Back to the (Branching) Future
The future is different from the past. What is past is fixed and set in stone. The future, on the other hand, is open insofar as it holds numerous possibilities. Branching-tree models of time account for this asymmetry by positing an ontological difference between the past and the future. Given a time t, a unique unified past lies behind t, whereas multiple alternative existing futures lie ahead of t. My goal in this paper is to show that there is an incompatibility between the way branching-tree models account for the open future and the possibility of time travel. That is, I argue that once time travel enters the picture, branching time fails to model the openness of the future by means of alternative future branches. I show how this holds independently of whether branching-time models are cashed out in A-theoretic or B-theoretic terms.
KeywordsOpen future Branching time Time travel A-theory B-theory
I thank an anonymous referee of this journal and the audience at the conference Modal Metaphysics Issues on the (Im)possible VI for helpful comments on earlier drafts of this paper.
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Conflict of Interest
The author declares that there is no conflict of interest.
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