After the shocking scenes in Washington DC this week, we ask war historian Margaret MacMillan if violence is an inevitable part of civilisation. Professor MacMillan, author of 'War: How conflict shaped us', reflects on whether the invasion of the Capitol qualifies as a coup. And she unravels the mystery of why we fight, from ancient times to the 21st century. Please subscribe to The Economist for full access to print, digital and audio editions: www.economist.com/podcastoffer See acast.com/privacy for privacy and opt-out information.