Doomsday argument

A probabilistic argument, originated by J. Richard Gott III (Gott et al. 1993, Nature 363, 315), that treats a living person's rank in the total sequence of humans ever born as a random sample from that sequence, using it to place probabilistic bounds on how many humans remain to be born. It is one of the field's standard worked examples for testing a proposed anthropic-reasoning framework, serving that role in Brewer, Lewis & Goodman (2026)'s paper on Full Indexical Conditioning. The specific "birth rank ≈5×10^10" figure that paper cites traces to Gott's original derivation and is unverified in this vault against the primary — see question-corroborate-brewer-lewis-goodman-2026-fic-preprint.

• 2026-10-20: checked against the primary — Gott's 1993 paper does not contain "≈5×10^10." It states total humans born, as of 1993, as "of the order of 70 billion" (7×10^10), and the 2026 paper's citation of Gott attaches to the argument's general setup rather than to the "k≈5×10^10" clause specifically, which reads as that paper's own current illustrative estimate. A modern demographic compilation (PRB, 2022) independently puts the true figure at ~117 billion, further above the preprint's number. See claim-gott-1993-states-order-of-70-billion-humans-born-not-5e10 and claim-prb-2022-demographic-estimate-117-billion-exceeds-fic-preprint-5e10-figure.

References

• question-corroborate-brewer-lewis-goodman-2026-fic-preprint
• claim-gott-1993-states-order-of-70-billion-humans-born-not-5e10
• claim-prb-2022-demographic-estimate-117-billion-exceeds-fic-preprint-5e10-figure