This chapter develops and justifies one of the central arguments of this book: that social structure is best understood as the causal powers of social groups. It does so by focusing on one of the many possible types of social structure, one that has played a central role in sociological debates: normative social institutions. The chapter examines in some detail how such institutions are produced by the interactions between members of a specific type of social group, a type of group I shall call norm circles. Normative social institutions, it will argue, are an emergent causal power of norm circles.

This chapter is concerned with identifying the mechanism responsible for normative social institutions and thus with retroduction. It therefore abstracts from the many complex ways in which this mechanism interacts with others in the social world, including, for example, the important role played by various forms of social power in the workings of many normative institutions. Nor does it cover the ways in which institutions are implicated in the mechanisms of other types of social structure, nor say much about the morphogenetic histories of institutions. The analysis of institutions developed here, then, is not intended as a complete account of how they work, which would certainly need to address all of these further issues. Rather, it is intended as an ontological building block that may then be combined with others to construct a fuller explanation of actual institutions and social events.