Iraq and consequentialism: what is the marginal product of war?

Many anti-war criticisms cite the badness of current events without asking how much of that badness was due to happen anyway.  To clarify, let us consider three arguments against the war:

1. U.S. behavior was wrong on deontological grounds, namely we should not kill innocents (and tax others to pay for this killing), even when the long-run consequences are good.  Of course if this is true, the arguments stops there.  Furthermore it would be irrelevant -- at least for judging rightness -- whether the war/reconstruction was going well or not.  So I doubt if this is all of the anti-war critique; let us move on to the rest.

2. It is not worth killing innocents to overthrow a tyranny.  This will also stop the argument, but most anti-war critics don't hold this view.  It would be hard to defend the rise of the West, or Allied participation in World War II, for instance.

Now consider #3:

3. The war is going badly.

The correct marginal question, however, compares the current badness to the badness which would have resulted after the reign of Saddam (or his sons? grandsons?) ended, however that might have happened.  Today we see many signals that things are going badly.  But most of those signals also imply that things would have gone very badly under the alternative scenario for Saddam's fall.  A civil war, for instance, may well have happened anyway, albeit later.

One might argue that U.S. participation makes an Iraqi civil war much worse than otherwise (perhaps the presence of U.S. forces motivates insurgents).  But I don't find this convincing.  First, a civil war could be much worse without the U.S. presence (keep in mind the alternative scenario also involves many years of continued sanctions, or what Saddam would have done without sanctions, plus further suffering under Saddam).  Second, the correct cost of the war -- at least to the Iraqis -- would be this difference in outcomes, not the current absolute level of badness.

The pro-war right seems keen to argue that much of the insurgency is foreign fighters.  This in reality weakens their case, as it opens the possibility that the U.S. role drew in these forces.  Insofar as the insurgents are Sunnis, fighting for domestic control, it is more likely they would have been fighting anyway, with or without the U.S. involved.  That would strengthen a consequentialist case for the war.

It also might be argued there is intrinsic value in postponing a civil war, although this I would dispute.

Relying only on #1 is not so popular among anti-war forces, even if it is a good argument.  It feels anti-patriotic to many people.  Thus a huge burden gets put on #3.  But citing #3 has less oomph than is commonly supposed.  The worse things get, the more we can conclude they would have been very bad -- sooner or later -- in any case.  And I've yet to be convinced that an Iraqi civil war -- without the U.S. involved -- would turn out so much better for the Iraqis. 

There is of course the separate question of what is good for the U.S. and for other countries besides Iraq.  If you think Iraq will go badly no matter what, those considerations may well be decisive.  But it sounds selfish and defeatist to cite those arguments alone, so we are again left with anti-war cases which do not make complete sense.

Addendum: Jane Galt recently surveyed some recent blogosphere arguments about Iraq and consequentialism.