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David Gamble wrote:<br><br>
<blockquote type=cite class=cite cite><font size=2>10%
FarRight>Right>Centrist>Left>FarLeft<br>
10% Right>FarRight>Centrist>Left>FarLeft<br>
15% Right>Centrist>FarRight>Left>FarLeft<br>
16% Centrist>Right>Left>FarRight>FarLeft<br>
15% Centrist>Left>Right>FarLeft>FarRight<br>
13% Left>Centrist>FarLeft>Right>FarRight<br>
11% Left>FarLeft>Centrist>Right>FarRight<br>
10% FarLeft>Left>Centrist>Right>FarRight<br><br>
I think I've commented on this example before. What would happen if we
applied Donald's model to this situation. Firstly, the wing candidates
would withdraw/lose support and the situation would become right 35%,
centre 31% and left 34 % ( as Adam predicted I'd say). What would
happen then ? There'd probably be a number of deadlocked ballots and
either voters would move to the centre or the support for the centre
would collapse. <br><br>
The relative strengths of the centre and the wings are important in a
situation like this,<br>
if the centre is stronger than one of the wings the weak wing's
supporters should move to support the centre. If the centre is weak
voters will desert it for the wing candidates. If the centre and
both of the wings are of approximately equal strength it is unpredictable
what will happen. The short answer is that the election is close and in
elections where the results are close a large number of voters are often
dissatisfied with the outcome.</font></blockquote><br>
OK sure... but which of the following is better:<br><br>
- roughly one third of the electorate is happy, one third is reasonably
satisfied, and one third is extremely unhappy, or<br><br>
- one third is happy, and two thirds is reasonably satisfied?<br><br>
The answer is obvious, of course. Basically, to argue that Right
should win the above example, you have to decide that the second choices
of the first and eighth factions are more important than the second
choices of the third and fifth factions. And there's just no
logical reason to do that.<br><br>
I guess my conclusion here IRV's way of eliminating candidates is, on
some level, pretty arbitrary. Sometimes it can work out pretty
well, but in an example like the one above it clearly drops the wrong
candidate.<br><br>
Now, your objection to Condorcet is that it can allow a centrist to win
with only a few percent of the first place vote, which, in your mind, is
just as bad. I have two responses. First, this can only
happen if that candidate can actually rally an overwhelming percentage of
the voters to give him second place support, which means he can't be all
bad. Having pairwise victories over every other candidate IS a
significant measure of support, second-place votes or not.<br><br>
Secondly, it's entirely possible for a wing candidate to pull off the
same trick. Consider this, perhaps even worse version of my
"nightmare scenario". I'll leave out some of the lower
preferences that never come into play (not exhausting any ballots, just
talking out the irrelevant parts so it's more readable):<br><br>
7%
FarRight>Right>LuckyRight>ModerateRight>ModerateLeft<br>
2%
Right>FarRight>LuckyRight>ModerateRight>ModerateLeft<br>
4%
Right>LuckyRight>FarRight>ModerateRight>ModerateLeft<br>
7% LuckyRight>ModerateRight>Right>ModerateLeft<br>
15% ModerateRight>LuckyRight>ModerateLeft>Right<br>
16% ModerateLeft>ModerateRight>LuckyRight>Left<br>
15% ModerateLeft>Left>ModerateRight>FarLeft>LuckyRight<br>
13% Left>ModerateLeft>FarLeft<br>
11% Left>FarLeft>ModerateLeft<br>
10% FarLeft>Left>ModerateLeft<br><br>
I called the winner lucky since he got lucky in where he put himself in
the spectrum. Really, all I've done here (besides re-name the
centrist as a left-winger) is splinter my right wing into four
candidates. LuckyRight is the second-most moderate, or the
third-most conservative.<br><br>
So now we have a situation where the third most conservative candidate
out of seven candidates wins, even though that candidate's is in tune
with the 17th percentile voter on the political spectrum. It's
worth noting he only has 7% first place support, much lower than the
examples you gave below of "weak centrists". What's more,
the right wing wins the election with 35% of the vote, simply because
they got their weaker candidates eliminated early on, rather than the
left wing which brought two strong candidates into the penultimate
stage.<br><br>
<blockquote type=cite class=cite cite><font size=2>Con
42.8%<br>
Lib Dem 25.2%<br>
Lab 28.8%<br>
Other 3.2%<br><br>
Assumptions: All Conservative voters express a second preference for the
Liberal Democrats, all Labour voters express a second preference for the
Liberal Democrats.</font></blockquote><br>
Well, you've assumed a centrist party that gets all second-place votes,
which may or may not be the case. But at any rate, I think that
Condorcet is much better suited towards executive positions than use in a
legislature. No single-winner method can be expected to produce
good proportionality.<br><br>
<blockquote type=cite class=cite cite><font size=2>Situations in which
candidates perceived as being in the centre would win with low first
preference votes under Condorcet are much more frequent than situations
in which centrists with substantial support would be defeated under IRV (
at least in England in recent history).</font></blockquote><br>
Personally, I'd hardly consider 25% to be low first preference
support. And as I showed above, IRV does NOT guarantee a strong
first-place showing from it's winner. All you need is to be in the
right position to take advantage of IRV's elimination
technique.<br><br>
-Adam</html>