Brad DeLong writes:
Altonji, Bharadwaj, and Lange do not know.
The whole post is interesting, but from this I can only conclude that Altonji, Bharadwaj, and Lange have never taught Introduction to Composition to a large group of freshman in a public university in the United States. Anyone who has taught such a class — or for that matter talked to anyone who has — will have some inkling why more people are not going to college. Herein lie the roots of growing inequality — on the bottom side at least — and don’t let anyone induce you to take your eye off the ball by playing switcheroo and bringing up the (separate) topic of the growing wealth of the top one percent.