Contributor(s): Professor Paul Collier | Mass international migration is a response to extreme global inequality, and immigration has a profound impact on the way we live. Yet our views - and those of our politicians - remain caught between two extremes: popular hostility to migrants and ‘open doors’ insistence by liberal and business elites. Collier takes a balanced look at the possibilities and challenges of migration for societies of origin and host countries, to enable us all, including policy-makers, understand how much migration is best. Paul Collier is Professor of Economics and Public Policy at the Blavatnik School of Government at Oxford University and a former director of Development Research at the World Bank. He is the author of, among others, the award-winning The Bottom Billion and The Plundered Planet. This event marks the launch of his new book, Exodus: How Migration Is Changing Our World.