Theories of emergence offer justifications for claims of causal efficacy. This book argues that they can justify the claim that certain sorts of social structures have causal power, and this chapter describes the version of emergence theory that will be used to justify that claim.

Recent years have seen a widespread revival of interest in emergence theories across a broad range of disciplines. They have been employed by philosophers (e.g. Kim 1999; Searle 1992), physicists (e.g. Gell-Mann 1995), sociologists (e.g. Archer 1995; Sawyer 2005), biologists (e.g. Kauffman 1995) and information scientists (e.g. Holland 1998), amongst others. But not all the scholars who have employed emergence theory have explained and justified their use of it, and those that have done so have often disagreed about what the concept of emergence means, let alone how it works. There will not be room in this chapter to examine those debates in detail, but it will explain the relational version of emergence theory that I propose to apply to the social world, and give some indication of its relation to these wider debates.

The chapter begins by explaining the relational conception of emergence, then more briefly contrasts this with the most influential alternative: the strong conception of emergence that is espoused by many philosophers of mind. Finally, the chapter addresses the relation between emergent properties and the causal histories of the entities possessing them, using the concepts of morphostasis and morphogenesis.