Epistemic Modeling with Justifications

Abstract

Existing logical models do not fairly represent epistemic situations with fallible justifications, e.g., Russell's Prime Minister example, though such scenarios have long been at the center of epistemic studies. We introduce justification epistemic models, JEM, which can handle such scenarios. JEM makes justifications prime objects and draws a distinction between accepted and knowledge-producing justifications; belief and knowledge become derived notions. Furthermore, Kripke models can be viewed as special cases of JEMs with additional assumptions of evidence insensitivity and common knowledge of the model. We argue that JEM can be applied to a range of epistemic scenarios in CS, AI, Game Theory, etc.