The philosophy of international relations – or more precisely its political philosophy – embraces problems about morality in diplomacy and war, the justice of international practices and institutions bearing on economic welfare and the global environment, human rights, and the relationship between sectional loyalties such as patriotism and global moral commitments.
Not everyone believes that such a subject can exist, or rather, that it can have significant ethical content. According to political realism – a widely-held view among Anglo-American students of international relations – moral considerations have no place in decisions about foreign affairs and international behaviour. The most extreme varieties of realism deny that moral judgment can have meaning or force in international affairs; more moderate versions acknowledge the meaningfulness of such judgments but hold either that leaders have no responsibility to attend to the morality of their actions in foreign affairs (because their overriding responsibility is to advance the interests of their constituents), or that the direct pursuit of moral goals in international relations is likely to be self-defeating.
Leaving aside the more sceptical kinds of political realism, the most influential orientations to substantive international morality can be arrayed on a continuum. Distinctions are made on the basis of the degree of privilege, if any, extended to the citizens of a state to act on their own behalf at the potential expense of the liberty and wellbeing of persons elsewhere. ‘The morality of states’, at one extreme, holds that states have rights of autonomy analogous to those of individuals within domestic society, which secure them against external interference in their internal affairs and guarantee their ownership and control of the natural and human resources within their borders. At the other end of the continuum, one finds cosmopolitan views which deny that states enjoy any special privilege; these views hold that individuals rather than states are the ultimate subjects of morality, and that value judgments concerning international conduct should take equally seriously the wellbeing of each person potentially affected by a decision, whether compatriot or foreigner. Cosmopolitan views may acknowledge that states (and similar entities) have morally significant features, but analysis of the significance of these features must connect them with considerations of individual wellbeing. Intermediate views are possible; for example, a conception of the privileged character of the state can be combined with a conception of the international realm as weakly normative (that is, governed by principles which demand that states adhere to minimum conditions of peaceful coexistence).
The theoretical difference between the morality of states and a fully cosmopolitan morality is reflected in practical differences about the justifiability of intervention in the internal affairs of other states, the basis and content of human rights, and the extent, if any, of our obligations as individuals and as citizens of states to help redress the welfare effects of international inequalities.