Samuel Huntington, who has died aged 81 of complications associated with diabetes, was one of the most controversial of American political theorists. Where his friends and contemporaries Henry Kissinger and Zbigniew Brzezinski, while authors of substantial works, were best remembered for holding high office, Huntington was essentially an academic, a Harvard professor who worked incidentally as a consultant for the State Department, the National Security Council and the CIA under the Johnson and Carter administrations.
A cold war liberal with a conservative cast of mind, he tossed highly personal ideas around like confetti. Some were wild and, for many, pernicious; others have come to be seen as wise and prescient. The Nuremberg war crimes trials prosecutor Telford Taylor summed him up as a man whose "store of iconoclasm" was "virtually inexhaustible".
Huntington aroused heavy criticism for each of his major books. The first, The Soldier and the State (1957), saw him compared to the Italian dictator Benito Mussolini. It was seen, perhaps unfairly, as a glorification of the military profession. It certainly praised the West Point military academy as Sparta surrounded by the American Babylon. A second, Political Order in Changing Societies (1968), became the subject of a furious academic debate, with Huntington denounced for describing apartheid South Africa as a "satisfied" state.
His most famous book, The Clash of Civilizations and the Remaking of World Order (1996), started life as an article in the establishment journal, Foreign Affairs. In it he argued that the conflicts of the future would not be between ideologies but between "civilisations" defined by culture. He enumerated seven or eight of these, in the manner of an Arnold Toynbee: the west, Islam, orthodox Christianity, Latin America, the "Sinic" (Chinese) civilisation, the Hindu world, Japan, and perhaps Africa. He predicted that the most likely conflicts would be between the west and Islam or China. Departing from his (critical) support for the US in the Vietnam war, he said: "Western intervention in the affairs of other civilisations is probably the single most dangerous source of instability and potential global conflict in a multi-civilisational world."
The book set off a thunderous debate in American academic and intellectual circles between Huntington's supporters and those of his former pupil, Francis Fukuyama. Where Huntington predicted divisions in which the west would be only one of several competing civilisations, Fukuyama (who has changed his mind since) saw the collapse of communism as marking the triumph of western and especially American ideas, "the end of history".
Huntington's last book was perhaps the most controversial and certainly the least well received. In Who Are We? The Challenges to America's National Identity (2004), he predicted dire consequences from Hispanic immigration. The US, he argued, is defined '"in large part by its Anglo-Protestant culture and its religiosity". Spanish-speaking immigrants would transform America into "a country of two languages, two cultures, and two peoples".
Most reviewers and many readers shared the opinion of the New York Times reviewer Michiko Kakutani that it was "a crotchety, overstuffed and highly polemical book", and "pockmarked with perplexing contradictions and curiously blindered [blinkered] observations".
Huntington was born into a white, Anglo-Saxon protestant, in his case Episcopalian, middle-class family in Queen's, New York City. He was precocious. He went to Yale University aged 16 and graduated in two and a half years (instead of the usual four) before going into the army. After the second world war, he earned a master's degree at the University of Chicago and a doctorate from Harvard, returning there as a tenured professor in 1962 and remaining for 45 years.
He was an influential teacher, though hardly because of his presentation. He delivered his lectures monotonously, hunched up, blinking and squinting. But he lacked neither moral nor physical courage. He joined in academic controversy with spirit and determination. And once, when he and another Harvard professor were attacked by muggers, he downed his opponent and went to the rescue of his colleague.
Huntington was in several respects typical of the American academics who used mathematical or, as their critics said, pseudo-mathematical political science to support their personal theories and the liberal nationalism known as "cold war liberalism". He claimed to be a disciple of the great protestant theologian Reinhold Niebuhr, but showed little evidence of sharing Niebuhr's awareness of the tragic moral dilemmas of American society. He was a natural target for the 1960s left.
When he was put up for membership of the National Academy of Sciences in 1968, a Yale mathematician, Serge Lang, led a bitter onslaught on his credentials. Lang objected to the academy "certifying as science" what were "merely political opinions". He sharply criticised Huntington's suggestion that apartheid South Africa was a more stable state than France, on the basis of "equations" based on the number of telephones and other randomly chosen numerical indications. He concluded that Huntington had given "primary evidence of professional incompetence and defective scholarship".
No wonder the heavyweights of political science leaped angrily to his defence. He was, after all, by the 1980s the most cited political scientist in America on international relations, and several universities made his works required reading. But would be a mistake to dismiss him as no more than an establishment mouthpiece. Even his most problematic ideas were usually balanced with a willingness to see other sides of a question.
In 1957 Huntington married Nancy Arkelyan, who survives him, along with two sons and four grandchildren.
• Samuel Phillips Huntington, political scientist, born 18 April 1927; died 24 December 2008
