Bayes’ rule is the unique rational way to update belief

Evidence

There is a formula, known as Bayes’ rule, that allows you to calculate what your degree of belief, or credence, should be after learning of some evidence, taking into account what you believed before you saw the evidence and how likely the evidence was. Bayes’ rule is the unique, rational way to update your beliefs, in the sense that if someone does not use it, there will always be some series of bets that you could offer them, all of which they would want to take, but which they are certain to lose. — Cailin O’Connor and James Owen Weatherall, The Misinformation Age, 108

Categorization

• DEFINE: Nontechnical statement of a precise normative result about Bayesian updating as a dutch-book-proof policy.
• XREF: connects to: Enough confidence to guide action suffices; absolute certainty is not needed — Cailin O’Connor and James Owen Weatherall, The Misinformation Age: How False…, 104; Evidence sharing alone drives groups toward uniform belief without conformity psychology — Cailin O’Connor and James Owen Weatherall, The Misinformation Age: How False…, 208; Trustworthiness beliefs are updated through a Bayesian-style learning process. (+3 more)

Broader Connections

• Intuitive representativeness heuristics systematically override logical probability reasoning #contradicts (0.92)
• Trustworthiness beliefs are updated through a Bayesian-style learning process. #exemplifies (0.88)
• Trust operates as Bayesian belief updating grounded in cooperation experience. #exemplifies (0.85) — Russell Hardin, Trust and Trustworthiness, 526