The Doomsday argument Adam & Eve, UN++, and Quantum Joe

The Doomsday argument purports to show that the risk of the human species g oing extinct soon has been systematically underestimated. This argument has something in common with controversial forms of reasoning in other areas, including: game theoretic problems with imperfect recall, the methodology o f cosmology, the epistemology of indexical belief, and the debate over so-c alled fine-tuning arguments for the design hypothesis. The common denominat or is a certain premiss: the Self-Sampling Assumption. We present two stran ds of argument in favor of this assumption. Through a series of thought exp eriments we then investigate some bizarre prima facie consequences - backwa rd causation, psychic powers, and an apparent conflict with the Principal P rinciple.