(This is a corrected version of an article that appeared in the Nov. 5, 2008, issue of PAW.)

Ninety or so juniors looked down at Gary Bass as he took the podium in Dodds Auditorium, in Robertson Hall, on a Monday in September. His job, following some quick remarks from Anne-Marie Slaughter ’80, dean of the Woodrow Wilson School, was to welcome the latest class of “Woody Woo tools,” as he warmly referred to them, into the fraternity of hard-core wonkdom.

“This is your building, this is your house, this is your architectural monstrosity,” he said of Princeton’s policy fortress. Bass’ light touch and his relative youth — he’s 39 — are two reasons Slaughter tapped him to be the faculty chairman for the undergraduate program. “We really like having you here,” he said. “It livens the place up. Left to our own devices, we are all pretty dreary.”

But the droll, blue-suited associate professor also made some serious points. He suggested, for instance, that the eager students ought to remember the role of luck in their lives: However hard they’d worked, whatever they’d overcome, they’d been born into circumstances where they could flourish. “There is, in fact, somebody who is just as smart, just as talented as you, who is right now contracting malaria somewhere in Zambia or who is sitting in a refugee camp in Darfur,” Bass said, without mawkishness. “There is some obligation — not an unlimited obligation, but some obligation — to give something back.”

Bass’ new book, Freedom’s Battle: The Origins of Humanitarian Intervention, is about obligation, too — but at the level of states, not individuals. With it, Bass, whose previous book explored the history of war-crimes tribunals, wades into one of the most contentious debates in foreign-policy circles: When should the United States use military might to protect threatened civilians abroad?

It’s been observed that “Never again,” the pledge uttered in the wake of the Holocaust, has been interpreted with cruel narrowness by Western diplomats fearful of the costs of intervention: Never again will the world permit a genocide against the Jews in the middle of Europe. But other states, other peoples? In Rwanda, members of the Hutu tribe killed some 800,000 Tutsis in 1994, as Western diplomats fled. The Khmer Rouge killed 2 million Cambodians before Vietnam intervened to unseat Pol Pot’s regime in 1979; U.S. officials protested the Communist intervention more than the mass murder.

Always a contentious issue, humanitarian intervention is an area in which ideological labels have been scrambled. After the Cold War ended, and Yugoslavia began to fracture, it was mostly liberals — so-called humanitarian hawks — who led the charge for intervention to protect civilian populations, first in Bosnia and then in Kosovo. The United States, European powers, and the United Nations dithered as Serbian thugs slaughtered 7,000 Muslim men and boys in Srebrenica (some 200,000 civilians overall died in the conflict), but the Clinton administration was finally roused, brokering a peace deal in 1995 and, with the U.N., enforcing it.

During the debate over Bosnia, foreign-policy “realists” — who believe that humanitarian intervention can cause more problems than it solves — ultimately lost the argument. But it was with the bombing of Serbian sites in 1999, conducted to protect the Kosovar Albanians, that the realists went apoplectic. Unlike independent Bosnia, Kosovo still was a province of Serbia, and President Clinton acted without congressional approval. In response, Henry Kissinger decried the “abrupt abandonment of the concept of national sovereignty” and “the advent of a new style of foreign policy driven by domestic politics and the invocation of universal moralistic slogans.”

Condoleezza Rice wrote a now-famous piece for Foreign Affairs in 2000 arguing that the United States had sent its military on too many humanitarian adventures, and that — cue irony — the U.S. Army ought not to be involved in nation-building. Sept. 11 and the Iraq war upended that philosophy. While the Bush administration seldom framed the war as a humanitarian intervention, others did. In a glowing review of Freedom’s Battle in the September-October issue of Foreign Affairs, the acerbic journalist Christopher Hitchens writes that a fatal contradiction occurs “every time someone who wants to leave, say, a Saddam Hussein alone is rash enough to wonder out loud what should be done about Darfur.” Disillusioned by the Iraq war, many leftists now sound a lot like realists, wary of “going abroad in search of monsters to destroy,” in John Quincy Adams’ words.

Enter Bass, who argues that humanitarian intervention was around long before Bill Clinton. To shed light on our current situation, he offers three chief instances from the 1800s in which European powers debated ferociously about whether to intervene to stop horrific massacres — and in two cases, did so. The first is the support in the 1820s of British “philhellenes” for Greek independence from the Ottoman Empire. The philhellenes — the most glamorous of whom was the poet Lord Byron — were appalled by atrocities committed by Turks against the Greeks. The episode ended with British ships joining with French and Russian vessels to smash a Turkish fleet, in the Battle of Navarino.

The second case is France’s incursion into Syria, in 1860–61, to curb bloody clashes between Christian Maronites and Druze (who practice a variant of Islam). And the third is the great debate in England, in the 1870s, between William Gladstone and Benjamin Disraeli, over whether to intervene against the Ottomans after thousands of Bulgarians were killed in a town called Batak. The liberal Gladstone, a former prime minister, roared out of political semiretirement to ignite a national fury with a pamphlet titled “The Bulgarian Horrors and the Question of the East,” which cataloged “unutterably vile” atrocities and argued that “human sympathy refuses to be confined by the rules ... of international law.” Gladstone lost the argument, but in 1880 he toppled Disraeli’s government, in part because he could paint Disraeli as heartless during the Bulgarian affair.

“Rediscovering this long history,” Bass writes, “levels the playing field in present-day debates between human-rights advocates and more conservative realists, rather than leaving realists dominant as the exponents of traditional statecraft.” Sovereignty, he says, was not nearly as sacred in the 19th century as Kissinger and his intellectual allies make it out to be. And Bass argues that the interventions he explores were not simply imperial bids for power. Indeed, Britain, in Greece, worked directly against its imperial interests by fighting the Ottoman Empire, Bass suggests. The English viewed the Ottomans as offering a crucial counterweight against Russia; anything that hurt the Ottomans helped Moscow.

In an enthusiastic review of the book in Slate, Samantha Power, author of A Problem from Hell: America and the Age of Genocide, places her friend Bass squarely in the humanitarian hawk camp. Indeed, he does sound hawkish at times. “In proper historical context,” he writes, “all liberals are asking is for the United States, the E.U., and the other major democracies to shoulder as much responsibility as Britain did as long ago as 1827.” Yet in an interview in his office in Bendheim Hall, Bass sounds more cautious than that label might imply.

“I think humanitarian intervention is a necessary evil,” he says. “There are going to be extreme cases in which nothing but military force is going to stop a genocide. But it is not something that you jump into without thinking about the consequences.” He then rattles off, realist-style, the risks of intervention — “that by seeming to take a side, you encourage that side to become more belligerent, that you spark great-power rivalries, that you stir up local resentments, that you try to impose yourself as a governing authority over people that you don’t really understand, that you can actually bring great powers into direct conflict. Those are all genuine risks, and people who want to wave the flag for the human-rights movement have to take those into account.”

Gary Jonathan Bass was born in Boston but grew up in Toronto, where he attended public school before moving on to Harvard, remaining there for his graduate studies. Canadians have a tradition of arguing that human rights should play a part in foreign policy, but at Har-vard, he says, “I was at first a totally cynical realist. It was all about power politics.

“Sophomore year I took a course on ethics in foreign affairs from Stanley Hoffmann,” he says, “and I realized I was wrong about everything.”

Like Bass, Hoffmann — an Èminence grise in European political studies — comes from a humanistic tradition in political science that is fading as more and more scholars take up game theory and other mathematical imports from economics. Hoffmann recalls, “There was this young man in the course who would come up to me after every class to object to this or that — particularly if the subject was Israel.” On that issue, they did not share the same views: Hoffmann remembers that he was skeptical of Israeli policy toward the Palestinians while his student found him too skeptical, “but I thought this was an extraordinary young man.” Bass ended up asking Hoffmann to supervise his thesis, which was on French policy toward the Middle East.

Between college and graduate school, Bass spent a year at The New Republic and flirted with journalism as a profession, reporting for The Economist. But he stayed on the academic path. The Bosnian war was raging, the West was vacillating, and Bass was in search of a fresh way to write about the moral issues at stake. “By 1994, it wasn’t news that the Clinton administration was letting Bosnians die,” Bass points out. “But it was news that there was a war-crimes tribunal, a quite weak and underfunded one, and that raised lots of its own issues. Why were the same Western countries that were so enthusiastic about Nuremberg now pretty indifferent about prosecuting war crimes in the former Yugoslavia?”

He wrote a dissertation that later grew into Stay the Hand of Vengeance: The Politics of War Crimes Tribunals. The book traced the development of such tribunals from Napoleon’s imprisonment on St. Helena, through debates over whether and how to try German leaders after World War I, on to Nuremberg and The Hague. War-crimes tribunals had a decidedly mixed legacy, Bass concluded: Despite the claims of some advocates, the threat of prosecution appeared not to discourage atrocities. Nevertheless, they had value in laying down standards of acceptable behavior and providing an undeniable record of atrocities.

“Until Gary wrote this book,” says Jack Snyder, a professor of political science at Columbia, “the subject was really in the hands of activists who wanted to promote international criminal trials. He opened the path to those of us who wanted to write on the subject of an explanatory, causal, social-science perspective.” In his own writings, Snyder is more pessimistic than Bass about the value of such tribunals. Surveys that Snyder helped conduct of Serbian attitudes toward war-criminal prosecutions, for example, suggest that Serbs who favor tribunals do so not because they believe they are fair or just (they don’t), but because they represent the price Serbia must pay to get aid from Western Europe. Snyder doubts the trials are doing much to spread moral ideals.

In Freedom’s Battle, a key thesis is that the explosion of newspapers in Europe in the 1800s, combined with an expanding electorate, put populist pressure on leaders who otherwise might have ignored grim news from abroad. When the Greeks rose against the Turks in 1821, ¨and the Turks lashed back remorselessly, England was watching. “The most civilized, cultivated, and interesting people, the flower of Greece, have been, the greater part, exterminated,” lamented the influential London Times, with some exaggeration.

As American elites try now to rouse the public about Darfur, so English elites did the same. Byron, David Ricardo, Jeremy Bentham, and a host of eminent worthies sat on the London Greek committee, raising money and urging the government to act. Their arch-nemesis, their Kissinger, was the foreign minister Lord Castlereagh. Unlike the poet Shelley (“I met murder on the way / He had a mask like Castlereagh”), Bass does not cast Castlereagh as an outright villain. At the height of his battle against the philhellenes, he notes, Castlereagh could still write that “it is impossible not to feel the appeal” of the Greek cause, yet he was guided by morality of a different stripe than Byron’s, believing respect for sovereignty, the balance of power, and opposition to revolution would prevent a return to the pre-1815 chaos in Europe.

Castlereagh would end up committing suicide by penknife. His more liberal successor, George Canning, held the realpolitik line for a while, but finally committed to sending British ships, in a three-power coalition of the willing, against the Ottomans. In Bass’ account, Byron, despite his hyper-romantic reputation, proved a pragmatic and moral humanitarian leader until he fell ill and died in Greece. He filed rigorously accurate reports about the situation and, unlike other philhellenes, refused to tolerate Greek atrocities.

If the Greek case showed that activism could change the foreign policy of a great power, the French incursion into Syria 30-plus years later demonstrated how the great powers could place limits on a humanitarian intervention by one of their own. Here, it was the Christian Maronites who rose up and soon found themselves outmatched, then massacred. France itched to intervene, sending ships to Beirut, as did England. As the Ottomans scrambled to tamp down the violence they knew could lead to meddling by outsiders, the Western powers worked out their own plan: France could send a small force (12,000 troops); it had to be out in six months; and it had to formally renounce any territorial or economic advantages from its actions.

“The idea of a treaty where an intervening power has to forswear exclusive political, economic, military advantages from the intervention — I think that is a very useful device for differentiating humanitarianism from imperialism,” Bass says. “Compare that to after the Iraq war, where the Bush administration is excluding Russia, Germany, and France from reconstruction contracts” because they had refused to support the coalition.

In 1876, an American-born journalist, Januarius Aloysius MacGahan, wrote the articles about the massacres in Bulgaria that ignited the great Gladstone-Disraeli war in Britain. Gladstone’s exhortations on behalf of the Bulgarians provided a precedent that a later prime minister, Tony Blair, would cite to justify his own support for intervening in the Balkans.

One objection to Bass’ contention that these cases are important precursors to modern humanitarian interventions is that in every instance the victims were Christians and the oppressors were not. That’s the point the George Washington University professor Martha Finnemore stresses in her book The Purpose of Intervention: Changing Beliefs about the Use of Force: The evolution from pan-Christian solidarity to the idea of defending threatened peoples regardless of faith or skin color represented the biggest shift in diplomatic thinking since the 19th century.

There’s no doubt that anti-Turk sentiment played a part in the attitude of some 19th-century “atrocitarians” (the liberal hawks of that era). But Bass argues that most philhellenes, and others, saw the Ottomans as part of the “system of civilized states.” Many atrocitarians (like Bentham) had unimpeachable anti-racist and anti-imperialist credentials. Still, it’s clear that the Turkish-Christian issue complicates Bass’ story. That’s one reason Joshua Muravchik, a self-described “proud neocon” and a resident scholar at the American Enterprise Institute, thinks Bass “went in the wrong direction” to justify humanitarian intervention. “I think the case rests more in natural law and natural right than in custom and practice,” he says.

But it’s the very complexity of the story that appeals to Michael Walzer, author of Just and Unjust Wars and a professor emeritus at the Institute for Advanced Study. “Humanitarian intervention is never going to be the product of a pure moral will,” Walzer says. “If you look for that, you’re not going to find it. There are always mixed motives and geopolitical and strategic motives all tangled up with humanitarian or ethical or political-ethical motives.”

So what is to be done? Are there lessons to be drawn from all this that might help resolve the controversies surrounding places like Darfur and Myanmar? Many of Bass’ historical lessons will sound familiar. Some realist truths must be acknowledged: In the 19th century, liberal states did not intervene when to do so would risk war with great powers. Ditto today: Few spoke of intervention to save the Chechens from Russia, nor, despite bellicose rhetoric from some quarters, is the United States likely to go to war to enforce international law in Georgia. Multilateralism always is preferable, according to Bass, as is concerted action by small, regional powers — but the great powers sometimes may have to cobble together ad-hoc alliances or even act alone.

Clearly, there’s no escaping the need for even humanitarian hawks to analyze cases and make hard trade-offs — something Bass’ students learn in his courses. This semester he’s teaching a Wilson School seminar on international justice; in the spring, he’ll teach his popular undergraduate course on human rights. “His classes are always full,” says Slaughter.

As for his own views of recent events, Bass supported the intervention in Bosnia wholeheartedly and, with reservations (namely on account of the unsavory nature of the Kosovo Liberation Army), that in Kosovo. In the case of the Iraq war, Bass says he accepted the mistaken view that Iraq possessed weapons of mass destruction, but was deeply ambivalent about the war itself. It did not qualify as a humanitarian intervention, he believes, because there was no ongoing catastrophe, yet he was appalled by Saddam Hussein's atrocities. He worries that intervention in Darfur would exacerbate regional tensions and tear Sudan apart. But he emphatically steers discussion away from any suggestion that he intends Freedom’s Battle to be a how-to primer on intervention. In the case of Darfur, for example, “I want the book to contribute to the debate, but it is people with real regional expertise who need to lead the debate,” he says.

Still, Bass worries that we may be taking steps backward from 19th-century standards and mores. Humanitarian intervention and the profession of the foreign correspondent were born at the same time, yet today newspapers across the country are shuttering their foreign bureaus. “At a time when you’d think it was so imperative that Americans know what is going on, that slashing of our foreign coverage is bizarre to me,” Bass says.

One solution to the humanitarian-intervention conundrum simply is to avoid it, except in the most extreme cases of slaughter, and when intervention would have extremely low costs or serve U.S. interests. That’s the counsel of the hard-core realists. But is it not unbearably coldhearted? “It may be coldhearted,” says Christopher Layne, a professor of international affairs at Texas A&M University. “But policymakers are, after all, charged with protecting the welfare of American citizens, not protecting the welfare of a rather hypothetical international community.”

Realists like Layne say that intervention has, by now, been built into the American DNA, and the presidential candidates showed no signs of changing that. In Kosovo, John McCain went even further than President Clinton, calling for sending American troops. During the second presidential debate, Barack Obama said that standing by while genocide occurs “diminishes us” as a nation. And two of Obama’s top foreign policy advisers wrote, in 2006, an op-ed piece for The Washington Post about Darfur, titled: “We Saved Europeans. Why Not Africans?” That brutal question, in its various disquieting permutations — why not the Burmese? Why not ... ? — will continue to haunt American policymakers, just as similar questions haunted 19th-century Britons.

Christopher Shea ’91 writes the Brainiac column (and blog) for The Boston Globe. He also has contributed to The New York Times Magazine and Preservation, among other publications.