Impossible worlds and logical omniscience: an impossibility result

Synthese 190 (13):2505-2524 (2013)
Abstract
In this paper, I investigate whether we can use a world-involving framework to model the epistemic states of non-ideal agents. The standard possible-world framework falters in this respect because of a commitment to logical omniscience. A familiar attempt to overcome this problem centers around the use of impossible worlds where the truths of logic can be false. As we shall see, if we admit impossible worlds where “anything goes” in modal space, it is easy to model extremely non-ideal agents that are incapable of performing even the most elementary logical deductions. A much harder, and considerably less investigated challenge is to ensure that the resulting modal space can also be used to model moderately ideal agents that are not logically omniscient but nevertheless logically competent. Intuitively, while such agents may fail to rule out subtly impossible worlds that verify complex logical falsehoods, they are nevertheless able to rule out blatantly impossible worlds that verify obvious logical falsehoods. To model moderately ideal agents, I argue, the job is to construct a modal space that contains only possible and non-trivially impossible worlds where it is not the case that “anything goes”. But I prove that it is impossible to develop an impossible-world framework that can do this job and that satisfies certain standard conditions. Effectively, I show that attempts to model moderately ideal agents in a world-involving framework collapse to modeling either logical omniscient agents, or extremely non-ideal agents
Keywords Impossible worlds  Logical omniscience  Rationality  Resource-bounded reasoning  Logical reasoning
Categories (categorize this paper)
Options
 Save to my reading list
Follow the author(s)
My bibliography
Export citation
Find it on Scholar
Edit this record
Mark as duplicate
Revision history Request removal from index
 
Download options
PhilPapers Archive Jens Christian Bjerring, Impossible worlds and logical omniscience: an impossibility result
External links
Setup an account with your affiliations in order to access resources via your University's proxy server
Configure custom proxy (use this if your affiliation does not provide a proxy)
Through your library
References found in this work BETA
Jens Christian Bjerring (2010). Non-Ideal Epistemic Spaces. Dissertation, Australian National University
David J. Chalmers (2011). The Nature of Epistemic Space. In Andy Egan & Brian Weatherson (eds.), Epistemic Modality. Oxford University Press.

View all 20 references

Citations of this work BETA
Similar books and articles
Analytics

Monthly downloads

Added to index

2011-04-02

Total downloads

256 ( #1,518 of 1,101,073 )

Recent downloads (6 months)

23 ( #6,232 of 1,101,073 )

How can I increase my downloads?

My notes
Sign in to use this feature


Discussion
Start a new thread
Order:
There  are no threads in this forum
Nothing in this forum yet.