In his autobiography Long Walk to Freedom, Nelson Mandela explains at what point a peace-loving individual must make the choice to take up arms against an oppressor.
It is, he says, the moment when you realise that the opposition regards you as less than human. Journalist Polly Toynbee argues that because of the Taliban's horrific treatment of women, this point has been reached in the war in Afghanistan. Any sane woman, she says, should be prepared to fight. Hilary Wainright, of Red Pepper magazine disagrees.
