But what all these doctrines had in common was that they constituted an effort to define, and answer, the specific challenge of a given time. For Monroe, it was hemispheric independence. For Truman, it was communist expansion. For Carter, it was threats to America’s oil supply.

That’s exactly what the Rubio “doctrine” does not do. The Rubio doctrine, which the Florida senator announced on Wednesday, “consists of three pillars.” Pillar number one is “American strength”: America must “adequately fund our military.” Pillar number two is “the protection of the American economy”: America must pursue “free trade.” Pillar number three is “clarity regarding America’s core values”: America must “support the spread of economic and political freedom by reinforcing our alliances, resisting efforts by large powers to subjugate their smaller neighbors” and “advanc[ing] the rights of the vulnerable.”

These, Rubio told moderator Charlie Rose, “are timeless truths.” But that’s precisely the problem. Historically, foreign-policy doctrines have been the opposite of “timeless.” They represent efforts to further American interests and ideals by offering a specific response to a specific geopolitical reality. Every president wants the United States to be strong, prosperous, and moral. Doctrines are supposed to outline a strategy for achieving those goals. They are not the goals themselves.