A modern variant of David versus Goliath is unfolding in academic economics. Ashwini Agrawal is David. He is a graduate student getting a Ph.D. at the University of Chicago Graduate School of Business. The A.F.L.-C.I.O. is Goliath. Here is the background, as I understand it: The A.F.L.-C.I.O. manages huge pension funds for its members. These pension funds are invested in . . .