[EM] Majority Judgement

Jameson Quinn jameson.quinn at gmail.com
Mon Jan 30 14:19:36 PST 2012

MJ strategy is:

>From polls and past elections, estimate the range of possible median scores
of whoever wins this election. For instance, if you can vote A+, A, B, C,
D, or F, then you might estimate that the winner will be between B+ and C-.
Then, vote anyone you want to win above this range, anyone you want to lose
below this, and anyone non-viable honestly.

Obviously, if everyone follows this strategy, then there will be inflation,
and eventually everyone will have to vote at the extremes. But it only
takes a relatively small fraction of non-strategic voters to stop the
strategic inflation in one or both directions. In fact, I believe that for
the large majority of voters in real elections, a perfectly honest vote
will be strategically optimal.


2012/1/30 MIKE OSSIPOFF <nkklrp at hotmail.com>

> 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.

MJ is not rated on a numeric scale, at least, not unless that same numeric
scale is used for academic grades in that area (such as the 5-10 scale in

> 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.

You can do exactly the same thing in range: vote Y 100 and X 0.

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

The exact same strategic dilemma applies, with the exact same outcome.

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

Yes. But at least you can afford to vote honestly until you hit that
dilemma; and so the habit might carry over.

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

Although I am a SODA advocate first, I consider myself an MJ advocate as
well. And I have mentioned countless times that it is subject to the
chicken dilemma.

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

A tip:... oh, forget it, I don't want to be that snarky.

> 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.

As I've repeatedly said, MJ does not resolve that problem, except insofar
as voters' good habits of honest voting carry over.


> Mike Ossipoff
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info
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