The Journal of Ethics

, Volume 14, Issue 2, pp 81–102 | Cite as

The Logical Structure of Just War Theory

  • Christopher Toner


A survey of just war theory literature reveals the existence of quite different lists of principles. This apparent arbitrariness raises a number of questions: What is the relation between ad bellum and in bello principles? Why are there so many of the former and so few of the latter? What order is there among the various principles? To answer these questions, I first draw on some recent work by Jeff McMahan to show that ad bellum and in bello principles are not, as often portrayed, independent—the justice of conduct in war largely presupposes the justice of the recourse to war. Undermining this independence claim is one important step toward revealing the unified logical structure of just war theory. I then argue that we can see the dependence of the jus in bello upon the jus ad bellum, not just in the content of certain principles, but also in the structure of the two sets of principles: I construct a one-to-one mapping between ad bellum and in bello principles. In doing so, I argue also that the shared structure successfully finds place for the questions central to the evaluation of the morality of war: what is a sufficient provocation to use force, what objectives may be sought by force, why or for what ends, who has authority to decide to use force, and when or in what circumstances? Despite variations in expression, the theory allows for a coherent and comprehensive evaluation of morality in warfare.


Just war theory jus ad bellum jus in bello Jeff McMahan 



Work on this article was assisted by a research grant from the Aquinas Chair in Philosophy and Theology at the University of St. Thomas. Earlier drafts were presented to the faculty of the United States Air Command and Staff College and to the philosophy departments of the United States Air Force Academy and Mount Saint Mary’s University, and I received helpful comments from all these audiences. I wish also to thank the editor of The Journal of Ethics and an anonymous referee for help with the penultimate draft. Finally, I owe special thanks to Professor Jeff McMahan for extensive and vastly helpful comments upon an earlier draft, and for granting me permission to draw on part of the unpublished manuscript of his forthcoming book, The Right Way to Fight.


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Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  1. 1.Department of PhilosophyUniversity of St. ThomasSaint PaulUSA

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