The subject of time travel has been receiving increasing attention in the recent philosophical literature. Most of the articles that deal with it have been concerned to defend the logical consistency of time travel against those who claim that it entails one or more contradictions. Two sorts of defences have been offered. The first sort of defence involves showing that time travel does not entail those consequences which other philosophers allege it does entail. The second sort of defence involves an (...) admission that time travel does indeed involve that which its opponents allege it does involve, e.g., being in more than one place at a time, but arguing that such consequences in no way vitiate the logical consistency of this notion.My first aim in this paper is to provide a defence of time travel of the second sort. More specifically, I want to cut the ground from under an argument which might run thus:Time travel entails that certain effects can precede their causes.It is logically impossible for an effect to precede its cause. (shrink)

There is an ancient puzzle about divine foreknowledge and human freedom. If God has already known that you will do a certain thing tomorrow, then it must already be a settled fact that God has known this. Since knowledge entails truth, it must also be a settled fact that you will do it. In that case, you really cannot avoid doing it. If so, then when you do it tomorrow, you won't do it freely. ;This dissertation consists of a careful (...) statement of the puzzle and an examination of its principal solutions. These are fatalism, the view that nothing about the past, present, or future is open, eternalism, the view that God exists outside of time, semantic indeterminism, the view that some propositions are neither true nor false, and Ockhamism, the view that some things about the past are open. ;In Chapter I the puzzle is stated carefully and its solutions are sketched. Chapters II through V each discuss one of the principal solutions. It is argued that fatalism and semantic indeterminism are not adequate solutions to the puzzle. These positions cannot accommodate or adequately explain away our intuition that there is something someone can but will not do. Eternalism is seen to be a formally coherent view, but it also does not provide a satisfying solution to the puzzle. It is argued that Ockham's solution succeeds where the others fail. Finally, it is argued that although Ockham denies the necessity of the past, endorsing his solution does not force one to hold that we can literally change the past. It is concluded that Ockham's solution accommodates our intuitions about freedom and the future without charging a price. (shrink)

In this paper I wish to examine the claim that it would be possible for us now to do something which would be the posterior efficient cause of some past event. I am not prepared to discuss the physics of elementary particles, and I will not consider what is sometimes called time reversal. Rather my analysis will be limited to cases in which it is alleged that we, in a world of middle-sized physical objects where most causes precede or are (...) simultaneous with their effects, could conceivably do something so that something else should have happened. I will argue that some of the cases which meet this description are indeed backwards causation if one is prepared to make certain assumptions about time. I will not evaluate these assumptions; rather I will try to clarify them and to make plain their implications for causality. For the argument about backwards causation is most fundamentally, or so I will try to show, an argument about the nature of time. (shrink)

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)