[EM] Majority Judgement

MIKE OSSIPOFF nkklrp at hotmail.com
Mon Jan 30 13:09:49 PST 2012

Does anyone here know the strategy of MJ? Does anyone here know what valid strategic claims can be made for it? How would one maximize one’s utility in an election with acceptable and completely unacceptable candidates who could win? How about in an election without completely unacceptable candidates who could win?

And no, I don't mean refer to a website. The question is do YOU, as an MJ advocate, know what MJ's strategy is?

Of course, if anyone here advocates MJ, then they, themselves, should know MJ’s strategy, and its advantages and disadvantages, and be able to state them here.

I’m just guessing, but isn’t MJ’s strategy the same as that of RV? (Maximum rating for candidates you’d vote for in Approval, and minimum points for candidates you wouldn’t vote for in Approval).

And surely the u/a strategy of MJ is to max-rate the acceptables and min-rate the unacceptables.

But of course MJ differs from RV in the following way: In RV, if you rate x higher than y, you’re reliably, unquestionably, helping x against y. In MJ, of course that isn’t so. In fact, if you like x and y highly, and at all similarly, and rate sincerely, then you’re unlikely to help one against the other, at all.

Another difference is that, in MJ, even if you correctly guess that you’re raising a candidate’s median, you can’t know by how much.

Suppose x is your favorite. y is almost as good. Say the rating range is 0-100. You sincerely give 100 to x, and 90 to y.

Say I prefer y to x, and, as do you, I consider their merit about the same. If I rated sincerely, I’d give y 100 and x 90.

But, unlike you, I don’t vote sincerely. Because x is a rival to y, and maybe also because I expect you to rate sincerely, I take advantage of your sincerity by giving y 100, and giving x zero.

Because different people have different favorites and near-favorites, your high rating of x and y is probably above those candidates’ median ratings. So you’re raising the medians of both candidates, with no particular reason to believe that you’re raising one’s median more than that of the other.

In our above-described example, that’s what you’re doing: Raising the medians of x and y. Probably by about the same amount. I, however, am raising y's median and lowering x's median. You’re raising my candidate’s median, and I’m lowering your candidate’s median. You aren’t helping x against y. I’m helping y against x.

You’ve been had. 

At least in RV, you’d have reliably somewhat helped x against y.

There's something familiar about that strategy situation :-)  MJ fully has the co-operation/defection problem.

Discussion of a method’s strategy shouldn’t have to come from someone who doesn’t advocate that method.

A tip: Don’t have confidence in a method whose advocates evidently don’t know its strategy.

Another thing: Just as one example, try MJ on the Approval bad-example. What you thereby find out is that, to be usable, MJ needs bylaws and patches, such as to make it too wordy and elaborate (and arbitrary?) to be publicly proposable. 

Mike Ossipoff

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