There was an interesting article by Daniel Finkelstein in last week's The Times (August 23rd 2006, p.17) about whether or not the Government was overreacting to the threat of terrorism. FInkelstein cited evidence carried out at the University of Michigan that indicates that the risk of an American dying in a non-stop airline flight was approximately one in 13 million - a much lower risk than dying in a car crash. So at first glance it might seem that the Government is overreacting. Finkelstein pointed out that this kind of calculation ignores the severity of the consequence, the 'payoff', and that just to concentrate on probability, is a mistake in this sort of situation (what we should worry about is the expectation = probability x the payoff). If the 'payoff' were minor, then no reaction would be appropriate; but as the 'payoff' should it happen is extremely severe, it still seems rational to take precautions. Add to this Finkelstein's excellent point that crime doesnt tend to rise or fall gently, but rather is more like a contagious disease due to copycat effects, and we can see that even with a one in 13 million chance of someone dying in flight, there can be excellent grounds for concern...
I'd add a further point. There is something peculariarly nasty about being harmed or killed by someone who is deliberately out to get you, and who doesn't mind killing or maiming children, and non-combattants, who might even have some sympathies with the killer's cause. In other words, even if the risk were the same as dying in a car accident, the fact that the accident was accidental rather than deliberate and indiscriminate murder could have a part to play in the calculations because of its side effects, even if the corpse count is comparable.
