[EM] Condorcet-Approval hybrid method

[Forest Simmons]

Russ asked about what we used to call "Approval Completed Condorcet."

The legendary Demorep was an avid proponent of several variations of this 
idea, one of which he christened ACMA for Approval, Condorcet, Maximum 
Approval, a three step method:

Step 1: Approval: first eliminate all candidates with more disapproval 
than approval.

Step 2: Condorcet: elect the Condorcet Winner among the remaining 
candidates if there is one.

Step 3: Maximum Approval: in the case of no CW in step 2, elect the 
candidate with maximum approval.

Like I say, Demorep and others came up with many variations on this, 
including using truncation for the approval cutoff.  But note advocating 
this truncation approach for an approval cutoff is tantamount to thumbing 
one's nose at the later-no-harm criterion that Kevin is trying valiantly 
to rescue.

My idea was to use standard ordinal ranking ballots with a kind of 
artificial candidate called MAC for Minimum Acceptable Candidate, or NOTB 
for None of the Below, or some other catchy name.  The voters indicate 
their approval cutoff by ranking all of their approved candidates above 
this artificial candidate, and all others below it. Approval scores can 
then be found in the column of the pairwise matrix corresponding to this 
artificial candidate.

More recently I suggest adding a suitable lottery to the list of 
candidates.  This lottery serves as a kind of approval cutoff.  One can 
then implement Demorep's ACMA with a ready answer to the frequent 
question, "What if no candidate gets more than 50% approval in step one?"

Demorep never really answered that to my satisfaction.  But if no 
candidate beats the artificial one, then the artificial candidate is the 
CW, and should be the winner.  If the artificial candidate is a lottery, 
and the lottery is the CW, then that means that the flesh and blood winner 
should be chosen by the lottery.

If the artificial candidate is NOTB, then the whole election should be 
done again from scratch.  But this may not be practical in many cases. 
One might elect the closest flesh and blood runner up to NOTB, i.e. the 
candidate that came the closest to achieving 50% approval, with the 
proviso that the winner has no "mandate," or something like that.

I kind of like the lottery idea, especially if the lottery is a nice one 
like Jobst has been advocating lately.

Forest

> Date: Thu, 03 Mar 2005 02:25:51 -0800
> From: Russ Paielli <6049awj02 at sneakemail.com>
> Subject: [EM] Condorcet-Approval hybrid method
> To: election-methods at electorama.com
> Message-ID: <4226E62F.2010503 at sneakemail.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi Folks,
>
> I just got an interesting idea. It's so simple that I'll be very
> surprised if it has not been proposed before, but I did not see it on
> Blake Cretney's methods page.
>
> Why not combine Condorcet and Approval into a hybrid election method?
> The voter ranks the candidates, but truncates at his approval cutoff
> point. If a Condorcet winner exists he wins, otherwise the winner is
> determined from the Smith set using Approval rules, where ranked
> candidates and considered approved and unranked candidates are
> considered unapproved.
>
> I would tend to oppose allowing equal rankings (except for implied equal
> rankings for the unranked candidates, of course). However, a variation
> would be to allow equal rankings. Another variation would be to allow
> full ranking without truncation but with an approval cutoff point
> specified separately from the rankings. For example, I could rank all
> eight candidates but somehow specify that I only want to approve the
> first three.
>
> How would this method stack up? What would the voting strategy look
> like? And has it been proposed before? If so, when and where? Thanks.
>
> --Russ
>