Abstract

The probability puzzle known as "Sleeping Beauty" raises interesting and difficult ques tions about the nature of evidence. It appears that the puzzle itself has already been solved, for there is a near consensus in the relevant philosophical literature that 1/3 is the correct answer.' Be that as it may, no new argument for that result is offered here. Instead, an at tempt is made to clarify the nature of certain problems that an answer of 1/3 raises for theories of evidential reasoning. Various approaches to solving the most important of these problems are then considered and rejected.