Marginalism and the Higher Ed Paradox

Steve Postrel:

By now, you may be getting sick of reading articles and blog posts about the crisis in higher education. This post is different. It proposes an explanation of why students have been willing to pay more and more for undergraduate and professional degrees at the same time that these degrees are becoming both less scarce and more dumbed down. And that explanation rests on a simple and plausible economic hypothesis.
First, let me dispose of the idea that “college (and business school) is all about signaling.” The explanation I present allows signaling to represent a major part of the value of higher education, but it says that the historical increase in willingness to pay for education is not caused by an increase in its signaling value. (And the evidence for signaling or screening education premia, as opposed to human capital accumulation, is pretty thin anyway.) I’m certain signaling plays a role in creating value for certain degrees from certain institutions for certain people in certain situations. That it dominates the value proposition for college seems like a stretch.
My hypothesis is that it is precisely the dumbing down of U.S. education over the last decades that explains the increase in willingness to pay for education. The mechanism is diminishing marginal returns to education.