Phil 89: Perry’s Second Night (Part 1)

Proposals #2-3

The second proposal about personal identity says that personal identity is just a matter of having the same body:

Proposal #2: A is the same person as B iff A and B have the same body.

A variant of proposal #2 would say instead:

Proposal #3: A is the same person as B iff A and B have the same brain.

But we won’t discuss this view until a few classes later.


Sam Miller objects to Proposal #2 with an argument much like the arguments Gretchen used against Proposal #1. He argues that, if Proposal #2 were correct, then it would be much more difficult to have knowledge or reasonable beliefs about personal identity than we ordinarily take it to be. One assumption that we ordinarily make is that one can have reasonable beliefs about one’s own identity over time, without having to check and see if one has the same body as one did formerly. But if Proposal #2 were correct, then it’s hard to see how we’d be entitled to that assumption (see pp. 19-21).

Sam also objects to Proposal #2 on the grounds that it seems possible for a person to wake up in a new body than he or she formerly occupied. Certainly we can imagine this happening. We can even imagine it happening to ourselves! But according to Proposal #2, this would not in fact be possible (pp. 21-22).

Proposal #4

The next proposal about personal identity will take several classes to introduce and evaluate…