[EM] IRV vs Condorcet

[Markus Schulze]

Dear Eric,

you wrote (24 July 2003):
> Markus wrote (24 July 2003):
> > Dave wrote (24 July 2003):
> > > DIFFERENCE: While Condorcet compares EACH pair of candidates and develops
> > > a matrix of pair counts to identify best liked, IRV puts emphasis on
> > > patterns, giving preference to those that are ranked first. See example
> > > below where B is much more popular than A, but IRV never sees this for C
> > > is more popular than B among B backers - even though all these C backers
> > > like B better than A.
> > > Some call this an argument for IRV, claiming that those C votes
> > > were against B. Could be, sometimes, but more likely is a simple minor
> > > disagreement within B's party that does not create a smidgen of desire to
> > > have A win.
> >
> > I wouldn't say that this is an argument for IRV against Condorcet or
> > an argument for Condorcet against IRV. In my opinion, this is simply
> > a description of the count. An argument is something like "Method X
> > violates independence from clones while method Y meets independence
> > from clones." but not something like "Method X counts the votes in
> > this manner while method Y counts the votes in that manner."
>
> Perhaps it isn't an argument for or against any particular method,
> but I would consider it an important point to make about any
> particular method.
>
> It is because IRV fails to count votes in a better way that
> contributes to (if not causes) its failing of more fundamental
> criteria important to every voting method.

Yes, but instead of saying e.g. "I don't like method X because
it counts the votes in such a way that monotonicity is violated."
it is sufficient to say: "I don't like method X because it violates
monotonicity."

Markus Schulze