 As noted above, the starting point for theories of social institutions utilising a rational choice framework is Lewis’ theory of conventions (Lewis 1969). According to Lewis—who was inspired by Hume (Hume 1740: Book III)—conventions are the solutions to coordination problems. (See also Schwayder 1965.) Thus the regularity in behaviour of driving on the right is the solution to the coordination problem confronting road users. Here there are two equilibria: everyone driving on the right or, alternatively, everyone driving on the left. Everyone driving on the right is an equilibrium since everyone prefers to drive on the right, given everyone else does, and everyone expects everyone to drive on the right. Conventions are certainly ubiquitous. However, social institutions evidently consist in more than conventions. Importantly, as noted above, they consist in part in rules, including but not restricted to laws and regulations. But regularities in behaviour that result from compliance with rules are not necessarily equilibria in the sense in use in rational choice theory. Accordingly, a serviceable account of social institutions looks like it needs to help itself (at least) to both conventions (or, at least, equilibria in the sense of Nash equilibria, i.e. (roughly) a combination of actions such that no actor has an incentive to change his or her action unilaterally), and rules. 