Some philosophers defend the possibility of synchronic multilocation, and have even used it to defend other substantive metaphysical theses. But just how strong is the case for the possibility of synchronic multilocation? The answer to this question depends in part on whether synchronic multilocation is wedded to other controversial metaphysical notions. In this paper, I consider whether the possibility of synchronic multilocation depends on the possibility of time travel, and I conclude that the answer hinges on the nature of time and persistence.
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For a recent monograph on these paradoxes, see Wasserman (2018).
Though I will be presupposing Hudson’s view, I do not think that much depends on this. Any theory of location which permits synchronic multilocation at least in principle would do.
Emphasis in original. The qualifier ‘real’ is meant to distinguish time from Lewis’s (1976) notion of personal time, and to emphasize the unreality of the latter. On Wasserman’s view, personal time is an assignment of coordinates to events in (real) time that tracks identity-preserving causal relations.
This is Wasserman’s term.
For causal loops, it could be that some event A simultaneously causes another event B, which simultaneously causes A. For a variant of the Grandfather Paradox, suppose A simultaneously causes B, which simultaneously causes not-A [This second case is borrowed from Swinburne (1994, 82), who may have cases like the first implicitly in view as well, for he employs the second case in a general argument against causal loops, simultaneous causation, and backward causation].
Thus, consider the clash between Hudson (2005, 2008a, b) and Parsons (2007, 2008). See also Donnelly (2010). Granted, the case for multilocation does not depend exclusively on the case for synchronic multilocation by concrete material objects, but the latter is clearly relevant. For example, a strong enough case for synchronic multilocation of concrete material objects would suffice to refute theories of location which rule out multilocation.
Some of these applications appear in the context of arguments against endurantism or perdurantism. But below I will argue that whether synchronic multilocation requires time travel depends in part on whether endurantism or perdurantism is true. So arguments for one or the other of these accounts of persistence are not dialectically positioned to benefit from showing that synchronic multilocation can be freed from time travel.
The arguments of the last two paragraphs were suggested by a referee.
The reasoning in this paragraph owes a debt to Rasmussen’s (2014) modal continuity approach to the epistemology of modality.
Though I will speak unqualifiedly of ‘diachronic identity’ and ‘diachoric identity’, my claims in this regard should be understood as tacitly restricted in scope to concrete material objects.
The referee also notes that even A-theorists, who reject the thesis that time is closely analogous to space, tend to require that a backward time traveler who has just arrived from the future is identical to someone in the future only if they stand in immanent causal relations to that future person. But the journey backward in time is a diachronic one, where the immanent causal relations hold between the person at a later and earlier time. So although the backward time traveler is synchronically multilocated, it is not at all clear that the synchronic multilocation, rather than her journey through time, lies behind the demand for an immanent causal link.
I here adopt the locational rather than the mereological characterization of endurantism (Gilmore 2014).
Alternatively, you might continue to insist on the analogy, and conclude that synchronic multilocation is impossible. Thus Hudson (2005).
As a referee points out, there are many ways to characterize endurantism, and what I have written here basically reflects Skow’s (2015, 184) characterization.
Another worry some have about the primitive tense approach to the problem of temporary intrinsics—one which it is very natural to raise in this context—is that it doesn’t help with cases of synchronic multilocation, e.g., a backward time-traveler who is simultaneously sitting over here and standing over there (the case is from Sider 2001, 101ff). On this point, I think the A-theorist should simply concede that a different approach is required for diachoric cases than diachronic cases. Given that time and space are disanalogous on the A-theory, this isn’t terribly surprising. (Miller (2006) makes a similar point.) And if the primitive tense solution to the problem of temporary intrinsics failed for this reason, it’s not clear that this would undermine my point about diachronic multilocation given the A-theory. For that point depends on an appeal to primitive tense, but not on the A-theorist using primitive tense to solve the problem of temporary intrinsics.
This point is inspired by similar comments made by Ned Markosian in a Seminar.
Thanks to Sam Schechter and three referees for this journal for comments on earlier versions of this article.
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