[EM] FBC, Clone-Winner, and pairwise components seem incompatible

Russ Paielli 6049awj02 at sneakemail.com
Sat Jun 25 12:47:37 PDT 2005

Kevin Venzke stepjak-at-yahoo.fr |EMlist| wrote:

> However, Majority Defeat Disqualification Approval ("MDDA," a good name even
> without the punctuation) satisfies SFC, which at first glance seems to
> require a beatpath notion: In practice, it seems to say that if there is a
> (majority) defeat A>B but no defeat anyone>A, then B can't win, while if I
> add a win C>A then B is no longer barred from winning. But MDDA "goes beyond
> the call of duty" by making all of the defeats damning, and if all candidates
> are damned, then adding C>A can only make A lose, no one else. So MDDA
> satisfies FBC and SFC without the use of beatpaths, although it does use
> a pairwise component.

You know how I feel about the concept of "majority defeat" for a 
pairwise race. I believe that *any* pairwise defeat is by definition a 
"majority" defeat because it requires a majority to vote for the defeat, 
where "majority" is defined in terms of the number of voters who chose 
to participate in that particular pairwise race.

We don't seem to be converging on this, but let me propose a criterion 
to support my view. I'll call it the "Blank Ballot Criterion," or BBC 
(if that acronym is not already taken). The criterion is that a blank 
ballot should count as a vote but should not affect the final result. A 
voter may turn in a blank ballot as a form of protest, indicating that 
he disapproves of *all* the candidates. His ballot should count as a 
valid vote, but it should not affect the final result.

No method that depends on "majority defeats" can pass this criterion if 
it defines a majority it terms of the total number of voters.

Consider the case in which a voter votes on some offices in an election 
but "abstains" from voting on others. How should his vote be interpreted 
for the offices he does not vote on? Should he be considered a non-voter 
for that office, or should his vote be interpreted as disapproval and 
equal-last ranking of all the candidates? If the method passes BBC, the 
interpretation doesn't matter. If it does not pass, then you need to go 
into the mind-reading business and declare the voter's intention. That's 
a bad business to be in when it comes to elections.


More information about the Election-Methods mailing list