In this chapter, the author starts his evaluation of the just war tradition by briefly stating what it says and then considering whether such an antique theory can have any possible relevance to politics in the latter half of the twentieth century. The theory presupposes that there is a prima facia moral presumption against war: war stands in need of justification. War is a moral tragedy: an ‘accursed thyng and not due’ in Christine de Pisan’s phrase. The moral presumption against war rests simply on the fact that war causes immense human suffering, the extent of which may be difficult to control once a war has started. On the contrary, war is an activity started and carried on by human beings and, like any other human activity, is subject to moral criticism and restraint. The key question is whether the just war tradition has adequately described the relevant moral rules.