SOPhiA 2021

Salzburgiense Concilium Omnibus Philosophis Analyticis

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Programme - Talk

Time travel, free will and the nomological impossibility to kill your younger self
(Metaphysics and Ontology, )

A The main aim of this talk is to present a connection between the problem of free will and time travel scenarios that may (or may not) involve paradoxes. The second aim is to respond to the claim made by Kadri Vihvelin (1996, 2020) that her argument for the nomological imposibility of autoinfanticide does not have the consequence that time travelers to the past can do only what they in fact do. _In the debates regarding time travel, the Grandfather paradox may be used to formulate an argument for the impossibility of backward time travel. If Tim can travel to the past to kill his Grandfather, then we would have to accept the contradiction that Tim can both kill and not kill his grandfather. In order to defend the possibility of time travel, David Lewis (1976) famously argued that there is a sense in which Tim can kill his grandfather and a sense in which he can't. Relative to the facts of his surroundings and his abilities, Tim can kill his grandfather, but relative to a more inclusive set of facts, Tim cannot kill his grandfather. Kadri Vihvelin disagrees that there is a sense in which time travelers to the past could kill their younger selves or their ancestors (before they could pass on their genes). Vihvelin (1996) argued that autoinfanticide is actually nomologically impossible. Suzy, an adult time traveler that would travel to the past in order to kill her younger self would always fail to commit autoinfanticide. If Suzy were successful in killing Baby Suzy, then this would mean that Baby Suzy would later resurrect and continue on to become adult Suzy. This is logically possible, but it is not something that is nomologically possible in worlds whose physical laws are closer to our own. We typically believe that our world's laws do not permit resurrections. The criticisms brought to her argument either concerned her use of counterfactuals or the supposed consequence that if she is correct, then time travelers to the past can do only what they in fact do and, therefore, lack free will. In her very recent paper, Vihvelin (2020) answered these objections. I am concerned in this talk with her response to the latter criticism. She claims that, while time travelers are unable to commit autoinfanticide, they may be able to do other things in the past as long as those things are nomologically possible. I will argue that more justifications are needed in order to show that her argument does not threaten the time traveler's freedom to do otherwise. The concern is that nomological impossibility may not stop only at autoinfanticide.

Chair: Blazej Mzyk
Time: 18:50-19:20, 09 September 2021 (Thursday)
Location: SR 1.003

Bogdan Andrei Dumitrescu 
(University of Bucharest, )



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