On Cohen and Miller’s analysis, Julia has had two bodies — her original one and Mary Frances Beaudine’s. Cohen and Miller agree that "Julia’s brain in Mary Frances’ body" must be Julia. In fact, most people, and the (fictional) U.S. Supreme Court, agree. The argument is that the brain is the seat of one’s psychological characteristics and memories — the elements that make one oneself. What matters here, then, is that Julia’s psychological states have been preserved, and hence Julia has been preserved. This person probably believes herself to be Julia, has Julia’s psychological characteristics, and thinks she has Julia’s real memories; furthermore, this person has Julia’s memories in the right causal way, because she’s got Julia’s brain. That Mary Frances’ body has been preserved simply does not matter, because bodily identity does not determine personal identity.

Weirob acknowledges that most people would think this is Julia. But Weirob disagrees. Weirob denies that Julia has had two bodies; Weirob thinks Mary Frances has had two brains. What matters for Weirob is that Mary Frances’ body is preserved. For Weirob, remember, a person is a live human body, and since Mary Frances’ body is still alive, this person is Mary Frances — not Julia, whose body is dead, and who is therefore dead, on Weirob’s view. A brain is a body part, after all. A person is not a body part. If my arm were cut off, no one would say I’ve ceased to exist — that my body without the arm is no longer me. I’m still the same person without my arm. In the same way, if my brain is removed, we shouldn’t say the body without the brain is no longer me. I’m still the same person without my brain.

The "WHO?" person only appears to have Julia’s memories, etc. She thinks she has Julia’s memories, but she is wrong because she doesn’t know who she really is. According to Gretchen, she’s really Mary Frances with a new brain. Gretchen is relying on our ordinary intuition that a person with a transplanted heart or kidney, for example, is still the same person. It would be absurd to suggest that a person who receives a transplanted organ becomes the dead person whose heart or kidney was donated.

The question is real, too, not just a matter of how we talk — aspirin example (41).

To Cohen and Miller’s astonishment, Weirob reveals that she has been offered the very same operation (a transplant of her brain into a different body), but has refused because she does not think the resulting person would be her!

What’s Weirob’s reasoning behind this surprising decision? It’s a version of the duplication argument from the Second Night. It’s an extended thought experiment.

Suppose, she says, that it were possible to duplicate one’s brain, preserving all information — like "Hubert" in Dennett’s story. Hubert, as you recall, existed only virtually; he had no body. Gretchen has in mind a duplicate brain preserving all information (like Hubert) but with an additional characteristic: unlike Hubert, this new kind of brain-copy could also be implanted in a living body. Got the picture? Weirob calls this a "brain rejuvenation."

Well, as a matter of fact, Weirob says, if she could have this kind of surgery, she would agree to it. She’d happily take a copy of her own brain, if it could be implanted in her own body. But alas, that surgery would require Weirob’s body to be healthy, and her brain in need of replacement — just the opposite of her current physical situation. But if it were possible, Weirob would agree to it, because she thinks she’d still be herself afterwards.

Weirob's brain (dies and is "rejuvenated")		Copy of Weirob's brain
in	-->	in
Weirob's body		Weirob's body

Here’s why Weirob’s-brain(copy)-in-Weirob’s-body is really Weirob. Suppose her brain were duplicated more than once, as shown below. One copy of her brain goes into her old body, resulting in Person #1. The other copy goes into a different body resulting in Person #2.