In The Anarchical Society, Hedley Bull devotes a chapter to each of the following institutions, which he sees as upholding order in an anarchical international society: the balance of power, international law, diplomacy, war, and the preponderant role of the great powers. In this chapter I propose to consider the balance of power, war, and the great powers as parts of a single 'institution', in Bull's sense of 'a set of habits and practices shaped towards the realization of common goals'. 1 Since I depart from Bull's schema in this respect, it is appropriate to begin with an explanation of why.
As numerous writers on the balance of power have pointed out, the concept is one that is capable of sustaining a great many different meanings. 2 However, the task of definition is simplified by narrowing the focus to its role as an institution of international society. In this context the balance of power may be seen as a shorthand expression for 'a set of habits and practices' that, alongside international law and diplomacy, serve the purpose of providing some degree of order in a society of sovereign states which share one central common interest: protection and preservation of their sovereign rights. Although the 'habits and practices' that have some bearing upon the balance of power are many (alliances, spheres of influence agreements, guarantees, compensations, and arms control arrangements, to name but a few), the central institution that they serve—the balance of power—has only two closely related meanings that concern its role in international society. The first defines it as a tendency in a world of competing