[EM] Re: Condorcet's strategy problem

Adam Tarr ahtarr at gmail.com
Tue Sep 13 21:51:47 PDT 2005

election-methods at electorama.com

On 9/13/05, MIKE OSSIPOFF <nkklrp at hotmail.com> wrote:
> I'll start looking for a BeatpathWinner FBC failure example, but I hope
> others will too, because it isn't so easy to find one.

There was an FBC failure example posted recently. It arises from a cycle 
with a lot of sincere indifference. It goes like this:

31% C>A>B
9% B>C>A
28% B=C>A
32% A>B>C

68% C > 32% A
63% A > 37% B
41% B > 31% C

Consider the 32% A>B>C faction. It takes 12% (38% of the faction) of them to 
win the election for B by "strong" favorite betrayal (B>A>C), making B the 
Condorcet winner. They can win the election for B by "weak" favorite 
betrayal (A=B>C) if 22% (69% of the faction) vote that way, but they have 
incentive for reversal unless they know for sure that that many will act in 
a similar fashion.

In my opinion, a method where favorite betrayal scenarios are restricted to 
a very narrow range of situations are not a major problem. If the polls 
start to look something like this, voters will know well in advance. In the 
vast majority of situations, there is no incentive to bury your favorite.

Forest has argued recently (with regards to DMC, but the argument still 
applies here) that voters will be very reluctant to vote full favorite 
betrayal unless they know for certain that it is necessary. This runs 
contrary to what Mike suggest, which is that voters will reverse order 
unless they are absolutely sure it is *not* necessary. Ultimately it is very 
hard for any of us to predict what effect wv Condorcet voting would have on 
the political climate and people's attitudes toward voting.

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