Terrorism is rare, far rarer than many people think. It’s rare because very few people want to commit acts of terrorism, and executing a terrorist plot is much harder than television makes it appear. The best defences against terrorism are largely invisible: investigation, intelligence, and emergency response. But even these are less effective at keeping us safe than our social and political policies, both at home and abroad. However, our elected leaders don’t think this way: they are far more likely to implement security theater against movie-plot threats.