His aim is to interpret these campaigns so far as possible as the work of rational agents employing violent means to pursue definite political ends: the motives of lone-wolf terrorists are liable to be inchoate. All four of English’s main examples have been very explicit about what they want and how they hope to get it, and he observes that they have all failed in their main aims, as have almost all other terrorist campaigns, with a few important exceptions. But he also looks closely at the full range of their effects, to determine whether they have ‘worked’ in some more qualified sense.
He distinguishes three further senses, short of strategic victory, in which terrorism might be said to work: partial strategic victory, tactical success and the inherent rewards of struggle as such – and there are further subdivisions within these categories. (It seems to me that the last item doesn’t really belong on this list. If, as English reports, the members of the IRA and other groups have enjoyed the inherent rewards of comradeship, excitement and an ennobling sense of purpose, that is at best a beneficial side-effect of their terrorist activity, not a way in which it succeeds or ‘works’.)