You are given a choice between two indistinguishable envelopes, each containing money, one with twice as much as the other. It can be argued that each envelope has an expected value of 5/4 the value in the other envelope; thus, whichever envelope you have, you should prefer the other. The paradoxical reasoning confuses variables with constants. A correct analysis would assign a coherent probability distribution to each possible way of distributing money across the two envelopes. This leads to both envelopes having the same expected value.