The ethics of peace and war is one of the central ethical issues in International Relations today. This book looks at three key theories which have implications for the role of ethics in war and armed conflict: cosmopolitanism; internationalism; and political realism. It argues for the appropriateness of cosmopolitanism above the other two general theories, with its emphasis on the equal worth of all human beings as the basis for a global moral community. This ethical theory is shown to have a vital role to play in international politics in light of changing conceptions of peace and security, the prevalence of internal over international wars, and the increasing emphasis on international humanitarian intervention as a justification for the use of military force. The book is divided into three parts - after a general introduction to peace and war in world ethics there follow sections on International Politics and the Morality of Peace and War; Ethical Approaches to Armed Conflict; and Cosmopolitan Strategies. A conclusion sums up the arguments. This is a topical book suitable for a range of courses in Philosophy, Politics, Peace Studies and International Relations. Key Features *Evaluates the relevance of the theory of cosmopolitanism to the specific problems of war and armed conflict *Examines two contrasting positions on the ethics of war and armed conflict: pacifism and just war theory *Analyses contemporary issues and debates including postmodern and asymmetrical war, and peace-building and conflict prevention *A central theme is the ambiguous role of the state in controlling and justifying the use of military force and in constructing a new cosmopolitan world order