Ah, but is it really that simple? :) For similar puzzles, you might enjoy Douglas Hofstadter's essay about "super-rationality" (there is a HTML version on gwer

Ah, but is it really that simple? :) For similar puzzles, you might enjoy Douglas Hofstadter's essay about "super-rationality" (there is a HTML version on gwern's site: http://www.gwern.net/docs/1985-hofstadter http://www.gwern.net/docs/1985-hofstadter), Adam Elga's "Defeating Dr. Evil with self-locating belief" (http://philsci-archive.pitt.edu/1036/ http://philsci-archive.pitt.edu/1036/), and Scott Aaronson's lecture about Newcomb's paradox (http://www.scottaaronson.com/democritus/lec18.html http://www.scottaaronson.com/democritus/lec18.html).