This article argues that, since war expends resources that can be used to alleviate poverty at home or abroad, poverty can render war unjust. More specifically, it argues that states which spend money on war rather than poverty risk violating two traditional just war theory conditions: proportionality and last resort. Poverty can render a war disproportionate because it is sometimes appropriate to add the costs of a failure to relieve poverty to the costs of war. Poverty can render a war unnecessary because sometimes poverty alleviation constitutes a means to achieve the same cause that supposedly justifies the war. The idea that a war could be unjust because it uses resources that might be better spent addressing poverty may seem intuitive, but it is almost entirely neglected in just war theory. The philosophers that do, very briefly, consider the idea, reject it: their arguments are examined in the article. If the article is right, war is much harder to justify than has traditionally been thought.
