Is there a 'physics of society'? Ranging from Hobbes & Adam Smith to modern work on traffic flow & market trading, & across economics, sociology & psychology, Philip Ball shows how much we can understand of human behaviour when we cease to try to predict & analyse the behaviour of individuals & look to the impact of hundreds, thousands or millions of individual human decisions, whether in circumstances in which human beings co-operate or conflict, when their aggregate behaviour is constructive & when it is destructive. By perhaps Britain's leading young science writer, this is a deeply thought-provoking book, causing us to examine our own behaviour, whether in buying the new Harry Potter book, voting for a particular party or responding to the lures of advertisers.