The modern consensus belief is that this was just awful superstition in action, and our modern courts of law are obviously a vast improvement. That's certainly what I had thought until I read a recent paper titled "Ordeals" by one Peter T. Leeson, who argues that these ordeals were in fact, in the given circumstances, a highly accurate way of separating the guilty from the innocent given the prevailing beliefs and customs of the time.

That's interesting. I think you're right that no one reacts too negatively to this news because they don't see any real danger that it would be implemented.

But suppose there were a real movement to bring back trial by ordeal. According to the paper's abstract, trial by ordeal was so effective because the defendants held certain superstitious belief. Therefore, if we wanted it to work again, we would need to change peoples' worldview so that they again held such beliefs.

But there's reason to expect that these beliefs would cause a great deal of harm — enough to outweigh the benefit from more accurate trials. For example, maybe airlines wouldn't perform such careful maintenance on an airplane if a bunch of nuns would be riding it, since God wouldn't allow a plane full of nuns to go down.

Well, look at me — I launched right into rationalizing a counter-argument. As with so many of the biases that Robin Hanson talks about, one has to ask, does my dismissal of the suggestion show that we're right to reject it, or am I just providing another example of the bias in action?