It is a truth universally acknowledged that education is the key to economic success. Everyone knows that the jobs of the future will require ever higher levels of skill. That’s why, in an appearance Friday with former Florida Gov. Jeb Bush, President Obama declared that “If we want more good news on the jobs front then we’ve got to make more investments in education.”

But what everyone knows is wrong.

The day after the Obama-Bush event, The Times published an article about the growing use of software to perform legal research. Computers, it turns out, can quickly analyze millions of documents, cheaply performing a task that used to require armies of lawyers and paralegals. In this case, then, technological progress is actually reducing the demand for highly educated workers.

And legal research isn’t an isolated example. As the article points out, software has also been replacing engineers in such tasks as chip design. More broadly, the idea that modern technology eliminates only menial jobs, that well-educated workers are clear winners, may dominate popular discussion, but it’s actually decades out of date.

The fact is that since 1990 or so the U.S. job market has been characterized not by a general rise in the demand for skill, but by “hollowing out”: both high-wage and low-wage employment have grown rapidly, but medium-wage jobs  the kinds of jobs we count on to support a strong middle class  have lagged behind. And the hole in the middle has been getting wider: many of the high-wage occupations that grew rapidly in the 1990s have seen much slower growth recently, even as growth in low-wage employment has accelerated.