The Self-Sampling Assumption (SSA): Foundations, Applications, and Philosophical Implications in Anthropic Reasoning

This comprehensive review paper provides a rigorous philosophical and mathematical investigation of the Self-Sampling Assumption (SSA), a central principle in anthropic reasoning. It traces the SSA’s origins from Carter’s weak anthropic principle through Leslie’s Doomsday Argument and Bostrom’s formalization, derives its probabilistic structure, compares it with the rival Self-Indication Assumption (SIA), and examines key applications including the Doomsday Argument, Boltzmann Brain paradox, youngness paradox, anthropic shadow, and simulation argument. The paper evaluates major criticisms (especially the reference class problem), surveys recent developments, and discusses broader implications for probability theory, self-locating belief, epistemology, and scientific methodology.