Professor Melko believes that the hesitancy to use nuclear weapons can be explained partly by the existence of peace in our time. We should develop the positive aspects of peaceful nations and share them with less peaceful countries. If his thesis is correct, it poses a serious challenge to the way many activists and policy makers look at the world.

MATTHEW MELKO is Professor of Sociology at Wright State University. He is also author of Peace in the Ancient World, and 52 Peaceful Societies.