Psychological/Decision
Two Envelopes Paradox
Should you always switch envelopes?
Overview
A probability paradox where switching seems always beneficial, which can't be right.
Two envelopes contain money, one has twice the other. You pick one with $X. The other has either $2X or $X/2, average $1.25X. So you should switch. But you could reason this way after switching too, leading to infinite switching - clearly wrong.