The possibility of continuous backwards time travel—time travel for which the traveler follows a continuous path through space between departure and arrival—gives rise to the double-occupancy problem. The trouble is that the time traveler seems bound to have to travel through his or her younger self as the trip begins. Dowe and Le Poidevin agree that this problem is solved by putting the traveler in motion for a gradual trip to the past. Le Poidevin goes on to argue, however, that (...) the gradual trip gives rise to the Cheshire cat problem, a concern about whether the traveler survives the gradual trip. We address the Cheshire cat problem by proposing and considering new continuity constraints on identity over time. Along the way, we come upon an endurantist conception of temporal parts. (shrink)

I criticize Lockwood’s solution to the “paradoxes” of time travel, thus endorsing Lewis’s more conservative position. Lockwood argues that only in the context of a 5D space-time-actuality manifold is the possibility of time travel compatible with the Autonomy Principle (according to which global constraints cannot override what is physically possible locally). I argue that shifting from 4D space-time to 5D space-time-actuality does not change the situation with respect to the Autonomy Principle, since the shift does not allow us to have (...) a coincidence-free local dynamical theory. (shrink)

This article discusses the possibility of some outlandish tropes from time travel fiction, such as people reversing in age as they time travel or the universe being destroyed because a time traveler kills their ancestor. First, I discuss what type of possibility we might have in mind, detailing ‘close possibility’ as one such candidate. Secondly, I argue that—with only little exception—these more outlandish tropes fail to be closely possible. Thirdly, I discuss whether these outlandish tropes may nevertheless be more broadly (...) possible (e.g., metaphysically or logically possible), arguing that whether they are or not depends upon your favored metaphysics of the laws of nature. (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)