The Self-Visitation Paradox

The Argument
1. Ted is sitting.
2. Ted is standing.
3. Ted is sitting and standing.

Suppose that, on Monday at noon, Ted was sitting. The next Friday, Ted time travels back to Monday at noon and stands while his younger self is sitting. Can Ted be both sitting and standing? Time traveling seems to have provided us a way in which he can, though it also seems obvious that a person cannot be both sitting and standing at the same time. What is going on?

Property Compatibilism

The compatible-properties solution accepts that the sitting and the standing can occur simultaneously, done by a single person. (It is a solution formulated but criticized by Sider 2001 and supported by Carroll 2011.) On this view, the apparent paradox stems from a failure to recognize that the arguments conclusion is not contradictory. This failure may stem from the natural assumption that, if Ted is sitting, then it is not the case that Ted is standing. But maybe that assumption is only natural because we are so used to thinking about situations that do not involve time travel. (Notice that it is also natural to assume that no one can exist before being born, though that conflicts with the possibility that one could time travel back to a time before one’s birth.) Thus, the compatible-properties solution asserts that sitting and standing are not mutually exclusive properties; one person may do both at one time. While there would be a contradiction if Ted were both sitting and it were not the case that he was sitting, or standing and not the case that he was standing, it is not contradictory that Ted is both sitting and standing. The self-visitation scenario may not be the problem that it first appeared.

Relativizer

Spatial-location relativists1 believe that the locations of the sitting and the standing are the key to finding consistency. According to these relativizers, it is not the case that Ted is sitting (simpliciter) and it is not the case that Ted is standing (simpliciter). It is true, though, that Ted is sitting, say, over here and also that Ted is standing over there. Just as Ted can be sitting at one time and standing at another time, so can he be sitting in one place and standing in a different place. So, Ted’s time travel scenario is not paradoxical.

The relativizer approach, however, takes for granted that an object can exist in two separate locations simultaneously. Ted is supposed to simultaneously be sitting here and standing over there. This is as (prima facie) puzzling as his being both sitting and standing; it is another paradoxical aspect of the situation. But with this aspect of the situation relativization to location won’t help. Perhaps the relativizer must accept a compatible-properties approach to the self-visitation paradox, at least with regard to the property of spatial location.

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