Rand Paul’s foreign-policy speech before the conservative Heritage Foundation on Wednesday represents an event of perhaps seminal significance to the Republican Party—and the nation. The Kentucky Republican outlined a foreign-policy outlook—and perhaps the beginnings of an actual foreign policy—that would guide America along a middle path between the boundless national ambition of Republican Party neoconservatives and the isolationism of his father. He declared himself "a realist."

This is consequential in itself, given the sway of the neocon philosophy over GOP thinking since the early days of George W. Bush and the paucity of enthusiasm for realist convictions. When such a prominent Republican senator embraces the realist label, it presents just a hint of a possibility that a foreign-policy debate actually could emerge in a Republican Party long frozen in the tundra of neocon thinking.

But greater significance is embedded in Paul’s effort to elucidate just what a realist foreign policy would look like. Granted, his formulations are a bit vague, lacking the specifics that would have to emerge eventually to give his thinking force and credibility. But he put forth some powerful ideas that could capture the imagination of the American people if presented with consistency and clarity.

Consider his view of the threat posed by radical Islam, which was presented with more nuance and depth of perception than is seen in the pronouncements of most politicians these days. The senator accepts the conventional view that the West is not in a conflict with Islam itself but rather with radical elements within Islam. But he adds: "the problem is that this element is no small minority but a vibrant, often mainstream, vocal and numerous minority." Whole countries, he adds, adhere to certain radical concepts of Islam, and the Muslim peoples are animated by powerful political sentiments born of a long history of frustration and passion.

"Radical Islam," declared Paul, "is no fleeting fad but a relentless force." It makes up for its military weakness "with unlimited zeal."

Thus does Paul dismiss those who seek to minimize the potency and durability of the Islamist threat. No, he says, it isn’t going away anytime soon, and it isn’t subject to the kind of friendly outreach that President Obama seemed to embrace early in his first term. As Paul puts it, "I don’t agree with FDR’s VP Henry Wallace that the Soviets (or Radical Islam in today’s case) can be discouraged by ‘the glad hand and the winning smile.’" By invoking the memory of Wallace, probably the country’s most dangerously naïve Cold War leader of serious stature, Paul signals a dismissive attitude toward such gauzy thinking. One key aim of strategic realism, after all, is to snuff out foreign policy naivety wherever it may be found.

But it is noteworthy that Paul’s pragmatic view of the true nature of radical Islam doesn’t lead him to calls for the kinds of open-ended military excursions pushed by such polemicists and politicians as William Kristol, Robert Kagan and Senator John McCain. Paul writes:

What the United States needs now is a policy that finds a middle path. A policy that is not rash or reckless. A foreign policy that is reluctant, restrained by Constitutional checks and balances but does not appease. A foreign policy that recognizes the danger of radical Islam but also the inherent weaknesses of radical Islam. A foreign policy that recognizes the danger of bombing countries on what they might someday do.

In putting forth his formulation, Paul comes closer than any politician of recent memory to the thinking of the late Samuel P. Huntington, the Harvard political scientist whose famous article (later expanded into a book) on what he called The Clash of Civilizations caused a major stir in intellectual circles in the 1990s. Like Paul, Huntington rejected the notion, embraced with such earnest conviction by many American leaders after the 9/11 terrorist attacks on U.S. soil, that Islam’s radical elements represent merely a small segment of the Muslim civilization. "Some Westerners," wrote Huntington, "…have argued that the West does not have problems with Islam but only with violent Islamist extremism. Fourteen hundred years of history demonstrate otherwise."

But, also like Paul, Huntington didn’t see this reality as calling for an extensive American attack on radical Islam to protect Americans. Indeed, he argued that such an approach could exacerbate existing tensions between the civilizations. That’s because civilizational conflicts, far more than territorial disputes or even ideological ones such as the Cold War, are extremely difficult to adjudicate or terminate. "Differences among civilizations are…basic," wrote Huntington. "Over the centuries…[these] differences have generated the most prolonged and the most violent conflicts."

Huntington, like Paul, opposed the Iraq War in large measure because he saw that it would enflame the world of Islam and heighten tensions between it and the West. They favored instead a more measured approach summed up by Paul when he said in his Heritage speech: "Containing radical Islam requires a worldwide strategy like containment. It requires counterforce at a series of constantly shifting worldwide points. But counterforce does not necessarily mean large-scale land wars with hundreds of thousands of troops nor does it always mean a military action at all."

In his speech, Paul lauded Cold War thinker George Kennan for articulating a strategy based on a careful calibration of U.S. interests. Kennan, he said, objected to President Harry Truman’s "implied obligation to act wherever Soviet aggression or intimidation occurred, without regard to whether American interests were at stake or the means existed with which to defend them." After all, not every cluster of Islamic radicals in far-flung outposts of the world constitutes a threat to the United States, just as not every two-bit Communist regime constituted a Cold War threat. Paul’s "saner, more balanced approach to foreign policy" would take account of these distinctions.

Paul was particularly intriguing in his assessment of Ronald Reagan, often invoked by neoconservatives as a model for their aggressive foreign-policy prescriptions. This is a false analogy, says Paul, adding that Reagan’s foreign policy was "robust but also restrained." He quotes Reagan adviser Jack Matlock as saying the fortieth president’s Soviet policy "had more in common with Kennan’s thinking than the policy of any of Reagan’s predecessors." The Cold War ended, Paul argues, because the engine of capitalism defeated the engine of socialism. "Reagan aided and abetted this end not by ‘liberation’ of captive people," but with tough talk accompanied by a willingness to engage diplomatically. And he praises Reagan’s "strategic ambiguity"—his willingness to keep the world guessing about just how he defined his own foreign policy.

This was far more effective, says Paul, than the current tendency to outline precisely what the United States will and won’t accept from other countries, which he suggests undermines effective diplomacy. He is particularly critical of how this has worked vis-à-vis Iran, which has been told that "all options are on the table" (meaning, obviously, the military option) while U.S. officials sternly remove from the table any prospect of containment and have handled the diplomatic option in ways suggesting limited interest in that as well. Just as it would be unwise to state unequivocally that we will accept containment as a policy against a nuclear Iran, says Paul, it is equally unwise to say we will never accept containment. "War," said Paul, "should never be our only option."

And yet Washington operates in a political environment in which it is not acceptable to question the bipartisan foreign policy consensus. Those who do so, says Paul, are "immediately castigated, rebuked and their patriotism challenged." He adds, "The most pressing question of the day, Iran developing nuclear weapons, is allowed to have less debate in this country than it receives in Israel."

He bolsters that assertion by citing Israeli high officials and former officials who have stepped forward with warnings about a military strike against Iran. These include the current head of the Mossad, a former head of the Mossad, the former chief of Israel’s domestic-security service, and the army chief of staff. Paul sees little of this kind of dissent in U.S. political discourse.

There is plenty in Paul’s speech worthy of debate, but that’s the point. He wants to generate debate on matters that in recent years have received little serious discourse within the Republican Party—and not much more within the broader confines of official Washington. This should be welcomed by anyone who wants the country’s foreign-policy decisions to be vetted, weighed, adjudicated and pushed through a process of sound and measured consideration. Perhaps prospects of another disastrous Iraq War could thus be diminished.

It is widely believed in Washington that Rand Paul plans to run for president in 2016. If he does, and if he hones and refines this Heritage message to a fine point, then we can learn if such views can find resonance among Republican voters in the primaries or whether the aggressive foreign-policy outlook of the party’s neoconservatives will inevitably hold sway. Either way, let the games begin.

Robert W. Merry is editor of The National Interest and the author of books on American history and foreign policy. His most recent book is Where They Stand: The American Presidents in the Eyes of Voters and Historians.