Are we living in a uniquely paranoid age? Catalysed by the threat of terrorism, fears about others have reached a new intensity. The roll call of apparent dangers seems to increase by the day: muggers, child abductors, drug dealers, hoodied teenagers. Crime has apparently reached such high levels that CCTV cameras are required in every town centre, and parents are so fearful that many children never go out alone.Until recently, no one suspected just...