Under what circumstances is it morally justifiable for a state to wage war? And how should combatants conduct themselves once hostilities are underway? These questions have been at the centre of the Just War Tradition since the Middle Ages, but contemporary moral philosophers have recently challenged many of the received orthodoxies of this tradition. Is “national defence” really a just cause for war? Are all civilians really innocent bystanders? Are all soldiers really legitimately targets of attack? Moreover, the scope of this inquiry is now being expanded. Even is recourse to war is sometimes morally acceptable, does that necessarily mean that military institutions as we know them are justified in existing? Or is there a compelling argument for military abolition in some circumstances? This course will introduce the ethical issues raised by the organised use of violence by states in the international arena, and equip students with the philosophical tools they need to critically interrogate these issues.