How do you deal with a bully without becoming a thug? In this wise and soulful talk, peace activist Scilla Elworthy maps out the skills we need -- as nations and individuals -- to fight extreme force without using force in return. To answer the question of why and how non-violence works, she evokes historical heroes -- Aung San Suu Kyi, Mahatma Gandhi, Nelson Mandela -- and the personal philosophies that powered their peaceful protests. (Filmed at TEDxExeter.)