[EM] IRV's Squeeze Feature

fsimmons at pcc.edu fsimmons at pcc.edu
Fri Dec 5 11:05:01 PST 2008

Suppose that the voters are distributed uniformly on a disc with center C, and that they are voting to 
choose from among several locations for a community center.

Then no matter how many locations on the ballot, if the voters rank them from nearest to furthest, the 
location nearest to C will be the Condorcet Option.

Therefore, if C itself is one of the options, it will be the Condorcet Option no matter what the other 
options are.  So C is more than just a regular run of the mill Condorcet Option, it is a kind of Universal 
Condorcet Option for this distribution of voters.

The center C of any distribution of voters with central symmetry through C will be a Universal Condorcet 
Option for that distribution.

But no matter how peaked that distribution might be (even like the roof of a Japanese pagoda) the center 
C is not immune from the old IRV squeeze play.

If the good and bad cop team gangs up on C, one on each side, they can reduce C's first choice region 
to a narrow band perpendicular to the line connecting the two team mates, thus forcing C out in the first 
round of the runoff.

If the team mates are not perfectly coordinated, then instead of a narrow band, C's first choice region 
becomes a long narrow pie piece shaped wedge, roughly perpendicular to the line determined by the two 
team mates.

This squeeze play can be used against any candidate no matter the shape of the distribution, symmetric 
or not.  But my point is that even in a sharply peaked unimodal symetrical distribution, the center C, 
which is the Universal Condorcet Option, can easily be squeezed out under IRV.  And what justification 
for winning does the IRV winner have?  Merely that it was the closer of the two team mates to the ideal 
location C.

Now leaving the concrete setting of voting for a physical location for a community center, and getting 
back to a more abstract political issue space: It doesn't really matter if the good cop and bad cop are 
really even anywhere near to opposite sides of a targeted candidate (say a strong third party challenger) 
as long as they can make it appear that way.

The two corporate parties are very good at this good cop / bad cop game, especially since the major 
media manipulators of public opinion are completely beholden to the giant corporations.


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