Now that we have considered some ethical traditions of major importance for international relations, what fundamental points of convergence and divergence in international ethics can be identified? The present chapter presents a taxonomy of these traditions, using it to gain a synoptic view of the conversation among them and of the implications of this conversation for international affairs. Any method of classification is bound to ignore much of the internal diversity within each tradition as well as many similarities and differences among the traditions. A taxonomy is like a caricature, which may reveal a face more clearly than a portrait but only by selecting and exaggerating a few prominent features. As we proceed we will explain why these traditions do not always fit neatly into the categories to which they have been assigned, but we also invite the reader to refer back to the fuller discussions of each tradition in earlier chapters, as well as to the larger literature on which those chapters are based.

Arguably, the most fundamental distinction between these traditions is whether they link judgments of right and wrong to consequences or to rules. Political realism, utilitarianism, and Marxism belong to the first class of traditions, which assign primary importance to consequences; international law, natural law, Kantianism, and contractarianism belong to the second class of traditions, which emphasize the interpretation of rules. The traditions of biblical argument and of rights also belong here because of the importance they assign to rules.