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....