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Earlier this week, Osama bin Laden praised the Christmas Day attack in which a Nigerian-born man living in London attempted to blow up a Detroit-bound airplane by igniting explosives in his underwear.

Mr. bin Laden's endorsement, along with recent attacks in Baghdad, raise concerns about a new round of attacks against the United States. Politicians, security experts, and pundits have therefore called for heightened security measures at airports and on airplanes.

It won't work without addressing why there are attacks to begin with.

Additional security measures may prevent a few attacks, at least until terrorists learn to circumvent the new policies. But these measures will have little lasting impact, as with many past tactics, because they do nothing to reduce the...