Neil Tennant

in Changes of Mind

Published in print June 2012 | ISBN: 9780199655755
Published online September 2012 | e-ISBN: 9780191742125 | DOI:

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This chapter distinguishes logic as a theory of belief‐statics from our sought account of belief dynamics. The various kinds of belief change are classified. These are: surrendering, adopting or switching individual beliefs; and thereby contracting, expanding or revising one’s system of beliefs. Our account of the epistemic norms involved is agent-centric. The idealized figure of the logical paragon (as opposed to the completely fictional figure of the ‘logical saint’) is introduced as the guiding model of a rational agent who is thoroughly competent in matters of belief change. The chapter discusses what a theory of belief change needs to characterize or make feasible. Two key constraints are formulated: both minimal mutilation and minimal bloating of systems of belief undergoing contractions and revisions needs to be explicated (and ensured). The explicit goal is to provide a computationally implementable account of belief change. The chapter foreshadows welcome results to be proved about the computational complexity of the contraction problem. It stresses that our account of belief dynamics will be able to cope with differences among different schools, or ‘‐isms’, in epistemology, regarding permissible global patterns of support or justification among beliefs. The chapter includes an important discussion of methodology, invoking the contrast between propositional and first-order logic as a case study, in order to highlight the virtues of simplicity in formal modeling. This chapter promises to be an account of belief change under judiciously chosen simplifying assumptions that nevertheless allow a rich structure to come into focus, and challenging problems to emerge.

Keywords: statics; dynamics; logical paragon; minimal mutilation; minimal bloating; computational implementability; computational complexity; contraction; logic

Chapter.  13515 words. 

Subjects: Philosophy of Mathematics and Logic

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