Let’s tax college.

It’s a basic rule of economics that if you want less of something, you ought to tax it. We have entirely too much intellectual smog in our culture, and a small excise tax on university endowment income could be a start on clearing the air.

The Tax Cuts and Jobs Act introduced in Congress recently is filled with excellent if relatively unpopular ideas to streamline the Tax Code and close loopholes. This tends not to work politically, as the loopholes all have their constituencies, some of them quite large.

Many of these ideas, from reducing the corporate income tax, to repealing the deductibility of state and local taxes, to restoring a territorial tax system, have been around for a while (and will probably stick around for a while, too, as it’s hard to imagine much getting done in the present climate). But one newish idea in the bill caught my eye: a 1.4 percent tax on the investment earnings of large, wealthy private colleges and universities.

Institutions with fewer than 500 students, or with endowments valued under $250,000 per full-time student, would be exempt from the tax. The top Ivy League schools have 20 times that much.

The wealthiest universities in the country can see returns of more than a billion dollars a year on the investments in their endowments. Harvard made nearly $3 billion last year, on top of all its federal grants and tuition money. The University of Texas System, the one public school as absurdly overendowed as the big Ivies, made $3.4 billion in 2014. What the private schools are doing with their money isn’t public record, but if they’re anything like UT, the money isn’t being used to keep costs down for students. The Texas Tribune found that even as UT Austin cashes out $600 million or more a year, the school’s 40,000 undergraduates saw just $3 million of it go for financial aid.

Meanwhile, in just six years, spending on general administration has quadrupled to $141 million a year. This part is the same everywhere. As universities continue to jack up tuition, and exploit the career dreams of adjuncts and lecturers, they pay salaries in the mid-six figures to diversity officers, and hundreds of millions for palaces to house them.

The point of this new tax isn’t simply to raise revenue, although it does represent a relatively painless way to offset tax cuts that are needed elsewhere. The point is to fire a warning shot, to signal some disapproval and reconsideration. It’s not even a change of course, necessarily; more like pumping the brakes a bit.

There’s no question that the United States has the greatest institutions of higher education in the world. We have funded both private and public universities lavishly at the state and federal level, but we have reached a point of diminishing returns. We probably reached it somewhere back when we first started telling kids that college was for everybody.

The present fashion for identitarian grievance-mongering has its intellectual lineage, of course, but one largely overlooked reason for its spread at this time is that many students are simply too dumb to handle anything more rigorous. The sort of thing one does in kindergarten — recognize this pattern, name that shape – has been made into college coursework. Point at this triangle of hierarchy. Select the correct -ism with which to label that opinion. Yes, that text is a sexist work of the patriarchy. No need to think about it further. Your work is done.

This sort of radical subjectivity emanating from the humanities departments undermines the very purpose of the university. It’s a betrayal of the serious empirical work done in other departments. To take just one absurd example I read about the other day, the director of Yale’s Native American Cultural Center argues that American Indian creation myths should be taken seriously, not just as folklore worthy of study, but as a valid alternative explanation for how this continent was first populated. Archaeologists, anthropologists, and geneticists are unanimous in saying that the first people to come to this continent crossed the Bering Strait, although there are of course variations on how that took place.

Native American author Vine Deloria, Jr. wrote a book about this “white lie,” and Yale’s Professor Theodore Van Alst, the cultural center director, goes along with it. As Indian Country Today reported:

Van Alst noted that it’s also convenient that the pro-Bering Strait Theory community’s evidence (if it exists) is “under water” and that the theory is invariably used “to [discredit] notions of indigenous rights to landholding.” “[The Bering Strait Theory] is used to support the notion that we’re just an earlier set of people on a long continuum of immigrants,” he said. “… There needs be a real reassessment of this thing.”

Point to the shape. Name the pattern. Anybody can do it. But this is a big part of what our colleges are up to now. The problem isn’t just that these explanations are wrong. It’s that, like Billy Madison’s infamous answer, listening to it actually makes everyone else dumber. Thinking along the lines of a pre-established rut isn’t really thinking at all.

Now whether or not dumb kids have anything to do with it, it’s obviously absurd to hold up the Lakota story of the Turtle Continent as a valid alternative to the Bering land bridge, or to subsidize this as scholarship.

As a society, I think, we may be headed for a drastic reappraisal of the university’s function. We’re not there yet, but it is time to consider the path we’re on, and the speed we’re traveling it. We’ve been spending hundreds of billions of dollars on building these institutions that are no longer as worthy as they once were. Maybe it’s time to pull back a little of that support in the form of this excise tax.