Thomas Jefferson recognized that a broad education could ensure the survival of the new democracy. He recognized that “even under the best forms, those entrusted with power have, in time, and by slow operations, perverted it into tyranny.” To defend against this threat, Jefferson wanted “to illuminate, as far as practicable, the minds of the people at large, and more especially to give them knowledge of those facts, which history exhibiteth, that, possessed thereby of the experience of other ages and countries, they may be enabled to know ambition under all its shapes, and prompt to exert their natural powers to defeat its purpose.”

The liberal arts, Jefferson recognized, have a practical value that has nothing to do with direct economic benefits: They are linked to the vitality of a commonwealth and the survival of a free people. It’s easy to see how such knowledge could help a politician, but Jefferson encouraged a general education for “the people at large” to protect themselves from politicians.

Considered in light of Jefferson’s argument, Mr. Rubio’s choice of Greek philosophy as a useless major seems especially inapt.