[EM] Re: IRV letter

[Chris Benham]

Participants,
In response  to me writing:

> To seriously make the case that IRV is not better than Plurality, 
> instead of talking about the made-up example a person
> should
> (a) make the case that compliance with mostly sundry mathematical 
> neatness criteria (like Participation and  Monotoncity)
> weigh as much as compliance with  (mutual) Majority  and  Clone 
> Independence. 

Bart  Ingles asked me (Sun.Apr.25):

>Any particular reason that the burden of proof should be on those
>favoring criteria other than Mutual Majority and Clone Independence?
>
Later adding the comment:

>Clone independence seems worthwhile, in that substantial failure would
>result in either a Duvergerian system or a rich-party problem.  But I
>don't see any practical value in Mutual Majority, which if met by IRV
>must be similar to Condorcet Loser.
>
I reply:
IRV  meets  Mutual Majority (what Woodall calls "Majority"). It implies 
 Majority Favourite and Condorcet Loser (which of course
implies Majority Loser).
Part of the definition of  democracy is majority rule. If, for whatever 
reason, the political landscape remains dominated by two very
large parties that get lots of  sincere first preference votes, and so 
are widely accepted as the only competive, legitimate contenders
for  the single-winner offices; then it is very important  that the one 
which is preferred by a majority over the other  is the winner.
That is what the Majority criterion guarantees and is all about.
Failing Clone Independence makes for all sorts of  absurdities and 
unfairness, and compliance with it is cheap (by which I mean it
isn't incompatible with anything anyone values).
Another line of  arguement I could take is that  I know  from living in 
Australia all my life that IRV in practice is far from disastrous,
so a cautious approach is to ask ourselves what are the most important 
 good qualities of  IRV  and  then make sure  we keep
them. (According to Woodall, IRV, like Plurality, has a  "maximal set of 
properties" which means we can't improve and keep all
of its criterion compliances)

Bart later wrote (Mon.Apr.25):

>If the two-party system weren't propped up by an anti-competitive voting
>system, I believe that this would change.  There is no evidence that it
>EVER would under IRV, in which case I would just  as soon stay with
>Plurality for partisan elections.
>
I could argue that IRV in Australia has helped lead to STV-PR being used 
in parts of it, and that has somewhat weakened the
two-party system. Bart's  arguement seems to be premised on the belief 
 that any  3-party system is better than any 2-party
system,  and that all 2-party systems are equally bad. I  might concede 
that IRV shares with Plurality the tendency to perpetuate
a 2-party system, but I strongly maintain that it  makes for a much 
BETTER two-party system.
For one thing, there is less of the big two staying the big two just 
because everyone thinks they are. Without the Plurality split-vote
problem, this bluff will be called more often and better. Both the big 
two have to be more responsive to the voters  to stay on top,
and  it should be easier for one of them to be supplanted. Then there is 
the idea that small parties will become more visible, and this
will help create demand for  PR.
I think the effect of the voting system in determining how many 
competive parties there are can be over-stated. The point has been
made that  Malta, with STV-PR, has a basically two-party sysem; wheras 
India, with Plurality in single-member disitricts, has hundreds
of parties.

Bart again:

>But even when IRV chooses the Condorcet winner, it's apt to be an
>artifical one, achieved by eliminating any possible independent
>Condorcet winners before the ballots are even printed.  You might as
>well outlaw third-party candidates altogether, so that you can guarantee
>a majority-favorite winner regardless of the method used.
>
I have almost no idea what he is talking about here. The last sentence 
seems ridiculous. If you don't allow  third-party candidates
to run, how do you know which is the "third-party"?

>I no longer view third-party candidates as automatic spoilers.  With a
>healthy mix of 3rd-party and independent candidates competing for
>dissatisfied voters, neither of the major parties is a net long-term
>beneficiary of a "spoiler effect".  Instead, 3rd-party predation will
>tend to draw voters away from the more lackluster of the top-two, thus
>tipping the balance in favor of the Social Utility winner.
>
So if  Bush wins because the "Left" vote is split, does that make him 
the  "Social Utility winner"??
It is almost irrelevant  that neither major party is a  "net long-term 
beneficiary of  a  'spoiler effect'".
The point is to pick the correct winner (at least in "two-party 
preferred" terms, to use the Australian term) in the short term.

Chris Benham