agm-postulates-8-specific-postulates

IN premise — summaries/2026/08/24/wiki-Belief_revision.md

Created 2026-08-24T17:11:07+00:00

The AGM framework defines exactly 8 postulates for belief revision: Closure, Success, Inclusion, Vacuity, Consistency, and Extensionality (first 6, 'basic') plus Superexpansion and Subexpansion (last 2, attributed to Darwiche–Pearl as 'higher-order').

Summary

The AGM framework pins down the rules for rational opinion-updating in a finite set of exactly eight constraints, split into a core six and two stronger "higher-order" rules added later by Darwiche and Pearl. This gives the system a clear, checkable standard: any proposed revision procedure either satisfies the full eight or it doesn't, and the layering tells you which constraints are the bare minimum versus the ideal.