"If he is a perfect predictor you have to abandon free will, that's always been the problem. Backwards causation solves that. If he is usually right you don't need backwards causation, just that people's choices are in part predictable.

"The story gets used as an argument for making yourself into someone who will always choose to only take the one box. But in order to choose to make yourself into such a person you have to be able to choose and if you don't have free will you can't, you are just observing what you do and imagining that you chose to do it. That's consistent with physics, at least before quantum mechanics, but I don't think anyone believes it.

"I wish I was back home so I could ask Apa what he thinks about it — whether divining is acausal or just being magically good at extrapolating from current data. We don't actually have an alien who is a perfect predictor but Mari did find that book for Masozi. If we had a true random number generator, using some mechanism that was entirely unpredictable like when an unstable atom would split, we could see if Mari can predict it. If she does better than chance ..."