How should we understand the teletransportation thought experiment?



Please read the short story here:Beam me up

First, I'd like to to know whether there is anything inherently inconsistent about this teletransportation idea? Is there fundamental reasons which say it's impossible in principle?

If not, what seems puzzling and absurd to me is this:

What matters to him is that, as far as he is concerned, he walks into the booth and wakes up on another planet. The physical mechanism is irrelevant... consider for a moment the possibility that one night, a few years ago, you were kidnapped in your sleep, processed by the teletransporter, and the resulting person returned, unknowing, to your bed. Had this happened, you would have no way of telling, because your conscious experience of your ongoing life as a continuing being would be exactly the same if it had not happened. The fact of teletransportation, in some sense, leaves your life and world exactly as it was. Perhaps then to ask whether Stelios is a clone or 'the same' person is the wrong question. Perhaps we should instead ask what matters about our past and future existence. And maybe the answer to that is psychological continuity, by whatever means necessary.

But presumably, whatever technology (or mechanism or whatever) that allows such a set of "cut+paste" operations shall also allow a less fatal "copy+paste" command, in which the target human is scanned but remains intact, and his exact copy reconstructed elsewhere as before. By the preceding paragraph, if it is true that by "cut+paste" the person "walks into the booth and wakes up on another planet", then if that person is told he's going to be cut+pasted, while in fact he's just momentarily rendered unconscious and copy+pasted, where should he find himself when he wakes up? The one on the earth, when he wakes up and discovers the truth, shouldn't he find the existence of his "paste" on a remote planet almost irrelevant? I mean, the two persons remain totally ignorant and detached of each other's thoughts and feelings. But the "paste" is exactly the same in the "cut" case as in the "copy" case. If it is irrelevant here, how could it possibly be relevant in the preceding paragraph? The paste will always have his thoughts, feelings and consciousness all inherited from the original, but that is totally irrelevant from the latter's perspective. Similarly, as soon as the paste springs into being, the original becomes sort of "external" to him, too.

Ask yourself if you are willing to undergo such a transportation! I am definitely not! But several people I spoke to say it doesn't matter if the machine can reconstruct them "100% correct".

I'm not sure if the above argument and conclusion are correct. Hope someone could help me straighten out my concept and logic.

Edit: Thank you for the answer and comments. With regard to @stoicfury's answer: What I want to know is what would such an experience look like from the first person perspective? To be specific, let's say when you are dismantled while in sleep and a duplicate reconstructed sleeping in your bed. Should it feel like (1)you sleep and never wake up (like dead) or (2)you sleep and wake up just as normal (like nothing happens)? Although it seems absurd to me, but by any reasons, could we expect (2) to be true? If we believe (as I almost do) that our thoughts and feelings and consciousness itself all emerge out of the physical activities of our brains in space and time, shouldn't we also accept (2) as true, because by definition of the process, the physical activities of the brain out there is the same in the same space-time in the case it has been dismantled and reconstructed as in the case nothing happens? The inconsistence to me is that by common sense and the reasoning before this edit, I will accept (1) instead.

Of course, one notice that by the dismantle-reconstruction process, one destroys the continuity of one's physical existence. I think this may hold the key why (1) instead of (2) is true.

2nd Edit: With regard to stoicfury: Yes, I use sleep as a metaphor for total unconsciousness.

...there would be no experience of anything between when you died and until you regained consciousness... your body was scanned into the machine, they killed you, and held onto you for a billion years before sending you to Mars, when you woke up it would feel to you as if no time passed at all...

It seems to me you already implicitly assumed that the person before death and the one later constructed is the same person (whatever that means), so when he's killed/dismantled, he's somehow still there, only devoid of consciousness and experience, waiting to "wake up" or "regain consciousness". It is true that for the duplicate later constructed (exactly how much time later is irrelevant, for the reasons you put forward in your answer), he will "wake up" and feel like a dreamless night has gone by and see nothing wrong. But for the original, my understanding is that the fact that a duplicate is constructed after his death is irrelevant. He should feel like he goes to sleep but never wake up (like dead). It is for this reason that I think (1) is right. For the duplicate, surely (2) is right.

My point was, could it be possible that (2) is right even for the original? And I gave my argument there.


Posted 2012-03-20T13:19:40.430

Reputation: 323


Dan Dennett talks about this thought experiment in detail in the introduction to The Mind's I (text here: ), of course naturally, as with anything so speculative, it results in more questions than answers...

– Tom Boardman – 2012-03-20T13:47:42.963

What a coincidence! I had thought of (or maybe heard of) this kind of teleportation, and I totally agree with you. Definitely not! I agree with your logic, and I'm interested in what the answers will say. – commando – 2012-03-20T14:11:53.987


There is a light-hearted animated film that grapples with this thought experiment here:

– Michael Dorfman – 2012-03-20T16:46:34.263



It's not entirely clear to me where you're having difficulty but I will attempt to go over the thought experiment and provide some clarity.

Note that this experiment depends on monism (e.g. physicalism) unless the teletransporter can copy "non-substance" as well.

So the assumption is that everything that makes you you is based on the physical location of particles that make up your body and brain. More precisely, that our psychological continuity -- the (relatively) uninterrupted flow of our memories -- is what we identify ourselves with. Scanning the position of every particle in your body and duplicating you elsewhere would create a functionally equivalent copy of you. Your personality, memories of your life, everything would be the same as the original you. So it is you in the psychological sense, but our personal identity requires more than just our personalities and memories in order to uniquely identify us, as this thought experiment demonstrates.

The other component besides function is form, and what would identify the original you as you is the physical matter that your body consists of. Again, since this matter would be perfectly duplicated it would be hard to tell who is who if the copy stood next to the original. But this is no different than you accidentally getting confused who's coffee cup is who's when you sit down at a table; the point is that there is actually one that is yours, even if the cups appear exactly the same. That is, there is one that is and will always be the original, whether or not you have the means to discern it or not. Time, in this case, will always be an inherent identifier.

And note that as soon as you are duplicated, the other person starts having distinct experiences from the original, and in all relevant senses becomes his or her own person. They would still be very similar to you, for a long time I might imagine, but that is no different than it is today. So would it be murder if you killed the original? It's a semantics game. Yes, you are arguably killing someone who is uniquely identifiable and thus his own person. But they likely consented to the teletransportation, so they must've been aware of how it works, even if they were too dim to fully grasp what it entails. I suppose you could file that the consent of teletransport passenger was invalid because he or she was not fully informed, but this is getting into legal-speak and out of philosophy. I imagine, however, if a system like this gets invented, many people will have no problem with it; the analysis is indeed correct that, if we live in a universe governed by physicalism, taking the transporter will appear instantaneous -- as if one moment you were on Earth and the next on Mars.

Essentially the entire "thought experiment" is just a fancy way of asking "what is personal identity?"; the SEP article covers it fairly well.

EDIT regarding the OP's update:

You write:

What I want to know is what would such an experience look like from the first person perspective? To be specific, let's say when you are dismantled while in sleep and a duplicate reconstructed sleeping in your bed. Should it feel like (1)you sleep and never wake up (like dead) or (2)you sleep and wake up just as normal (like nothing happens)?

To begin, option (1) is not a good analogy because sleep is not a complete loss of experience; since your brain is still active you can still experience things (dreams, nightmares) and have memories of them when you wake. If the teletransport technology you speak of existed, you would at one moment be awake on Earth and the next you would be awake on Mars; there would be no experience of anything between when you died and until you regained consciousness. It is very important to note that this is irrespective of how long it actually took to transfer you to Mars. Our experience is continuous — we don't experience things when we are otherwise incapacitated — so even if your body was scanned into the machine, they killed you, and held onto you for a billion years before sending you to Mars, when you woke up it would feel to you as if no time passed at all. Why? Because you did not experience that time. It would just as if you were instantly frozen in a block of ice; your experiences would halt immediately. Any number of years could pass: one, a thousand, a million, it doesn't matter because you're not aware of it, so when you were unfrozen, it would appear to you as if you were just frozen only moments before. Bottom line: You can't experience things when you're dead / your brain is inactive. So (2) is essentially the correct answer, but be careful with the notion of "sleep" for the reasons I mentioned before. They may very well put you to sleep for the procedure, in which case it would feel like any other dreamless night -- like we went to bed and woke up right away. But it is easier to understand what would occur using the "being frozen in ice" example, as it is clearer that experience is completely halted.

EDIT 2 for OP:

It seems to me you already implicitly assumed that the person before death and the one later constructed is the same person...

Actually I avoided that question because you asked for what the experience would be like. So the person on Mars, whether or not you decide he's a new person or the same person as the one who's body was just destroyed, he would feel as if he was in one moment on Earth and the next on Mars. That's what his experience would be like. The debate about whether this person is in fact the same person or someone new is a separate issue from the phenomenological experience this man has, and it will depend on your particular views on what makes a person a person. For example, some people say that your body must be in tact, but what if you lose your arms and legs in a war, are you now 50% less the person you were before? What if I told you that your cells are constantly dying and new cells are replacing the old ones, meaning your body is made up almost entirely new physical matter every time a full cycle of new cells replaces the old ones. So most people recognize it's not just a body that makes us us, but also perhaps our personality and memories. But the problem is that our personalities do change over time, sometimes very rapidly due to trauma or mental illness, and our memories are often fragmented or forgotten entirely. Does that mean we are a different person? Some people want to think that we are the same person; others think that we are for all intents and purposes a new person if our entire personality were to change and memories lost. But again, all this is irrelevant to how the person would experience such a teletransportation device.

In my own personal view, I think it's easiest to rest under the notion that we are at every moment new persons. We are constantly changing, constantly learning and adapting, and while from moment to moment we may appear similar, it is unnecessary to force ourselves into thinking we are the same "thing" all the time. We are not the same and I'm grateful, otherwise life would be very boring. :P

Although this is my personal view and I came to it independently, this is not "novel" way of looking at it. Pre-Socratics such as Heraclitus (535–475 BCE) even toyed with this idea, writing:

No man ever steps in the same river twice, for it's not the same river and he's not the same man.

I hope that helps.

EDIT 3 regarding OP's comments below (I suppose I ought to streamline this whole answer at some point):

You write:

If you kill the original after his duplicate is made, you'll find the inconsistency of those who "have no problem with it": If you make the duplicate, wake the original and ask him, "Now that your duplicate is made, would you live up to your promise and get killed?" I doubt any of them will agree anymore. But everything is the same as when they agreed with the plan, except that the original now needs to be killed in order to be in full agreement with it. If they don't want it now, what could possibly explain the fact that they "have no problem with it" before, if they reason consistently?

There is no real inconsistency there because the two situations are different. In asking to be scanned, destroyed, and transported to Mars, you are asking to have yourself be moved from one point to another (via duplication). You are fine with this because even though you will be killed and have a new body on Mars, your identity will be consistent (there is no doubt who YOU really are) and will feel as if you are the same person psychologically. And that's ok, because that's all we can ask for. I don't mind going to sleep and having a gap in my consciousness because even if my body was secretly duplicated in the middle of the night, I feel like the same person.

But when you do the duplication process but don't delete the original, now you have two distinct beings. Two distinct beings whose body's and minds are their own now (even if they are almost exactly alike). Asking if either would like to volunteer to die is not the same thing as the original scenario. I bet either of the two individuals would agree to the teletransportation process again (the original version) because again they would feel like one continuous being. That is not the same as asking one of them to voluntarily end their life (and not continue their being).


Posted 2012-03-20T13:19:40.430

Reputation: 11 008

Just hoping for a confirmation: you did note that monism is the premise for this argument. From the dualist point of view, would (1) be the accepted theory? I would expect so, because of the whole "identity" issue. – commando – 2012-03-21T15:05:03.103

2Well no it still wouldn't be (1), because even if the particular form of dualism allowed you to experience things without a physical body, you still wouldn't experience what it's like to "never wake up". Your experience is still continuous in dualism (you don't know what it's like to not experience something, i.e. to "never wake up" because you have to be awake to experience it...). So if dualism simply presumes more than merely 1 substance, but you cease experiencing things when your physical body dies, then the experience would be the same as it was for the physicalist. – stoicfury – 2012-03-21T17:09:38.917


I used to discuss this exact issue with my brother a few decades ago. I think it was all sparked off by the Star Trek transporter room.

He was always of the opinion that if he could be "digitised" and re-created, the new entity would still be "him", but I always disagreed. I wish I'd known then about David Deutsch's use of the word "fungible" (in my answer there) - unlikely, since I think he only "coined" it last year, but it would have been just the word I was looking for. Well, it is, now.

So far as I'm concerned, my body is inherently not "fungible" - it's the only one I've got, or indeed can have. Suppose a totally trustworthy doctor/scientist told me I had an incurable condition which would inevitably kill me suddenly, 3 months from now. And that he could digitise everything about me (including current brain state) today, and after 3 months working out the practicalities, create a new "me" from the digitised copy - identical to me today in every respect except I wouldn't have that incurable condition.

Did I forget to mention the other thing? The process of digitising me would unavoidably destroy the original.

So - would I give up my last 3 months of healthy life, in order for someone very like me to have perhaps decades of future life? Partly because of social conditioning, I can imagine that I might do this if "someone" was my child - but for another "me"? No, I wouldn't (luckily, I could expect him to understand my position).

I know that technically speaking every time I fall asleep, I've no certainty that the person who wakes up in the morning is really "me", but solipsism taken to that level seems a bit pointless.


Posted 2012-03-20T13:19:40.430

Reputation: 373


This begs the question of what is your body. You are shedding cells all the time, and gaining new ones, which leads us straight to the Ship of Theseus (

– Michael Dorfman – 2012-03-21T07:58:13.627

@Michael Dorfman: You may as well ask *"what is your consciousness?"*, given that it disappears every time you go to sleep, and reappears/is recreated every time you wake up. As I said, you reach a certain point where it's just an even more extreme form of solipsism. Not only can you only know the self exists - you can't even say it's the same self it was at any particular point in the past, either physically or in terms of how the "network" is configured. – FumbleFingers – 2012-03-21T15:16:57.293

"What is your consciousness?" is a very good philosophical question, and one that has been grappled with for millenia. You keep mentioning solipsism, but this is not about that at all-- it is about the nature of the persistence of identity over time. The standard solution is to say that physical continuity is the identity condition for physical objects, so the Ship of Theseus at the time of arrival is "the same" boat as the Ship at the time of departure, even if none of the components are the same. If this is the standard we use, then the reconstituted, transported body is the same body. – Michael Dorfman – 2012-03-21T15:32:43.757

@Michael Dorfman: I understand your point - in the British sitcom "Only Fools and Horses", Trigger proudly holds up a paintbrush left to him by his father 25 years ago, saying "I know it's had 20 new brush-heads, and 10 new handles, but it's the best brush I've ever had!". But my point is that - notwithstanding philosophical musings over "persistence of identity" (of body, consciousness, mental characteristics, whatever), I would not "swap" my body in the circumstances outlined in my answer. If you think that answer doesn't address the question, so be it. – FumbleFingers – 2012-03-21T16:34:34.253

2I guess what I am raising is how we'd tell the difference between this you and this someone very much like you; if the current brain state (and all memories, etc.) are indeed kept intact, this could have already happened to you several times in the past, and you wouldn't know the difference. You say your body is not fungible, but how would you know? – Michael Dorfman – 2012-03-21T17:25:28.890

2Well you obviously couldn't tell the difference, because as I said the "new me" would be an exact copy. And the old I couldn't tell the difference, since I'd no longer exist. But the "new me" would know, since his memories would know everything about me up to the point where I was "extinguished". And since he'd think like me, he would obviously agree that he was not me, at the level we're talking about. But he'd probably not keep banging on about this, since he'd feel guilty about my demise (I know he would, because I already know exactly how he'd think! :) – FumbleFingers – 2012-03-21T17:52:57.247

@FumbleFingers: This last comment precisely expresses my understanding of this matter, too. Please have a look at my second edit for it. But to be honest, with this view, what's stopping you from thinking that you experience the same demise everytime you fall out of consciousness, too? – Eric – 2012-03-22T02:34:41.957

1The irony and inconsistency of those who agree with such plan is this: If you make the duplicate, wake the original and ask him, "Now that your duplicate is made, would you live up to your promise and get killed?" I doubt any of them will agree anymore. But everything is the same as when they agreed with the plan, except that the original now needs to be killed in order to meet full agreement with it. If they don't want it now, what could possibly explain the fact that they wanted it before, if they reason consistently? – Eric – 2012-03-22T03:32:37.893

@Eric: You're focussed on "self", and forgetting other people. Every morning, I believe I'm still the same person I was last night, because other people tell me that. If they told me I was created from a digitised copy made 3 months or a billion years ago, I guess I'd have to believe that. If they didn't tell me that, they'd be lying, and it would be a meaningless future existence. Your mind is a matrix of codes given "reality" by being instantiated on a physical substrate, but also by virtue of its ongoing interrelationships with other minds, without which you are nothing meaningful. – FumbleFingers – 2012-03-22T03:39:24.640


To continue your computer analogy (copy-paste). In software, identity of entity A is impossible to express without at least one namespace NS. Namespaces are strong unambiguous global/universal unbreakable agreements of everyone who is a witness of entity A about expressing which one of any is A, for the timespan T which is usually eternity. Namespaces serve as discrete sets containing identities. The containment once started never ends. This is just an agreement, it includes all possible witnesses in infinite future and for simplicity the agreement considered to be applicable "once and forever and for everyone ever".

For example the domain naming system of internet contains unique names of web sites. It is absolutely possible to replicate an individual host down to last bit. It will be functioning perfectly, but only on one condition, if witness will create and access it using another new internet.

The thought experiment can be extended to, say situation that part of humanity was not aware about existence of internet and one morning was presented with exact copy. They will never discover that it is genuine or not, but for someone, who knows the truth, the identity will be resolved by simply merging doubled namespace into single larger namespace: and

Back to teleportation: In the story with person the key element is existence of person with knowledge of fact that cloning did happen, the role of observer is to supply absolutely required numeration attribute for "clone 1" and "clone 2". If somehow this knowledge does not exist, and fact of identicality of persons will be discovered it will have no more consequences than discovery of 2 completely identical ants or coins. Because a numeration or some equivalent will be naturally forced on both clones. The difficulty for clones themself will be no greater than for a 2 year old child to discover another child with the same "First Name", so the "Last Name" will come for the rescue.

My answer is that: Identity is just a fully qualified name. If you are alone in the universe, then you do not need the name. Name is a public resource. And it is infinite resource.

Note: when I use the word "Identity" in this context I mean also "Self", "Name", association of "Name" to "Self", Essence, Person, Mind, Entity, etc. whatever is pleasing you.


Posted 2012-03-20T13:19:40.430


If someone had a 'New Me' made by 'tele-transportation' FumbleFingers said it would be an exact copy. But what does that mean? Would the New Me be an individual Human Being in its own right or would it in its outward behavior have to do the exact same things as the 'Original-Me'? Would the New-Me be capable of 'causing' its own internal sequences of neuronal activity that is not identical to the Original-Me? – user128932 – 2014-08-15T03:56:24.873


The is how you should understand this thought experiment: it is an intellectual game from which no useful or otherwise valuable insight can be gained.

The game starts by making absurd assumptions (the possibility of making a perfect copy of a person is absurd), proceeds to endless pointless questions which have multiple contradictory answers that cannot be resolved. Every question posed has multiple answers and every possible answer is impossible to verify.

This thought experiment is just entertainment. Fine as a diversion until you get tired of it, but not as much fun as white water rafting.


Posted 2012-03-20T13:19:40.430

Reputation: 149