[EM] Criteria (Re: IRV ballot pile count (proof of closed form))

[Kristofer Munsterhjelm]

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.