Walzer’s theory is innovative, in contrast to the older tradition, in five areas relevant to my argument about just cause. Walzer’s theoretical contributions to the just war category of “just cause” include new arguments in support of the aggressor-defender paradigm, a new doctrine of pre-emption, new arguments about the underlying justification for defense of a neighbor (Walzer calls this collective self-defense), new formulations about the circumstances when intervention in civil wars is permissible, and new restrictions on the occasions for humanitarian intervention. Walzer himself does not always make clear where his theory of aggression is innovative and where he is endorsing traditional doctrine. Although he makes use of traditional just war sources, he does not comprehensively engage them as he elaborates his own theory of aggression. Walzer touches upon Emerich de Vattel, Francisco de Vitoria, Francisco Suarez, and Hugo Grotius, so I will look to these theorists in particular to show more clearly how Walzer’s theory departs from theirs. There are additional elements in Walzer’s theory that are innovative in other areas of the jus ad bellum and (especially) jus in bello, but I will only focus on just cause for this section. In this section, I will contrast Walzer’s five innovations (to just cause) against other important voices in the tradition in the following order:
a Aggressor-defender paradigm upheld and strengthened by Walzer; b Underlying motivation for collective self-defense is self-interest (it is in the
self-interest of states to maintain an international order free of inter-state aggression) not love of a neighbor;
c Walzer’s pre-emption doctrine is more restrictive than the older prevention doctrine;
d Rationale for whether and when intervention in a civil war is permissible takes no view on the justice of either side’s position, but solely on likelihood of success, i.e. self-determination;
e New specific prohibitions on humanitarian intervention: the wide gulf between genocide and “ordinary brutality” is new and relies upon a reformulation of the concept of self-determination.