The Paradox Portal
Psychological/Decision

Sleeping Beauty Problem

What credence should you give to a coin flip when awakened?

Overview

A probability puzzle about self-locating belief and the interpretation of probability.

Sleeping Beauty is put to sleep Sunday. A fair coin is flipped. If heads, she's awakened Monday only. If tails, she's awakened Monday and Tuesday (with Monday's memory erased). When awakened, what probability should she assign to heads? 1/2 (halfers) or 1/3 (thirders)?

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