Teletransportation paradox
The teletransportation paradox or teletransport paradox is a thought experiment on the philosophy of identity that challenges common intuitions on the nature of self and consciousness. It was formulated by Derek Parfit in his 1984 book Reasons and Persons.
If a person is somehow re-created, say by teletransportation, is the re-creation the same person?
The paradox
Derek Parfit and others consider a hypothetical "teletransporter", a machine that puts a person to sleep, records their molecular/atomic composition and relays the recording to Mars at the speed of light. On Mars, another machine re-creates the person, each atom in exactly the same relative position. Parfit poses the question of whether or not the teletransporter is actually a method of travel, or if it simply kills and makes an exact replica of the user.Then the teleporter is upgraded. The teletransporter on Earth is modified to not destroy the person who enters it, but instead it can simply make infinite replicas, all of whom would claim to remember entering the teletransporter on Earth in the first place.
Using thought experiments such as these, Parfit argues that any criteria we attempt to use to determine sameness of person will be lacking, because there is no further fact. What matters, to Parfit, is simply psychological connectedness, including memory, personality, and so on.
Parfit continues this logic to establish a new context for morality and social control. He argues that it is morally wrong for one person to harm or interfere with another person and it is incumbent on society to protect individuals from such transgressions. If that is accepted, it can be further concluded that it is also incumbent on society to protect an individual's "Future Self" from such transgressions; tobacco use could be classified as an abuse of a Future Self's right to a healthy existence. Parfit resolves the logic to reach this conclusion, which appears to justify incursion into personal freedoms, but he does not explicitly endorse such invasive control.
Older versions
The same thought experiment of teleportation to Mars and its effect on the person's consciousness appears in Daniel Dennett's introduction to the book The Mind's I. Elsewhere, that book's co-author Douglas Hofstadter, after describing the experiment itself, briefly discusses the question of whether Dennett and Parfit's versions of the story are a “clone” of one another or whether their pedigrees are independent, but does not ultimately come to a conclusion.The Polish science-fiction writer Stanisław Lem described the same problem in the mid-twentieth century. He put it in writing in his philosophical text Dialogs in 1957. Similarly, in Lem's Star Diaries of 1957, the hero visits a planet and finds himself recreated from a backup record, after his death from a meteorite strike, which on this planet is a very commonplace procedure. In chapter 6 of his later discursive book "Summa Technologiae", first published in 1964, he discussed in detail the identity paradoxes associated with teleportation and hibernation of human beings.
He presents two teleporters in exactly the way Parfit did later and shows that it is not possible for a person to experience being teleported. The original person experiences everything up to the scan or through the scan and for however long the original lives. The original never experiences being successfully teleported.
The copy has the memory of first being the original then continuing existence as the copy. If there are multiple copies, each has the same experience. Lem does not draw any conclusions as to whether any copy can claim to be a continuation of the original. He only says each copy would naturally make such a claim. This is the paradox: the original and the copy have different experiences, and from the viewpoint of the original, teleportation is unsuccessful.
Similar questions of identity were raised as early as 1775: