Hi Rob, I congratulate you for focusing on some questions that underlie the endless debates about which is the "best", "fairest", etc. voting method.
To restate the questions my own way: What do we _mean_ by "best", "fairest", "most democratic", etc. Is there some standard (criterion, figure of merit) that we can all agree upon for evaluating and comparing voting methods? It appears that, so far, there is no widely agreed-upon definition for "best", fairest", "most democratic", etc. that can be used for comparing voting methods. Nor is there some "gold standard" that we can all agree upon for comparing methods. I had thought there were only a couple commonly held standards, but I see from this thread that there are perhaps four or more: The Majority Criterion: roughly speaking, the majority of voters get their way. Social Utility: pick the winner that maximally benefits society, or gives maximal overall voter satisfaction, etc. Equal voting power: all voters have equal influence over the election. Minimize or eliminate the need or temptation for voters to vote strategically. Some people (anarchists) reject the idea of voting entirely! Many thousands of words have been written to try to define those standards or criteria more precisely. I won't add to that verbiage here. I think it's not very productive to haggle over detailed definitions when we don't agree about which of those broad criteria is "best". Instead, I'll say a few words to promote my view that Social Utility / Overall Voter Satisfaction / "Maximum Net Tangible Utility" (I like it :-) is the "best" standard. Preface: I don't think there is a way to "prove" that any of these standards are "correct" or "best", using mathematical or philosophical arguments. It seems to me that this is a discussion about personal values - do you value social utility more, or do you value equal voting power more? It seems almost axiomatic to me that Social Utility is the "obvious" "best" standard. But I recognize that others may feel the same way about the other standards. How can we move beyond such an impasse? My approach to persuasion is to present voting scenarios where I hope it will make sense to most readers that preference strength should trump majority rule, equal voting power, etc. I am also striving for some degree of realism, in the sense that people can see how similar situations could occur in real elections. At the same time I don't want the scenarios to be so realistic that some readers will identify strongly with the majority and therefore conclude that majority rule is best! (I'm explaining my strategy here because I want to invite people to contribute more scenarios, in support of Social Utility, or in support of the other criteria.) Preface: Except for my initial infatuation with IRV, I have always chosen my criteria first, and then chosen to support voting methods that best satisfy those criteria. I have NOT chosen voting methods first, then chosen criteria that justified my choice of voting method. Ok, here are a couple of scenarios: (Inspired by Clay Shentrup.) Consider an election where the choices are: A. Spend $10 billion to find a cure for the common cold. B. Spend $10 billion to find a cure for multiple sclerosis. (Assume equal high probability of success for either choice.) Presumably a lot more people suffer from colds than from MS, but MS is devastating, while colds are generally just a nuisance. So, if voters are selfish and shortsighted (and "honest" about expressing their preferences), option A might win with a simple majority vote. But, let's assume that option B gives better social utility. Wouldn't that be the better outcome? A method such as fine-grained Range Voting, which allows voters to express preference strength, would have a better chance of making the "right" choice, if voters who are not afflicted with MS and not worried about getting MS vote "honestly" their weak preference for option A. On the other hand, if the A voters strategically exaggerate their preference for A, then A would win. That's no worse than the majority rule result. Here's another, similar scenario. The choices are: A. All people pay income tax in proportion to their income. B. People whose last names begin with A through F pay twice as much as they would in option A, and the rest pay $1 less than they would in option A. Assume the extra taxes collected in B are just wasted. So option B has lower social utility, but the majority of voters - those whose last names begin with G through Z - would slightly prefer option B. I think/hope that most readers would agree that A is the "better" and "fairer" choice. A simple majority vote would choose B. Range Voting with honest voters is more likely to choose A. But if the G-Z voters strategically exaggerate their preference for B, then the result is the same as majority vote - no worse. Would voters vote "honestly" with intermediate values, thus voluntarily "weakening" their vote under Range Voting? Warren D. Smith's 2004 exit poll study showed that a surprisingly high fraction of the respondents (about 75% if I recall) voted with other than max and min values. However, that poll had 6 candidates, so it might not be a good indicator of what would happen in a 2-candidate election. I personally have voted on bylaws or platform issues at political conventions, where I wanted to cast a weak vote rather than a strong yes or no vote. The reason was that I had only a weak opinion, and would have preferred to let those with strong opinions have their way - but if nearly everyone had only weak opinions, then I might as well register my opinion and participate in the decision. Cheers, - Jan ---- Election-Methods mailing list - see http://electorama.com/em for list info
