Josh linked to Michael Walzer's piece in TNR (sub req). There's a whole lotta elision goin' on. I'm certainly not going to argue about who started this, or that the Hamas and Hezbollah's part in the war is just. I'm also not going to take issue with Walzer's conclusion as much as with the "therefores" in his argument.

1) It is an important principle of just war theory that justice, though it rules out many ways of fighting, cannot rule out fighting itself--since fighting is sometimes morally and politically necessary. A military response to the capture of the three Israeli soldiers wasn't, literally, necessary; in the past, Israel has negotiated instead of fighting and then exchanged prisoners. But, since Hamas and Hezbollah describe the captures as legitimate military operations--acts of war--they can hardly claim that further acts of war, in response, are illegitimate. The further acts have to be proportional, but Israel's goal is to prevent future raids, as well as to rescue the soldiers, so proportionality must be measured not only against what Hamas and Hezbollah have already done, but also against what they are (and what they say they are) trying to do.

Not exactly. Just war theory does not rule out fighting since fighting is sometimes morally necessary. Political considerations do not enter into the question, however. And any putative claims by Hamas and Hezbollah that further acts of war by Israel are illegitimate are irrelevant. Just because they can't claim that further acts of war are illegitimate does not make them legitimate.

2) It doesn't matter that, so far, the Gazan rockets have done minimal damage; the intention every time one is fired is to hit a home or a school, and, sooner or later, that intention will be realized.

If this could be shown to be true, Israel would have a much stronger case, in my opinion. But this is just an unsubstantiated claim on Walzer's part.

3) When Palestinian militants launch rocket attacks from civilian areas, they are themselves responsible--and no one else is--for the civilian deaths caused by Israeli counterfire. But (the dialectical argument continues) Israeli soldiers are required to aim as precisely as they can at the militants, to take risks in order to do that, and to call off counterattacks that would kill large numbers of civilians.

Clearly the thesis can only be true if the antithesis (Israel being careful) is also true. Practically speaking, in war this never happens, so the thesis is refuted; the responsibility for civilian deaths is shared.

4) The trickiest part of Walzer's argument is the final section. Here he argues that

a) Attacks by Hamas and Hezbollah were not inevitable since they commenced after Israel's withdrawal.

b) Said attacks have probably made future unilateral withdrawals impossible.

c) Israel's actions make it less, rather than more, likely that it will have a security partner on the other side.

d) Until Israel has such a partner (with help from the US and the international community required), it is entitled to act militarily on its own behalf.

Even taking his assumptions at face value, it is a strange perspective on inevitability that holds that things that happened in the past were not inevitable, but things Walzer thinks will happen in the future are. Especially c) and d), taken together, call his conclusion into question.

Most of Walzer's argument is about jus in bello (the conduct of just war once war has begun). I don't have a problem with much of what he says in this regard. I do have a problem with his eliding this to a general defense of Israel's decision to enter into the war in the first place, at the scale that it did. Especially the principle of last resort seems not to have been followed. To my mind the thorniest question to answer when assessing jus ad bellum (whether going to war in the first place is just) is this: if both sides have legitimate grievances, can either side claim that their warmaking is just?