In the Twilight Zone one can often shop for items not usually thought to be available for purchase. In “I Sing the Body Electric” a family shops for a replacement grandmother. In “The Trade-Ins” an aging couple shop for replacements for their aging bodies. The difficulty they face is not metaphysical, but economic: The Holts simply cannot afford to buy two replacement bodies. They have the cash for one transformation only.
After he almost loses all his money trying to double his savings in a card game, Mr. Holt agrees to have get a new body, leaving his wife to wait until some unspecified future time for her transformation.
When Mr. Holt comes out of the transformation, in a new, young, spritely body, is he still Mr. Holt, or is the resulting person someone else? Every indication is that he is: He recognizes his wife, talks of their plans, and though he’s lost his accent, the operation was a success. If we have any doubt that the old Mr. Holt is waiting in the wings, and this is an imposter, that doubt is set aside when we see a dead Mr. Holt body being wheeled out of the operating room.
What makes it plausible to think that Mr. Holt survived the shedding of his old body? The philosophical question is the genetic one: Could one survive a change from one body to another? If you traded in your body for a new one, would you still exist? Mr. Holt gets a young, vibrant body, but that thought experiment doesn’t make it easy to infer that Mr. Holt survives, since he seems, at least outwardly, so different from his former, elderly self. To aid our intuitions here, it might help to consider a range of possibilities:
- Mr. Holt gets his body overhauled. It isn’t a completely new body, but has lots of new parts replacing the old parts.
- Mr. Holt gets a new body, but it looks just like his old body. (For the purposes of the story, we can imagine that while it looks like his old body, it no longer has the illnesses that made him want a new body in the first place.)
- Mr. Holt gets a new body that looks something like his old body, but it’s clearly a younger model. Perhaps it’s based on Mr. Holt’s body as a younger man.
- Mr. Holt gets the young body as shown in the episode, but with this difference: They placed his original brain in that new body. Thus he has a new “shell” body, but his original “core” body.
- Mr. Holt gets the young body as shown in the episode, presumably with a new brain as well. His memory, beliefs, desires, etc. have been transferred from his old brain to the new one. This is the scenario presented in the episode.
If you think Mr. Holt doesn’t survive in case 5, what do you think of case 1? Do individuals who have heart transplants retain their identity? As you consider this range of options, try to articulate the principles you’re using to guide your judgments of identity, and think about whether those principles give you plausible judgments in other possible cases.