I think the answer is yes but I know a lot of people disagree. So, I would like to ask these people when exactly does it stop being me.

Let's say I want to upload my brain into a computer using the following procedure:

I have each of my neurons replaced by electronic neurons. By electronic neurons I mean chips with the necessary hardware and software to perform the exact same function that the neuron being replaced was performing. This means that given the same inputs that the biological neuron was given it would produce the same outputs. Then I connect that electronic neuron to all the neurons that former biological neuron was connected to.

At the end of this process is it still me? If not when did it stop being me? When one neuron was replaced? When 1,000 were replaced? When 1,000,000 were replaced?

(assuming it is still me) Then, I divide these electronic neurons into groups and for each group I perform the following:

  • Write software to simulate the group of electrical neurons in my computer such that given the same inputs that go into the group of electronic neurons in my brain, it will produce the same outputs.

  • Replace each group of neurons with another chip that communicates with my computer. Each of the chips will communicate to the corresponding software module in order to determine how to transform its inputs into the necessary outputs.

  • Connect all of the inputs and outputs of the group of electronic neurons to that new chip.

At the end of this process is it still me? If not when did it stop being me? When one group was replaced? When 1,000 were replaced? When 1,000,000 were replaced?

(assuming it is still me) Now, what I have is a bunch of these new chips in my head, connected to each other and for each of these chips I have a small neural network software module in my computer. So, now for each pair of chip/software module I do this:

  • Transfer all connections going into and out of the chip into the computer version (i.e. connect the software module to the other software modules that represent the other chips that this chip is connected to)
  • Disconnect the chip from the other chips and remove it

At the end of this process is it still me? If not when did it stop being me? When one of the new chips was replaced? When 1,000 were replaced? When 1,000,000 were replaced?

If it is still me then I have successfully moved my brain into a computer without ceasing being myself.

So, again the question is if at the end it is not me anymore when exactly does it stop being me and why does it stop being me?

EDIT: This question assumes that our universe and everything in it (including ourselves) follows the (testable) laws of physics. As it stands it also assumes that neuroscience is mostly right, although the question could also be considered without that requirement if instead of neural simulations we were to implement physics simulation of the brain. Of course this is a lot less practical. However, if your view is that our minds have a supernatural component then the question does not make any sense.

It was also pointed out that this is related to the Ship of Theseus, i.e. is something still the same if all its parts have been changed. With regards to that I think it is useful to consider that most of the cells in our body (not including brain cells) are regularly replaced anyway and some people even get entire organs replaced. Yet, we don't say that they stopped being themselves. Note, however, that if you are assuming a supernatural component of the mind that this explanation is not really adequate or relevant.

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    You should probably be careful to avoid asking leading questions like "Am I Still Me?". It makes your puzzle sound like you already have an answer. You might try asking the question from an external perspective. Also, there are two aspects to this question, and it makes sense to pull them apart if you look at it more objectively. Firstly, given the identity of a person A, does this process allow for the persistent identification of A? Secondly, does the process allow for the persistent identification of A's Brain? – Paul Ross Aug 12 '12 at 4:32
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    this seems to be basically identical to the ship of Theseus? – Dr Sister Aug 12 '12 at 5:21
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    @digitalbrain, that's one possibility we might allow. I was thinking that the result of doing all this to some initial person A might still be identified as that same person A, but that you've destroyed the only reasonable thing that might be identified as A's brain in the process (if we think that brains are biological organs, we might say person A had her brain removed in the course of the procedure ). This is a possibility if personal identity doesn't solely depend on facts about a person's physical organs. – Paul Ross Aug 12 '12 at 15:28
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    I want to answer this question, but there's just so much here. One can easily take an entire course on "The Self" and only touch a fraction of the literature out there... – stoicfury Aug 14 '12 at 4:00
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    'uploaded' is quite a "loaded" term, if you forgive the pun – user35983 Feb 17 at 21:22

15 Answers 15


My friend, you stopped where things get really interesting.

The result of the process you described is a human consciousness whose substratum is a computer program instead of a bodily organ. Much more importantly, you did the transformation in a way that preserved what I call the continuity of consciousness.

Let's assume that this computer program is implemented as a single (say, Unix) process running in the operating system of an immense computer. Now, in Unix, processes can very easily be stopped and later continued from that point.

What are the implications of this? Will my continuity be preserved if the process that "performs" me is stopped for a second? (Presumably yes, a human's biological substratum can be suspended for seconds, even minutes -- would a grand mal seizure interrupt the continuity of the consciousness?) Or a year? A century? A million years? And "where" am I when the process is sleeping? (Another argument would be that a

A process suspended is just a heap of data sitting in RAM (or in swap!). Now, even everyday desktop computers can be hibernated. During this process, the whole memory image is written to disk, and the machine powers off. Then, maybe years later, the machine is started, the image is loaded back, and the programs run from where they left off. In this case, it is even more evident that the computational substratum can be reduced to a series of numbers -- or, to make things more dramatic, a number, since any amount of digital data can be regarded as a single (very large) integer.

So, the continuity of you can be preserved in a number.

This is where things really start to get out of hand. A hibernated system image can be resumed at the same time on any number of computers. Now, which one would be you?

My current answer to this paradox is that there is no such thing as continuity of consciousness, it is an illusion. You are bound to the single instance in time and space of a process that creates a consciousness.

Chapter 2: what criteria does an algorhythm/natural phenomenon need to fulfill to cound as such a process?

  • Nicely put! The principle of processes on a computer and cloning the entire computer to more (virtual) computers is a great model to derive answers for a lot other questions as well. – Mike de Klerk Aug 25 '15 at 16:23
  • Have you read the short story "Dust" by Greg Egan? – ekl Feb 18 at 21:42

Your neurons are constantly turning over their component molecules, changing synapses in response to input patterns, and so on. You are, at a neuronal level, not exactly yourself after a matter of minutes, much less decades. Given that you postulate an exact algorithmic copy implemented in a different way, and therefore that computer-you is more like real-you-now than real-you-now is like real-you-in-a-year, of course one must say it's still you.

Or one can invent unobserved phenomena that prevent you from retaining identity (souls, dualism, etc.), but this would be an evidence-free leap. So at least we can say that there's no reliable evidence to indicate that you wouldn't be you throughout the entire transformation.

Of course, this is hypothesizing the existence of technology that might not even be physically possible. So it's likely to remain a thought experiment for a very long time (perhaps always).

  • 'therefore that computer-you is more like real-you-now than real-you-now is like real-you-in-a-year, of course one must say it's still you.' I think not: 'real-you-now' is the real-you that will later become 'real-you-in-a-year'. The computer? Not necessarily so. – Vector May 10 '13 at 23:36
  • @Mikey - Those atoms that are the real you now need not be part of you in a year; the chain of identity might also be broken so that there is nothing idetnifiable as you. You might die, for example. No fundamental difference, therefore, between physical and digital implementations. – Rex Kerr May 11 '13 at 18:13
  • Understood. But that doesn't make it "more like real-you-now", only equal, since the future is indeterminate, to both the computer and 'the real you'. – Vector May 11 '13 at 21:30
  • @Mikey - Nihilism notwithstanding, an exact algorithmic match is closer than an approximation. Did you miss the "a year from now" part? – Rex Kerr May 12 '13 at 6:01
  • Certainly did not miss it. That's the whole point of the question. "an exact algorithmic match is closer than an approximation"?? The 'approximation' is the 'real you' - the 'real you' is an organic system, not an exact algorithm! – Vector May 12 '13 at 6:39

Your question is based on a physical reductionist model of consciousness; this is a model that very few philosophers subscribe to, as it entails all kinds of difficult consequences.

For a good view of the problems of physical reductionism, see Raymond Tallis's recent book Aping Mankind which does a nice job of refuting these theories.

If we eliminate the physical reductionist portion of the question, and reframe it using another metaphor, it reduces to the Ship of Theseus problem. There's no shortage of literature addressing that problem.

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    Ouch! I read a bit of that book and being just a lowly scientist and engineer I have to ask: is the type of analysis of scientific literature and experiments found in chapter 1 and the type of reasoning in chapter 2 (esp. the H2O/water and neurons/color perception part) really representative of the way modern day philosophy works? I have co-workers who keep saying that philosophy is mostly pseudo-science, which I always dismissed as ignorance of the field but after reading this I'm not so sure anymore... – digital brain Aug 13 '12 at 4:44
  • Now, back to the actual question - yes, it assumes at absolute minimum that our universe and everything in it (including ourselves) follows the (testable) laws of physics. Without such an assumption the question makes no sense at all, so I will add that clarification to the question. As for the Ship of Theseus, well, our body constantly replaces most cells (this does not include neurons though) and some people even have entire organs replaced and I don't think anybody seriously claims that this makes them somebody else. But then again, if we are not grounded in physics this is irrelevant. – digital brain Aug 13 '12 at 4:44
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    And to be clear, with the previous comments I do not mean to attack this answer. I do appreciate every answer, especially when it has references, even if I disagree with the reasoning. – digital brain Aug 13 '12 at 5:20
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    One of the problems I had with Tallis is that he seemed to misrepresent some of the studies and their purposes (I checked a few of the papers) or at least he seemed to twist them quite a bit until he could actually make his points about the "impossibility" of a physical basis of the mind. Also, to me the water/colors part seemed to be illogical and at times, dare I say outright wrong given what we already know but that could be just me. – digital brain Aug 15 '12 at 14:02
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    Sorry, I downvoted cause you didn't present any arguments, you only referred us elsewhere. That's essentially the same as just putting a link, which is not only against policy, but not at all immediately helpful. What arguments from Tallis or the Ship of Theseus would you like to use to answer the question. As it stands, this is more of a comment than an answer – B T Oct 29 '16 at 9:08

Let's look at this in another way. Most of our body is technically shifted out for a new one every 7-15 years or so. Are we still ourselves, or new people?

See here for more information on this.

What that suggests is either that there is something outside of our physical selves that makes us who we are, or that we are only our memories (or in other words, the electrical signals and synapses firing in our brain. If it is the latter, there is nothing that makes you any less you if you can transfer that into digital information.

If, however, it is the first, you are in effect just copying the information that is stored in your brain and creates an A.I that has your information, but at that point is just that. An A.I. with your memories. You will then either go on living (if the information is not deleted from your brain), or die and move onto wherever you end up when you die.

It all depends on what school of thought you subscribe to. One where your brain creates your mind, or one where your mind controls your brain.

  • If you have any references, say to the concept that every cell in our bodies is not the same after 7 years, these would help support the answer as well as guide the reader to places to go for more information. – Frank Hubeny Feb 18 at 2:41
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    Added a link to more on cell regeneration in. (Y) – Lexipaichnidi Feb 20 at 12:52

It's basically the ship of Theseus; and it is exactly this when considering how under our natural conditions of life, like is replaced by like: an oxygen atom for another, say.

However, in your fictional situation, like is not replaced for like; this assumption, for it is an assumption, is being forced. ie this:

I have each of my neurons replaced by electronic neurons. By electronic neurons I mean chips with the necessary hardware and software to perform the exact same function that the neuron being replaced was performing.


As a counter argument, I might argue the wild fantasy of one particular line limits the usefulness of intuition regarding the question:

By electronic neurons I mean chips with the necessary hardware and software to perform the exact same function that the neuron being replaced was performing.

What is the "function of the neuron?" Have you 100% defined what the purpose of the neuron within your self is? If so, then you can probably argue that it was replaceable. However, defining that function is hard. As one strains for 100% replacement of function, small nuances begin to require a great deal of attention. 100% is a high bar to reach.

Now consider the possibility that you have just one truly chaotic region within your brain, perhaps inside a single neuron. We know that chaotic systems are remarkably unpredictable. However, as stated earlier, it's very hard to discern the "noise" of this chaotic system from its function with 100% certainty. Accordingly you have to reproduce the entire state of the chaotic system. This is not known to be physically possible. No known measurement tool is capable of measuring the state of a chaotic system sufficient such that both the original and the clone evolve identically. The measurement device inevitably perturbs the system as it takes its measurements, and those perturbations can lose essential content.

So what you describe involves a godlike ability to perceive the true state of the system, and a godlike ability to create perfect replacements. It should thus be no surprise that our intuition of what we are is insufficient to intuitively handle a "self" in the presence of a god. In fact, it may be valid to argue that one's "self" is better defined by the behaviors of the deity doing the measuring and replacing: "you" are that which the deity chooses not to clone/replace.

And thus the question approaches the well trod class of paradoxes involving omnipotence and omniscience. The particular way you elect your deity to be able to go through with this thought experiment of yours will define when you cease to be yourself. It also may imply that, after complete replacement, you are still you; the Ship of Theseus may still set sail. After all, you had a deity doing the work, all sorts of non-intuitive things are valid and reasonable in such a light.


Your question can't be answered with yes or no. Would it still be you or not. Because it depends on YOUR perspective. No one else can decide your perspective for you.

In the holistic sense. Where there is just one, one being, one system, one consciousness(,whatever you name it), there has never been something else but you. So in that case, the brain upload to a computer is already you from the very first moment. Even while it is only uploaded for 50% it is you. Because everything is you. So yes, if you would be able to clone the entire functioning of your brain to another system, it is still you. It has always been you.

On the other hand (the perspective you are likely having now) is the dualistic perspective. No it won't be you. Because you identify yourself to be your ego (most likely). And if you upload the functioning of your brain to another system, that other system is not you (your ego). Your ego does not identify itself with that newly created clone. Your ego would still be the one that started the uploading process. If the functioning of your brain is completely cloned, then another ego is created, as it probably has the same perspective before the cloning started.

So the answer is yes and no. Yes because all is you, and no because your ego won't identify with the new clone.

The in fact, the answer lays within yourself, your perspective.

  • I think this is mostly right. The new you would think it was, the old you would think it wasn't, and everybody else has nothing to say on the matter. – kbelder Feb 18 at 20:14

Well defined premise ! But not as complete as I imagine it. Willing to accept all possibilities the question is just the intro to a very interesting topic.

Suppose you don't turn "on" the duplicate (digital) neurons until the entire system is complete: all connections (synapses, axons, etc) are ready to be as dynamic as in a biological brain, but your new "you" doesn't exist yet

Missing part: where does this system exist? what environment (just a generic operating system will not have any similarities with your own environment)

Taking it further, suppose we create a physical body for the new computer, where not just the brain is duplicated but the entire nervous system to provide identical external sensory input like touch, smell, vision, hearing, etc

Missing part: memories of your past (childhood) - the new computer will not have your identity

But the main issue is that the new system will not have your perceptions: new synapses will form based on changes of the surrounding environment, or the way you interpret the world around you

You want to accept that you can transfer all your memories as well, the main issue is still valid, unless you manage to somehow make a direct connection to your double, where you observe everything perceived by the double, and the double observes the world through your eyes as well, as soon as you turn it "on"

But still, YOU remain YOU as long as you make even the slightest distinction between you and your double. Your consciousness is never really "transferred" to your double, and your experiences will never be exactly the same

As a note, the link to Aping Mankind provided by @Michael Dorfman made me realize, based on superficial info, that I'm a reductionist (or "neuromaniac") - if our neurons don't exist, we don't exist


Why it isn't just a physical problem

It might already be pretty apparent that there is more going on here than just physical comparisons, but there is a decent thought experiment to show the issue. Say you follow the process you described, except in the last step you never disconnected the chips from each other, thus leaving "you" inside your head as well as within the computer. Most would say there is only one you, and it seems fair that the older one, the network of chips in your head, is the "you". However, what is now in the computer? A duplicate of your mind, but not "you". Yet, by disconnecting your own neurons, say simultaneously instead of piece by piece, the computer mind may very well become "you". Nothing physical changed in the computer, but the mind went from being a duplicate to you. Then, clearly, the definition of "you" is dependent on more than just physical or functional structure.

So the question of course becomes that of what the extra piece is. This is itself a much discussed topic, i.e is there a soul that stays with the body, stream of consciousness, uniqueness? Maybe when there are two duplicates of your mind, neither one is you?



If we had an adequate mechanistic understanding of how the brain achieves consciousness, then I suppose your thought experiment could be more compelling towards a "yes", however, we do not. In short, the answer to your question is: "no" - the uploaded copy is not you, nor was it ever, and, you remain you for only as long as you can stay alive during the neuron replacement surgeries.

If this kind of neuronal replacement surgery were viable, then at the very least your self-consciousness includes the unified experience of your body, and the computer upload you describe would have a different body, therefore, a different sensory nervous system and a different motor nervous system. It would not be you.

Also, considering Professor John R. Searle's "Chinese Room" and his critique of the notion that computation is causally sufficient to produce consciousness, I think all you might end up with is a, at best, a clunky simulation of something like your brains electrical patterns at the time the copy was uploaded. Considering the damage you might have suffered, tho, whether this simulation could be anything like you and your personality prior to all this brain stabbing... I think doubtful.

Lastly, isn't "electronic neurons" kind of redundant? I get that you mean individual neuron simulators, but I would suggest you analyze your metaphors to come up with a more succinct and powerful thought experiment. Thanks, tho - fun stuff to think about!


If you define "me" as your behavior, the answer is obviously yes. However, if you define "me" as your experience, the answer isn't as clear.

Instead of talking about whether "you" remain "you", I'm going to use the word "experience", so the first question becomes: "If I replace every neuron in my brain with a computer, do I now experience the thoughts of that computer brain?"

We don't know how your experience operates so no one can say for sure. Its a question I'm very interested in answering, but seems to have only dead-end leads.

Most cells in the body are replaced regularly, but not neurons. I haven't been able to find convincing information about whether the molecules and atoms inside neurons are replaced at any regular rate. But neurons do die and are replaced (causing memory loss). If most people have a single "experience" throughout their entire life, the answer to the main question might be yes. But it also might be no.

Another consideration is that you may not have a consistent experience throughout your lifetime. In fact, you may only exist for an instant, only to be replaced by another you the next instant. If this were the case, it would still feel like its still you because you may be accessing some memories about a previous time (when in fact, the memory is stored in a way that exists in that instant). In short, extended experience may be an illusion. But also maybe not. If experience is a very temporary illusion, then not only would "you" not be "you" when you got turned into a computer, but you wouldn't even be you when you finish this sentence.

The problem is that the experience we feel, with all its qualia, could theoretically be an input-only device: a black box that takes in information and doesn't output anything to our bodies. If this is the case, we can't use our usual cause-effect paradigm to measure it. We know that each of our experiences extends at most to the outside of our skin, but since we don't know what causes that experience, we don't know what things have experiences. Perhaps multiple experiences are "viewing" through our body. Perhaps there's an experience that just feels our arm. Perhaps inanimate objects have some kind of experience. We just don't know.

Imagine you're in a room in an undisclosed location. In that room is a computer with an advanced neural VR headset. By wearing that VR headset, you no longer experience your own body and instead experience whatever the VR headset wants you to by blocking the inputs to your brain (your senses) and adding inputs of its own. The computer is connected to an autonomous robot that has senses of its own and acts according to its programming. While wearing the headset, you see what the robot sees and think what the robot thinks. You think you are the robot. Are you still you?

This scenario is a metaphor for what our "experience" (as I'm calling it) might be. It doesn't illuminate where the experience comes from, but illustrates the difference between your experience and your brain. Perhaps your whole brain somehow generates an experience, or perhaps there is only a part of your brain that generates the experience. Or perhaps it is something else entirely. The point is that "you" may not even have any relation to your brain and may have rules completely different than physics as we know it. The main problem I can see is that reductionist physics disallows multiple things happening at the same time in the same place. But our experience seems to see multiple pieces of light, smell, taste, feel, and hear all at the same time. Perhaps this is what the soul is. Not someone's human essence that determines whether they're good or bad, but an inanimate viewer of our body that is receiving signals from our brain.


At the end of this process is it still me? If not when did it stop being me? When one neuron was replaced? When 1,000 were replaced? When 1,000,000 were replaced?

Under hysteresis arguments, there is no fixed turning point, but instead multiple turning points, which are dependent on your starting state and direction of change.


The question can be framed in terms of vagueness, explored by the Sorites paradox, which asks "when does a pile of sand become a heap if you keep adding grains to it?".

Your case can be viewed as a question about the vagueness of identity, rephrasing the Sorites paradox as "when does a clump of carbon neurons forming you become not-you, if you keep replacing them with silicon neurons?"

In Unruly Words, Diana Raffman advances hysteresis arguments to resolve the paradox. Roughly, hysteresis arguments attempt to resolve the paradox by saying that your answer to the heap+pile/you+not-you question will depend on your history.

In this case, for example, the turning points might be at, say, 40% or 60% silicon neurons, depending on whether you started with a carbon or silicon brain, respectively.


A fun answer!

transfer (data) from one computer to another, typically to one that is larger or remote from the user or functioning as a server.

It likely depends on how analogous the brain is to the computer you are "uploading" it to. I find the question pernicious, on both an individual and collective level.

With the perfect computer, I reckon you could (we know that minds can "interface" with computers), as I really don't believe in an immortal soul. Without, it's just Russian Roulette with data!


You will be in coma.. Are you still you.. you do not know.. If you are connected to computer chip then, if you are not identified with your body and memory then you are there. If not, you are not there.. It is all about how do you identify yourself.

Surely I will tell you that you are not the brain and you are not the memory. you are more than that..


I do agree that everything should have a scientific reason...and I do believe that it must be testable, yet what I don't agree is that I ( or anyone else) can easily say that if it's not testable then it can't happen. Part of being a scholar/researcher is to have patience for what you can't understand/grasp at the moment, perhaps maybe days/months/centuries later someone could prove otherwise

In my opinion Never! You presume to start from a point that isn't actually the beginning, neither you are correctly relating your brain to yourself!

From where to start:
From square one in your life... I mean from the first few seconds that your brain or wisdom or your whatever started to work in a meaningful way ( I don't mean the first 6 months that all your libido was to drink milk), how was it geared to what it was geared to?

Relating your brain to the definition of self:
Your definition of brain, of a human, to me is nothing more than a CPU with some RAM and Hard. And a computer does what it does based on it's inputs. Yet for human beings... They all agree to an extent that many things are bad without reason. For instance killing/hitting/cursing/nagging/being selfish/jealousy/etc. are all bad without reason or loving/caring/affection/humbleness/honesty are all good without reason... HOW can you transfer that without reason part to a computer?

And example of wisdom: if a 2 year old child kicks another child (for no reason), then do you go and explain to the child saying: "kicking is bad! If you kick someone it will hurt them and kids won't like you anymore?" What you normally do is you say "honey, why did you kick him?" and the child because of the injection of a moral compass, has nothing to answer, he doesn't even have the courage to look at you in the face he already knows what he did was wrong!, he says: "I'm sorry". He knows what is bad and what is good, though not 100%, by growing older, he would then know better as a result of the growth of wisdom & polishing of his senses through social interactions. I do agree that society would help him to better shape his moral compass, but it's not what creates it! ( Though saying that God was the one who created our wisdom and not society needs a kind of proof that only one can obtain for itself)

The only place I kind related to is The sayings from Ja'far al-Sadiq, from book Usul al-Kafi, chapter wisdom and intelligence. ( its actually the first chapter of the book, as he mentions its God's most magnificent creation)

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    Can you add some philosophical sources to this? Right now, it's quite literally just some opinions. – virmaior Aug 21 '15 at 3:34
  • @virmaior IMHO The philosophy I have been taught was that everything either comes of your brain/logic or it doesn't. Giving it sources wouldn't help, perhaps sometimes misleading because once we know who said it then we could favor it or not! Would you still like me to go and find some philosopher who approves it? – Honey Aug 21 '15 at 3:40
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    @asma22: sources show that it's a serious position; it's kind of presenting your credentials; someone who does not know the area that you're discussing can't distinguish between mere opinion and an opinion that is backed by reasoned argument. – Mozibur Ullah Aug 23 '15 at 11:52
  • @virmaior I tried to find some references similar to what I said and added it – Honey Aug 23 '15 at 15:00
  • Why do you say that these things (killing, hitting, cursing, nagging, being selfish, jealousy, loving, caring, affection, humbleness, honesty) are without reason? for example, someone might kill for survival; someone else might be raised to be honest by their parents; someone loves her children as result of evolution, since it improves their chance of survival, or nag a partner since it is a pattern of behavior they have learnt as children, and so on... if you meant something else please clarify, since your answer is not very clear. – nir Aug 23 '15 at 21:47

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