Earlier versions of this paper were presented at the 2014 Australasian Association of Philosophy Conference at the ANU, the Just War and Pacifism workshop at UNSW Canberra, the Merton College War Workshop at the University of Oxford, and at the Global Justice Program seminar at Yale. I am grateful to all who attended and provided immensely helpful comments and suggestions, especially Andrew Alexandra, Joshua Andresen, Peter Balint, Janina Dill, Cecile Fabre, Michael Gibb, Adam Henschke, Douglas Lackey, Seth Lazar, Matthew Lindauer, Jonathan Parry, Thomas Pogge, Igor Primoratz, Cheyney Ryan, Henry Shue and Adrian Walsh. All blunders are my own. This research was conducted while I was a visiting scholar at the Oxford Uehiro Centre for Practical Ethics and at the Macmillan Centre for International and Area Studies at Yale in 2013'14. I thank both institutions for their kind support.