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This book analyzes the justification of preventive war in contemporary asymmetrical international relations. It focuses on the most crucial aspect of prevention: uncertainty. It builds a new framework where the role of luck-whether military, political, moral, or normative-is a corrective to the traditional approaches of the just war tradition.

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Introduction: New Departures in the Military Arena PART I: ON THE FORMS OF PREVENTIVE WAR Narrating, Explaining, Defining Preventive War A Just War? PART II: WAGING WAR On Temperance Precision as Justification Targeted Killings: Manhunts PART III: MORAL LUCK Good or Bad Fortune Possible Worlds Conclusion: The Gamble on the Best of All Worlds

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"As Ariel Colonomos shows in this penetrating book, the fog of war is never thicker than when states contemplate preventive force. Mixing astute commentary on history, ethics, political theory and current events, he offers very wise counsel to political leaders contemplating whether to attack before (they think) they will be attacked."

-Michael Doyle, author of Striking First and Harold Brown Professor of U.S. Foreign and Security Policy at the School of International and Public Affairs, the Department of Political Science, and the Law School, Columbia University

"A brilliant exploration of the vexatious necessity of justifying preventive war when the availability of weapons of mass destruction excludes waiting for an attack to materialize but when uncertainty about the future excludes a ´proportional´ response to an attack whose extent is unknown because it has not yet occurred." - Stephen Holmes, Professor of Law and Political Science, New York University

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Ariel Colonomos is a senior research fellow at the CNRS (National Center for Scientific Recearch) in Paris and a research professor at Sciences Po.

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