Full Idea
Using possible worlds to model truth-conditions of statements has led to considerable clarity about the logic of modality. Attempts to use the system for epistemic purposes, however, have been plagued by problems.
Clarification
'Modality' is to do with what is possible or necessary. 'Epistemic' issues involve knowing minds.
Gist of Idea
Possible worlds thinking has clarified the logic of modality, but is problematic in epistemology
Source
John Perry (Knowledge, Possibility and Consciousness [2001], §8.1)
Book Reference
Perry,John: 'Knowledge, Possibility and Consciousness' [MIT 2001], p.170
A Reaction
Presumably what lurks behind this is a distinction between what is logically or naturally possible, and what appears to be possible from the perspective of a conscious mind. Is there a possible world in which I can fly?