So, on the one hand it's important to try to understand the mind of the terrorists, but on the other hand it is wrong to look at what things America has done which may have helped shape that mind.

I don't find easy to reconcile those two positions. Clearly some people seem to have managed to do so.

Whether the stack of things a country has done that's benefited people is higher than the stacks which have hurt people is an interesting mind experiment, though I can't really imagine how you could calibrate that kind of thing. But I can't see that it is too relevant anyway.

What I mean is this. If the people who are closest to you have been hurt by somebody, I doubt if you'd be too interested in good deeds done by that somebody to third parties elsewhere.

A thought experiment. Imagine that evidence were produced that showed conclusively that Bin Laden's organisation had been responsible for the attacks on September 11th - and also that, through various charitable works the same organisation had saved tens of thousands of people from dying from famine and disease.

It just wouldn't be relevant, would it? It wouldn't be something to set in the balance against September 11th - "Six thousand dead in the attack - twenty thousand saved in the famine. That's a credit balance of fourteen thousand. So thank you, on balance you're a good fellow."