[EM] 3 or more choices - Condorcet

[robert bristow-johnson]

On 9/29/12 4:49 PM, Juho Laatu wrote:
> What is a "strong" Condorcet method?
>

yeah, and Kristofer, since the word is quoted, who is using the label? 
  i think it might very well be something to agree with (the use of a 
really general adjective like "good" or "favorable" or even "optimal"), 
i would like to know w.r.t. what?  it's like my high school teacher 
prohibited us from writing "This book was good" in a book report. 
  certainly not saying the word is meaningless in context, but it semms 
to me meaningless when naked.

but, that said, i still think that a cycle with a Smith set bigger than 
3 is soooo unlikely since i still believe that cycles themselves will be 
rare in practice.  since Minmax, Ranked-pairs, and Schulze all elect the 
same candidate in the case of the Smith set of size 1 or 3, it seems to 
me that simplicity of tabulation becomes a "strong" property for two 
different but related reasons:

1. simplicity is a strong selling point and a necessary one in an 
environment of public opposition to "tricky" government procedure. 
  sometimes complexity in government is unavoidable (how many pages of 
text is in a typical bill?) and sometimes the simplest method is clearly 
not the best (say, flat income tax rates vs. progressive income tax 
rates).  but when it comes to seeing how our leaders are elected and how 
our miscreants and recalcitrants are dealt with, the public has an 
interest in transparency and some of this transparency is mandated in 
our national constitutions.  but we *do* put up with reasonably complex 
regulations and tax codes, we can put up with a teeeny bit of complexity 
(the Ranked ballot vs. the "traditional" ballot) in voting.

but the method of tabulation must be reasonably simple for the method to 
gain public acceptance and trust.  i think most people can understand 
the statements: "If more voters prefer Candidate A to Candidate B, then 
Candidate B is not elected."  and i think that people can understand the 
concept that if Candidate A is ranked above Candidate B on their ballot, 
this voter would simply vote for A on a traditional ballot if only the 
two candidates were running.

selling the additional "burden" of having to commit to and mark their 
contingency vote(s) is the challenge, and i usually respond with the 
common argument we used in the old IRV days, and it still applies: it is 
worth it to collect your (and others) contingency vote because, to get 
it later (in a run-off) decreases voter participation and makes the 
election less legitimate, particularly if it's close.

2. predictability of operation of a system (like government) is pretty 
useful to people affected by the system.  we want cars and other 
vehicles to behave consistently so that when someone pushes the lever, 
the system moves in the direction they intend it to.  it may not move 
the system sufficiently to accomplish their goal, but it doesn't move 
the system directly away from their intended direction.  in a modern, 
free, and decent society we need consistent laws and proceedures to have 
some idea what to expect and what is expected of us.  capriciousness or 
"flakiness" is a quality to avoid.  now when this happens, it's good in 
its own right (because it's fair and likely more ethical) but it also 
provides more for public acceptance because the rules are clear.


lastly, i know is anecdotal, but the Burlington 2009 IRV election really 
bolsters my confidence in cycles being rare (and then cycles bigger than 
3 being even more rare).  it was a close election.  one candidate was 
the Plurality winner, one candidate was the IRV winner, and one 
candidate was the Condorcet winner.  all three candidates were viable 
players and there was a fourth, independent, candidate that had a lot of 
support but was the first to be eliminated.  but when ordered by 
Condercet, it is clear who is consistently preferred over everyone else. 
  remove the CW and it is clear who comes in next.  remove the 2nd-place 
CW and it is clear who came in 3rd.  it was very consistent and nothing 
would change if various candidates were removed from the roster and the 
same voters came and vote (ranked) identically in another election.  no 
spoiler scenario in any manner.  and that was a close election.

maybe, once in a blue moon, there will be a cycle involving Candidates 
Rock, Paper, and Scissors, and then Ranked-Pairs, which is simple, will 
do just as well as Schulze.

Markus, i think Schulze would work better for bigger Smith sets, but i 
still think it's harder to sell for multip-party, multi-candidate, 
governmental elections.  and since, i believe it would likely never make 
a difference, i would advocate ranked-pairs.  i know you sent me that 
one paragraph language for possible legislation, but it surely read 
opaquely when i read it.  i couldn't figure it out from that concise 
language (but i think i *do* understand how Schulze based on margins works).


-- 

r b-j                  rbj at audioimagination.com

"Imagination is more important than knowledge."