[EM] The responsiveness of Condorcet / Monotonicity
Dgamble997 at aol.com
Dgamble997 at aol.com
Mon Jul 14 15:29:02 PDT 2003
Adam Tarr wrote:
"Doesn't that suggest that arguing that Condorcet is bad because it fails to
produce proportionality, is sort of missing the point?"
No not exactly, Plurality and IRV in single seats can give a party 70 % of
the seats for 35- 40% of the vote. This is a bad thing.
Condorcet in single member seats has the potential to give a party that
positions itself in the centre 70 % of seats with 20% of the vote. This is a worse
thing ( even if the party is the most generally preferred party).
Adam also wrote:
"Right, candidates who appeal to the largest group of voters tend to win
Condorcet elections. You say this like it's a bad thing. Such a candidate also
always wins IRV elections if the voters use sufficiently intelligent strategy.
Smart voters who realise their edge candidate will lose in the final runoff
will abandon their first choice and vote for the centrist. It's just easier
and requires less guesswork on the voter's part with a good Condorcet method."
A lot of the argument in the well explored turkey thread involved how the
word appeal could be replaced with the words " does not offend" or " is disliked
"The point was simply that, if you had to pick a party that was going to be
disproportionately represented, you'd want it to be the most moderate party.
IRV (and plurality for that matter) can produce disproportionate results that
swing wildly from too far left to too far right."
Yes I suppose that's true. I'd really prefer that nobody was over (or under)
"Has ANYONE on this list said that they want single-member districts using
Condorcet voting? I don't remember ever hearing that. Some people have
expressed a desire to have single-winner districts in the past (to get a closer link
to the voters) but most offer a caveat of some mixed member proportionality."
Yes you are correct, I thought I had seen such posts but I can't find them
now . I am glad to be proved wrong on this point. It is reassuring that nobody
has proposed such a dubious idea.
Eric Gore wrote:
What about situations where PR is not appropriate?
Would it be accurate to say that you disagree with Arrow that a
voting system should be monotonic? (IRV is not)
The only situations when PR is not appropriate is when PR is not possible. In
those instances ( for a single position) we are left with trying to use the
least bad single seat method.
Whilst leaving to one side what Arrow may or may not have said about
monotonicity. I think the following:
Monotonicity is undoubtedly a desirable feature of an electoral method. I do
however feel that no method can be perfect and that other features are more
important ( proportional representation of parties, proportional representation
of opinion, maximum freedom of voter choice regarding the individuals who
represent you, etc).
As to the non-monotonicity of IRV and STV let me give an alternative
definition of non-monotonicity
" Non-monotonicity -something that occurs more frequently in theoretical
examples than real elections "
I am aware that certain people who post to electoral systems list have a "
thing" about monotonicity ( or a lack of it) and that for certain people ( and I
wasn't thinking of Eric) this can sometimes appear to reach the proportions
of a morbid obsession.
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