John Gray argues that the power of the imagination fuels the worst kind of politics.

'Nobody', he argues, 'is in overall charge of events. There are patterns in history, but particular human events are mostly random. We prefer an illusion of order to the brute fact of chaos.'

But, he says, pessimism may be the key to changing our fate.

Producer: Adele Armstrong Sound: Peter Bosher Production coordinator: Gemma Ashman Editor: Richard Fenton-Smith