


35 A>B>C
36 C>B>A
16 B>C>A
13 B>A>C

B is the Condorcet winner.  C is the IRV winner.  This is a simple case of
Left, Right, and Center, with Center having the fewest first-place votes. 
If Left and Right can moderate their stances without losing credibility
they can always make sure that Center has the fewest first-place votes.

So it would seem pretty realistic to have plenty of cases where IRV and
Condorcet will give different results.  If Left and Right just become more
moderate they can win over voters who were undecided between Left and
Center or Right and Center.  (OK, voters sufficiently close to Center will
still list Center as their favorite, but the point is that Left and Right
can at least poach a good number of voters.

Anyway, whatever one might think of IRV and Condorcet, I have to question
the assertion that IRV and Condorcet will rarely give different results. 
I just gave a very plausible example corresponding to a standard
left-right situation.



Alex