Bridging the contending theories of natural law and international relations, this book proposes a 'relational ontology' as the basis for rethinking our approach to international politics. Amanda Beattie challenges both the conventional interpretation of natural law as necessarily and intractably theological, and the dominant conception of international relations as structurally distinct from the ends of human good, in order to recover the centrality of other-directed agency to the promotion of human development. Offering an important contribution to the study of international political thought, the book contains a number of challenging and controversial ideas which should provoke constructive debate within international relations theory, political theory, and philosophical ethics.