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#578 “Am I the Same Person Who Came in Here?”

May 13, 2018

I know that you have specialized in the philosophy of time, so I figured that you were the best person to bring this issue to. I had recently had a discussion in which I presented my reasons for believing the A Theory of Time is true and that the B Theory of a Time has serious problems. My main problem with the B Theory was the persistence of identity throughout time. How, on the B Theory, is a person the same person from lunch as they are at dinner, seeming as both would be equally real and existent? I thought this to be a pretty good objection but then the question was asked to me, “On the A Theory how does your identity persist throughout time? How does the A Theory provide a better explanation for the persistence of identity?” I’m not sure if I’m either not thinking about this properly or I’m thinking about it too hard, but I can’t figure it out. I have no answer. I keep asking myself, “How, on the A Theory, am I the same person I am today that I will be tomorrow?” If you could help give your best explanation that would be awesome. Thank You!


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Dr. craig’s response


For the benefit of those who lack the background to understand Austincole’s question, let me explain that according to the so-called A-Theory of time temporal becoming is an objective feature of reality, so that the past, present, and future are not on an ontological par, whereas on the so-called B-Theory temporal becoming is an illusion of human consciousness and past, present, and future are equally real. 

Now the point is not that the A-Theory provides “a better explanation” of personal identity over time. There may not even be anything that explains a person’s identity over time. Rather the point is that the A-Theory affirms personal identity over time, whereas the B-Theory denies it.

On the A-Theory things endure through time. The person who exists at 1:00 doesn’t just disappear but continues to exist and will exist at 1:01, assuming all goes well with him. That’s “how, on the A Theory, I am the same person I am today that I will be tomorrow.”

By contrast, on the B-Theory things perdure across time. That is to say, a temporally extended thing has a part or stage that exists at 1:00 and a different part that exists at 1:01. None of these parts endures through time; each one is fixed at its spatiotemporal coordinates. So the B-Theory is incompatible with personal identity over time, insofar as we think that a person is a self-conscious subject rather than an unconscious, four-dimensional object.

This is important because the B-Theory makes nonsense of moral praise and blame, since the person who did the heroic deed or committed the crime is not the same person who stands before us now. It would be unjust to reward or punish this person for deeds done by another. If one says that one is rewarding or punishing a temporal part that includes both stages, the problem is unsolved, for in rewarding or punishing it, one is also rewarding or punishing an infinite number of other person stages that do not include the part that did the deed, which would be unjust.

- William Lane Craig