I will discus only IRV vs Condorcet.
On Tue, 29 Jul 2008 09:45:47 +0100 James Gilmour wrote:
Aaron Armitage > Sent: Tuesday, July 29, 2008 1:11 AM
IRV and all
other ranked choice systems ask for the same input from
voters
This is where you make your first mistake. IRV and other ranked choice voting
system do not all ask for the same input from the
voters. IRV asks voters to mark preferences in the knowledge that those
preferences will be used as contingency choices, so that a
later preference can in no way affect the chance of election of an earlier
preference. Some other ranked choice voting systems, in
a variety of different ways, make simultaneous use of all the preference
information recorded on the ballot paper, such that the
later preferences can affect the chances of election of the earlier
preferences. The voters know in advance which counting rules
will be used in any particular election and modify their marking of preferences
accordingly. So the inputs are not the same.
While the meaning of ranking is not identical, few voters should
notice the difference.
In both the voter lists first the most desired candidate.
In Condorcet all that the voter says will be part of the tournament.
In IRV candidates will be considered only after those the voter lists
first have lost.
Method matters little since preference controls electability.
and produce the same kind of output, namely a single
winner.
Here is your second mistake. Both kinds of voting system do result in the
election of a single winner, but the outcome (output) can
be quite different in terms of what that winner represents. In the case of IRV
that winner is the contingency choice, with all the
implications of that. In Condorcet, the winner may be decided in a very
different way from IRV and represent something very
different in relation to the voters. In a Borda count, the winner may
represent some sort of compromise even when there is one
candidate who has an absolute majority of the first preference votes. So all
these outputs are quite different.
Who cares that the method of doing the analysis varies since the
result is usually an identical winner?
IRV, often not looking at all that the voter says, sometimes
selects winners other than who the voters truly prefer.
Condorcet, when presented with a near tie among three or more,
invests effort IRV does not attempt to match in deciding on the best
winner.
For you to say they differ so fundamentally that no
common standard can be appealed to looks an awful lot like
special pleading.
There was no special pleading - just a request that the differences in the
inputs and outputs be recognised for what they are -
fundamental - and not ignored.
And how can you argue that we should adopt
IRV instead of Condorcet or Borda or Bucklin if you have to
common standard from which to argue that IRV is better?
I don't think I have said anywhere that "we" should adopt IRV instead of the
other voting systems, but since you ask:
I would reject Borda because it can elect a candidate other than the one with
an absolute majority of the first preference votes.
I would reject Buckilin because it does not comply with "one person, one vote".
I am VERY sympathetic to Condorcet and think the basic concept is "sellable" to the
electors (presented as a "head-to-head
tournament"), despite the inevitable opposition of most politicians, big
business and the media moguls. I foresee bigger problems
in selling any of various cycle-breaking and tie-breaking solutions that have
been proposed. But the real problem with Condorcet is
the weak Condorcet winner. It is my judgement (based on long experience as a
practical reformer, but only in the UK) that such an
outcome would not be politically acceptable to the electorate in an election to
public office. Such a winner would, of course, be
the real Condorcet winner, but that would not, of itself, make the result
politically acceptable to real voters.
This truly is a challenge, but might we be able to package the
arguments more usefully?
Most elections have only one or two serious candidates. Therefore a
serious candidate is going to win:
Sensible to just vote for one of these as in Plurality.
Those wishing to can do ranking. Their vote for a serious
candidate (or even both of such) will get counted as above; their
votes for other candidates will be too few to matter.
Elections with more serious candidates may become more common:
Voting ala Plurality remains doable - just less adequate for
most voters.
Ranking allows more voters to express their desires.
Primaries become less useful because there is no need for
parties to try to prevent having multiple candidates in the general
election.
"cycle-breaking and tie-breaking"? This is one topic - near enough to
a tie to need analysis. I claim it does not happen often enough that
most voters should demand more than that someone should have provided
rules for such analysis. Look at the horror stories from France and
Louisiana - they are arguments for disposing of Plurality.
Remember that one group of voters cannot vote A>B & B>C & C>A -
it takes multiple strong groups with conflicting opinions.
IRV has, of course, a corresponding "political" weakness, in that it can reject
the candidate who might be everyone's second choice
(the Condorcet winner). But experience shows that the electors are prepared to
accept that outcome.
"everyone's second choice" may not bother those who get blindly sold
that being, at least, someone's first choice is important.
Packaging a bunch of the horror stories that IRV can cause should help
in promoting Condorcet.
James Gilmour
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