[EM] Markus: Copeland isn't Condorcet

[Markus Schulze]

Dear Mike,

you wrote (19 Jan 2003):
> Copeland isn't a Condorcet version. Copeland is a Condorcet Criterion
> method, but it isn't an interpretation of one of Condorcet's proposals
> for solving circular ties.

That's hair-splitting. You said that "in all Condorcet versions a
candidate wins if he has no pairwise decisions for or against him"
without explaining what a "Condorcet version" is. Now you say that
a "Condorcet version" is "an interpretation of one of Condorcet's
proposals for solving circular ties" without explaining who decides
whether a given method is a feasible interpretation.

For the clearness of your mails it would be advantageous if you used
terms like "Ranked Pairs" or "MinMax" or "Kemeny-Young" instead of
vaguely using the term "Condorcet".

You wrote (19 Jan 2003):
> Now, just in case you've found a passage of Condorcet's writing in
> which Condorcet _did_ propose Copeland, it's still true that Copeland
> isn't one of the Condorcet proposals that we refer to when we say
> "Condorcet". "Condorcet" is used to refer to interpretations of 2
> proposals by Condorcet. One of those drops weakest defeats; the other
> keeps strongest defeats.

Condorcet also proposed a Copeland method. He wrote:

  "To compare just 20 candidates two by two, we must examine
  the votes on 190 propositions, and for 40 candidates, on 780
  propositons. Besides, this will often give us an unsatisfactory
  result; it may be that no candidate is considered by the
  plurality to be better than all the others, and then we would
  have to prefer the candidate who is just considered better
  than a larger number; and when several were considered better
  than the same number of candidates, we would have to choose
  the candidate who was either considered better by the greatest
  plurality, or worst by the smallest plurality."

I know that you don't like Copeland methods. Neither do I like
Copeland methods. But I see no right to say that only Condorcet's
top-down proposal and his bottom-up proposal were "Condorcet
proposals".

Markus Schulze

----
For more information about this list (subscribe, unsubscribe, FAQ, etc), 
please see http://www.eskimo.com/~robla/em