[EM] my letter to CVD

[Adam Tarr]

James Green-Armytage wrote:

>         I agree that lacking monotonicity isn't a huge problem for IRV. 
> It does
>have *some* tactical significance, but it's not fatal. Actually I think
>that the problem is theoretically worse in the traditional two round
>runoff. For example, a case where a Republican had 45% and two Democrats
>were in a near tie around 22% or 23%. Clever Republicans might vote in the
>initial election for the Democrat whom they perceive of as being easier
>for the Republican to defeat. The problem in IRV is analogous to this, but
>less severe because the Republican's vote would have to stick with the
>'weak' Democrat until he got eliminated. Successful exploitation of IRV's
>lack of monotonicity would indeed be difficult.

I think you're being a bit too kind to IRV here.  Say it was a general 
election in an area with a large progressive base, and the 22% Democrat was 
actually a Green.  If the Green loses first, the Democrat wins 55%-45%, but 
if a few Republicans push the Green over the Democrat by putting him in 
first place, then the Republicans will win as long as roughly a third of 
the Democratic voters prefer the Republican to the Green.

-Adam