Lots has been written about the letter that Harvard law prof Laurence Tribe sent to President Obama last year, urging the President to pick Elena Kagan and not Sonia Sotomayor or Diane Wood to replace David Souter on the Supreme Court. I found the following assessment in the letter quite striking:
Diane Wood -- who is more powerful intellectually than Sonia Sotomayor or any of the others mentioned as plausible prospects at the moment with the sole exception of Kagan, who is even smarter -- would be likely to serve nearly a decade less than Elena . . . .
It's safe to say that being smart is a valuable trait for a Supreme Court justice. It's less clear that additional units of smartness continue to add value once you're beyond a certain level of smartness, which one would have to stipulate that Sotomayor, Wood, and Kagan all surpass easily. It seems unlikely that additional smartness is of increasing linear value, and even less likely that it's of increasing exponential or geometric value.
But putting that aside, I am curious as to the methodology that one would employ to determine who is smarter between Kagan and Sotomayor, or Wood and Sotomayor, or Wood and Kagan. This isn't like asking, "Who is the best baseball player today?," for which there at least are numerous relevant statistics that can get crunched into a single stat like "wins above replacement value" -- which is still subject to debate about its validity. How "smart" someone is, is much more subjective.
It would be one thing for Tribe to opine on his perception of the relative intelligence between Kagan and, say, Kathleen Sullivan (also mentioned in his letter), since both were his students at one point. Even then, one has to wonder whether being a student's professor provides enough context to assess how "smart" a person is, but at least there's some comparative basis there. Although a statement like "X is the best student that I've seen in my N years of teaching" has some possibility of error as well, I'm at least using the same basis for measuring the students in the comparison.
Sotomayor, however, went to Yale for law school, not Harvard; and Wood went to Texas for law school. Therefore, Tribe didn't have either one for a student, and can't compare them on that basis with Kagan. Both have been judges for a long time, with many judicial opinions, and as a constitutional law expert, Tribe is certainly capable of evaluating the quality of those opinions. And he no doubt has had interaction with the two of them in various fora. But is that really enough context to make a sweeping statement along the lines of who is more powerful intellectually?
To be sure, I'm not suggesting that one can opine about one's perception of relative intelligence only when you have seen the candidates in the exact same context. When I was clerking, I started to develop a sense of which judges I thought were pretty sharp even though I wasn't clerking for them. But that's making a broad distinction, in the sense of sharp or not sharp, and not something as fine-tuned as "the #1 smartest judge on the 9th Circuit"; "the #2 smartest judge on the 9th Circuit"; and so on.
For what it's worth, elsewhere in the letter, Tribe does raise a number of points in Kagan's favor -- "an appealing public persona," "a well-grounded image of justice as fairness and of law as common sense"; "dynamic personality"; and "extraordinary diplomatic gifts for inspiring confidence"; and "best Harvard dean" in Tribe's time at the law school. The letter seems more persuasive and sensible when arguing these positive traits of Elena Kagan than when engaging in the esoteric and probably meaningless exercise of whether supersmart person #1 is smarter than supersmart person #2.