[EM] (2) MJ -- The easiest method to 'tolerate'

steve bosworth stevebosworth at hotmail.com
Tue Aug 2 19:12:27 PDT 2016


From: Kevin Venzke <stepjak at yahoo.fr>
Sent: Tuesday, June 28, 2016 11:03 PM
To: steve bosworth; EM list
Subject: Re: [EM] The easiest method to 'tolerate'

Hi Steve,

K:  Majority Judgment [MJ] is a variety of "median rating" methods which I see as pretty similar.

[….] The most noteworthy [of its] failures [are] Later-no-harm and Mono-add-top. (Both are failures that IRV does not share.)

[….] I should note that while IRV does not have these issues, probably *most* of our proposed methods do, so they aren't necessarily deal-breakers.

While median rating is more resistant to manipulation than Range, I still view the manipulation potential as bad. For example, if you "defensively" rate A as zero, in the Later-no-harm example above, out of a quite reasonable fear that you need to do this to help B win instead of A, this is the type of thing meant by manipulation. It is less likely to have an effect than in Range, but you will still have the incentive to do it.

My main distaste for median rating comes from my feeling that in most scenarios (i.e. availability of information on others' rating intentions) strategic-minded voters would only use the top and bottom ratings. This is because (as we see from the Later-no-harm example) median rating doesn't really offer guarantees about how your ratings will be used in relation to each other.

S:  As I understand it, MJ does guarantee exactly how all the gradings will be counted but not how every voter will use them.   Belinski claims that MJ has the advantage of allowing each voter clearly to express his or her evaluation of each candidate.  MJ invites each voter to ‘grade’ each candidate as being either EXCELLENT, VERY GOOD, GOOD, ACCEPTABLE, POOR, or REJECTED -- each candidate being graded according to each voter’s concept of an EXCELLENT candidate.  Thus each candidate would receive the same grade, independently of which other candidates are available, i.e. each grade (‘rating’) can be given not ‘in relation to’ the other candidates.  He says that this also allows MJ’s not to violate either the Arrow or Condorcet paradoxes.  Do you disagree?

At the same time, in contrast to the use of any of the ‘traditional methods’ which still must violate these paradoxes, Belinski argues that a MJ voter can only be up to half as successful strategically if she focusses instead on voting to maximize the chance that her favorite candidate will win.

Currently, these features incline me to see MJ as the best method for electing a President.  However, you do not seem to agree, given your next sentence, even though ‘approval voting’ does not allow each voter to express the deferent intensities with which they might approve of the different candidates:

K:  The rating/grade values have no independent, practical meaning. If [MJ] voters have this perception and respond with this behavior, then the method is just an overly complicated form of approval voting. In that case I'd rather just use approval, because it's clearer what's going on. (There are arguments about whether median rating voters would actually try to be so strategic, and about whether it would be bad if they did, but I will skip over that.)

S: Given the above, it seems that MJ voters would be much less likely to ‘actually try to be so strategic’ and this conclusion seems to be supported by the ‘Orsay experiment’.


K:  I find a lot of methods tolerable, and I've designed a lot of methods too (most of them tolerable). I care about certain properties more than others, but the ones I like aren't even all compatible with each other.

S:  Which ‘properties’ do you most care about?  How are they ‘incompatible’ with each other?  Still, which method do you see as superior to MJ, all things considered?

K:  In general I feel that election methods should produce an outcome that would be plausible if the voters had been able to gather and vote in person, just as a legislature.

S:  Why would you not see MJ as ‘plausible’ in this sense?


Steve Bosworth

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