[EM] percentage support

Curt Siffert siffert at museworld.com
Mon May 2 16:06:44 PDT 2005

I know many of us are here to work on the best method for various 
social choice purposes.  But many of us are specifically interested in 
political elections.

And there's a problem with this.  Plurality actually serves two 
purposes.  It is a bad way to select a winner, but it is also a way to 
track percentage support over a period of time, and by determining 
proportional support when it's relevant.

Democratic primaries are an example.  The proportion of votes a 
candidate receives determines how many delegates they receive.  But 
even if that particular decision structure is done away with, there are 
plenty of other reasons to track proportional support - polling, for 

And this is something that Condorcet methods cannot do.  You cannot 
derive, from a Condorcet ballot collection, how much percentage support 
each candidate got.  You can't give each candidate a share of 100% in a 
way that all candidates would agree on.  If you can, I'd love to know 

Is this an already identified criteria?  The ability to determine 
percentage support?  The Siffert Criteria?  :-)  If so, Condorcet fails 
it; at least, I haven't seen a technique that would allow it to pass 
it.  What voting methods can convincingly a) identify the total 
available support (in terms of that vote method) for all candidates, 
and b) determine what percentage of that support each candidate 
received ?


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