Tuesday, June 24, 2003
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Michael Kinsley flunks logic class
Here's how Kinsley's latest Slate essay starts:
Now, while I actually agree with Kinsley that "O'Connor's opinion... sinks back into a vat of fudge," the logic he uses above is incorrect.
Let's ignore the concept of the wait-list and grant Kinsley's point that admission is a binary decision. His next logical leap to assert that each factor has a binary quality because, "it either changes the result or it doesn't. It makes all the difference, or it makes none at all."
What Kinsley is describing is a necessary and sufficient condition: if X, then Y, if not X, then not Y. However, many admissions criteria are necessary but not sufficient. For example, it's safe to say that you cannot get into a good law school with a felony record. Not having a felony record is a necessary condition, but it does not make "all the difference"; it's not sufficient.
Other admissions criteria are sufficient but not necessary. For example, if an applicant had a letter of recommendation from William Rehnquist saying "this is the brightest undergraduate I've met," that person will be accepted. However, it's not necessary to have such a letter to be accepted.
One can parse conditions further. There are SUNI conditions -- sufficient but unnecessary parts of a necessary but insufficient condition. There are also INUS conditions -- insufficient but necessary parts of an unnecessary but sufficient condition.
Race, in the Michigan admissions criteria, is a INUS condition. To be let in for reasons of diversity, it's necessary for the person to be a minority. There are other criteria that must be satisfied -- no felonies, remember. Race, in and of itself, is not a necessary and sufficient condition.
[Er, does this actually matter?--ed. Let me ruminate on that. I'll update this post if it does. The abuse of logic bugged me, however.]
UPDATE: The abuse of logic bugged Kieran Healy in exactly the same way.posted by Dan on 06.24.03 at 08:03 PM