Re: Dec 15 voting amendment draft

[Markus Schulze <markus.schulze@alumni.tu-berlin.de>]

Dear Clinton,

you wrote (14 Feb 2003):
> Participation Monotonicity.
>
> If
> (i) There is an election X in which option A wins.
> (ii) There is a vote V ranks option A over option B.
> (iii) There is an election Y identical to election X except that it has
> an additional vote V.
> then
> Option B must not win election Y.
>
> What Participation Monotonicity says is, that participation will never
> cause a less prefered option to win than non-participation. That is, it
> is never advantagous to not participate.

The participation criterion and the Condorcet criterion are incompatible.
(Proof: Herve Moulin, "Condorcet's Principle Implies the No Show Paradox,"
Journal of Economic Theory, vol. 45, pp. 53-64, 1988.)

As far as I know, only point methods (e.g. plurality, Approval Voting,
Borda) meet the participation criterion.

Markus Schulze