By David Lewis
Publisher: Cambridge University Press
Print Publication Year: 1999
Online Publication Date:February 2010
Chapter DOI: http://dx.doi.org/10.1017/CBO9780511625343.012
Subjects: Epistemology and metaphysics
Ordinary things, for instance we ourselves, undeniably persist through time. As we persist, we change. And not just in extrinsic ways, as when a child was born elsewhere and I became an uncle. We also change in our own intrinsic character, in the way we ourselves are, apart from our relationships to anything else. When I sit I'm bent, when I stand I'm straight. When I change my shape, that isn't a matter of my changing relationship to other things, or my relationship to other changing things. I do the changing, all by myself. Or so it seems. What happens must be possible. But how? Nothing can have the two incompatible shapes, bent and straight. How does having them at different times help? In On the Plurality of Worlds (Blackwell, 1986; henceforth PoW), p. 204, I listed three solutions, and said that only the third was tenable.
The first solution is that the ‘properties’ are really relations to times. That lets us say that things persist by enduring: the one thing is present at different times; and not mere temporal parts of it, different parts at different times, but all of it, wholly present at each of the times. The whole of me stands in the bent-at relation to some times and the straight-at relation to others. I complained that shapes are properties, not relations. No doubt a friend of the first solution will draw a distinction that he will call the distinction between matters of one's own intrinsic character and matters of one's relationships: having a shape will go on one side, being an uncle on the other.