Goldstone Research Unit

Document Type

Journal Article

Date of this Version

12-2008

Publication Source

The Review of Symbolic Logic

Volume

1

Issue

4

Start Page

514

Last Page

529

DOI

10.1017/S1755020308090072

Abstract

Among the many possible approaches to dealing with logical omniscience, I consider here awareness and impossible worlds structures. The former approach, pioneered by Fagin and Halpern, distinguishes between implicit and explicit knowledge, and avoids logical omniscience with respect to explicit knowledge. The latter, developed by Rantala and by Hintikka, allows for the existence of logically impossible worlds to which the agents are taken to have “epistemological” access; since such worlds need not behave consistently, the agents’ knowledge is fallible relative to logical omniscience. The two approaches are known to be equally expressive in propositional systems interpreted over Kripke semantics. In this paper I show that the two approaches are equally expressive in propositional systems interpreted over Montague-Scott (neighborhood) semantics. Furthermore, I provide predicate systems of both awareness and impossible worlds structures interpreted on neighborhood semantics and prove the two systems to be equally expressive.

Copyright/Permission Statement

Copyright © Association for Symbolic Logic

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Date Posted: 02 March 2015