In a presidential field as crowded as this year’s Republican one, every candidate needs a niche. Marco Rubio is trying to own three: generational change, Hispanic outreach, and foreign-policy gravitas.

It was in pursuit of the third that he went to the Council on Foreign Relations on Wednesday to lay out his foreign-policy “doctrine.”

Presidential “doctrines” have a long history in American foreign policy. The earliest, and most famous, was James Monroe’s insistence that the United States would prevent European powers from gaining a beachhead in the Americas. More than 80 years later, Theodore Roosevelt added the “corollary” that in order to prevent the kind of instability that might invite foreign meddling in the region, the United States could intervene to topple Latin American governments. In 1947, in an effort to justify aid to anti-communist regimes in Greece and Turkey, Harry Truman outlined the doctrine of containment, by which the U.S. would “support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures.” Jimmy Carter refocused that doctrine on the Persian Gulf, where he vowed that the U.S. would use military force to repel Soviet domination. Ronald Reagan turned containment on its head by insisting that the U.S. would not merely prevent Soviet expansion but aid anti-communist rebels seeking to roll back pro-Soviet regimes. Finally, in response to the 9/11 attacks, George W. Bush took this aggression a step further by arguing that rather than deterring or containing hostile regimes seeking weapons of mass destruction, the U.S. would launch preventive wars to overthrow them.

Not all these doctrines served America well. And not all of them were even announced as presidential doctrines. Reagan, for instance, simply began arming Nicaragua’s Contras, Afghanistan’s Mujahideen, and Angola’s UNITA rebels in their fights against communist regimes. Which prompted columnist Charles Krauthammer, seeing a pattern, to call such aid the “Reagan doctrine.” The phrase stuck.

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.

In his speech, Rubio did discuss certain policy preferences. He supports giving the president fast-track authority for trade agreements. He wants to boost military spending. He opposes President Obama’s negotiations with Iran. What he didn’t do was explain what sets this age apart from past ones, and outline the precise strategy America needs right now.

To be fair, that would have been hard. Rubio and most of the other GOP candidates want the United States to go on offense overseas after the perceived retrenchment of the Obama years. But Americans have little appetite for additional wars, and the threat that Republicans focus on most—“radical Islam”—lumps together states and organizations that are not only disparate, but bitterly hostile to each other. Truman’s “containment” doctrine and Reagan’s doctrine of “rollback” each had problems. But at least they were aimed at a specific enemy. Rubio can’t lay out a doctrine like that today because the two enemies he and other Republicans talk about most—Iran and ISIS—are only linked in the conservative imagination. On the ground, they’re at war.

When you’re running against candidates like Scott Walker and Mike Huckabee, appearing serious on foreign policy isn’t hard. But the closer you look at the “doctrine” that supposedly guides Rubio’s approach to the world, the less serious it looks. Anyone can enunciate “timeless truths.” Serious candidates explain novel ways to pursue them given the particular circumstances of their time. At the Council on Foreign Relations on Wednesday, Rubio barely tried.