This article defends the Doomsday Argument, the Halfer Position in Sleeping Beauty, the Fine-Tuning Argument, and the applicability of Bayesian confirmation theory to the Everett interpretation of quantum mechanics. It will argue that all four problems have the same structure, and it gives a unified treatment that uses simple models of the cases and no controversial assumptions about confirmation or self-locating evidence. The article will argue that the troublesome feature of all these cases is not self-location but selection effects.

In this paper, I shall provide a simple argument for the thirder analysis of the usual version of Sleeping Beauty\c and the hslfer analysis of a bare-bones version of the scenario. This argument depends upon a calculation of relative frequencies when the Sleeping Beauty experiment is repeated, but it is crucial that we be dealing with independent repetitions of the same experiment. The versions of repeated Sleeping Beauty discussed in the literature violate the independence requirement.