Thought Experiments

Originally Submitted by emil10001 on Fri, 11/26/2010 - 15:36

I was listening to some lectures by Shelly Kagan, where he is discussing the idea of self, identity and what do we follow to determine where the self is. He lays out three options, the soul, the body (more correctly, the brain), or the personality. He dismisses the soul argument as not being compelling, and I agree. He then says that he is sort of stuck on which to follow, the body or the personality. He provides a few thought experiments to try to tease out our intuitions. He offers Peter van Inwagen’s thought experiment counter to the body theory.

Here is that though experiment:

Suppose that my son builds a tower out of wooden blocks. We have a set of wooden blocks at home. Suppose that he builds some elaborate tower. It’s very impressive. And he says, “Please show it to mom when she comes home.” And he goes to bed. And I’m very good. I’m cleaning up the house after he goes to bed and oops, I knock over the tower. I say, “Oh my god, he’s going to be so angry. I promised him I’d be careful.” So what I do is I take the blocks and I put them back together, building a tower in the very same shape and the very same structure, the very same order as the tower that my son had built. And in fact I’m so careful–perhaps the blocks are numbered–I’m so careful that every block is in exactly the same position as in the case where my son built it.

All right, I rebuild or I build this tower and my wife comes home and I say, “Look what our son built. This is the tower that our son built.” Ah, that doesn’t sound right. That’s not the tower that our son built. That’s a tower that I built. This is a duplicate tower.

The idea here is that it’s not really the same body if it has been destroyed and rebuilt, even with the same parts, in some important sense. Kagan then offers a couple of thought experiments from Bernard Williams involving a mad scientist:

First experiement

All right, so case number one. Here you are. The mad scientist has kidnapped you and he says: I’ve been working on mind transfer machines. And what I’m going to do is I’ve got you and I’ve also kidnapped somebody else over here, Linda. And I’m going to hook you up to my machines and swap your minds. And what that means is, I’m going to read off the memories and the beliefs and the desires from your brain and read off the memories and desires and beliefs from Linda’s brain. And then I’m going to electronically transfer Linda’s memories and beliefs and so forth over here and implant them onto this brain. And take your memories and beliefs and so forth and implant them onto Linda’s brain. First, we’ll put you to sleep when we do all this procedure. Then when you wake up, you will wake up in Linda’s body.“ There’ll be something here that, you’ll wake up and you’ll say, "What am I doing in this new body? What happened to my beard? How come I’m speaking in this high female voice?” Whatever it is, but you’ll think to yourself, “Well, here I am, Shelly Kagan. I seem to be inhabiting Linda’s body. Don’t know how that happened. Oh yes, the mad scientist kidnapped me and he transferred us, he swapped us. He swapped our bodies, swapped our minds. I guess the whole thing works.”

So the mad scientist explains all of this to you, but in order to give it a little kicker, because he’s also an evil mad scientist–that may be evil already, but because he’s an evil mad scientist–he says, “And then when I’m done–” So over here we’ve got Shelly’s body but Linda’s personality. So Linda thinking “What am I doing?” and “What am I doing in Shelly’s body? How did I get a beard?” So over here, Linda, in Shelly’s body. Over here, Shelly, in Linda’s body. “I’m going to torture one of these. But because I’m a generous evil mad scientist, I want to ask you which one should I torture?”

Second experiement

Now, let’s tell a different story. Both of these stories, as I say, come from Bernard Williams. Bernard Williams says here’s another example we can think about. Mad scientist, again, kidnaps you, kidnaps Linda. And he says, “Shelly, I’ve got some news for you.” I’m switching between you and me. He says, “Shelly, I’ve got some news for you. I’m going to torture you.” I say, “No, no! Please don’t do it to me! Please, please, don’t torture me!” He says, “Well, you know, I’m in the mad scientist business. This is what I do. I’m going to torture you.” He says, “But because I’m a generous mad scientist, before I torture you, what I’m going to do is give you amnesia. I’m going to completely scrub clean your brain so that you won’t remember that you’re Shelly Kagan. You won’t have any memories of growing up in Chicago. You won’t have any memories of deciding to become a philosopher. You won’t remember getting married or having children. You won’t remember the–you won’t have any desire. The whole thing wiped clean, complete perfect amnesia before I torture you. Don’t you feel better?”

No, I don’t feel better. I’m still going to be tortured and now we’ve added insult to injury. I’ve got amnesia as well as being tortured. No comfort there. “Well,” he says, “Look, I’ll make the deal sweeter for you. After I give you amnesia, before I torture you, I will drive you insane and make you believe that you’re Linda. I’ve been studying Linda. There she is. I’ve been reading her psychology by looking at her brain waves and so forth and so on. And so I’m going to delude you into thinking that you’re Linda. I’m going to make you think ‘Oh, I’m Linda.’” You won’t talk like that. “Oh, I’m Linda.” “And you’ll have the memories of Linda growing up in Pennsylvania and you’ll remember Linda’s family and, like Linda, you’ll want to be an author, or whatever it is that Linda wants to be. And then I’ll torture you. Are you happy now?”

No, I’m not happy now. First of all, I’m being tortured. I was given amnesia. And now you’ve driven me crazy and make me–deluded me into thinking that I’m Linda. No comfort there. He says, “Okay, last attempt to make–you’re not being very reasonable,” he says. “Last attempt, I’m going to, after I drive you crazy and make you think you’re Linda, I’m going to do the corresponding thing for Linda. I’m going to give her amnesia and then I’m going to drive her crazy and make her think that she’s Shelly. Give her all of your memories and beliefs and desires. Now is it okay that I’m going to torture you?”

My personal view is that as soon as you destroy the information on your brain, you no longer exist. The person who thinks that they are you is just a copy. I think that it would be interesting to add in the term ‘copy’ or 'clone’ in the above experiments, when talking about the body containing your personality, to see if your intuitions change. I have thought up a bit of a twist to Bernard Williams’ experiments:

Smith has decided to murder his neighbor. But, before he does, a mad scientist has kidnapped Smith and Jones. The mad scientist hooks up Jones and Smith to a machine that he says describes as a brain swap machine. The way the machine works is that it reads does a complete brain scan of one individual and writes that information onto the brain of the other individual. The same is done in the opposite direction. There is no movement of the physical brain. He does the brain swap, and then releases both individuals. The body of Jones goes out and murders his neighbor. Who is responsible?
A mad scientist has kidnapped Jones and Smith. The mad scientist hooks up Jones and Smith to a machine that he says describes as a brain swap machine. The way the machine works is that it reads does a complete brain scan of one individual and writes that information onto the brain of the other individual. The same is done in the opposite direction. There is no movement of the physical brain. He does the brain swap, and then releases the body of Jones on the condition that he go out and commit a murder. Who is responsible?

Original responses on Reddit.