Chapter 11, Problem 64RE

Newcomb's Paradox Suppose there are two boxes, A and B. Box A contains $1000. Box B contains either $1,000,000 or nothing. You have a choice of taking both boxes or just box B. Suppose there is a being who is able to predict in advance what choice you will make. The being will put nothing in box B if he knows you will choose both boxes, and put $1,000,000 in box B in advance if he knows you will just choose box B. What should you choose? Some argue that you should obviously just choose box B, because then you will end up with $1,000,000, while if you choose both boxes, you will end up with just $1000. Others argue that at the moment you make your choice, the being has already put either $1,000,000 or nothing in box B, so you might as well choose both boxes, guaranteeing that you will get $1000 more than if you just choose box B, What do you think?

Source: Essays in Honor of Carl G. Hempel.