…and the self that remains when memory is lost.
This is the concern of cryonicists: what is the nature of identity?
If you don’t have any recollection of your own past, are you still you? If you forget who you are, but have maintained a record of your life, when you go back and read it and refamiliarize yourself, are you “you” again? If so, why wouldn’t anyone who read it become “you”? And if that is “you,” then why not just clone yourself and educate the clone with your memories? Intuitively, it feels like it might be someone else who thinks it’s you, but it’s not really you. Of course, Star-Trek-like teleportation has the same problem — is the person who stepped out of the transporter you, or a physical copy of you with the same memories? Is that continuity sufficient? How does it differ from the you that went to bed last night and woke up this morning (or in my case, the several mes that woke up repeatedly during the night)? Is that the same continuity, or one different in kind?
I’m sure that I’ve told this story before, but years ago, at the California Science Museum in Exposition Park, there was a display on health and medical ethics and it had various questions to poll the visitors. One of them was:
You have an inoperable brain tumor. If a donor became available because their body had failed, would you accept a brain transplant to save your life?
An astonishing number of people said “yes.” Which means they apparently had difficulty with the concept.
Honestly, I might say yes as well. It might not help me, but their is no reason for both of us to die.
But that wouldn’t be to save your life — it would be to save someone else’s.
I had an aunt who suffered a stroke late in life. She was a bubbly, vivacious person whom everyone loved and loved to be around. After the stroke, everything about her was exactly the same except for one thing: she had absolutely no emotions. And it wasn’t like Spock, who merely repressed everything. She had none whatsoever. Star Trek never achieved the portrayal of an emotionless person in Spock, but I’ve seen it first hand — and it is quite unnerving.
I am convinced that the “soul” is the sum of the experiences a person has had encoded into the brain, and that loss of any part renders a person a completely different person.
I think Robert Heinlein tossed some theories out about that one in one of his later novels, now didn’t he?
Start there.
At any rate, if you were a “donor” body, you’d probably not know it. Those inoperable brain tumors tend to swarm on you before they kill you, as often as not.
The nature of identity is an old problem. Here is Wikipedia on the Ship of Theseus.