This book traces the implications for international society of the national idea. It seeks answers to three questions. What is meant by international society? On what normative principles is the idea of international society based? How has nationalist doctrine, and more broadly the national idea, influenced its evolution? Its focus is different from much of the recent literature on nationalism, which seeks to explain its rise as a consequence of social, economic or intellectual developments. The focus in this study is on the consequences of nationalism for international society. It is thus about the impact of one idea on the fate of another.

Of these two ideas, whose encounter has helped to shape the twentieth century, nationalism is likely to be more familiar to many readers than international society. The meaning of both terms, however, is contested, and it may be helpful to identify the sense in which I use them in this book.

Even the possibility of international society is often denied by those who regard the prevalence of conflict in international relations as proof that they are not governed by the minimal solidarity which is necessary to ensure social cohesion. The possibility of international society is also denied by those who insist that the state establishes the boundaries of both political organisation and social morality. On this view, any order in international relations arises merely from the prudential calculations of competitive powers.