#790 The Multiverse and Counterparts of Me
July 03, 2022The concept of the multiverse is something that is a familiar part of our culture now. This year has seen two very popular movies (Dr. Strange in the Multiverse of Madness; Everything Everywhere All at Once) gross big box office and receive favorable views. They both have as their conceit that a person has many different versions of themselves that have superficial changes throughout the multiverse. Example: It is me but with a different job or different appearance. While this is a popular level understanding of a scientific concept I still feels it points to something missing in my (our) understanding of the multiverse. If some core of myself is the same but has different changes made to it then what does self mean? I find it interesting that a time travel movie will come out and people will have long discussions about the internal logic but people take the idea of self at face value. Is their current modern work on the self? Can materialists even talk about a self?
Seth
United States
Dr. craig’s response
A
Your misgivings are well-placed, Seth! The multiverse hypothesis is very similar to the modal theory of the late philosopher David Lewis, which has been described as “extreme modal realism.” In contrast to most philosophers, Lewis thought that possible worlds are not abstract or conceptual entities but concrete, spatio-temporal universes like ours. To say that possibly, I have a different job or appearance is to say that in some other universe there is a counterpart of me who fits that description.
I shan’t go into the reasons why Lewis’s account of modality is widely rejected, for the relevant point here is that I am not identical to any of these counterparts. The Indiscernibility of Identicals requires that if x and y are identical then x has all the same properties as y and vice versa. So these other persons are not identical to me; rather they are mere counterparts of me.
So you are quite right in saying that those who think that I myself exist in these other universes are confused about the self. Your self is unique and exists nowhere else but here. So it is not the case that “some core of myself is the same but has different changes made to it.” These counterparts are distinct persons from yourself; there is no other person who is you. So you needn’t worry about what happens to them; it literally doesn’t affect you.
You’re also quite discerning in seeing that time travel also raises interesting issues about the self. For if time travel into one’s own past is possible, then one could visit oneself at an earlier time, in which case there would be two non-identical selves, two “you.” You would be distinct from yourself! In order to avoid this problem, the vast majority of time travel theorists adopt a view of persons as extended, four-dimensional entities, non-identical slices or parts of which exist at different times. That implies that you are not the same individual who existed one minute ago! I think this gives good reason to think that time travel is metaphysically impossible.
There’s a ton of literature on the self in discussions of the mind/body problem. For a start look at what my colleague J. P. Moreland has written in our Philosophical Foundations for a Christian Worldview, 2d rev. ed. (Downers Grove, Ill.: InterVarsity Press, 2017). You’ll find there a discussion of the challenge that the self poses for materialist philosophers.
- William Lane Craig