Among those who do not support aggressive government reaction to the terrorist threat, a common argument is that terrorism is actually not much of a threat at all. After all, they point out, you are more likely to be killed in a car accident, to be shot, even to be shot by a toddler, than to die in a terrorist attack. (This argument is so well known that I'm not going to bother linking to instances of it, but they aren't hard to find if you don't believe me.)
As far as the death statistics go, they're not wrong. Even at the worst year, 2001, the number of deaths to terrorism was minuscule compared to almost any other cause, most of which (such as automobile accidents) we tolerate with hardly a word of protest. If its sole purpose was to save lives, the government could do far more good by increasing automobile safety regulations than by trying to stop terrorism.
The trouble, as anyone who stops to think about it for a few minutes realizes, is that it's not all about saving lives. Not because saving lives is unimportant, but rather because there is so much more to the consequences of terrorism than the number of deaths that result from it. For one thing, deaths to terrorism, while apparently random, are not accidental. We will never live in a world without accidental deaths, and I would argue that we already spend far too much effort trying to achieve that goal than we should. It is an entirely different matter when someone is trying to kill you. I get in my car every day knowing that I could be in a fatal accident, and I hardly think about it; but I would not walk at night in a dangerous part of a big city unless there really seemed to be no alternative. I am far more afraid of the possible existence of an individual who wants to do me in than I am by the probability of an accident.
Even that danger might become routine, and therefore less consciously threatening, if I had to live in such an area. The things that people put up with to live in Beirut would appall anyone who grew up in America, but if that kind of violence became routine here, I have no doubt that we would learn to live with it. The fact that terrorism on American soil is a relatively new threat makes it more frightening than it would otherwise be.
But these psychological explanations only hint at the greater significance of major acts of terrorism. It is not the immediate consequences of an act such as 9/11 -- the dead bodies and destroyed buildings -- that cause such concern, but rather the significance of it as a signalling event. America had been relatively safe from Islamic terrorism prior to that date; our sense of safety was shattered suddenly. Again, it is the fact that it was an organized attack that made it more significant. We knew that there was a movement in the Islamic world that viewed the United States as the Great Satan and wanted to harm us, and which had done harm repeatedly to other countries, including our European allies. When members of that movement deliberately planned an attack on us, we assumed that it was the first of a series of attacks that they would make in the future. By contrast, the Oklahoma City bombing, although equally shocking, was the work of one or two people without any coherent program (however unjustifiable). There was no prospect of repeat attacks, and, indeed, there hasn't been anything similar.
These fears do not mean, of course, that our response was appropriate. Leaving aside the issue of the resulting foreign wars, our efforts at domestic defense have been largely panicked and of dubious effectiveness. I particularly thought that the hasty attempt to fix airline security was drastically overdone.
But the fact that we had such fears was, I believe, on the whole rational. Again, not that I expected the death rate from terrorism to increase suddenly, but there were other consequences. The stock market suffered its biggest one-day loss ever after remaining closed for 4 days. Economic actors are particularly sensitive to disruption. They depend on being able to calculate financial risk, which is only possible in a stable situation. If people are suddenly afraid to fly, that throws all kinds of calculations out the window. Tourist destinations suddenly expect to receive many fewer visitors than before, so any capital improvements they made previously become financial burdens rather than investments. The airline industry, of course, suffered the biggest hit. Any industry that depends on air freight -- which is to say, just about all of them -- are suddenly faced with higher than expected costs. The 9/11 attacks were bound to have those consequences even if there was no reason to expect future attacks. Given the context of the attacks, however, it seemed almost certain that we would face more attacks in the future.
This does provide some justification for aggressive government action. It is important to signal that those in charge are going to do everything possible to keep things safe, even if the danger is illusory. Not because they are particularly concerned about the possibility of a few extra terrorist deaths, but because they need to re-establish the conditions for normal economic calculation. We have been very fortunate to have suffered few attacks since 9/11, and none on the same scale. If we had, however, you can be sure that the economy would have suffered as a consequence.
The problem of how to deal with the terrorist threat is complicated, and I would be among the first to say that our government reacted badly in several respects, and continues to operate under faulty assumptions about the best approach. One thing that is clear to me, however, is that we can't measure the importance of the attacks by the likelihood of a citizen's dying at the hands of terrorists.