Introduction

What rules govern the conduct of warfare? Do state and non-state actors conduct themselves in accordance with rules? These are long-standing questions in the study and practice of war. There are, however, some underlying questions that may also be worthy of investigation. How stable are those rules? What foundations do they have? Even more provocatively, are rules the best way to govern the conduct of warfare? Many areas of public life are conducted in terms of rules, yet rules and rule following can become fetishized. Judith Skhlar’s famous critique of law and international criminal law introduced the idea of ‘legalism’, or the use of rules and laws to cover over ideological or political conflicts. Rules guide us through complex situations; at the same time, rules can constrain and limit our ability to respond when those situations change or when a rule simply does not work. In fact, rules can even generate their own forms of violence, especially when yoked to ideas like the national interest.

Nicholas Rengger did not address rules directly in his scholarship. Instead, the idea of rules and law formed a backdrop to many of his critical interventions in world politics. From his studies of order to just war, Rengger engaged with and contested the idea that law and rules alone could structure our political lives. At the same time, as I will argue in this chapter, Rengger did not set aside rules in their entirety, for he understood the necessity of rules in both domestic and international political order more broadly. Instead, Rengger argued for a more casuistic approach to political life. Drawn from ancient and medieval moral and political theory, this idea highlights the importance of the contexts within which rules operate. Rules and laws still play a role, but they cannot be seen as the only way to approach political conflict. As such, the focus of this chapter will be on Rengger as a reluctant rule follower.

The chapter will use Rengger’s writing on just war and violence to orient the argument. The first section sets out his understanding of rules and their relation to political order. Following this, and building upon it, the next section explores his reading of the Just War tradition as found in his book Just War and International Order.