In Chapter 5 distinctions were made (especially) between social institutions, social groups, and organisations, and a detailed account of organisations, and especially the “actions” of organisations provided. I now want to look in more detail at social institutions and social groups. We begin with social institutions.

In order to understand social institutions we need to first understand the notion of a sphere of activity, which in turn depends on the notion of generic joint activity. Roughly speaking, a joint activity is a complex of differential, interlocking, joint actions and individual actions directed to some overarching collective end. So building cathedrals and sailing ocean liners are joint activities.

We can further distinguish between different, albeit connected and overlapping, generic kinds of joint activity, including communicative, economic, educative, sexual, and religious activity. The repetition over time, and duplication in space, of any one of these different kinds of generic joint activity can give rise to a more or less connected, and more or less continuous, stretch of joint activity, which I earlier (in Chapter 1) termed a sphere of activity. So the ongoing series of economic transactions across Australia constitutes a sphere of activity.

Spheres of activity (by stipulative definition) are regulated by conventions. They thereby take on different specific forms according to the specific conventions that structure them. Often, though not necessarily, they are also regulated by explicit rules, including laws. And they are also often – but again, not necessarily – regulated by social norms.