Reasons and Persons: The case against the self
You want to go to Mars. There’s a machine that will scan and destroy all the matter in your body, send the locations of every atom to Mars, and then recreate it. You worry: Does this transport you, or does it kill you and make a new copy?
Still, your friends use the machine and they seem fine. And you figure you’re a pattern of atoms, not the atoms themselves, so you decide to take the machine. After you press the button to start it, you’re surprised to find that you’re still on Earth. You ask the technician, “Did the machine fail?”
“No, no”, he responds, “Did we not tell you? The new scanner records your blueprint without destroying your body. Not to worry, we’ve already transmitted the information to Mars. This body will be destroyed in a few minutes.” You see that the final effect is the same. But still, are you upset about this?
You’ve probably heard some version of this thought experiment before. It originally comes from Derek Parfit’s 1984 book Reasons and Persons. He claims to answer if you’re being transported or killed. (Though you may not like the answer.) He then uses that answer to reflect on how to think about your future self, abortion, the morality of prisons, and your own mortality.
Let’s start with three “spectrum” arguments that are reminiscent of the ship of Theseus or the sorties paradox.
Napoleon’s surgery
You’re going to have a painful surgery, for which you must be awake. But before the surgery, a doctor will use a machine to make your neurons fire so that your personality and memories are completely replaced with those of Napoleon. Does this make you less worried about the pain during surgery? Will it be Napoleon who suffers rather than you?
Or, suppose there is a dial: At one end it does nothing, while at the other end it replaces all your memories with those of Napoleon. At what intermediate position do you stop being you and start being Napoleon?
The death machine
Scientists are going to subject you to another machine with a dial: At one end, nothing happens. At the other end, 100% of your cells will be destroyed and replaced with exact duplicates. As the machine is about to start, you wonder, “Am I about to die?” Would that be true if 1% of your cells were replaced? 30%? 90%?
The Garbo maker
Scientists are going to subject you to another machine with a dial: At one end, nothing happens. At the other end, 100% of your cells will be destroyed and replaced with those of Greta Garbo. At intermediate positions, the resulting body, memories, and personality will be a mixture. At what position at which you stop being you and start being Greta Garbo?
Parfit answers these questions through an analogy. Say there’s a club that meets for a few years and then stops meeting. A few years later, most of the same people decide to get together at the same place and hold meetings under the same name.
Now: Is that the same club, or another club?
Parfit calls this question “empty”. This means that without answering the question, we already know everything that has happened. If you do answer the question, that will be you deciding what “same club” means, not you discovering any new facts about the situation.