Janet Yellen, chair of the Federal Reserve, spoke at the University of Baltimore's midyear commencement on Monday, and her message was about as upbeat as any the students will ever hear from a practitioner of the dismal science.

The economy is nearly at full employment, with prospects especially strong for college graduates, for whom the unemployment rate is an infinitesimal 2.3 percent.

What's more, grads can expect a "large" advantage in lifetime earnings over contemporaries with only a high school education.

Last year, college graduates' earnings averaged 70 percent more than high school graduates' pay; that is up from 20 percent in 1980, she said.

And the advantage kicks in quickly: Only a few years after graduation, it's almost $18,000 a year, Yellen reported.

Moral of the story: Higher education is a good long-term investment. That notion is being questioned as never before, though, due to concern about student debt, which now totals $1.3 trillion, spread out over 44.2 million borrowers. Yet as Yellen pointed out, government data shows that the vast majority of student borrowers who complete their degree programs find work that allows them to keep up with interest payments and eventually pay off the principal. According to studentloanhero.com, about 40 percent of student debt was incurred to finance graduate and professional degrees - that is, MBAs, MDs and law degrees, which enhance future earnings even more than a four-year bachelor's.

Yellen's words were a useful corrective to the view, expressed at great but tendentious length by presidential candidates this year, that student loans are "crushing" America's young people - and that a major federal initiative is needed to correct that. In fact, debt distress is disproportionately concentrated in certain segments of the market, including professional schools and for-profit four-year colleges.

Solutions, if any, should be targeted and limited so as not to waste resources that could go toward other purposes, such as enhancing the prospects of those who do not attend college. In that respect, we had reservations about Hillary Clinton's plan for "debt-free college" - but that's academic now, and President-elect Donald Trump's ideas are the ones that matter.

They are still rather murky at this point. During the campaign, a Trump adviser spoke of returning the student-loan business to private banks, as opposed to having the government originate them, and profit directly, as at present. The candidate advocated incentives for colleges to reduce tuition costs, as well as capped payments and long-term loan forgiveness - all of which already have been suggested or attempted, in some form, by the Obama administration.

This would be a good subject on which to probe education secretary-designate Betsy DeVos at her confirmation hearing next month.

Whatever the next Congress and president do about student loans, policy must reflect the fact that the benefits of investment in higher education accrue not only to society but also to the individuals who receive the education.

It is therefore perfectly reasonable both to subsidize that investment - and to expect individual beneficiaries to pay for some of it themselves.

(c) 2016, The Washington Post