Focusing on spacetime singularities, Earman engages with a host of foundational issues at the intersection of science and philosophy, ranging from the big bang to the possibility of time travel.

Humans have long been fascinated by the idea of visiting the past and of seeing what the future will bring. Time travel has been one of the most popular themes of science fiction. Most people have seen the TV series ‘Dr Who’ or ‘Quantum Leap’ or ‘Star Trek’. You’ve probably seen one of the ‘Back to the Future’ or ‘Terminator’ movies, or ‘Twelve Monkeys’. Time travel narratives provide fascinating plots, which exercise our imaginations in ever so many ways. But is (...) the idea of travelling forward and backward in time pure fantasy—or can it be done? To be sure, not all time travel scenarios are coherent. But we hope to persuade you that the most common objections to the very idea of time travel have no real force. (shrink)

This chapter illustrates a theory that describes how certain modal statements, including counterfactual sentences, are dependent on context. Building on the work of Robert Stalnaker and David Lewis, its application to a familiar argument for fatalism and a recent exchange about time-traveler freedom between Kadri Vihvelin and Ted Sider is considered. This chapter presents a new perspective on the flaws and the seductiveness of both the fatalist argument and the freedom paradox. This new perspective may be applied to arguments for (...) incompatibilism advanced by Carl Ginet and Peter van Inwagen. The issue of the compatibility of free will and determinism is generally regarded as one of the most serious metaphysical issues about human freedom. Consequence arguments of the sort made famous by Inwagen and Ginet are the leading arguments in favor of incompatibilism. (shrink)

Kadri Vihvelin, in "What time travelers cannot do" (Philos Stud 81: 315-330, 1996), argued that "no time traveler can kill the baby who in fact is her younger self, because (V1) "if someone would fail to do something, no matter how hard or how many times she tried, then she cannot do it", and (V2) if a time traveler tried to kill her baby self, she would always fail. Theodore Sider (Philos Stud 110: 115-138, 2002) criticized Vihvelin's argument, and Ira (...) Kiourti (Philos Stud 139: 343-352, 2008) criticized both Vihvelin's argument and Sider's critique. I present a critique of Vihvelin's argument different from both Sider's and Kiourti's critiques: I argue in a novel way that both V1 and V2 are false. Since Vihvelin's argument might be understood as providing a challenge to the possibility of time travel, if my critique succeeds then time travel survives such a challenge unscathed. (shrink)

Analyses of dispositional ascriptions in terms of conditional statements famously confront the problems of finks and masks. We argue that conditional analyses of dispositions, even those tailored to avoid finks and masks, face five further problems. These are the problems of: (i) Achilles' heels, (ii) accidental closeness, (iii) comparatives, (iv) explaining context sensitivity, and (v) absent stimulus conditions. We conclude by offering a proposal that avoids all seven of these problems.

"This is an important book, and no one interested in issues which touch on the free will will want to ignore it."--Ethics. In this stimulating and thought-provoking book, the author defends the thesis that free will is incompatible with determinism. He disputes the view that determinism is necessary for moral responsbility. Finding no good reason for accepting determinism, but believing moral responsiblity to be indubitable, he concludes that determinism should be rejected.

This paper argues that the most famous objection to backward time travel can carry no weight. In its classic form, the objection is that backward time travel entails the occurrence of impossible things, such as auto-infanticide—and hence is itself impossible. David Lewis has rebutted the classic version of the objection: auto-infanticide is prevented by coincidences, such as time travellers slipping on banana peels as they attempt to murder their younger selves. I focus on Paul Horwich‘s more recent version of the (...) objection, according to which backward time travel entails not impossible things, but improbable ones—such as the string of slips on banana peels that would be required to stop a determined auto-infanticidal maniac from murdering her younger self—and hence is itself highly improbable. I argue that backward time travel does not entail unusual numbers of coincidences; and that, even if it did, that would not render its occurrence unlikely. (shrink)

Philosophers on all sides of the contextualism debates have had an overly narrow conception of what semantic context sensitivity could be. They have conflated context sensitivity (dependence of truth or extension on features of context) with indexicality (dependence of content on features of context). As a result of this conflation, proponents of contextualism have taken arguments that establish only context sensitivity to establish indexicality, while opponents of contextualism have taken arguments against indexicality to be arguments against context sensitivity. Once these (...) concepts are carefully pulled apart, it becomes clear that there is conceptual space in semantic theory for nonindexical forms of contextualism that have many advantages over the usual indexical forms. (shrink)

In an article in Scientific American (March 1994, pp. 68–74) entitled “The Quantum Physics of Time Travel”, Oxford physicist David Deutsch and Oxford philosopher Michael Lockwood give a defense of the physical possibility of time travel based on the “Many Worlds” interpretation of quantum mechanics. This positive view of theirs is not my concern, however—I want to quarrel with their argument that time travel cannot be accommodated in any other way.1 The best way to spell out the traditional “grandfather paradox” (...) that appears to threaten the possibility of time travel involves the notion of ability, or personal possibility, or free will. An example of David Lewis’s: Tim travels back in time with the intent to kill his grandfather.2 Let us fix the case as one in which Tim in fact will not kill Grandfather; still, it seems that he can kill Grandfather because he is a good shot, has a gun, and is alone with Grandfather at close range. As Lewis says, Tim “has what it takes” to kill Grandfather. However, it is also compelling that Tim cannot kill Grandfather, because if Grandfather had been killed in his youth, Tim would not have existed to kill him. It is important to realize that the paradox essentially involves the notion of ability. No inconsistency results from supposing that Tim does not kill Grandfather. As for the case in which Tim does kill Grandfather, there are various possibilities. We could tell a consistent time travel story in which Tim kills Grandfather, but Grandfather is miraculously resurrected. Or one in which Tim kills Grandfather, but in which Grandfather has already had a child. Or one in which Tim kills Grandfather permanently, before Grandfather has any children, but in which Tim’s grandfather is someone other than Grandfather. As for the story in which Tim both kills Grandfather permanently in such a way that Grandfather has no children, and also is descended from Grandfather, this is an inconsistent time travel story; but of course the existence of some.... (shrink)

Time travel has been a staple of science fiction. With the advent of general relativity it has been entertained by serious physicists. But, especially in the philosophy literature, there have been arguments that time travel is inherently paradoxical. The most famous paradox is the grandfather paradox: you travel back in time and kill your grandfather, thereby preventing your own existence. To avoid inconsistency some circumstance will have to occur which makes you fail in this attempt to kill your grandfather. Doesn't (...) this require some implausible constraint on otherwise unrelated circumstances? We examine such worries in the context of modern physics. (shrink)

David Lewis has recently deployed a contextualist strategy for defending ordinary claims to know.1 In this paper, I wish to extend that strategy to ordinary claims about freedom.2 The result is a species of compatibilism that, while foreign to current debates, has a good deal going for it.