There’s a saying: no true Scotsman would ever drink Irish whiskey. Or move to London. Or put sugar on his porridge. But this saying’s not actually about Scottish people. It’s about our own willingness to play with our categories, stretching them to fit our prejudices. For example, if you claimed that “no religious believer would start a war,” current events – particularly the ISIS assault on Iraq, which has claimed thousands of lives and threatens to extinguish entire cultures – would prove you wrong. So you might backpedal: “Well, no true religious believer would start a war.” But this would be a fallacy. What’s going on in Iraq has everything to do with real religion. Fundamentalism is a real piece of the religious puzzle – and a surprisingly fragile one.