Abstract

The chapter examines the traditional requirement that a humanitarian war must be proportionate to be justified. It distinguishes proportionality from necessity and, further, narrow from wide proportionality. The chapter discusses the concept of culpable threat, which is particularly important in humanitarian intervention, as there is no such thing as a non-culpable tyrant. It then introduces a distinction between collateral proportionality and supervening proportionality. The first one is the harm done to bystanders in the battle. The second one is the more remote harm done to bystanders after the war has ended. The distinction determines different degrees of blameworthiness for commanders who start a war that ends badly. Finally, the chapter analyzes the relationship between knowledge and permissibility of action.