[EM] IRV vs Condorcet vs Range/Score

[Chris Benham]

Aaron,
I agree that not electing a voted CW is undesirable, and any method
that fails the Condorcet criterion needs to be justified by complying
with at least one desirable criterion that isn't compatible with Condorcet.

"Low social utility (SU)" Condorcet winners with little solid support and
depend for their status as the CW on weakly-held lower preferences can
begin to look quite chimera-like and not necessarily the only legitimate
winner.

One ok Condorcet method is Smith,IRV: voters strictly rank from the 
top however many candidates they wish, before each normal IRV 
elimination check for a candidate X that pairwise beats all the other 
remaining candidates, elect the first such X to appear.

Is this what you mean by "Smith/IRV"? Or did you mean "Smith//IRV"?

I'm not sure if you suggested otherwise, but all methods that meet the
Condorcet criterion are vulnerable to Burial strategy.

Chris Benham

 

Aaron Armitage wrote (Sat.Oct.11):
Condorcet methods are the application of majority rule to elections which
have more than two candidates and which cannot sequester the electorate
for however many rounds it takes to produce a majority first-preference
winner. If we consider majoritarianism an irreducible part of democracy,
then any method which fails to elect the CW if one exists is unacceptable.

Which particular method is chosen depends on what you want it to do. For
example, if we at to make it difficult to change the outcome with
strategic voting Smith/IRV would be best, because most strategic voting
will be burying a potential CW to create an artificial cycle in the hopes
that a more-preferred candidate will be chosen by the completion method. A
completion method which is also vulnerable to burial makes this worse, but
Smith/IRV isn't because it breaks the cycle in a way the ignores all
non-first rankings.


      Make the switch to the world's best email. Get Yahoo!7 Mail! http://au.yahoo.com/y7mail
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20081012/80efa860/attachment-0003.htm>