Proportionality is a widely recognized constraint on acts of punishment, acts of self and other-defense, and acts of war. While common sense morality recognizes constraints on acts of these types that are primarily deontological in character, proportionality is thought to be a constraint that is concerned solely with consequences. But I will argue that it too incorporates various essentially deontological elements.
Jeff McMahan is Professor of Philosophy at Rutgers University, a Visiting Research Collaborator at the Center for Human Values at Princeton, and a Research Fellow of the Uehiro Centre for Practical Ethics at Oxford. He is the author of The Ethics of Killing: Problems at the Margins of Life (Oxford, 2002) and Killing in War (Oxford, 2009), and has several other books forthcoming from Oxford University Press, including The Values of Lives and The Right Way to Fight.