[EM] eliminate the plurality loser until there is a Condorcet winner

[Kristofer Munsterhjelm]

robert bristow-johnson wrote:
> 
> On May 11, 2011, at 3:51 PM, fsimmons at pcc.edu wrote:
> 
>>
>> James Green-Armytage asked
>>
>> Quick question for everyone: Do you happen to know when the method
>> described in the subject line (eliminate the plurality loser until
>> there is a Condorcet winner) was first proposed?
> 
> by Plurality Loser, do you mean the candidate who was ranked 1st the 
> fewest times or the candidate ranked last the most times (all who are 
> unranked are tied for last place)?

The Plurality loser is the one who ranks last (loser) in the ordering
given by Plurality. Hence, among those that you state, it is the former.
Essentially, it is IRV, but at every step, you check if there's a CW
among the candidates remaining; if there is, that person is elected and
you're done.
> 
> i made mention of either in a paper i wrote in 2009 ("The Failure of 
> Instant Runoff Voting to accomplish the very purposes for which it was 
> adopted: An object lesson in Burlington Vermont") right after i figgered 
> out that the Condorcet winner was not the same as the IRV winner (and 
> happened to be the candidate i supported).
> 
> i would think that this would have preceded by anyone thinking about 
> Condorcet cycle for a minute.

Another way of getting a Condorcet compliant runoff method is to do IRV
with Borda (Nanson's method), or better, eliminate-below-mean-scores IRV
with Borda (Baldwin's method). These methods have actually been used in
the real political world, which is not something many Condorcet methods
can say, and apparently they also elect from the Smith set. Being runoff
methods, however, they are not monotone, and I remember reading that
they're quite manipulable.

> well, when a few more towns toss out IRV, i hope that FairVote gets the 
> message and starts promoting other tabulation methods than STV with the 
> ranked ballot.  what makes me so mad is that Burlington people that are 
> IRV supporters (because they are election reform people and do not 
> believe in the two-party religion), these people had no idea that there 
> was another way to look at those very same ballots.  Fairvote 
> essentially sold ranked-choice voting with IRV as if they were the same 
> thing.  as if there *is* no ranked-choice voting without IRV.

FV didn't swerve in their game of chicken, so to speak. They decided to
link ranked ballots directly to IRV, presumably so that when people get
the (commonsense) idea that perhaps ranking would help break the nation
out of the two-party stranglehold, they'll immediately think of IRV.
That strategy does have its benefits from FV's point of view, since it
makes it more likely that people will pass IRV, but it also is very
damaging against the ranked ballot concept in general if/when people
then find IRV not good enough.

Whether or not they're pursuing IRV for its own sake (and think it's a
good singlewinner method) or they're doing it to have IRV be a stepping
stone to STV, I don't know.