In a single-iteration fake barn case, the agent correctly identifies an object of interest on the first try, despite the presence of nearby lookalikes that could have mislead her. In a multiple-iteration fake barn case, the agent first encounters several fakes, misidentifies each of them, and then encounters and correctly identifies a genuine item of interest. Prior work has established that people tend to attribute knowledge in single-iteration fake barn cases, but multiple-iteration cases have not been tested. However, some theorists (...) contend that multiple-iteration cases are more important and will elicit a strong tendency to deny knowledge. Here I report a behavioural experiment investigating knowledge judgments in multiple-iteration fake barn cases. The main finding is that people tend to attribute knowledge in these cases too. Ironically, the results indicate that the presence of fakes could prevent iterated errors from lowering knowledge attributions. The results also provide evidence that ordinary knowledge attributions are based on attributions of cognitive ability. (shrink)

We consider the following question within both Newtonian physics and relativity theory. "Given two point particles X and Y, if Y is rotating relative to X, does it follow that X is rotating relative to Y?" As it stands the question is ambiguous. We discuss one way to make it precise and show that, on that reading at least, the answers given by the two theories are radically different. The relation of relative orbital rotation turns out to be symmetric in (...) Newtonian physics, but not in relativity theory. (shrink)

Being alive throughout all history need not save you from dying, even if history extends infinitely into the past and future. Infinitely-long lives can fall short of genuine immortality and suffer all an ordinary mortal’s diminution in experience. Adapting David Lewis on time travel, Roy Sorensen imagines quasi-immortal ‘spore gods’, whose finite personal lives are distributed across infinite external time. While criticising the ‘Eleatic’ terms in which Sorensen presents spore gods, this paper argues his essential claims are correct: ‘spore god’ (...) worlds are logically and metaphysically possible. Indeed, going beyond Sorensen, spore gods are even nomologically accessible within General Relativity. (shrink)

I wish to discuss a supposed implication of one sort of time travel. The sort of time travel is time travel into one’s past along a closed timelike curve. The implication is that in spacetimes with CTCs there can be no temporal passage or “flow” of time. I will argue that the implication does not hold.

Here, we show that one may "time travel" in Gödel spacetime with less total acceleration than was previously known. This answers a question posed by Malament.

This paper deals with those time travels mostly considered by physics, namely those in the form of the so-called closed timelike curves. Some authoritative scholars have raised doubts about the status of these journeys as proper time travels. By using David Lewis’ famous definition of time travels proposed in 1976, we show that this proper status may actually be recovered, at least in some cosmological contexts containing spacetime regions, such as those concerning black holes described by the Kerr–Newman metric, that (...) allow the formation of local closed curves. But, the mathematical incompatibility between ordinary black hole solutions to Einstein field equations and the cosmological solutions induces us to take into consideration the more general issue pertaining to the slippery interplay between models related to local and global aspects of the world, highlighting, in particular, the different notions of time that these domains inevitably imply. This leads us to think that time is not a univocal entity of the world, but is a scale-related characteristic which claims the adoption, when investigating its ontological status, of a sort of regional approach. We also briefly dwell upon the most appropriate form of realism that such a kind of dispute between local and global models may involve. (shrink)