Belief change as propositional update

Abstract

This study examines the problem of belief revision, defined as deciding which of several initially accepted sentences to disbelieve, when new information presents a logical inconsistency with the initial set. In the first three experiments, the initial sentence set included a conditional sentence, a non-conditional (ground) sentence, and an inferred conclusion drawn from the first two. The new information contradicted the inferred conclusion. Results indicated that conditional sentences were more readily abandoned than ground sentences, even when either choice would lead to a consistent belief state, and that this preference was more pronounced when problems used natural language cover stories rather than symbols. The pattern of belief revision choices differed depending on whether the contradicted conclusion from the initial belief set had been a modus ponens or modus tollens inference. Two additional experiments examined alternative model-theoretic definitions of minimal change to a belief state, using problems that contained multiple models of the initial belief state and of the new information that provided the contradiction. The results indicated that people did not follow any of four formal definitions of minimal change on these problems. The new information and the contradiction it offered was not, for example, used to select a particular model of the initial belief state as a way of reconciling the contradiction.The preferred revision was to retain only those initial sentences that had the same, unambiguous truth value within and across both the initial and new information sets. The study and results are presented in the context of certain logicbased formalizations of belief revision, syntactic and model-theoretic representations of belief states, and performance models of human deduction. Principles by which some types of sentences might be more "entrenched" than others in the face of contradiction are also discussed from the perspective of induction and theory revision.

Reasons for withdrawing belief in vivid autobiographical memories

“…Retention of belief in light of contradictory evidence might be facilitated by the centrality of the memory to the individual's current sense of identity. It is likely that greater resistance is met in changing belief for events that are currently viewed as more central for the self, or that are more strongly connected with central self-related themes, as suggested by both work on self-consistency (e.g., Wilson & Ross, 2003) and work showing that factual belief change is difficult (e.g., Elio & Pelletier, 1997). It is also possible that some memories once challenged by credible evidence are rendered inaccessible.…”

Deductive reasoning from uncertain conditionals

“…Finally, there is a newly developed paradigm in psychology initiated by research in arti cial intelligence that is highly relevant to the present topic, namely belief revision (Elio & Pelletier, 1997). This deals with how people accommodate a new piece of information that contradicts some of their previous beliefs.…”

Model theory of deduction: a unified computational approach

“…Contradictions are definitely possible within knowledge representation. People often hold contradictory beliefs without knowing it -and sometimes even knowing it (Elio & Pelletier, 1997). But complications arise as soon as one becomes aware of two contradictory states of affairs.…”