[Slightly OT] Re: Voting (was Re: PEP 318

Joe Mason joe at notcharles.ca
Wed Mar 24 23:14:37 CET 2004


In article <89feb3ba.0403241233.32ea8604 at posting.google.com>, Eric wrote:
> Joe Mason <joe at notcharles.ca> wrote in message news:<slrnc63985.3n2.joe at gate.notcharles.ca>...
>> (The crux of the flamewar is that Condorcet tends to elect
>> "compromise candidates" who are few peoples' favourite but palatable to
>> most, while IRV is more likely to elect people that are the first choice
>> of a large block but hated by others.  Which is preferable is a matter
>> of philosophy.)

<snip>

> I cannot see how IRV and a Condorcet method would differ should a
> certain candidate receive a large block of first place votes. For if a
> certain Candidate is the first choice of a large block, it has a
> distinct advantage in both IRV and Condorcet over all the other
> candidates, but will not necessarily be the winner in either.

I think the contentious scenario was two large opposed blocks and a
small centrist block (C):

49  A > C > B
48  B > C > A
 3  C > B=A

In Condorcet, we get:

 A>B 49
 A>C 0
 B>A 48
 B>C 48
 C>A 51
 C>B 52

So C is the winner.  But, say the IRV proponents, only 3% of the
population actually want C to win!

With IRV, we note that C has the fewest 1st place votes and drop all C
ballots.  Now we have:

 49  A > B
 48  B > A
  3  (no preference)

So A wins by an incredibly narrow margin.

Centrists say that Condorcet is correct, because obviously we should
have the winner that everybody at least mildly approves of.  Partisans
say that if the A/B split is pretty traditional and shifts by only a few
percentage points, then endorsing Condorcet is essentially endorsing a
centrist as an acclaimed winner.  Many (at least, the vocal ones) appear
to prefer the 50% chance that their party will get in for a cycle even
at the cost of a 50% chance of total failure.

But then, if they *really* didn't want C to win, they'd vote them last,
wouldn't they?  I'm just reporting the flamewar here, I'm not saying I
agree - I'm a Condorcet fan myself, but then, I'd vote for the centrist
party if there was one.  (Well, there is or was in my country, but
that's another story...)

To avoid tarring the IRV proponents as extremists, I should mention that
another argument in favour is that it's a smaller step from IRV to a
proportional method like STV.  So electoral reform in the USA, for
instance, it makes more sense to use IRV to elect the President and STV
to choose a proportional Congress than it does to have completely
separate methods for each vote.

Anyway, the real question in this forum is whether Condorcet is a good
method for voting on a PEP.  The standard objections - especially the
difficulty to explain to a non-technical audience - don't seem to apply
here.

Joe



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