Why do terrorist organizations target innocent people with their violence? What do they hope to achieve by doing this? This is a critical question because we know that people do things that they believe produce a benefit for themselves, even if that benefit is short-sighted or misinformed. If the terrorists believe they are achieving what they intend, they will continue to attack.
The actual suicide bomber who detonates himself in a crowd of people likely has motivations that are too complex and strange for anyone not of that mind to truly understand, but it is not the bomber I am considering here, it is the people who planned the attack, recruited the bomber, and made the bomb.
Al Qaeda did not kill 3,000 Americans in the World Trade Center out of any expectation that they could significantly impact U.S. population, obviously. They did not do this to gain territory, capture resources, or to in any way materially effect their lot in life. They did this to effect behavior, to make people around the world change what they are doing, and thus to prove to themselves and others that they can.
I suspect the nature of this change is less important to them than the existence of the change, any change, that they can foment through their violence. I think it's no accident that terrorism grows in parts of the world that are relatively powerless to actually effect the rest of the world. They feel powerless because they are, and when they see an event like the recent scare in midtown Manhattan, even though it was a completely failed attack in every sense of the word (nobody got hurt, the attacker was arrested quickly, and he spilled his guts immediately to the authorities), dominating the airwaves and capturing the attention of legislators in the halls of real political power, they feel satisfied. And encouraged to do more.
I'm sure there are other motivations. Revenge for predator attacks, religious fervor, internal power struggled within these organizations, etc... But it seems to me the major goal of any terrorist attack is to show the world that these powerless people can force others to change what they are doing, in any way. They make us endure invasive body scans, give up our mouthwash and nail clippers, and wait in long lines. They force powerful governments to pass new laws, change policies, and withdraw (or send) troops.
It's understandable that our social and political leaders want to respond (or at least appear to respond) to terrorist attacks by making new rules, instituting restrictions, etc... but this will simply not have any effect. It will not make us any safer: the terrorists will do the unexpected, as they always have, and in showing a response they give the terrorists exactly what they want. We won't see more planes flown into buildings... the next significant attack will be something we are not talking about right now. As a casual observer, I can think of a dozen ways to kill a lot of people quickly. I am sure the people who are focusing their entire attention to this question can as well.
Imagine a bomb going off in a Miami shopping center, killing hundreds, and for some reason nobody anywhere said anything about it. No news stories, no congressional investigation, nobody talking about it over the water-cooler the next day. The terrorist would feel that they had failed, because they would have. Dead bodies get them nothing, getting attention and altering behavior is the entire point of such an attack.
That will never happen, of course. It's unreasonable to suggest that it could. But, I say every time we mitigate our response to these attacks in any way, we're moving in the right direction. Let's ignore them as much as we can, and perhaps they will engage in this behavior less and less until, perhaps, one day they will realize these attacks are not an effective way to prove their existence to the world.
The popular wisdom about dealing with terrorists seems to be split between two camps: those who want to punish them, and those who want to remove their motivation. The former send troops, the latter say "why do they hate us?" and seek to fix whatever they think is the cause. Sending troops plays into their hands, but so does "reaching out".
Living our lives normally and ignoring them entirely would be the only defeat for them. If only.