Editorial Introduction—25 Years of AGM Theory

Abstract

Twenty-five years have passed since the publication of “On the logic of theorychange: Partial meet contraction and revision functions” by Carlos Alchourron(1931–1996), Peter Gardenfors, and David Makinson (AGM) [1]. In order tocelebrate the anniversary we have brought together a group of leading scholarsin the field to comment on some of the many developments and ramificationsthat have their origin in the 1985 paper.We are particularly proud to have both Peter Gardenfors and DavidMakinson among the contributors. Gardenfors shares his memories of thebackground and early history of AGM theory. Makinson provides an intro-duction to the as yet largely unexplored connections between belief revisionand probability theory.Hans Rott discusses two classical issues in the AGM literature, Ramsey con-ditionals and iterated belief change, proposing a way to reconcile the Ramseytest for conditionals with AGM-style revision.Richard Booth and Thomas Meyer propose a way to represent iterated revi-sion, employing enriched epistemic states that make it possible to go beyondthe first revision step of the revision operator.Sebastien Konieczny and Ramon Pino Perez provide an overview overbelief merging and point out important connections between merging andsocial choice theory.