[EM] minmax is not a good public election method

Kevin Venzke stepjak at yahoo.fr
Fri May 27 13:08:24 PDT 2005


--- James Green-Armytage <jarmyta at antioch-college.edu> a écrit:
> 	For public elections, I think that it would make more sense to use IRV
> than any minmax version, because at least IRV passes the mutual majority,
> Condorcet loser, and independence of clones criteria.

Despite those criteria, I consider IRV to be less majoritarian than MM(wv)
or MMPO, since IRV can't even respect majority preferences with three
candidates. That is a bigger failing than MMPO failing mutual majority.

> 	I consider this to be a fatal "failure example" for minmax:
> 100 voters, strict rankings as follows:
> 22 RSTZ
> 21 STRZ
> 21 TRSZ
> 12 ZRST
> 12 ZSTR
> 12 ZTRS
> 	The set {R, S, T} is supported by a 64% mutual majority, and yet Z (the
> Condorcet loser) wins.
> 	Any mutual majority up to a 2/3 supermajority can potentially be thwarted
> by a three candidate cycle in minmax. Note that voters who oppose the
> mutual majority can contribute to its downfall, which opens up extra
> possibilities for strategic manipulation.

This is very pessimistic. If minority voters have enough coordination to
vote insincerely *in a cycle*, surely the majority voters have enough 
coordination to simply not rank those candidates strictly!

> 	I argue that minimax makes no sense as a public election proposal. If
> we're going to try to implement pairwise count methods on a big scale, we
> should choose good ones. In my opinion, that absolutely cuts out minmax
> methods (because of MMC failure, CL failure, etc.) and margins methods
> (because of lack of strategic stability). These methods have the potential
> to greatly embarrass pairwise count methods in general.

On the other hand, I'm not sure that a ranked ballot method which fails
Later-no-harm would be publicly acceptable.

Kevin Venzke


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