“A just cause can be undone if it is pursued in unjust ways.”

Central to Walzer’s argument is the premise that jus ad bellum, the justice of war, is distinguished from jus in bello, justice in war. A just cause does not give soldiers free rein to use unjust means, such as killing civilians. Soldiers on all sides have equal rights and responsibilities.

“The morality I shall expound is in its philosophical form a doctrine of human rights, […]. Considerations of utility play into the structure at many points, but they cannot account for it as a whole. Their part is subsidiary to that of rights; it is constrained by rights.”

Walzer’s theory of just and unjust conduct in war is grounded in the human rights of noncombatants. Military strategies must be devised so as to minimize civilian deaths. It is not sufficient to justify the killing of civilians solely on grounds of military usefulness and good intention. The gross violation of human rights in wartime is the underlying basis for common moral perceptions about wartime behavior.

“Even when world views and high ideals have been abandoned – as the glorification of aristocratic chivalry was abandoned in early modern times – notions about right conduct are remarkably persistent.”

Walzer emphasizes the historical longevity of the war convention. Even though there is general agreement on morals, there are heated disputes about their application to historical events and military strategies. The persistence of notions of rightful conduct speak to a common sense of morality.