Consider another sci-fi story. In this one, you get a one-way trip to Planet X. Maybe.
Aliens from Planet X, who possess Star Trek transporter technology, are among us. Of course our primitive sensors cannot detect them. They want to bring a typical human back to their planet to become their new king. They pick you. Five versions:
#1 Token but not type identity. They throw a net over you, put you in their space ship, and transport you to Planet X, where you spend the rest of your life as King of Planet X. No question that you are the same person—token identical—throughout the process, just as you would have been had you stayed on earth. The trip to the planet is traumatic and life changing. Therefore, upon arrival you are token identical but not type identical with the person you were on Earth. You’re the same person, but you’ve changed. You miss home. However, it’s good to be the king.
#2 Type but not token identity. They probe your body with remote sensors while you are sitting in your kitchen, tracking the position of every atom. You cannot feel this. When they carry the bits back to their planet, they construct a duplicate of you from local materials. When complete, this alt-you springs into consciousness. It thinks it is you. It thinks you have been mysteriously and instantaneously transported from your house to Planet X. The real you is still on earth and knows nothing at all about the alt-you. The alt-you is type identical to you, but not token identical. Whatever experiences the alt-you has on Planet X are unknown to you. Your life will continue here on Earth uninterrupted. The alt-you and the real you are two different entities, which start out type identical, then diverge since the rest of their lives are very different. The aliens make the alt-you king of Planet X. Obviously, you did not become king. A duplicate of you did.
So far, so good. Now for the puzzles.
#3 Same as #2, but sadly you die in a routine car accident shortly after the aliens duplicate you on Planet X. Now there is only one version of you, the alt-you about to become King. Does the existence of the type identical alt-you do you any good? Presumably not, you’re dead and no events anywhere can help you now. The coronation experiences of the alt-you will not be your experiences. It’s hard to see how your death can magically transfer your token identity to the alt-you
#4 Same as #2 but this time the alien sensors vaporize you during the probe. All your atoms stream up to the spaceship, along with the information about how to put them back together again. This is like the “original atoms” version of the Star Trek transporter. Upon reconstitution aboard the ship, the “new” person is type identical to you and thinks it is you. The original you at home is gone. Is the new you token identical to the old you? Are the dramatic experiences it has aboard ship your experiences? Answering yes is analogizing this to a high tech version of throwing a net over you and carrying your up to the ship. They make him king of Planet X. Did you become king, or did your duplicate? How is this different from #3?
#5 Same as #4 except the aliens do not bother with your original atoms. They have plenty of the necessary kinds of atoms in storage. They need only the information about how to put the atoms together. During the probe, you are vaporized and your atoms scatter to the four winds. Aboard ship, they use the information to reconstitute you out of the atoms they have handy. This is like the “local materials” version of the transporter. They make him king. Did you become king? Or is this just like #2 except they killed you during the process? If copying you as in #2 does not suffice for token identity, why should copy plus annihilation help?
So in which of the four versions did you — the guy presently right here on earth—become King? Definitely in #1, because you simply travel to Planet X in an ordinary way. Definitely not in #2. #3 appears no better than #2.
In #4 and #5, which are similar to the Star Trek transporter, we are not sure. Our intuitions might be stronger in #3, because in that version your original atoms are used for the reconstruction. Those atoms, at least, are token identical to those that constituted your body on earth. Does this guarantee that the reconstituted person is token identical, and not just type identical, to the person on earth? All atoms of the same element are type identical to each other. So why should it matter which hydrogen atoms are used in the reconstruction? One is the same as another. Plus, as Carroll points out, in our bodies “our atoms are lost and replaced all the time” without affecting our token identity. And we are nothing but those atoms.
Yet how are #4 and #5 any better than #2 or #3 for transferring your token identity to Planet X? A Star Trek style transporter does not transmit token identity? Only a ride in a spaceship will do that? That’s not what we have been thinking when we watched all the routine transports on Star Trek all these years.