Commencement at the University of California, Irvine, in 2014. (Larry Downing/Reuters)

Does our education system serve mostly to reinforce inequality? Bryan Caplan thinks so.

When President Trump declared, “I love the poorly educated,” the highly educated could only cackle. Despite (or perhaps because of) their credentials, they couldn’t see that their derision was driving the working class into Trump’s arms. And despite (or perhaps because of) their credentials, they couldn’t see that America would be greater if Americans were less educated.

That’s the contention of George Mason University economist Bryan Caplan’s controversial new book, The Case Against Education. Arguing against education might seem as un-American as arguing against apple pie. But apple pie is mostly empty calories, and quite unhealthy in large quantities. So too, Caplan contends, is education.

Schooling is kind of bizarre, if you think about it. You spend years learning things of no professional benefit. You forget most of what you learn. And strangest of all, the longer you do this, the more handsomely employers reward you. How does that make any sense?

The answer, Caplan says, is signaling. Most of education isn’t about building human capital. It’s about sending a signal to prospective employers that you are intelligent, diligent, and conformist enough to spend years jumping through hoops to demonstrate those qualities. Caplan doesn’t claim that education builds no skills, but he thinks that human capital formation is about 20 percent of its value.

After all, an employer can’t tell simply by appearance whether Jonny or Joel is smarter or harder-working. But if Jonny has a bachelor’s degree, and Joel doesn’t but swears that he’s very smart and very hard-working, an employer has every reason to believe Jonny over Joel.

Caplan’s “signaling” thesis doesn’t make for pleasant cocktail conversation — certainly not in elite policy-making and opinion-making circles. For the highly credentialed, education has paid handsomely.

And on an individual basis, more education is usually a good idea, though not quite as good an idea as most people say. Caplan does his readers a service by attempting a fuller accounting of the costs and benefits of education, and comes up with more modest projections for the return on investment. Graduate school is not a good bet for all but the very best students; college is, due to the strong risk of dropping out, usually not a good bet for bad students.

But what’s good for individuals and what’s good for society are two different things. Americans like to tell themselves that the arms race for additional degrees is a good thing. We need more education to prepare our workforce for the 21st-century economy. We need to invest more in education to increase opportunity. So we tell ourselves.

Caplan says that’s nonsense. Even as Americans pay lip service to those idealistic arguments, many admit private doubts whether it isn’t just lengthening the rat race. But Caplan argues that it’s worse than inefficient: it’s deeply regressive.

If education is more signaling than human capital formation, then it’s more of a zero-sum game than we’d like to think. Every additional master’s degree hurts those with only a bachelor’s. Every additional bachelor’s degree hurts those with only a high-school diploma. Every additional high-school diploma hurts those without one.

If education is more signaling than human capital formation, then it’s more of a zero-sum game than we’d like to think.

Add to all this the fact that college is an engine for assortative mating, locking out the poorly educated from the dating market of the more educated. Charles Murray contends that this is a key driver of why our country is coming apart, dividing into two increasingly unequal parts.

Life on campus increasingly revolves around self-flagellation for privilege and inarticulate anger at American civilization. Perhaps part of the reason for this is that elite students realize, however dimly, that they’re the beneficiaries of an institution that’s accelerating inequality.

Caplan says the solution is radical austerity. Don’t tinker around the edges. Don’t try to make the system work better. Slash spending in order to reset signaling.

Caplan is, however, quite cognizant that this will not happen. No politician would ever run on this platform, partly because it would be a surefire political loser and partly because Caplan’s thesis is open to an easy objection that is nearly impossible to rebut. His critics say, “Caplan’s thesis is true, just not half as true as he thinks.” Signaling, they say, is closer to 20 percent of education’s value than the 80 percent Caplan contends. It’s just one man’s education guess against another’s. Very few readers are educated enough to weigh all the merits.

Still, even if we side with Caplan’s critics, his reminder of the role of signaling should help reorient a conservative approach to education policy in at least three key areas.

First, stop all subsidies to graduate students. There is no “market failure” rationale for government intervention here. Anyone who gets accepted into medical school, for example, can get his loans underwritten from the private sector. Given that there are so many more humanities Ph.D.s minted each year than there are open professorships, graduate students aren’t wrong to feel exploited — an exploitation enabled by federal subsidies. And we’re not just wasting money on the well-off by subsidizing master’s-degree mills; because of signaling, we’re also hurting students downstream who would sensibly stop at a bachelor’s degree.

Second, retool high school to emphasize vocational education. Teaching useful skills should be the focus. Liberals may lament that making students more immediately employable could lower their incentive to attend college. But if we accept even a modest role for signaling, then from a societal perspective, this is a virtue rather than a fault.

Third, stop the misguided effort to increase high-school graduation at all costs. An investigation into Washington, D.C., schools revealed that half of students who missed half their senior year graduated anyway. Liberals see this as a crime that benefits the victim. The signaling thesis tells us that there are victims. If only half of local students get a high-school diploma, employers could feel comfortable hiring dropouts. But if 90 percent of students do, that sends a signal to employers that there must be something profoundly wrong with a young person without a diploma. Without employment prospects, these kids are funneled into the school-to-prison pipeline.

Since George W. Bush, Republicans have largely viewed education as a bidding war, arguing alternately for more or less than what Democrats have on offer. While Caplan’s radical austerity will not make it into any party platform, his Case Against Education should help conservatives approach the issue with clearer eyes.