Causality And Blame

I've noticed an interesting flip-flop in some right-wing discussions of terrorism after the murder of a man by British police in the Underground.

The normal right-wing position on terrorism is that the proximate cause of a terrorist act bears full responsibility, while underlying causes bear none. Things that disposed or motivated al-Qaida toward terrorism -- such as US mideast policy -- are innocent, because the terrorists themselves could have chosen not to kill anyone despite the provocation.

Yet one of the right-wing responses to the Underground murder takes the opposite view. The proximate cause -- the police -- is innocent, and we should blame the underlying cause -- terrorists -- that provoked the police to shoot. The arguments are thus ostensibly about apportioning the blame between proximate and ultimate causes, but the inconsistency of the rhetoric in different situations suggests that the real principle underlying the opinions is that blame should always fall on the Other and never on "one of us." (The charge that left-wingers make the opposite mistake by always blaming one of us and never the Other is a straw man -- I have yet to meet anyone of any political leaning who would claim that the terrorists are innocent.)

A better approach to apportioning blame would draw on expected utility theory. We should recognize that blame is not a zero-sum game. Blame is proportional to the magnitude of the harm, and to the amount that a person's actions raised the probability of the harm occurring relative to the best choice available to them. Thus the proximate causes of both the terrorist bombing and the police shooting bear the maximum blame for those outcomes, since they had the option of ensuring that the harm would not occur (by not pulling the detonator/trigger), but chose the option that guaranteed it would occur. The underlying causes, on the other hand, bear blame in proportion to the amount they raised the probability of the harm. In the case of the shooting, this is a fairly large share, as my impression is that pre-al-Qaida British police were fairly gentle, while ratcheting up security -- with the risks of false shootings that it brings -- was a reasonable thing to expect in the wake of a terrorist attack. Of course, even a large fraction of the blame for a single innocent death is dwarfed by the blame the terrorists bear for being the proximate causes of thousands of deaths. And insofar as blame is not a zero-sum game, blaming the terrorists does nothing to exonerate the police. (Note that another right-wing response to the shooting is consistent with this approach -- the claim that it was reasonable for the police to think the man was a terrorist and would detonate a bomb if they didn't kill him. Here I simply disagree with the assessment of the facts.)