MENTAL MODEL · M8146

Principle of Indifference

DecideHigh supportDecision Science

Included

Version 1.0.0 · Updated 2026-07-30

CORE DEFINITION

In the absence of reasons to consider some possibilities more likely than others, assign equal probability to all possibilities.

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

Default choice in ignorance. When information is insufficient to distinguish possibilities, equal probability distribution is the least biased choice.

anchor

Anchor fast decisions

Also known as the principle of insufficient reason: when there is no evidence to distinguish among several mutually exclusive possibilities, assigning equal probability to each is the least biased default; it formalizes "ignorance" as a uniform distribution and is a common starting point for Bayesian priors.

MINIMUM ACTION

In progress 0/4

Practice this model in one real situation:

① List all mutually exclusive and exhaustive possibilities
② Check whether there is truly no evidence favoring any
③ Assign equal prior probabilities
④ Update according to Bayes' rule when new evidence arrives.

Check to track your progress (stored locally)

Learning progress0%

account_treeGenealogyexpand_more

menu_bookReferencesexpand_more

Source support: Explicit

link
en.wikipedia.orghttps://en.wikipedia.org/wiki/Principle_of_indifferenceZH · Explicit
verified