In this essay I attempt to examine critically Michael Walzer's just war theory. I begin by pointing out what I take to be philosophically sound about his conception; in particular, his philosophical commitment to a doctrine of human rights as being morally decisive for questions of war. He argues, and I think correctly, that questions of justified wars and justified means within wars are ultimately questions about whether or not human rights are being respected. Unfortunately, Walzer does not always formulate his war principles in light of his fundamental commitment to human rights, and where he fails to do so, supreme emergencies and nuclear deterrence, I argue that his account becomes incoherent. At bottom, Walzer supposes, in these instances, that while individual rights may not be overriden for purely utilitarian reasons, rights may, nevertheless, be overridden for the sake of the political community. What this amounts to, for Walzer, is the following claim: that it is more just to secure the rights of a collection of individuals than it is to secure the rights of one individual. If so, it is morally permissible to suspend some individual rights for the sake of many individual rights. And even though I will hold that this argument is very persuasive, I will suggest that it is mistaken from a moral point of view which takes human rights to be morally conclusive.

Large-scale humanitarian crises in foreign countries raise the question of whether or not other countries have a duty to alleviate that suffering. In extreme cases, humanitarian intervention, that is: military intervention for the purpose of alleviating human suffering, is sometimes advocated as the morally required course of action. This thesis suggests that while the international community has a general moral responsibility to prevent and ameliorate humanitarian crises there is no simple duty of military humanitarian intervention. Hitherto, the question has typically been treated as a matter of either moral or legal principle. This thesis argues that empirical factors, which affect the international community's ability to carry out interventions effectively, have not been given their due weight in the debate. On the basis of evaluations of international responses to crises in Somalia and Rwanda, 1992 - 1994, it is suggested that a range of factors undermine the efficacy of humanitarian interventions. These factors include the impact of state interests, the effects of domestic politics in intervening states and, contrary to expectations, the role of humanitarian considerations in decision making on intervention. By showing the limitations of a simplistic view of a duty of humanitarian intervention the thesis seeks to contribute to reconciling idealism with realism in international crisis-responses. Based on sound moral and political judgment military interventions in humanitarian crises would hopefully be less ambitious and ultimately more effective.

Why has international society been unable to develop political and judicial collective-security arrangements to limit external aggression? The thesis argues that efforts to limit aggression in moral and legal theory have created an unjust order in which great powers have used these theoretical traditions to reinforce their power in the global order. The thesis argues that is not a new development but can be found in one of the oldest traditions of moral reflection on war, the just war tradition. To substantiate this point, the thesis critically surveys the philosophers of the ancient Greek, Roman, Medieval Christian Renaissance, and early modern theorists of just war and demonstrates that their just war ideas contain assumptions about exclusion, identity and power reflecting their cultural superiority which underlie the practices and theories of the leading states and justifications of their aggressive wars. The thesis connects these moral reflections to the emergence of modern international law and the European pluralist international society of states based on mutual respect for sovereignty and the norm of non-intervention, highlighting how justifications of its colonial aggression against non-Europeans established an unjust solidarist order against them which persists in the post-Cold War era. To conclude it presents suggestions for improvement in the current pluralist international arrangements to address the issue of aggression.