[ESD] Single-seat cumulative voting options

Forest Simmons fsimmons at pcc.edu
Fri Jan 17 16:02:08 PST 2003

On Fri, 17 Jan 2003, Forest Simmons wrote:


> In fact, suppose that your favorite candidate is A, and that there are two
> front runners B and C, of which your preferred is B, so that your sincere
> preferences (restricted to these three candidates) look like A>B>C.
> What would be the worst that could happen if you voted your MCA ballot
> sincerely (under the cumulative rules for preferred status and approval
> rules for acceptable status)?
> There are realistically only two bad possibilities:
> (1) Candidate C wins with more than 50 percent of the favored status
> votes.
> (2) No candidate wins in the "majority choice" round, but candidate C wins
> in the approval round.
> In case (1) it wouldn't have helped to put B ahead of A on your ballot,
> because only one candidate can have a 50 plus percent majority in the
> cumulative stage, and (in the case under consideration) candidate C is
> that candidate.
> In case (2) it wouldn't have helped to put B ahead of A on your ballot,
> because in the second round, favored status and merely approved status are
> not distinguished.
> So if this method does not satisfy the strong FBC, it is because of some
> other much less likely scenario that we haven't considered here.

Actually, there is one other likely possibility associated with case (2):

since nobody won in the first round, it is possible that compromise B
would have won in the first round if you had voted him over favorite A.

The fact that neither B nor C had actual majority first place support, and
that B lost to C in the approval round make it very unlikely that B would
have gotten a majority in the first round if you (and others like you) had
betrayed favorite.  Still, that possibility is there to haunt you.

I still claim that this version of MCA comes closer to satisfying the
strong FBC than most other (more complicated) methods, including IRV.


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