The Logic of Justified Belief Change, Soft Evidence and Defeasible Knowledge

  • Alexandru Baltag
  • Bryan Renne
  • Sonja Smets
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7456)


We present a logic for reasoning about the evidence-based knowledge and beliefs and the evidential dynamics of non-logically -omniscient agents. We do this by adapting key tools and techniques from Dynamic Epistemic Logic, Justification Logic, and Belief Revision so as to provide a lightweight, yet fine-grained approach that characterizes well-known epistemic and doxastic attitudes in terms of the evidential reasoning that justifies these attitudes. We then add the dynamic operations of evidence introduction, evidence-based inference, strong acceptance of new evidence (evidential “upgrade”), and irrevocable acceptance of additional evidence (evidential “update”). We exemplify our theory by providing a formal dynamic account of Lehrer’s well-known Gettier-type scenario involving the famous Ferrari and the infamous Messrs. Nogot and Havit.


Dynamic Epistemic Logic Justification Logic Belief Revision 


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© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Alexandru Baltag
  • Bryan Renne
  • Sonja Smets

There are no affiliations available

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