Four great forces have changed human cultures, says Olivier Roy distinguished political scientist and expert on radical Islam: a change in sexual mores since 1968, the internet, the liberalisation of global finance, and the free movement of people. the result is a flattened world, in which old hierarchies count for little and implicit culture is being replaced by explicit norms, a world without a way forward, and therefore a profoundly conservative one. Floor us in this fascinating exploration of cultures in crisis and what might replace them.