Introduction

We suggested in Chapter 1 that for law to guide human interaction it must be broadly congruent with the practices and patterns in society. Law must rest on a foundation of shared understandings. At the same time, law is also more than simply those understandings; not because it takes a particular form or can be enforced in particular ways, but because it arises only when shared understandings come to be intertwined with distinctive internal qualities of law and practices of legality. In this chapter, we examine these twin propositions in detail.

We begin by exploring how shared understandings emerge in international society. To illuminate the underlying processes, we rely on constructivist IR and social learning theories. Next we examine the relationship between shared understandings and international legal norms. We ask what kinds of shared understandings must exist for law-making to be possible, and take a closer look at the transition from social norms to legality. Finally, we address what kinds of shared understandings can exist in a deeply diverse world and one in which power imbalances are so marked. We argue that while our approach may initially seem unduly optimistic in the light of diversity and power imbalances, the interactional approach actually reveals with clarity the limits to international law-making, while also illuminating opportunities. Interactional international law can exist in weak or strong forms; the deeper the shared understandings, the greater the possibility of ambitious law. Limited shared understandings do not mean no law, but they limit the possibilities of law-making.