Kevin Drum and Steven Levitt Agree on Anti-Terrorism Logic

The Levitt/Dubner Freakonomics blog has just moved to the NYTimes server. Levitt's first post discussed ways possible terrorists could attack the U.S. cheaply. (First one, have 20 teams of snipers emulate the DC two, but truly at random.) He caught a lot of heat (surprise!). In his
response today he outlines two alternative interpretations, this is the second:

The alternative interpretation is that the terror risk just isn’t that high and we are greatly overspending on fighting it, or at least appearing to fight it. For most government officials, there is much more pressure to look like you are trying to stop terrorism than there is to actually stop it. The head of the TSA can’t be blamed if a plane gets shot down by a shoulder-launched missile, but he is in serious trouble if a tube of explosive toothpaste takes down a plane. Consequently, we put much more effort into the toothpaste even though it is probably a much less important threat.

Kevin Drum says the same, in the context of the Democrats and the bill on FISA:

Note the way the incentives work here. If you pass the bill, the results are ambiguous. Sure, a lot of people will be angry, but they'll probably get over it eventually (or so the thinking goes). But if you stall the bill and a terrorist strikes, you are firmly and completely screwed. Goodbye political career. So which choice do you think a risk-averse politicians is likely to make?

This same dynamic was at work before the war, too. If you favored the war and things went south, the resulting mess would be long-term and ambiguous. There would almost certainly be a way to weasel your way out of any trouble and stay in office. But if you opposed the war and then, after the invasion went ahead over your objections, the Army discovered a serious nuclear arms program or an advanced bioweapons lab — both considered distinct possibilities at the time — you'd be out of office at the next midterm. For risk-averse politicians, the choice was obvious.

Nobody wants to risk being proved wrong in a way that's so crystal clear there's simply no chance of talking your way out of it. It's this fear that gives national security hawks the upper hand in any terror-related debate. Still.

I have to agree--as far as I can see, the "terrorist cells" that have been captured weren't very scary. If you assume that our security can catch 90 percent of the threats, that means the threats generally aren't potent. If you assume a lower level of averted threats, where's the attacks?