Abd ul-Rahman Lomax wrote:
I don't think it's true that it has been "without problems." There are
and have been problems. But if IRV were an optimal method, it might be
worth the trouble. For multiwinner STV, indeed, it might well be worth
the trouble. But for single-winner? I don't think so. There are simpler
methods that produce better results, by all objective measures.
(Frankly, there is only one clearly objective measure, which is how a
method performs in simulations, particularly with reasonable simulation
of actual preference profiles -- full utility profiles -- and voting
strategies as voters are known to use or are likely to use. "Election
criteria," like the Condorcet Criterion, tend to be criteria that are
intuitively satisfying, but that can actually fail completely and
obviously under certain conditions, and a method failing a criterion may
mean nothing if the failure is so rare and requires such unusual voting
patterns that it will never be encountered under realistic conditions.
Basically, how do we judge the criteria? And there are only two ways
that I see, one is through utility analysis and the other through basic
democratic principles, broadly accepted, such as the right of decision
that is held by a majority; a majority of voters voting for a single
proposition, with no opposing majority voting simultaneously for a
conflicting proposition, must have the right to implementation. When
there are multiple majorities there is not a simple question and there
remains doubt as to a majority decision.)
I'm not quite sure about this. Say you have an almost-perfect method:
usually it elects great candidates, but once in a while, it picks a very
bad dictator, or respects the wishes of a tiny minority, or somesuch. It
does this seldomly enough that it's just ever so slightly better than
the best alternative, on average.
However, those who hold democracy as an ideal would probably not like
this method, because once in a while, it "hiccups". The jitter or
hunting, itself, provides a bad outcome; and in a sense, criteria are
guarantees that a bad outcome (according to the criterion) won't happen,
period.
To make it somewhat more familiar: Range may be the best Bayesian Regret
method, but that won't help once people notice that it gives a minority
power to outvote a majority. Sure, that may be "better" according to BR,
but it's not majority-rule democracy, which is the context in which
these methods are considered. If you're going to fail Majority, you at
least need a runoff so it's intuitively possible for people to keep that
from happening.
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