My former student and good friend Andrew Gillen and I argued recently in the Wall Street Journal that applying the Obama era “gainful employment rule” (used to harass for-profit schools) to all universities would lead to denying federal student financial aid for students in many collegiate programs, including at illustrious schools like Harvard, Yale, University of California at Berkeley and the University of North Carolina. For example,we noted that U.S. Department of Education College Scorecard data shows undergraduate majors in rhetoric and composition at Columbia University had median annual earnings upon graduation of $19,700 (less than a full-time barista in a New York coffee shop makes), far less than the median debt load of $28,556.

By contrast, if you went to the less distinguished university that I teach at, Ohio University, and majored in electrical engineering, median annual earnings would be a relatively high $65,900, over 2.7 times the median debt of $24,812. Much more earnings than the Columbia English major, with less debt. Similar examples can be found throughout higher education: graduates in such high demand fields as engineering, mathematics, accounting and finance typically take jobs easily paying enough to cover debt payments, whereas graduates in such fields as psychology, English, art and music, not to mention politically correct but vocationally dubious majors as gender studies, face high probabilities of ultimately not repaying much of their debt because employers simply won’t pay them high wages, because society doesn’t much want their services.

Generalizing about all the major/earnings/debt data: the choice of field of study is about as important as the quality of the school attended in determining ones future earnings. From a societal point of view, we can say that labor productivity and thus total output is enhanced by college attendees majoring in subjects increasing skills that we value highly, and probably diminished where the cost of education exceeds low postgraduate rewards for the training.

This, of course, raises a host of issues and possible solutions. Some politicians at the state level have proposed denying university subsidy money for students in low paying majors, and/or doubly rewarding schools for their students studying majors that labor markets find useful. One way of doing this would be to calculate by major the ratio of student earnings to the average of all college students, and use that in granting subsidies.

For example, say the average graduate of XYZ University earns $40,000 a year, but the average XYZ engineer earns $60,000 while the average sociology graduate only earns $30,000. Give XYZ University 1.5 times the average subsidy for each engineering major (or enrollee) and 0.75 times the average for each sociology major, providing the university incentives to increase the number of trained engineers and reduce the number of sociologists. In time, if a big supply surge of engineers occurs and engineering wages wane, the formula would need to be changed.

One side of me cringes at this approach, even though I teach in a discipline (economics) whose graduates are relatively high valued by society. I think educated persons should take courses in English literature, history, philosophy, art history, and music—all low paying fields. I think the year I studied French literature (in French) at Northwestern somehow was good for me, probably as much as more courses in economics. College is about developing basic skills—the ability to write and talk intelligently, to have some mathematical literacy, and basic core knowledge that lets one navigate civil society competently.

But here’s the rub. Should society pay for it? If most of the benefit of a college education accrues to students obtaining it, shouldn’t they pay for it? It is true that college graduates of today who take high paying jobs incur a larger proportion of the burden of financing public needs in the future, and maybe that justifies subsidization in general and in high paying fields of study in particular, but I am far from certain. I think Bryan Caplan is, minimally, mostly right: college is mainly a screening device, separating the bright, innately productive, and diligent from the dullards, the relatively less disciplined lazier persons who form a part of every society. And it is a very expensive screening device at that.