“There’s a deeper question of what public money should be used for,” said Anthony Carnevale, a Georgetown University professor who runs the Center on Education and the Workforce.

Education tends to be justified in terms of personal exploration and fulfillment, as well as creating informed citizens who make a functioning democracy possible. The humanities have traditionally been seen as crucial to both endeavors.

“The problem is that education is now the principal determinant of earnings, and we pay no attention to it at all. That’s gone too far,” Mr. Carnevale said. “There’s a lot of buyers’ regret out there.”

Mr. Carnevale argues that there should be much more information available to students about employment and wage prospects before they choose a major so that they can make informed choices. “We don’t want to take away Shakespeare. We’re just talking about helping people make good decisions,” he said. “You can’t be a lifelong learner if you’re not a lifelong earner.”

A graduate with a higher-earning degree could make up to $4 million more in lifetime earnings than other college graduates, Mr. Carnevale said. Most of the top earners in the liberal arts end up matching only the bottom earners in science, technology, engineering and mathematics — known as the STEM fields — and some will earn less than high school graduates who have vocational skills, like welders and mechanics.

A recent salary survey from the National Association of Colleges and Employers, a nonprofit membership organization that connects campus career officers with business recruiters, found once again that new STEM graduates were expected to command the highest overall average salaries in 2016. New engineers, for example, are expected to earn nearly $65,000 a year.