Just and Unjust Wars: A Moral Argument with Historical Illustrations

Walzer argues that moral concepts can be applied to war and have been throughout history. He rejects the realist view that 'in time of war the law is silent'—the idea that war is beyond moral judgment [citation:8]. The book is an attempt to work out a modern, secular theory of just war drawing on medieval just war theory and historical illustrations, resulting from Walzer's reflections on the Vietnam War [citation:1]. He assures us that just war is an inherited code of conduct conforming to a morality of which all men are aware [citation:4].

Walzer formalized the distinction between jus ad bellum (the justice of going to war) and jus in bello (the justice of conduct within war), and introduced the 'moral equality of combatants' as a formal doctrine [citation:6]. This principle holds that soldiers fighting on both sides are equally honorable regardless of whether they fight for a just cause. It underpins international humanitarian law, which applies the rules of war equally to both sides [citation:6][citation:16]. The Stanford Encyclopedia of Philosophy calls the book 'the major contemporary statement of just war theory' [citation:1].

Jeff McMahan's revisionist school, beginning in 2006, directly contests the moral equality of combatants [citation:6]. Revisionists argue that soldiers fighting an unjust or illegal war are not morally equal to those fighting in self-defense, and that individual soldiers have a moral obligation to assess the justice of the war they are asked to fight [citation:6][citation:16]. Walzer responds that individual soldiers are not well-placed to determine the justness of a war, and that responsibility for an unjust war is borne by military and civilian leaders who choose to go to war [citation:6].

Early British reviewers, including Hedley Bull and W.B. Gallie, concluded that it is a 'shallow book, lacking in philosophical depth' [citation:3]. A more substantive and enduring criticism is that the book, despite its foundation in individual rights, is ultimately 'statist'—that the rights of states come to enjoy primary status over the rights of individuals [citation:18]. Critics like Wasserstrom argue that Walzer's theory of aggression elevates state sovereignty above individual human rights, undermining its own professed foundations. Walzer has responded to these critics directly [citation:18].

A supreme emergency is a moment when a political community faces a threat so grave—specifically, a 'Nazi-like power' that must be defeated at all costs—that leaders may override the war convention and embrace evil, accepting guilt for doing so [citation:2]. Walzer uses the British bombing of German cities as his case study. The concept is controversial because it appears to allow the very atrocities the book otherwise condemns. Walzer's answer is that such moments are extraordinarily rare and must be followed by a 'reinstatement' of moral rules, as illustrated by the postwar 'dishonoring of Arthur Harris' [citation:2].

The book remains the standard account of just war theory and is widely taught in graduate schools [citation:1][citation:17]. It has been reissued in five editions, each adding an introduction addressing the wars of its time: the Gulf War, humanitarian intervention, regime change, and asymmetric warfare [citation:4]. Terry Nardin argues that while critics have raised genuine issues, their objections do not undermine the book's argument, which 'stands in a complex relationship with political realism' [citation:17]. Walzer himself continues to apply its framework to contemporary conflicts [citation:20].