Annica Vieser
Université de Genève
This paper explores different conceptions of personal time and their relevance to the debate on object persistence.
Personal time can be invoked in defense of endurantism and perdurantism alike to solve problems arising in the context of time-travel scenarios in which an object travels to a time at which it already existed. For the perdurantist, such scenarios challenge the definition of instantaneous temporal parts (ITPs) (Effingham, 2011). The endurantist, on the other hand, seems unable to distinguish between two intuitively different situations: the situation where the past-version of the time traveller has a certain property while the future-version does not, and the situation where it is the other way around (Sider, 2001, 101–109).
Both problems could be solved through an appeal to a notion that David Lewis famously invoked in defining time travel (Lewis, 1976): personal time. In defense of perdurantism, this strategy is advocated by Kim and Sakon (2017). Their appeal to personal time rests on the assumptions that 1) the modified definition of ITPs refers to an instant both in personal and in external time; and 2) no other object than o exists at any instant of o’s personal time. I demonstrate how the notion of personal time can provide us with new resources to think of further time travel scenarios if we drop 1). This aligns with the approach adopted by Carroll et al. (2017). However, dropping 1) makes it unclear whether 2) can still be maintained, without which personal time does not help solve the problems we started out with.
To move beyond this impasse, I precisely formulate the conditions under which the different conceptions of ITPs and time-relative property instantiation coincide and diverge. I then map out several options for analysing personal time, ultimately proposing a diagnosis for why most philosophers tend to dismiss appeals to personal time in the persistence debate.
Chair: Clelia Repetto
Time: September 12th, 10:40 – 11:10
Location: HS E.002
SOPhiA 2026 