[EM] Condorcet and Participation, Moulin's proof

[Chris Benham]

Michael Ossipoff wrote:

> Sure, Condorcet fails Participation. And of course it would be better 
> to not fail Participation. But Partilcipation isn't about a strategy 
> dilemma. It's about an embarrassment. You know that no method can 
> aviod embarrassments of some kind or other. You know, that goes back 
> to Kenneth Arrow. 


My intention in drawing attention to that proof  was to provide 
ammunition in favour of  Condorcet, not against it. Condorcet's 
Participation failure
apparently requires there to be four candidates in a cycle, which I 
don't consider to be a practical concern.

> But I use Partilcipation when comparing Approval to IRV. Some say 
> that's dishonest, to use Participation when my favorite method, 
> Condorcet, fails Participation.


I would say that it is somewhat misleading and inconsistent, and  
counter-productive to the goals of  educating people and promoting the 
Condorcet criterion.

> But it isn't, because, unlike Condorcet, IRV has no redeeming 
> qualities to outweigh its Participation failure. 


To be charitable, that is an absurd exaggeration made purely for the 
sake of being provocative. A more intelligent and appropriate attack on IRV
could be made along the lines that it's Participation failures are much 
more severe than Condorcet's because they are possible in relatively
common-place scenarios with just three candidates and no cycle. (This 
seems to be  Auros/M.Harman's main objection to IRV.)

So it seems to me that some weakened form of  the Participation 
criterion that captures one of  IRV's problems versus Condorcet might be of
some use/interest.

Chris Benham





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