Belief Revision as Propositional Update

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  • Technical report TR96-01. Five experiments investigated human belief revision, defining belief revision as a required change to an initial set of beliefs, modeled as a set of propositional sentences, when new information presents a logical inconsistency with the initial set. Certain prescriptive notions of belief revision, such as epistemic entrenchment and minimal change, depend on the representational assumptions adopted for modeling the belief state, in particular whether a syntactic or model-theoretic perspective is taken. These perspectives were examined by manipulating the syntactic form of sentences comprising the initial belief state. Subjects selected among several alternative sets of sentences as their preferred new set of beliefs. These alternatives differed according to which of the initial beliefs were abandoned in order to define a new consistent belief set. Subjects did not follow a minimal change strategy, as defined by four different algorithms on these problems; further, subjects preferred to eliminate logical inconsistency by abandoning conditional statements rather than non-conditional ones, even though either option would lead to a consistent new belief state. Revision choices were also affected by whether the initial belief state included a modus ponens or modus tollens inference, and whether the problems involved abstract symbols or natural-language cover stories. We discuss the role of deductive reasoning in relation to certain aspects of belief revision, and the empirical evidence of these studies for notions like minimal change and epistemic entrenchment as prescriptive and descriptive principles of belief revision. | TRID-ID TR96-01

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    Attribution 3.0 International