This chapter scrutinises just war theory generally, and later chapters concentrate specifically on the core just war principles of just cause, last resort, proportionality and noncombatant immunity.

The chapter is divided into five parts. The first part addresses the question of how received just war principles should be elucidated, revised or supplemented, so as to be applicable from the standpoint of the Security Council. The second part considers the pertinence of just war theory to the intertwined topics of armed humanitarian intervention and the responsibility to protect. With the aim of ensuring that uses of armed force are sufficiently morally constrained, the third part discusses how a demanding just cause principle ought to be counterbalanced especially by means of a stringent principle of last resort. In the fourth part, the main thesis – namely, that received just war principles should be generalised – is illustrated. The fifth part introduces the related main thesis that received just war principles should be temporalised.

I. THE RESPONSIBILITY FOR SECURITY