[EM] MCA

[MIKE OSSIPOFF]

Forest--

You wrote:

How about Majority Choice Approval ?  Like RV it is strategically equivalent 
to Approval,  but allows for more expressiveness than Approval.

I reply:

But can a voter give that favoriteness vote to two or more candidates? 
Because, if not, then MCA would fail FBC. And if so, the meaning of _the 
favorite_ of a majorilty, as opposed to an Approval count, would be diluted, 
especially for the public that it's being proposed to. Allowing more than 
one "favorite" vote, which could be given to a nonfavorite compromise too, 
could complicate the method for the publc that it is proposed to.

Maybe, even then, MCA is a little simpler than MDDA, but not much simpler:

"A candidate is disqualified if another candidate is ranked over him/her by 
a majority. The undisqualified candidate ranked by the most people wins."

[end of MDDA definition]

(As you said, if everyone is majority-defeated, then no one is 
majority-disqualified)

I don't know if that's any more complicated or wordy than MCA. And it meets 
SFC & SDSC.

Additionally, it doesn't attract the fallacious 1-person-1-vote objection 
that always besets Approval.

You wrote:

It [MCA] has the nice explicit reference to Majority: If any candidate is 
marked "favored" on a majority (more than fifty percent) of the ballots, 
then the one with the greatest majority wins.

I reply:

True.

MDDA matches MCA's majority favorite advantage:

In MDDA, if a majority rank X alone in 1st place, that gives X a majority 
defeat against every one of the other candidates, resulting in the 
disqualification of everyone but X. If you rank X in 1st place, maybe with 
other candidates, then you're helping X have a majority defeat against 
everyone except for the others you rank in 1st place.

And indifference is the only thing that could make MDDA fail Condorcet's 
Criterion. Without at least a little indifference, a CW has majorities 
against everyone. One could argue that the more indifferently-supported a CW 
is, the less important it is. The only way for that CC failure to need only 
very little indifference, would be if it's a very close pairwise race.

You wrote:

Also, do I remember correctly that MDDA starts by eliminating all candidates 
defeated by a majority of voters, and if there are any left, electing the 
most approved of these, otherwise falling back to most approved of all the 
candidates?

I reply:

Yes, that's MDDA. In its standard definition, in MDDA a ballot gives an 
Approval vote to (only) all the candidates that it ranks.

Mike Ossiopff

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