Samuel Huntington, 81, a political scientist best known for his views on the clash of civilizations, died Wednesday on Martha's Vineyard, Mass.

Dr. Huntington had retired from teaching in 2007 after 58 years at Harvard University. His research and teaching focused on American government, democratization, military politics, strategy, and civil-military relations.

He argued that in a post-Cold War world, violent conflict would come not from ideological friction between nations, but from cultural and religious differences among the world's major civilizations.

He made the argument in a 1993 article in the journal Foreign Affairs, and then expanded the thesis into a book, The Clash of Civilizations and the Remaking of World Order, which was published in 1996.

- AP