The new issue of The Atlantic magazine contains an article notable for its topic and its author. The topic is John J. Mearsheimer, the brilliant and controversial political scientist at the University of Chicago, known for his powerful arguments in behalf of foreign-policy “realism” and his searing study (with Harvard’s Stephen M. Walt) of the “Israel lobby. “ The writer is Robert D. Kaplan, the itinerate adventurer/reporter/thinker who gained prominence nearly twenty years ago with his probing and timely study—Balkan Ghosts: A Journey Through History—of the cultural crosscurrents in the old Yugoslavia, published as those crosscurrents were turning the region into a bloodbath that Kaplan had predicted.

The article’s title is, “Why John J. Mearsheimer Is Right.” But there’s an asterisk that points to a qualifier lower on the page: “*about some things.” No doubt this was added to separate author and magazine from some of Mearsheimer’s more incendiary expressions, particularly his blurb for a book on Jewish identity that was widely seen as crudely anti-Semitic. Kaplan calls the blurb “a blight on Mearsheimer’s judgment,” particularly given other expressions by the book’s author that Kaplan calls “revolting commentary.” But Kaplan adds: “The real tragedy of such controversies, as lamentable as they are, is that they threaten to obscure the urgent and enduring message of Mearsheimer’s life’s work, which topples conventional foreign-policy shibboleths and provides an unblinking guide to the course the United States should follow in the coming decades.”

Kaplan then goes on to probe, with thoroughgoing approval, Mearsheimer’s provocative foreign-policy outlook.

It isn’t surprising that Kaplan, himself a muscular-minded realist, would write a laudatory piece on Mearsheimer’s scholarship. But it is significant because Kaplan’s judgment carries weight. He is the author of thirteen books, nearly all on the geopolitical forces swirling around the turbulent surface of the globe—and all demonstrating a capacity to cut through the wispy idealisms that often guide foreign-policy thinking in our time and probe the potent forces of culture, geography and power that actually drive global events and developments.

There is another reason why the piece is significant. The Mearsheimer-Walt study of America’s Israel lobby, first in an article in the London Review of Books and later in a book called The Israel Lobby and U.S. Foreign Policy, was attacked by people seemingly bent (in some instances) on marginalizing the authors. Many considered it nourishment for anti-Semites, and Eliot Cohen of Johns Hopkins University, writing in the Washington Post, declared flatly, “why, yes, this paper is anti-Semitic.” He went on to say the authors impugned the patriotism of Jews throughout the country. This is the kind of allegation that, if it sticks, can upend careers.

But it didn’t stick. Though Mearsheimer and Walt remain highly controversial, with abundant and vocal detractors, they survived the Israel-lobby controversy with stature generally intact. And many believe their willingness to absorb the attacks has served to expand the range of acceptable discussion on that highly emotional matter. Kaplan’s piece can only add to their stature and further validate that expanded range of discussion.

But Kaplan’s central interest is Mearsheimer’s passionately held views on what really drives geopolitical events, as examined in his 2001 defining opus, The Tragedy of Great Power Politics. Kaplan says of the book, “its clairvoyance is breathtaking.” He quotes Columbia University’s Richard K. Betts as calling Tragedy one of the three great works of the post-Cold War era, along with Francis Fukuyama’s The End of History and the Last Man (1992) and Samuel L. Huntington’s The Clash of Civilizations and the Remaking of World Order (1996). Betts has suggested that, if world events unfold as expected (and as predicted by Mearsheimer), his opus likely could surpass the others in influence.

The Tragedy of Great Power Politics rests upon a foundational insight that all great nations will seek to project their power to the fullest possible extent. Status-quo powers don’t exist, Mearsheimer maintains. Great powers are always on the offensive, always in expansion mode, because they can never know how much military capacity and geographic positioning they will need for survival. Hence world history is not a chronicle of ongoing peace interrupted by occasional wars; it is rather a chronicle of perpetual struggle that can be stabilized only when a balance of power is maintained.

It isn’t surprising that Mearsheimer harbors a goodly level of contempt for liberal interventionism, which shrinks from the brutal realities of power relationships and inserts morality into foreign policy. He quotes the British scholar E. H. Carr, who wrote in 1939: “Whatever moral issues may be involved, there is an issue of power which cannot be expressed in terms of morality.”

What this means in practical terms is that the United States may have unfurled moral exhortations during its 1990s Balkan interventions, but in reality it pursued those policies only because Serbia was weak and had no allies that could make trouble for America. Or take America’s actions this year to bring down the Qaddafi government in Libya, undertaken against a hapless regime that couldn’t fight back effectively or pose diplomatic or geopolitical challenges. Meanwhile, the United States watches as the more ferocious Syrian regime brutalizes its citizens and the Saudi military helps Bahrain suppress street demonstrations in that tiny but strategic land. As Kaplan explains: “States take up human rights only if doing so does not contradict the pursuit of power.”

What contradicts the pursuit of power, according to this thesis, is contravening power. That’s why the balance of power is so crucial to stability. Indeed, as Kaplan writes, liberal interventionism and neoconservatism are “more likely than offensive realism to lead to the spilling of American blood.” Realism seeks the avoidance of war through the maintenance of a balance of power.

This focus on the balance of power yields up a number of complementary subconcepts. They include “buck-passing” and “offshore balancing.” Buck-passing refers to the tendency, and the wisdom, of powers to get other powers to do the balancing. Prior to World War II, Britain, France and the Soviet Union all sought to get the others to take on the rising Nazi Germany. Ultimately, Britain and America held back while the Soviets absorbed the brunt of the job—a policy that aided the West in its later Cold War against an aggressive but weakened Soviet Union.

Offshore balancing, a hallmark of modern realism, posits that great powers should seek to maintain stability and peace by prudently calibrating power balances in strategic locations of the globe—rather than seeking to maintain dominance over those locations. If hardware and boots are required, they should be devoted merely to restoring the appropriate power balance.

Hence, Mearsheimer supported the First Gulf War after Iraq’s Saddam Hussein invaded Kuwait and positioned himself to gobble up Saudi oil fields. Had he succeeded, he would have obliterated the regional balance of power. America couldn’t allow that and appropriately restored power equilibrium through military action—and then got out. But he vehemently opposed George W. Bush’s later Iraq invasion because it sought to stabilize the region through American military might on the ground—and on the basis of a gauzy notion of creating Western-style democratic institutions where such no such thing had ever existed. Rather than maintaining or restoring a balance of power, Bush’s policy obliterated the regional balance, removing the Iraqi power check on Iran that had contributed to stability in the region for centuries.

“Mearsheimer’s theory of international relations,” writes Kaplan, “allowed him to get both Gulf wars exactly right—and he’s one of the few people to do so.”

On Mearsheimer’s views on America’s Israel lobby (and Walt’s), Kaplan is more critical in his portrayal. He notes that, while Tragedy is a theory, The Israel Lobby is a polemic—and one that “distorts key episodes in Israel’s history.” While it doesn’t seek to delegitimize Israel, says Kaplan, it does seek to delegitimized the American-Israeli special relationship. But he adds: “Nevertheless, The Israel Lobby contains a fundamental analytic truth that is undeniable: the United States and Israel, like most states, have some different interests that inevitably push up against any enduring special relationship….”

Kaplan notes that Mearsheimer and Walt advocate military support for Israel if ever it faces a mortal danger, but they think America should demand more flexibility and cooperativeness from Israel given the billions it has received from the United States over the years. The Israelis don’t show that flexibility or cooperative spirit, they add, for the simple reason that they don’t have to. And they don’t have to, the reasoning goes, because of America’s pro-Israel lobby.

Writes Kaplan, noting his past service in the Israeli Defense Forces: “I see nothing wrong or illegitimate about this core argument. And no amount of nitpicking by their critics . . . can detract from it.” Indeed, Kaplan adds, echoing Mearsheimer and Walt, that the “cost to Israel of its unwillingness to make territorial concessions will grow rather than diminish.”

It’s a worthy point. And this is an important article—certainly for Mearsheimer, who is described by Kaplan as “not modest.” But it’s important also for Kaplan and for The Atlantic. It makes a penetrating and robust case for realism in international affairs, an outlook that has been in eclipse in American policy making for the better part of two decades. It is good to see a thinker of Kaplan’s caliber turn to the pages of the venerable Atlantic for such a tight and robust exposition of such a worthy philosophy.