It is not uncommon in time travel stories to find that the mechanism by which the time travel is achieved is not invented. A time traveller could journey to his/her own past and give the designs of the time travel machine to his/her earlier self as s/he was given the designs as a younger person. These designs never get thought up by anyone. Such a situation would conflict with the usual conception of the acquisition of knowledge. This situation is called (...) the Temporal Epistemic Anomaly and would arise if knowledge is gained at a time prior to the information in question being transmitted but is not discovered or invented at any time. This article examines the implications of information propagating around a causal chain that is closed in time (which is required to create the Anomaly) and whether this information need have a specific origin point. (shrink)

Causal loops are a recurring feature in the philosophy of time travel, where it is generally agreed that they are logically possible but may come with a theoretical cost. This paper introduces an unfamiliar set of causal loop cases involving knowledge or beliefs about the future: self-fulfilling prophecy loops (SFP loops). I show how and when such loops arise and consider their relationship to more familiar causal loops.

It has sometimes been suggested that backwards time travel always incurs causal loops. I show that this is mistaken, by describing worlds where backwards time travel occurs and yet no causal loops occur. Arguments that backwards time travel can occur without causal loops have been given before in the literature, but I show that those arguments are unconvincing.

How can a present or future event causally influence one in the past? Even though the case of such a relationship is often quickly dismissed as impossible, this paper suggests that this reaction is hasty and omits interesting as well as substantive arguments and considerations. In an introductory synopsis of the metaphysics of causality, we first present and discuss arguments for and against the possibility of backwards causation. On the other hand, we suggest that a probabilistic notion of causality according (...) to Suppes need not exclude that causes occur temporally after their effects. (shrink)

Whether we’re reading H.G. Wells, Robert Heinlein, Ray Bradbury, or Kurt Vonnegut, time travel is a wonderful narrative trick, freeing a story from the normal ‘one damn thing after another’ progression of time. But many philosophers claim it can never be more than that because backwards causation in general, and time travel in particular, are logically impossible.In this paper I examine one type of argument commonly given for this disappointing conclusion: the time travel paradoxes. Happily for science fiction fans, these (...) arguments fall far short of showing what they are intended to show. Why they fail can be better understood in the light of an analogy between these arguments and some arguments libertarians offer against determinism. (shrink)

Dummett and others have failed to show that an effect can precede its cause. Dummett claimed that 'backwards causation' is unproblematic in agentless worlds, and tried to show under what conditions it is rational to believe that even backwards agent-causation occurs. Relying on considerations originating in discussions of special relativity, I show that the latter conditions actually support the view that backwards agent-causation is impossible. I next show that in Dummett's agentless worlds explanation does not necessitate backwards causation. I then (...) show why even relative backwards causation is impossible in his and Tooley's scenarios of parallel processes in which causes apparently act in opposite temporal directions. We thus have good reasons for thinking that backwards causation is impossible. (shrink)