"It's like talking to a brick wall" and "We'll have to agree to disagree" are popular sayings referring to the frustrating experience of discussing issues with people who seem to be beyond the reach of argument.
It's often claimed that some people--fundamentalists or fanatics--are indeed sealed off from rational criticism. And every month new pop psychology books appear, describing the dumb ways ordinary people make decisions, as revealed by psychological experiments. The conclusion is that all or most people are fundamentally irrational.
Ray Scott Percival sets out to demolish the...