A Dynamic Solution to the Problem of Logical Omniscience

Journal of Philosophical Logic 48 (3):501-521 (2019)
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Abstract

The traditional possible-worlds model of belief describes agents as ‘logically omniscient’ in the sense that they believe all logical consequences of what they believe, including all logical truths. This is widely considered a problem if we want to reason about the epistemic lives of non-ideal agents who—much like ordinary human beings—are logically competent, but not logically omniscient. A popular strategy for avoiding logical omniscience centers around the use of impossible worlds: worlds that, in one way or another, violate the laws of logic. In this paper, we argue that existing impossible-worlds models of belief fail to describe agents who are both logically non-omniscient and logically competent. To model such agents, we argue, we need to ‘dynamize’ the impossible-worlds framework in a way that allows us to capture not only what agents believe, but also what they are able to infer from what they believe. In light of this diagnosis, we go on to develop the formal details of a dynamic impossible-worlds framework, and show that it successfully models agents who are both logically non-omniscient and logically competent.

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Author Profiles

Mattias Skipper
Inland Norway University of Applied Sciences

Citations of this work

Impossible Worlds.Francesco Berto - 2013 - Stanford Encyclopedia of Philosophy (2013).
Hyperintensionality.Francesco Berto & Daniel Nolan - 2021 - Stanford Encyclopedia of Philosophy.
The Logic of Hyperlogic. Part A: Foundations.Alexander W. Kocurek - forthcoming - Review of Symbolic Logic:1-27.
The Fundamental Problem of Logical Omniscience.Peter Hawke, Aybüke Özgün & Francesco Berto - 2020 - Journal of Philosophical Logic 49 (4):727-766.

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References found in this work

The Impossible: An Essay on Hyperintensionality.Mark Jago - 2014 - Oxford, United Kingdom: Oxford University Press.
Impossible Worlds: A Modest Approach.Daniel Nolan - 1997 - Notre Dame Journal of Formal Logic 38 (4):535-572.

View all 25 references / Add more references