Don't you know your left from your right?

As a child of politicised parents, Observer columnist Nick Cohen followed in their tradition and became a trenchant voice on the liberal-left in the 1980s and 90s. But the Iraq War changed all that and forced him to rethink. In an exclusive extract from his incendiary new book about the failings of the modern left, he argues that anti-Americanism has left it blind to the evils of militant Islam.