[EM] Arrow's Theorem.

[Markus Schulze]

> I really want Approval to fail a condition of Arrow's
> Theorem somewhere.

Arrow's Theorem says that there is no preferential paretian
non-dictatorial single-winner method that meets IIA.

Approval Voting, Average Rating, Median Rating, etc. are no
preferential methods.

To be a preferential method, the method must be defined
on every possible set of orders of merit and must not
take more into consideration than just the orders of
merit.

Markus Schulze