They don't even claim to believe that killing innocent schoolgirls is objective good, so that's a total straw man. Obviously, the ones who believe (and I'm not saying all of them do, of course), believe that protecting innocent people is good, and killing evil people is good, and so on. In some cases, they and we would disagree on what "innocent" entails.
I would say that at least some of the Taliban are evil, sure. Does that mean they can't change, or that they can't be reasoned with, or at least intimidated into not harming people? No, though that might be the case with some. I dunno.
How does it benefit us to assume that about our enemies?
Seeing your enemies as they are can only help, as far as I can see. Assuming that they really believe what you do, but for some reason have acted as though they don't -- well, I don't think that's going to be very helpful in predicting their future actions.
Well yes, I understand that they would claim that murdering schoolgirls is good, taken in isolation. Of course the act has to be taken in context.
The distinction I'm after is this:
Nate's brand of Taliban: Blowing up this school serves a greater good, which overwhelms whatever bad is inherent in the act.
Your brand of Taliban: Blowing up this school and killing everyone inside, in this situation, is unambiguously good.
My problem is that I don't believe that the Taliban, in general and as a rule, are completely without a trace of Nate's description. If there's any evidence at all that I'm right, and I think there is, then recognizing this gives us at least something to work with-- makes them less alien.
However, I do understand your overall point about the danger of ascribing moral bases across cultural lines, and you may well be right. We've waded into territory where I'm largely a layman.
I also do not believe that the Taliban are completely without a trace of Nate's description. I just think that, as a rule, they'd see things in general as either good or bad, but not really as a mix of good and bad. I grew up in a worldview that was similarly inflexible, where an action was either a good action or an evil one, but never "kind of good" or "kind of evil"; we might be uncertain about which side it's on, or wrong about it, but the fuzziness isn't ascribed to the action or the Deity's view of the action. Possibly for this reason, I don't actually view the Taliban's beliefs as "alien", or hard to understand. I just have goals that conflict with their goals.
I would say that at least some of the Taliban are evil, sure. Does that mean they can't change, or that they can't be reasoned with, or at least intimidated into not harming people? No, though that might be the case with some. I dunno.
How does it benefit us to assume that about our enemies?
Seeing your enemies as they are can only help, as far as I can see. Assuming that they really believe what you do, but for some reason have acted as though they don't -- well, I don't think that's going to be very helpful in predicting their future actions.