[EM] Condorcet Criterion for plurality.

Markus Schulze schulze at sol.physik.tu-berlin.de
Tue Dec 12 06:02:10 PST 2000


Dear Bart,

you wrote (25 Nov 2000):
> Markus wrote (25 Nov 2000):
> > FPP violates Condorcet and beat path GMC.
> >
> > Example:
> >
> >    40 voters vote A > B > C.
> >    35 voters vote B > C > A.
> >    25 voters vote C > B > A.
> >
> >    Due to the Condorcet criterion, candidate B must be
> >    elected. Due to beat path GMC, candidate B must be
> >    elected. But the FPP winner is candidate A.
> >
> >    In the example above, I didn't make any presumptions
> >    about whether the voters vote sincerely or strategically.
> >    In the example above, I didn't make any presumptions
> >    about the sincere opinions of the voters. Did I?
> 
> The example is not sufficient to show A as the FPP winner.

Why?

You wrote (11 Dec 2000):
> You are also making an unstated assumption that voters have no
> knowledge of the other voters' preferences, or at least of the
> candidates' relative positions in the political spectrum.

Please explain!

You wrote (11 Dec 2000):
> Anything can be defined as anything, but defining Plurality
> on preferential ballots doesn't make it the same Plurality as
> is used in the U.S. and U.K.  To use two different meanings of
> the same term interchangeably is a logical fallacy (equivocation).

Please explain!

Markus Schulze



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