MENTAL MODEL · M2683

Doomsday Argument

StructureHigh supportLogic

Included

Version 1.0.0 · Updated 2026-07-30

CORE DEFINITION

Based on Bayesian inference, assume you are a random member of all humans who have ever been born and will ever be born. If you are in the 'early' part of human history (e.g., the first 5%), that is an extremely unlikely event. More likely, you are in the 'middle' of human history. This implies that the total number of future births will not be much greater than the number of past births, suggesting that human civilization may go extinct in the near future. -

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

Pessimistic inference from positional probability. - This is a highly controversial but logically self-consistent model. It reminds us: do not take for granted that human civilization is just beginning and has billions of years of future. If we consider humanity as a whole...

anchor

Anchor fast decisions

Based on Bayesian inference and the 'self-sampling assumption': you are more likely to be a typical observer rather than an extremely early or late sample. If about a hundred billion humans have already been born, you as a random sample are more likely to fall in the middle of the total, thus inferring that the future population will not be several orders of magnitude larger than the past.

MINIMUM ACTION

In progress 0/4

Practice this model in one real situation:

First estimate the number of people already born N
assume your serial number is approximately n (i.e., the position of the already-born population)
use Bayesian updating to assign probabilities between the 'short total human lifespan' and 'long' hypotheses
from this, derive a confidence interval for the upper limit of future population.

Check to track your progress (stored locally)

Learning progress0%

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Source support: Explicit

link
en.wikipedia.orghttps://en.wikipedia.org/wiki/Doomsday_argumentZH · Explicit
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