[EM] IRV vs Condorcet vs Range/Score

[Aaron Armitage]

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.


--- On Sat, 10/11/08, Chris Benham <cbenhamau at yahoo.com.au> wrote:

> From: Chris Benham <cbenhamau at yahoo.com.au>
> Subject: Re: [EM] IRV vs Condorcet vs Range/Score
> To: eutychus_slept at yahoo.com
> Date: Saturday, October 11, 2008, 10:30 AM
> All possible Condorcet methods?  
> 
>  
> 
> 
> 
> ----- Original Message ----
> From: Aaron Armitage <eutychus_slept at yahoo.com>
> To: Chris Benham <cbenhamau at yahoo.com.au>
> Sent: Sunday, 12 October, 2008 1:19:24 AM
> Subject: Re: [EM] IRV vs Condorcet vs Range/Score
> 
> I think his point is that he prefers any and all Condorcet
> methods over
> IRV, and probably over any non-Condorcet method. I happen
> to agree.
> 
> 
> --- On Sat, 10/11/08, Chris Benham
> <cbenhamau at yahoo.com.au> wrote:
> 
> > From: Chris Benham <cbenhamau at yahoo.com.au>
> > Subject: [EM] IRV vs Condorcet vs Range/Score
> > To: "EM"
> <election-methods at lists.electorama.com>, "damon
> rasheed" <damon at pokernews.com>
> > Cc: "Dave Ketchum"
> <davek at clarityconnect.com>
> > Date: Saturday, October 11, 2008, 5:14 AM
> > Dave Ketchum wrote:
> > 
> > Let's see:
> > 
> > A Condorcet method finds the candidate which would
> beat
> > each other 
> > candidate in a run-off election, assuming such a
> candidate
> > exists.  Thus 
> > such a method meets the Condorcet criterion.
> > 
> > Having copied such from Wikipedia, don't seem like
> I
> > grabbed much.
> > 
> > Having no such candidate, we have a cycle of three or
> more
> > leaders in a 
> > near tie and debate how to pick from them.
> > 
> > Perhaps Chris is into this debate, which I agree is
> > important but am trying 
> > to keep out of this thread, whose business is IRV vs
> > non-IRV.
> > 
> > Perhaps there are other exceptions.
> > 
> > DWK
> > 
> > Dave,
> > "Condorcet" isn't decisive enough to
> qualify
> > as "a method". IRV is a method.
> > All I ask is that you specify some particular
> > "Condorcet method" (i.e. a method
> > that meets the Condorcet criterion) that you are sure
> you
> > prefer over IRV, so
> > that we can compare one method with another (and not
> one
> > method with one
> > criterion).
> > 
> > 49: A
> > 24: B
> > 27: C>B
> > 
> > A and C have only first-preference votes, A 49 and C
> 27. 
> > Is that a "near tie"??
> > 
> > Chris  Benham
> > 
> > 
> > 
> > On Fri, 10 Oct 2008 13:26:55 -0400 Terry Bouricius
> wrote:
> > >Dave,
> > >
> > >You are using the term "Condorcet" in a
> way
> > that is increasingly common, 
> > >but confusing to election method theorists, to
> mean a
> > ranked voting method 
> > >that is easiest to explain by imagining a series
> of
> > one-on-one comparisons 
> > >using a ranked ballot. What Chris B. was getting
> at is
> > that Condorcet is a 
> > >CRITERION (in fact there is also a Condorcet-loser
> > criterion, which I 
> > >think is more useful), which is used in evaluating
> > voting methods, rather 
> > >than an actual voting method itself. There are
> probably
> > a dozen different 
> > >voting methods that are Condorcet compliant, and
> many
> > others that aren't 
> > >(complying with other criteria that some believe
> are
> > more crucial). The 
> > >issue separating the various Condorcet methods is
> how
> > you find a winner 
> > >when there is no Condorcet winner.
> > >
> > >Terry Bouricius
> > 
> > 
> > 
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