Juho wrote:
Many of the criteria would be nice to have. One must however remember that often they have two sides. Winning something in some area may mean losing something in another area (e.g. the LNH property of IRV has been discussed widely on this list recently) especially when trying to fix the last remaining problems of the Condorcet methods. And if one assumes that strategic voting will not be meaningful in the planned elections then one should pay attention also to performance with sincere votes, not only to the resistance against strategies. Different elections may also have different requirements, so the question of which one of the methods is best may depend also on what kind of winner one wants to get (e.g. in some cases the best winner could be found outside the Smith set).
That's true. Some of the criteria are mutually exclusive, yet others are not. By picking criteria of "worth", one might build a Pareto front: those methods on the front are those that fulfill as many criteria as possible subject to that some are mutually exclusive.
If we didn't forget notable criteria (and thus exclude from the Pareto front methods that by all means should be there), then the front provides the best methods we can get. It's up to one's judgement which of the criteria count more, i.e. which method on the Pareto front one should pick.
For convenience's sake, I've ignored the problem that criterion compliance might degrade the method's "goodness" when given honest votes, and that we don't know which criteria are mutually exclusive. For the former, we (E-M members) disagree about how to go about measuring how good results a method provides on honest votes, and for the latter, we can still build a Pareto front based on the methods we know so far - but it might be incomplete.
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