Sen. Marco Rubio has done America a great service by offending navel-gazers. “Welders make more money than philosophers,” he declared at last week’s Republican debate. “We need more welders and less philosophers.”

Fact-checkers cited data showing that philosophy professors earn more than welders. But Rubio is essentially correct: Many jobs for skilled tradespeople pay more than those requiring academic credentials. There just aren’t enough qualified workers to fill them.

Many skills that are essential to a high-performing economy – and that garner middle-class wages – aren’t taught in college. Welding is just one example. Carpenters, electricians, ironworkers, machinists, masons, mechanics, steamfitters, plasterers, plumbers and many other skilled tradespeople earn incomes that often exceed those for white-collar jobs.

An 18-year-old might earn $100,000 or more during four years as an apprentice plumber, and avoid paying as much for college. After the apprenticeship, a young plumber can make $50,000 a year, with the prospect of steady income growth: Master plumbers can earn $100,000 to $200,000.

The typical college graduate makes about $60,000 at the peak of his or her career, and is likely to pay about $3,000 a year in loans.

To improve the prospects of millions of young people, guidance counselors and teachers need to shift their thinking about the skilled trades. Rubio hasn’t detailed how he would go about expanding vocational training and the debate moderators didn’t ask. Next time, they should – and not just of Rubio.