Mrs. Sheehan’s song is, I think, already fading in the charts, and “I ain’t no hollaback girl” is too ripe a metaphor to last much beyond Labor Day. Before it goes the way of all metaphors, let’s give it a cheer. On Sunday the New York Times gave an advanced peak at a forthcoming article in The Georgetown Law Journal that is yet another demonstration that higher education has become host to an extraordinary uniformity of political opinion. In this case, the campaign contributions over 11 years of professors at the top 21 law schools were reviewed. Of those who professors contributed anything, 89 percent at Duke gave to Democrats; 90 percent at Columbia; 91 percent at Harvard; topping out at 94 percent at Stanford.