Samuel P. Huntington, one of the most creative social scientists of our time, died this Christmas Eve. In 1950, when Huntington began his long tenure at Harvard's government department, there was a great deal of optimism about our capacity to solve social problems. After all, the Second World War seemed to demonstrate that a little elbow grease and Yankee know-how was enough to fix the world. Many very smart people--we'd later call them "the best and the brightest"--believed the impoverished states just then emerging from colonialism could be "fixed" with a little New Deal-style rural electrification.

There was a lot to this idea: The developing world is still starved of necessary investments in basic infrastructure and public health, and you'd be a fool to argue otherwise. But Huntington understood something that the rest of the bright young men tended to forget: Without order, social progress is impossible.

Best known in his later years as a provocative foreign policy thinker, Huntington was interested first and foremost in this question of political order--where it comes from, how and why it slips away, and how it can be restored.

Rather than shrink from controversy, Huntington argued that democratization would prove a long and wrenching process for the developing world, and that many--if not most--post-colonial states would slide into authoritarianism. He also saw the Maoist-inspired rural revolutions spreading across Asia for what they were: a grave threat to human rights.

Suffice to say, this wasn't a popular cause at Harvard in the late 1960s. Huntington was demonized for using his expertise on societies in transition to help strengthen the government of South Vietnam. Among other things, Huntington called for reaching a political accommodation with the Viet Cong in rural areas while promoting an urban revolution that would sap the movement's strength by increasing prosperity.

Though South Vietnam eventually fell, Huntington's work contributed mightily to American counterinsurgency efforts. Moreover, his vision for a more prosperous and more stable South Vietnam later took hold across East Asia.

Huntington was an extremely modest man, and it is impossible to imagine him claiming even the smallest shred of credit for peaceful democratic transitions in South Korea, Taiwan, Brazil and Chile. But there's a real sense in which Huntington wrote the playbook on how to build better societies, a playbook that included many uncomfortable truths.

For example, Huntington was condemned for calling for slow and steady transitions to liberal democracy. He feared that too-rapid democratic transitions would result in states that were illiberal at best and thuggish kleptocracies at worst. Amazingly enough, Huntington's caution led some critics to call him a bigot. That was before the rise of Vladimir Putin and Hugo Chavez and, sadly, Nuri al-Maliki--a veritable rainbow coalition of tin-pot Napoleons--vindicated Huntington yet again. Of course, Huntington didn't always hit the mark. In the wider world, he was best known for The Clash of Civilizations and the Remaking of World Order, which argued that the ideological conflicts of the Cold War years were being replaced by cultural conflicts rooted in ancient religious and ethnic differences. At this point in his career, Huntington had moved from careful scholarly work to grabbing people by the lapels and warning of the dangerous world to come.

A Democrat for his entire adult life, Huntington was a true conservative, highly skeptical of crusades and radical experiments. Given that Huntington spent so much of his life studying vulnerable societies, this should hardly come as a surprise. In foreign policy, he embraced the value of strategic restraint. The "Clash" thesis was, in part, Huntington's response to American efforts to stop bloodshed in the Balkans and Somalia, societies that few Americans understood--or, frankly, could find on a map. This ignorance led even seasoned policymakers to underestimate the scale of the challenge involved in rebuilding these societies and the resentments that would inevitably follow an armed intervention.

Like many critics, I worried that Huntington was paying too much attention to clashes between civilizations and not enough to clashes within civilizations. As an unapologetic neoconservative, I was also far more optimistic about the prospects for liberal values across different cultures, and I still am. But there's no denying that Huntington was right to argue that the U.S. should tread lightly in a world it doesn't always understand.

Later in his career, Huntington--who, I should finally note, was a professor of mine, one who always encouraged me despite our many disagreements--turned his formidable analytical lens on the future of American identity.

Between 1981, when he published American Politics: The Promise of Disharmony, and 2004, when he published Who Are We? The Challenges to American National Identity, Huntington came to view America's prospects through a darker lens. The first book emphasized the American creed of liberty, democracy, and equality which he saw as the essence of American identity. But by the second, he became convinced, rightly in my view, that American identity was less about an ideological creed and more about America's highly idiosyncratic Afro-Anglo-Protestant ethnic heritage.

Instead of emphasizing the extraordinarily malleable and absorptive quality of this quirky creole culture, however, Huntington maintained that the days of the melting pot were drawing to a close. More specifically, he worried that the mass influx of Mexican immigrants would turn America into a bilingual and bicultural society, one that would steadily grow less stable and more conflict-prone, not unlike divided societies elsewhere in the world.

My own guess, and it's only a guess, is that America's ethnic mix will be a source of strength. I say this not because I'm a Pollyanna. Diverse societies really are conflict-prone, as Huntington's colleague and occasional critic Robert Putnam has recently found. I'm basing this mainly on the notion that a more open and interconnected world will need a society that serves as a template and as a hub--a cultural and institutional lingua franca, or an Operating System for Earth.

In a memorable essay in Foreign Affairs, Huntington worried that America was no longer an agent but an arena in which different diasporas and interest groups duked it out for influence. I think that's probably right. But I also think that being the world's arena is not a bad thing to be.