LINK: Interesting discussion (and remarkably even-headed) at Crooked Timber about whether or not root-causes explanations of terrorism are any good. I found one bit particularly interesting:
"Mahmoud Mamdani in “Good Muslim, Bad Muslim” compared Palestinian suicide bombers to the practice of “necklacing” in apartheid South Africa. When black radicals caught a black informant for the government, the put a gasoline-soaked tire around his neck and lit it on fire. A brutal tactic, but the minority white government needed black informants to maintain control, and terrorizing them was effective in breaking that control. Mamdani points out that the black radicals gave up necklacing just as soon as other routes to achieve change were open. So terrorism can possibly be an intellectual choice when no other routes seem open."
As far as intellectual defenses of terrorism go, this is a pretty good one. But I don't think it works, because there's a troublingly subjective aspect to the claim that terrorism can be justified when "no other roots seem open." Is it actually the case, in the example the commenter quoted above cites, that there was no other means of acheiving the same end? It seems pretty clear that other methods were available, and that necklacing was merely an extremely expedient and effect alternative (do note that one could employ exactly the same logic to justify torture of terrorists).
But I think the problem goes a little further: from whose perspective must it seem like there are no alternatives available? If from the perspective of those doing the terrorism, you either have to accept the ludicrous proposition that a potential terrorist is always right in their assessment of their alternatives (Bader-Meinhof and the weather underground are discussed later in the comments, and seem fine examples of people whose analyses were substantively incorrect). Or it's the case that terrorists are sometimes wrong, but they get intellectual cover because it needs to remain there for the gray-area cases.
Obviously, I find neither alternative particularly appealing, but that's just me.