There are many ways things might be, for all I know. For all I know, it might be that there is life on Jupiter, and it might be that there is not. It might be that Australia will win the next Ashes series, and it might be that they will not. It might be that my great-grandfather was my great-grandmother’s second cousin, and it might be that he was not. It might be that brass is a compound, and ...

Three formal approaches to public knowledge are “any fool” knowledge by McCarthy (1970), Common Knowledge by Halpern and Moses (1990), and Justified Knowledge by Artemov (2004). We compare them to mathematically address the observation that the light-weight systems of Justified Knowledge and ‘any fool knows’ suffice to solve standard epistemic puzzles for which heavier solutions based on Common...

Stalnaker introduced a combined epistemic-doxastic logic that can formally express a strong concept of belief, a concept which captures the ‘epistemic possibility of knowledge’. In this paper we first provide the most general extensional semantics for this concept of ‘strong belief’, which validates the principles of Stalnaker’s epistemic-doxastic logic. We show that this general extensional se...

This article introduces a type of uncertainty that resides in textual information and requires epistemic interpretation on the information seeker’s part. Epistemic modality, as defined in linguistics and natural language processing, is a writer’s estimation of the validity of propositional content in texts. It is an evaluation of chances that a certain hypothetical state of affairs is true, e.g...

The questions are obviously related, but they should not be conflated, at least not well in advance of theory. Very roughly, the first is a question of semantics, the second of pragmatics (or of the semantics– pragmatics interface). The puzzle about supposition and epistemic modality I raised in section 1 of Yalcin 2007 was primarily used to motivate a specific answer to the first question — th...

By treating belief as a modality and combining this with problems about constant truth tel lers and constant l iars (knights and knaves) we obtain some curious epistemic counterparts of undecidability results in metamathematics. Godel's second theorem gets reflected in a logician who cannot believe in his own consistency without becoming inconsistent. Lob's theorem reflects i t se l f in a vari...

The epistemic modals possible, probable, likely, and certain require a semantics which treats them both as modal operators and as gradable adjectives. An analysis of these items in terms of Kennedy & McNally (2005)’s theory gradability suggests that they are associated with a single, fully closed scale of possibility. An implementation using the standard (Kratzerian) theory of modality is shown...

This paper studies a particular interpretation of propositional modal logic into propositional modal logic. Under an epistemic reading of the modality this interpretation can be understood as taking knowledge to be true belief. All normal modal logics of belief that under this definition of knowledge give rise to S5 as the logic of knowledge are determined. And all the normal modal logics of be...