Kenneth N. Waltz, a pre-eminent thinker on international relations who was known for his contrarian, debate-provoking ideas, not least his view that stability in the Middle East might be better served if Iran had a nuclear weapon, died on May 12 in Manhattan. He was 88.
The cause was complications from pneumonia, said Columbia University, where Mr. Waltz was a senior research scholar.
Leslie H. Gelb, emeritus president of the Council on Foreign Relations, characterized Mr. Waltz as one of five “giants” who shaped the study of international relations as a discrete discipline, the others being Hans Morgenthau, Henry A. Kissinger, Samuel P. Huntington and Zbigniew Brzezinski.
The field developed in the 1950s, when the experiences of two world wars and the beginning of the cold war drove scholars to try to explain more precisely how nations interacted. The goal was to build a conceptual framework on which international politics could be analyzed, something earlier courses on military and diplomatic history had not offered.
“Without a theory, we’re just lost,” said Robert Jervis, a political science professor at Columbia. “We just have all these random phenomena we can’t make any sense of.”
One of Mr. Waltz’s propositions was that wars are not caused simply by human aggression or bad governments but by the anarchic, dog-eat-dog nature of international relations. Each nation-state, he said, will push as far as it can to advance its own self-interests.
He used as an example the collapse of the Soviet Union, which he said freed the United States to become a bully because it no longer had an opponent in its own weight class. In this new “unipolar” world, the United States “abuses its power, singling out poor, weak countries — that’s what we specialize in — and beating them up,” he said in 2011 in an oral history interview at the University of California, Berkeley.
“It is sad,” he continued, “but this is a typical behavior of powers that are dominant, or used to be dominant in their regions, and now are globally dominant.”
Mr. Walz shook conventional wisdom by regarding the “bipolar” nuclear stalemate between the United States and the Soviet Union as one of the most stable balances of power ever — not the knife-edge of planetary annihilation. His critics, however, saw the failure of the bipolar model in the experience of World War I, in which two rigid, pre-existing alliances clashed with devastating results.
Mr. Waltz countered that the cold war was fundamentally different, because the 20th-century superpowers were so much stronger than their allies that only the superpowers mattered.
Even more, Mr. Waltz endorsed nuclear proliferation as a force for peace. “The measured spread of nuclear weapons is more to be welcomed than feared,” he wrote in 1981. He argued that nuclear states had always safeguarded their weapons carefully, and that no nuclear state had ever been involved in a major war. (He said the fighting between nuclear India and nuclear Pakistan in 1999 did not constitute a major war.)
Mr. Waltz’s goal was to clarify thinking about international politics by offering a perspective he called “structural realism,” or neorealism, in which interactions between nations matter most in fomenting war.
“Even when you disagree, he moves your thinking ahead,” Mr. Jervis said.
More than his views on particular foreign-policy issues, it was Mr. Waltz’s theoretical work that influenced policy makers most, Mr. Jervis said. And yet his most controversial pronouncement was indeed about a specific issue: Iran’s getting the bomb.
Writing in Foreign Affairs last year under the title “Why Iran Should Get the Bomb,” Mr. Waltz argued that in a region, the Mideast, that had only one nuclear power, Israel, another would be a stabilizing force. Iran, he said, would be unlikely to use the bomb because Iranian leaders, however hateful, were not self-destructive. He pointed to Maoist China as a precedent; even in the midst of the Cultural Revolution in the 1960s and ’70s, he said, China assiduously guarded its nuclear arsenal against political radicals.
Critics responded that Iran’s Islamic leaders might not be so self-restrained, given their belief that martyrdom wins God’s approval; that Iran might share the bomb with terrorists, just as it shares conventional weapons; and that having nuclear protection might encourage Iran to be more provocative in local conflicts involving lesser arms.
“Some have even said that Iran with nuclear weapons would stabilize the Middle East,” Prime Minister Benjamin Netanyahu of Israel said a month after Mr. Waltz’s article was published. “I think people who say this have set a new standard for human stupidity.”
Equally controversial was Mr. Waltz’s pronouncement that North Korea, however odious its government, would be ill-served by giving up its nuclear weapons as a means of deterring enemies. Here he pointed to the example of Col. Muammar el-Qaddafi of Libya, who Mr. Waltz argued may have hastened his own destruction by relinquishing hisnuclear program in 2003.
Recently, Mr. Gelb arranged a luncheon with Mr. Waltz and Mr. Kissinger, who categorically opposed the idea of Iran having the bomb. “One rousing argument after another,” Mr. Gelb recalled.
Kenneth Neal Waltz was born on June 8, 1924, in Ann Arbor, Mich. He served in the Army during World War II and then earned a bachelor’s degree in economics from Oberlin College in Ohio. He studied political science as a graduate student at Columbia, and his dissertation was published in 1959 as a book, “Man, the State, and War: A Theoretical Analysis.” His “Theory of International Politics” (1979) advanced understanding of the concept of a “bipolar” world, with two dominant powers. Though he did not invent the concept, he showed how it worked. The book became a standard text. In 1995, Mr. Waltz and the Stanford University scholar Scott D. Sagan published “The Spread of Nuclear Weapons: A Debate,” which also became popular in international relations courses. They updated and expanded the discussion in subsequent editions.
Mr. Waltz had begun teaching at Columbia in 1950 when, as a member of the Army Reserve, he was called to serve in the Korean War. He returned to Columbia after the war and taught there until 1957. He then taught at a number of colleges and universities, including Swarthmore, Brandeis and the University of California, Berkeley, before returning again to Columbia.
His wife, the former Helen Lindsley, died in 2008. He is survived by two sons, Daniel and Kenneth Jr., and four grandchildren.
Mr. Waltz was the president of the American Political Science Association in 1987 and 1988, and in 1999 received the association’s James Madison Award, given once every three years. In 2008, Aberystwyth University in Wales held a conference in his honor titled “The King of Thought: Theory, the Subject and Waltz.”
A version of this article appears in print on May 19, 2013, on page A22 of the New York edition with the headline: Kenneth Waltz, Foreign-Relations Expert, Dies at 88.