Here are some short comments also to the 40k mail.
On May 11, 2008, at 22:21 , Abd ul-Rahman Lomax wrote:
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Ranked methods in general make an assumption that is blatantly
false: that all preferences have the same strength.
I think ranked methods rather make the assumption that it is
difficult (or unnecessary) to use more information that the rankings
in a competitive election.
Just to give an example of how this distorts thinking, it's very
common to assume that the Condorcet Criterion is practically golden
for election methods (even though IRV fails it). If there is a
candidate preferred by a majority over all other candidates, that
candidate should win.
In many environments (typically e.g. in politics) that is indeed a
good rule. The majority principle is a long an accepted and sensible
principle that can easily be extended to what we know as Condorcet
criterion.
On the other hand this need not be the case always. For example the
challenge of Jobst Heitzig ("method design challenge + new method
AMP") presents another group of methods where majority decisions are
not what we want. And also such methods can be needed in many
environments.
And of course in some less competitive environments one could use
e.g. sum of sincere ratings as well as the target.
There are thus many possible utility functions to approximate with
the voting methods.
But we routinely avoid taking that choice in small groups and
organizations, when the preference of the majority is small and the
preference of the minority is great (and there is not a large gulf
in numbers between the majority and minority). Thus the ideal
winner of an election, in situations where all voters will, after
the poll, agree that this was the best result, is not uncommonly
other than the Condorcet winner. But ranked methods can't collect
that information, the ballot form does not allow it.
Yes, for some uses the ranked ballots have too little information.
One ranked method comes close: Borda count, and it does it by
making a rough approximation: that the preference strength between
two candidates is proportional to the number of candidates ranked
between those two by the voter.
Borda ballots may actually collect less information than some ranked
ballots (if ties are not allowed in the Borda ballots), but it uses
this limited information in a specific way that assumes also
preference strengths.
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Yes. I prefer IRV to all other systems for electing a single
winner to
an executive office because it elects a majority winner in a single
election without the need for a separate expensive runoff election.
Yes.
Again, what I've seen with many students of election methods is
that they start out with this. But the incorporated assumption just
stated is false. IRV doesn't find a majority winner in a single
election, and not just rarely.
I intended to say yes to the fact that IRV eliminates the multiple
rounds.
Use of term majority is of course quite weak here. The IRV winner is
a majority winner when comparing the two last given alternatives and
those voters that expressed an opinion. But there may be also other
similar majority winner. Maybe the sentence was carefully formulated
"a majority winner" instead of "the majority winner" :-).
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This is an old debate trick. Instead of stating an argument
directly, it is stated indirectly, as an incorporated assumption,
as part of an argument about something else.
Yes, that is unfortunately way too common in many election method
related discussions.
---
, and it encourages positive
issue-oriented campaigns instead of mudslinging opponent-attacking
campaigns.
Probably better than plurality here but not as good argument against
other methods.
Again, Juho swallows the argument because it sounds reasonable. It
hasn't done it. Show some evidence to the contrary, if you want to
claim this benefit.
My basic thinking here was that methods that collect also second
preferences typically make it sensible for the candidates to try to
attract those second preference votes from the supporters of the
competing candidates, and therefore it doesn't make sense to attack
those candidates (and indirectly their supporters) in whatever
possible ways.
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What I've seen, though, in every forum where the question has been
asked, the experts have agreed that Approval makes very good sense
as a simple reform; quite a few have, of late, as well, come to
understand Range Voting and to recognize it as theoretically ideal.
I guess you mean that Approval could be considered an improvement
when compared to plurality.
Saying that Range is theoretically ideal is a quite strong claim. I
already noted at the beginning of this mail that there may be many
different targets. Range might provide an "ideal" utility function
for some use cases but not all. There are also some alternative
target utility functions that are close to Range, e.g. ones that try
to find some relatively even utility to all instead of caring only
about the sum of the utilities (and potentially leaving some voters
without any utility at all). And of course if also strategic voting
is considered then the definition of ideal becomes different.
---
The problem with the whole discussion of strategic voting is that
it's often backwards. Voters use strategic voting to improve the
outcome. Some Condorcet methods make strategic voting difficult.
But that's making it difficult for voters to improve the outcome!
Strategic voting is probably more often a result of trying to improve
the outcome from one's own perspective (and against the interests of
others (not necessarily intentionally but from the point of view of
the others)) than an attempt to improve the outcome to all (possibly
against one's own personal interests).
If you refer to the lack of ratings information as a reason why it
may be difficult in Condorcet to improve the overall outcome, then
one solution is to use some external poll information (or just plain
personal guess) on what candidates would be the best for the society
as a whole and then rank the candidates in this preference order.
This does not give the sincere preferences of sincere Range but might
actually yield better results (ffs), also from Range style utility
perspective, in a competitive environment where other voters are not
expected to generally vote for the best of the society as a whole.
What is really lost is that ranked methods don't collect the
information necessary to determine the best winner, because the
assumptions about pairwise victories are defective.
As already indirectly noted, in a competitive environment it may make
more sense to measure only the one-man-one-vote style preferences and
forget the more fine grained expressions of utility (either since
they can not be measured reliably or since majority opinions are
considered to be the best approach to measuring the opinions of the
(competitive) society).
Juho
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