Psychological/Decision
Newcomb's Problem
Should you take one box or two when a predictor knows your choice?
Overview
A decision theory paradox pitting evidential decision theory against causal decision theory.
A predictor places $1M in box A if it predicts you'll take only A, or $0 if you'll take both. Box B always has $1000. The predictor is highly accurate. One-boxers get rich, but taking both boxes seems rational since the money is already there.