In the June issue of The Atlantic, “Professor X” rants,

Students routinely fail; some fail multiple times, and some will never pass, because they cannot write a coherent sentence

Perhaps Tyler Cowen was implicitly referring to that article. In any case, in order to know whether there is much to be gained at the margin by more students attending college, one needs to look at the relevant margin. Comparing average salaries of college graduates to non-graduates is not what counts, because the former have higher cognitive abilities. Better would be to compare the salary of someone who graduates with someone of similar cognitive ability who does not attend college. Or to compare the salaries of the no-hopers who try college at institutions like Professor X’s with those who instead forego the attempt.

Note: != is a computer-language expression for “not equals”