In my estimation, most terrorists fit in to the "stupid" catagory on one level or another.
How stupid do you have to be, to believe that you will achieve martydom and glory in the afterlife if you blow up X many hundreds or thousands of people. Lets face it, it isn't democracy or the peoples of western states which terrorists despise. It is the leaders and their policies. The mass killing in between is simply a means to an end. I cannot think of a better way to get governments to sit up and take notice. I agree with AA, most suicide bombers and the like are the result of religious fanaticism which has completely consumed whatever rationality they once had.
The stupidity, however, lies mainly in an unfounded belief that their actions stand the slightest chance of changing anything (to their benefit and in relation to their goals). All that is achieved by terrorism is an increased determination to "hunt and destroy" those responsible for it. How any terrorist organization can think that their actions are likely to change a situation to their favor is beyond me. After 9/11 the public swarmed to the support of a President who, until the attacks, had been plagued by a mood of general economic dissapointment - clearly displayed by opinion polls. Sure, terrorism spreads fear, but that fear turns in to anger, and anger means that life for the terrorist is going to be made a whole lot harder.
RC