The fact that Americans remain fearful of terrorism is surprising in several respects. Judged in purely probabilistic terms, terrorism poses a far less significant threat to human life than a host of hazards, from lightning strikes, to collisions with animals, to falling household furniture. “An American’s chance of being killed by a terrorist,” note Mueller and Stewart, “has been, and remains, one in four million per year with 9/11 included in the calculation, or one in 110 million for the period since 2001.” More Americans have been killed by weather incidents in the last two weeks than have been killed by attacks by Islamist extremists on U.S. soil in the last 14 years.
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But we generally refuse to assess the costs and benefits of different counterterrorism measures. Our reactions to terrorist events that claim tens or hundreds of lives differ from other horrific events, from hurricanes to wars, which kill thousands or millions. Extreme anxiety about terrorism leads to far greater tolerance for public policies that impinge on individual liberty, even though they may or may not actually reduce our likelihood of being killed or injured by a terrorist attack.
Responsible counterterrorism policy, therefore, must not merely disrupt terror cells, impede their planning, and thwart their ability to attract new recruits; it must also tackle the fear that terrorists seek to induce.