HOW are we to talk about Mohammad B? One cold November day, he murdered Theo van Gogh calmly and brutally on a street in Amsterdam. When the filmmaker was cycling, Mohammad B ambushed him and fired his pistol six times. Shot in the knee, van Gogh fell to ground. He was dragged along. Wounded, he looked up at the man who had shot him and tried to speak. But Mohammad B did not answer. Coolly, he slit van Gogh's throat, almost right through. The