Online research in philosophy

We examine the paradox of the surprise examination using dynamic epistemic logic. This logic contains means of expressing epistemic facts as well as the effects of learning new facts, and is therefore a natural framework for representing the puzzle. We discuss a number of different interpretations of the puzzle in this context, and show how the failure of principle of success, that states that sentences, when learned, remain to be true and come to be believed, plays a central role in understanding the puzzle.

Gary Ostertag (Philos Stud 146:249–267, 2009 ) has presented a new puzzle for Russellianism about belief reports. He argues that Russellians do not have the resources to solve this puzzle in terms of pragmatic phenomena. I argue to the contrary that the puzzle can be solved according to Nathan Salmon’s (Frege’s puzzle, 1986 ) pragmatic account of belief reports, provided that the account is properly understood. Specifically, the puzzle can be solved so long as Salmon’s guises are not identified with sentences.

Abstract: I argue that the solution to the Red Hat Problem, a puzzle derived from interactive epistemic logic, requires S5. Interactive epis- temic logic is set out in formal terms, and an attempt to solve the red hat puzzle is made in K, K, and K, each of which fails, showing that a stronger system, K is required.

In this note I argue that, relative to certain largely uncontroversial background conditions, any instance of Mates’ Puzzle is equivalent to some instance of Frege’s Puzzle. If correct, this result is surprising. For, barring the radical move of rejecting the possibility of synonymous expressions in a language tout court, it shows that there is no strictly lexical solution to at least some instances of Frege’s Puzzle. This forces the hand of theorists who wish to provide a semantic (rather than pragmatic) solution to Frege’s Puzzle. The only option open will be modify in one way or another the standard formulation of semantic compositionality.

Alfred Mele and M.P. Smith have presented a puzzle about omnipotence which they call “the new paradox of the stone.” They have also proposed a solution to this puzzle. I briefly present their puzzle and their proposed solution and argue that their proposed solution is unsatisfactory. I further argue that if their suggested solution to the original paradox of the stone succeeds, a similar solution also solves the new paradox of the stone.

Uzquiano (Analysis 70:39–44, 2010 ) showed that the Hardest Logic Puzzle Ever ( HLPE ) [in its amended form due to Rabern and Rabern (Analysis 68:105–112, 2008 )] has a solution in only two questions. Uzquiano concludes his paper by noting that his solution strategy naturally suggests a harder variation of the puzzle which, as he remarks, he does not know how to solve in two questions. Wheeler and Barahona (J Philos Logic, to appear, 2011 ) formulated a three question solution to Uzquiano’s puzzle and gave an information theoretic argument to establish that a two question solution for Uzquiano’s puzzle does not exist. However, their argument crucially relies on a certain conception of what it means to answer self-referential yes–no questions truly and falsely . We propose an alternative such conception which, as we show, allows one to solve Uzquiano’s puzzle in two questions. The solution strategy adopted suggests an even harder variation of Uzquiano’s puzzle which, as we will show, can also be solved in two questions. Just as all previous solutions to versions of HLPE , our solution is presented informally. The second part of the paper investigates the prospects of formally representing solutions to HLPE by exploiting theories of truth.

The Hardest Logic Puzzle Ever was first described by the late George Boolos in the Spring 1996 issue of the Harvard Review of Philosophy. Although not dissimilar in appearance from many other simpler puzzles involving gods (or tribesmen) who always tell the truth or always lie, this puzzle has several features that make the solution far from trivial. This paper examines the puzzle and describes a simpler solution than that originally proposed by Boolos.

Rabern and Rabern (2008) and Uzquiano (2010) have each presented increasingly harder versions of ‘the hardest logic puzzle ever’ (Boolos 1996), and each has provided a two-question solution to his predecessor’s puzzle. But Uzquiano’s puzzle is different from the original and different from Rabern and Rabern’s in at least one important respect: it cannot be solved in less than three questions. In this paper we solve Uzquiano’s puzzle in three questions and show why there is no solution in two. Finally, to cement a tradition, we introduce a puzzle of our own.

Rabern and Rabern (2008) have noted the need to modify `the hardest logic puzzle ever’ as presented in Boolos 1996 in order to avoid trivialization. Their paper ends with a two-question solution to the original puzzle, which does not carry over to the amended puzzle. The purpose of this note is to offer a two-question solution to the latter puzzle, which is, after all, the one with a claim to being the hardest logic puzzle ever.