The Aims of Just Wars and Jus Ex Bello

The chapter discusses the just aims of defensive wars, and, by implication, the duty to end wars, viz., the jus ex bello. It starts with a discussion of the idea of ‘uncompromising wars’ according to which wars may go on until one’s enemy military forces is completely destroyed. We offer a contractarian argument for a rule that categorically prohibits such wars. We then develop two asymmetries between the justice of resort to war and the justice of continuing it. In particular, we show that the conditions of proportionality and of probability of success function differently in constraining resort to war and in constraining its continuation.