Does Lewis’ Theory of Causation Permit Time Travel?

David Lewis aimed to give an account of causation, and in particular, a semantics for the counterfactuals to which his account appeals, that is compatible with backwards causation and time travel. I will argue that he failed, but not for the reasons that have been offered to date, specifically by Collins, Hall and Paul and by Wasserman. This is significant not the least because Lewis’ theory of causation was the most influential theory over the last quarter of the 20th century; and moreover, Lewis’ spirited defence of time travel in the 1970s has shaped philosophers’ approach to time travel to this day.

Time to Conceive: a New Argument for the Possibility of Time Travel

<p>Ordinarily, philosophers arguing for the possibility of time travel restrict themselves to defending time travel against allegations of inconsistency and contradiction. These objections are usually based on particular theories about time and causality. I believe, however, that this way of arguing can be turned on its head. By using the conceivability thesis – that is, the thesis that if something is conceivable, then it is also possible – we can put forward a positive argument for the possibility of time travel, and then consider how this should inform our metaphysical views. I do this by assuming the truth of the conceivability thesis and then presenting a simple piece of time travel fiction. I argue for the conceivability of this story and, in doing so, attempt to show that the time travel journey it describes is logically possible. I then develop this argument by considering other more controversial cases of time travel. I make minor alterations to the original time travel story in order to show that there are a number of different kinds of time travel journeys (including cases of both forwards and backwards time travel) which are conceivable and, therefore, logically possible. Finally, I ask how the conceivability of different types of time travel should affect the metaphysical views we choose to adopt. I argue that since the conceivability of time travel entails the logical possibility of journeys to other times, any plausible theory of time must be able to accommodate such journeys. I also explain how the conceivability of time travel entails the logical possibility of two particularly unusual cases of causation. I argue that the conceivability of instantaneous time travel entails the logical possibility of causation at a distance, and that the conceivability of backwards time travel entails the logical possibility of backwards causation. Any plausible theory of causation must therefore be able to account for the possibility of these two types of causation. I consider one particular theory of causation which does not (namely, that put forward by D.H. Mellor), and then attempt to establish where it goes wrong.</p>

Time to Conceive: a New Argument for the Possibility of Time Travel

<p>Ordinarily, philosophers arguing for the possibility of time travel restrict themselves to defending time travel against allegations of inconsistency and contradiction. These objections are usually based on particular theories about time and causality. I believe, however, that this way of arguing can be turned on its head. By using the conceivability thesis – that is, the thesis that if something is conceivable, then it is also possible – we can put forward a positive argument for the possibility of time travel, and then consider how this should inform our metaphysical views. I do this by assuming the truth of the conceivability thesis and then presenting a simple piece of time travel fiction. I argue for the conceivability of this story and, in doing so, attempt to show that the time travel journey it describes is logically possible. I then develop this argument by considering other more controversial cases of time travel. I make minor alterations to the original time travel story in order to show that there are a number of different kinds of time travel journeys (including cases of both forwards and backwards time travel) which are conceivable and, therefore, logically possible. Finally, I ask how the conceivability of different types of time travel should affect the metaphysical views we choose to adopt. I argue that since the conceivability of time travel entails the logical possibility of journeys to other times, any plausible theory of time must be able to accommodate such journeys. I also explain how the conceivability of time travel entails the logical possibility of two particularly unusual cases of causation. I argue that the conceivability of instantaneous time travel entails the logical possibility of causation at a distance, and that the conceivability of backwards time travel entails the logical possibility of backwards causation. Any plausible theory of causation must therefore be able to account for the possibility of these two types of causation. I consider one particular theory of causation which does not (namely, that put forward by D.H. Mellor), and then attempt to establish where it goes wrong.</p>

Narrative and persistence

Many philosophers say that the nature of personal identity has to do with narratives: the stories we tell about ourselves. While different narrativists address different questions of personal identity, some propose narrativist accounts of personal identity over time. The paper argues that such accounts have troubling consequences about the beginning and end of our lives, lead to inconsistencies, and involve backwards causation. The problems can be solved, but only by modifying the accounts in ways that deprive them of their appeal.

Dispositional Essentialism, Directedness, and Inclination to an End

Dispositional essentialists U. T. Place, George Molnar, and C. B. Martin hold that dispositions are intrinsically directed to their manifestations. Thomists have noted that this directedness is similar to Thomistic directedness to an end. I argue that Place, Molnar, and Martin would benefit from conceiving of dispositional directedness as the sort of directedness associated with Thomistic inclinations. Such Thomistic directedness can help them to account for the production of manifestations; to justify their reliance on dispositional directedness; to show the causal relevance of dispositions; and to motivate their view that dispositions are not reducible to categorical bases. I argue, moreover, that Thomistic inclination to an end does not succumb to the most common objections to finality: it is not mentalistic or vitalistic, and it does not involve backwards causation. Place, Molnar, and Martin, therefore, can embrace the directedness associated with Thomistic inclination—and reap its benefits—without incurring any high metaphysical cost.

Defending Backwards Causation against the Objection from the Ignorance Condition

Since Michel Dummett published “Can an effect precede its cause?” (1954), in which he argued for the logical consistency of backwards causation, the controversial concept has turned to a subject of all kinds of interpretations and misinterpretations. Some like Ben-yami, Peijnenburg and Gorovitz have wrongly ascribed to Dummett the view that the argument for the consistency of believing in backwards causation applies only in cases where the agent doesn’t know about the occurrence of the past effect. In this paper I defend Dummett’s argument by clearing up the confusion caused by ascribing the ignorance condition to Dummett.