Kenneth Waltz

Kenneth Waltz, who died May 13 at 88, was the leading theorist of international politics over the past half-century. He developed the most precise and analytically rigorous version of the realist school, and his books defined the terms of debate even for the many who disagreed with him. He argued that attempts to prevent conflict in the world by applying solutions that work within properly governed nations will fail as long as there is no enforcement authority above those nations–no real world government. This simple point put him at odds with liberal theorists who hoped to make war obsolete by spreading democracy or supporting flimsy international organizations like the U.N.

However, Waltz believed that mankind is not doomed to constant war if governments apply the lessons of balance of power. He regularly challenged conventional wisdom, even arguing that the spread of nuclear weapons would promote peace in unstable regions by making the price of war unthinkable.

Betts is director of the Saltzman Institute of War and Peace Studies at Columbia University