"Should we redistribute grades like we do income?" Response to Megan McArdle

Megan McArdle does not think much of my response to Robin Hanson's implied argument that redistributing income is no more rational or right than redistributing students' GDP would be.  Let's take her rebuttals one by one (leaving out the final one, "hand-waving," which is mainly a repetition). The italics are hers, generally followed by a quote from my original post, shaded blue. My responses are below each indented excerpt from McArdle.

a) Comparing apples to oranges:  "GPA is more tightly tied to individual performance than earnings are. Granting that a) grading is an imperfect measure of the quality of student input, and b) earnings bear some relationship to performance, it's still true that student performance bears a closer relationship to grade than the social utility of the average person's work does to that person's earnings"  So the correct metric by which we assess grades is accuracy (does it correlate with performance) while the correct measure of income is whether it serves some larger social purpose.  Obviously, comparisons should be of like to like: either how accurately income/GPA are tied to performance, or how accurately they are tied to social utility.  It's not clear that GPA would win on either score.

Income is a measure of a performance that's valued by social means. Pay is generally awarded by a collective entity or a community of customers, which gets the ability to pay by its relationship to the larger community; the value pay confers is by definition social. We collectively pay athletes, mainly by watching commercials with which broadcasts of their games are interspersed and buying branded gear; we collectively pay Goldman Sachs investment bankers by buying stuff from the companies that see fit to pay their M&A fees; we collectively pay teachers by allocating tax money for education. We may pay contractors individually, but their value is determined by how large a subset of the community decides to hire them. Money gets its value by being equally valued by others; every "distribution" is a redistribution; and taxes are simply part of the mix.  Grades, in contrast, we at least attempt to tie to only one factor: the student's work.  Money is meant to be redistributed, student performance assessments are not.

Inchoate moral intuition is not "hypocrisy"

UPDATE 5/4/11: Megan McArdle rebuts my points one by one; my response here.
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Andrew Sullivan predicts that the assertion below from Robin Hanson, glossing a video in which students struggle to answer why students' GPA shouldn't be "redistributed" as pay is by taxation, will "piss off some liberal readers."  Boy is he ever right -- and Andrew, doesn't it piss you off? Just what was your position on the PPACA, or on the extra revenue called for in Bowles-Simpson? In any case, here's Hanson:

Most people believe that redistributing money within a nation is good, but that redistributing GPA within a school is bad, and if asked why these should be treated differently, have little to say. My point isn’t to say one can’t come up with reasons to treat these differently.  One could, for example, argue that we prefer differing school signals to help employers sort people into jobs, to achieve higher productivity so that the pie is bigger when we redistribute money. My point is that most people can’t think of such reasons, making it pretty unlikely that such reasons are the cause of their opinions...

We humans are much better at coming up with reasons for opinions than at choosing coherent sets of opinions – we clearly have a powerful inbuilt capacity for hypocrisy.

I should proceed with caution here, because I get the impression we're dealing with a very smart (if smug) cookie.  Still, in response to this challenge from Hanson added as a postscript...

Those who think it unfair to evaluate what students said on the spot, how much better do you think the reasons would have become if the students were given an hour to think about it by themselves?  A week?

Let me grant myself an hour. And I'm happy to share whatever grade I get.

1. GPA is more tightly tied to individual performance than earnings are. Granting that a) grading is an imperfect measure of the quality of student input, and b) earnings bear some relationship to performance, it's still true that student performance bears a closer relationship to grade than the social utility of the average person's work does to that person's earnings.  Also, we have the right as a community to take some pay back as price of admission, and no right because no motive to take GPA back. Collectively, we pay someone for performing a service because we want what they're selling. Taxing back a measure of that payment is as organic to human society as paying it out  in the first place, since tax of one kind or another is the price of admission to any human community. "Taxing" the measure of school performance, on the other hand,  only makes sense if you regard GPA as a commodity rather than as a condition for further learning.