a six-part theory of aggression (Walzer 61-2): 1. There exists an international "society" of independent states. 2. That society respects the territorial integrity and political sovereignty of all members. 3. Use of force against such integrity and sovereignty is a crime. 4. Aggression may justly be opposed by a member state that is defending its sovereignty, or by a coalition of members against the aggressor state. 5. Only aggression justifies war. 6. Aggressors can be both repulsed and punished. In particular, if if states claim entitlements wrongly, "they must also be (somehow) the objects of punishment" (Walzer 63).
While it cannot be said that Corinth was an independent state vis-à-vis Sparta, it can be said that Athens was not respecting its territorial integrity. Just because Corinth was already subject to Sparta did not prove that Athens could somehow justify its aggression in the region. As it turned out, Sparta also went to war and eventually won, but at great cost.
A war is just, in Walzer's view, when it helps a state protect territorial integrity or political independence from an aggressor. Victims of aggression have a right of self-defense against aggressors, and this defends not only the direct victims but other possible victims of the aggression, which is also a criminal offense against the law of nat
...