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I read a whole lot of Oz books back when I was growing up (there’s tons of them), and the Tin Man is an example of this. Nobody dies in Oz (don’t ask me about the movie), which can lead to some pretty horrible situations. The Tin Man was a regular guy and a lumberjack. One day he gets cursed by someone and he lops off his foot. He can’t find it and he gets a tin prosthetic. He then lops off the other foot. And then his legs, his arms, and his torso. He gets tin prosthetics for all of them. Then he lops off his head and gets a tin replacement for that, too.
The reason he never found his body parts is because someone else was collecting them. I think it was a witch? And she would assemble the parts with Meat Glue, which repaired them. And eventually she got his head, which she placed onto his intact body and he lived again, whole and hearty. And then there were 2 people who shared the same memories, the same identity, where there was once one. Oz books were full of body horror.
I read those as a kid, but that’s too many decades past for me to remember them much. Amazingly similar.
I have replaced nearly every cell from the time of my deepest regrets. There is a certain gratification to it. I’m still me though. I am transitory, a wave passing by, shaped by the past.
the continuity of identity is what answers this for us: that’s still Thomas.
That’s what
StarfleetBig Train wants you to think.One of my favorite topics! I wrote this about it: https://phil.red/blog/2025/9/5/identity-illusion
just have to believe we are all more than the sum of our parts
Cyberpunk addresses this with cyberpsychosis. If you get too chromed up you lose too much of your humanity and develop a dissociative disorder.
Unless your name is V
V kills more than any cyberpscho they encounter.
True
The answer to ship of theseus is simple. If you have to change the keel, you’ve got a new boat. You can’t change that without removing every other part of the boat
Which part, if any, would be the keel equivalent on a train?
The boiler?
Easily replaced.
More likely it is the chassis.
I was thinking more that his face is affixed to the boiler.
There are 3 types of continuity.
- Continuity of material
- Continuity of identity
- Continuity of memory
Teleport me, and I can continuity of identity and memory. The same applies slower to material replacement.
(Mind) Clone me and I have continuity of memory only. I would consider this me me, but close enough to count, unless the original was still in play.
Wipe my memory and I have continuity of identity and material. Legally it’s still me, but I would consider the disconnect the loss of myself.
Basically, I want continuity of memory and identity, but only memory is critical to it. Thomas has his memories intact, and has continuity of identity. He’s definitely still Thomas.
if you lose to your memory, id argue that is losing your identity.
You would lose your self identity. Identity as a whole is more than just self identity. It’s an amalgam of self, social, familial, governmental identities. This matters even more with things. A car has no sense of self. However, if someone lovingly repaired and replaced the parts, it would maintain its continuity of identity through the changes.
Similarly memory is more complex than one term. I could lose my explicit memory (remembering my past) but keep my implicit memory (skills and muscle type memories). In that case, am I still me? What about the reverse?
At that point it is no longer a yes no question, but a lot of grey creeps in.
I don’t believe it’s possible to remember skills without remembering your past. muscle memory is, linguistically, not tied to the brain, so I don’t know if that’s worth discussing.
Given there are people suffering from exactly that. It’s also unfortunately common in Alzheimer’s patients. The classic example is piano playing.
Muscle memory is a short hand for changes to the low level reactions. It’s a mix of brain spine and muscle nerves. E.g. I can still do martial arts moves fine from reflex, even though I no longer have explicit memories of learning them. A large chunk of our personality is built up of implicit memory. They act in the same way, just internally. E.g. your maths skills are based on implicit memories. The memories that created the skills are long gone, but the skills remain.
What do you mean with “continuity of identity”?
PS: Sorry for the long text lol.
The only important thing for a human mind is subjective continuity of your mental process. Only the subjective perspective of the human mind matters to this question, and this subjective experience determines the morality of how we should treat others.
Material continuity is iffy. The cells of the human body continually renew themselves and take on new material, humans know this and do not care, as long as it is slow and not a complete break. But mental processes are irrevocably tied to physical material, and can’t magically move from one to the other. So there can be no continuation of mental process without continuation of material. Both is the same.
Memory is constantly altered, forgotten, added to. It’s crucial, but not an absolute since changes occur constantly. Humans know this and do not care much as long as they remember the important things, so this not that relevant.
People go to sleep or anesthesia or coma and the brain functions largely shut down, but the overall neuronal hardware stays like it is. People experience an interruption and continuation of their mental process as something perfectly fine. A pause in mental process does not end continuation.
The only thing one has to ask oneself is this:
If you could be copied perfectly and saw a clone appear next to you and knew they were a perfect copy with all your memory and thoughts, you would still not want to die. Even if that copy was improved, like younger or faster. We would not want to end our own subjective existence. We would still fear death. One only has to imagine seeing your own perfect copy and then being asked to put a gun to your own head and pull the trigger. Nobody sane who isn’t suicidal would be fine with that, except in extreme situation. Like someone might volunteer for a suicide mission because it’s important or vital or save many lives, but as a general rule it would be immoral to ask or expect people to do this. Or to normalize this, or to be dishonest about how it is experienced internally. There would always be outliers, but they are irrelevant to the general question.
So copying or mind uploading is theoretically impossible because it’s unacceptable for the human mind in general. This will never change no matter the technology.
Some people might not realize what is happening and be fine with with being copied while the original dies (or freezes) at the same time, and since their personal experience of being clone number 100 feels like perfect continuation, they never figure out they die with each move (copy and delete). A self delusion. Human minds could also be altered to be fine with dying, but this would be such a fundamental and deep reaching change it would be very problematic and could be very dangerous too. It would be quite likely they are driven by pathological desires or fanaticism.
Merging two diverged minds might be possible, but this too would ultimately be fooling yourself. You might have two perfectly synchronized minds running in parallel on two different substrates, and both get the same inputs and thinks the same and neither knows which one is which, but neither would want to stop existing.
This would be a fundamental limitation and defining characteristic of human minds, and comes from having evolved from an animal. An artificial intelligence might not share these limitations at all and be much more powerful for it, constantly duplicating and deleting instances of itself without it feeling like dying.
There is still a theoretical sci-fi way to upgrade a human brain, to slowly upgrade one neuron and their synapses at a time over a long enough time span, like a year. The human mind would not notice or see any changes, only see the changes or improvements once it’s done. That’s really what the ship of Theseus tells us, if we change slowly, like humans naturally do, we do feel fine about it.
So instead of uploading we could slowly transform our brains into an upgraded substrate, transform into some kind of superior biology. Nobody would want to give up self-repair and that means biology, no matter what elements that biology would be based on. Features like complete introspection of all synaptic connections and activity would still be theoretically possible, even without being “digital”. This could then be considered an objectively higher level of consciousness. You could review thought processes and emotional reactions. Also one could alter his own synaptic pathways and save revisions, but this would be brain surgery and physical alterations.
One could also add computing substrates to the human mind to improve your math skills and memory, run simulations or enter virtual worlds all within your own internal mind, or shared external worlds. Or move your upgraded brain to a new body or put yourself into tiny space probe. But without changing fundamentally what it means to be a human mind that evolved to fear death more than almost anything, you cannot upload or beam yourself somewhere else and expect either the original or copy to give up their life.
Presumably the brain of Thomas (if he has one) wasn’t touched, so Thomas should be fine, as far as that goes. A horrifying existence lol, but organ transplants do not fundamentally change your identity.
I’d argue that identity and memory are the same thing. Like if you lose your memory, your identity becomes as strange as anyone else’s. Or if you’re a copy of someone else, you won’t know it unless you were told and would think you’re just that person when you wake up. Like if there was a transporter malfunction where it didn’t destroy the original copy. You’d have one copy at the original site thinking the transport just didn’t work and another one at the destination going about their life while Harry wonders how to tell Janeway.
Identity is as much a social structure as a personal one. E.g. in star trek, when Will riker is duplicated. Both have continuity of memory, but Thomas has his continuity of identity broken. Though he doesn’t realise this until he meets his eigen twin, who’s been continuing on. Even though both are nominally identical at the moment of creation, Will’s continuation of his career maintained continuity of identity. Thomas Riker had his broken by being stranded. Hence why Thomas changed his name, while Will continued using Will.
How does this apply to something like the game SOMA?
He was not even alive to begin with. Literally a robot following the instructions left by a recording of a human mind. He just thought he was a real human because the recording said/believed so.
True, but could it not be continuity of memory in that case?
I would say no, because he never was a part of the original. IIRC, he’s a copy of this person’s memories before they even died, so he forked the progression of memories? The original would have lived, and died, with no continuity going over to the clone. The clone, upon receiving these memories, believes himself to be the original, but he’s wrong.
Oh that’s a really good point. God that game is such a trip.
I’ve not played that one, so no idea.
Cloning is just making a new person with your DNA, it’s not continuity of any of those
Hence why I put “mind” in brackets. I was more referring to Hollywood style “cloning” variants.
ah, like body copying
The full copy, “cloning” adult body and up to date brain. Think “The 6th Day” film.
Body swap would be continuity of memory, but not identity or material.
It depends if the swapped mind considered themselves me or not (clone’s brain?). If not then perceived identity would follow the mind, even if the legal identity didn’t.
If it were a clone’s mind, we would have to come to some sort of understanding on the subject.
It can quickly get convoluted. E.g. if I became a digital identity, would I be willing to split off versions of myself for particular tasks, only to absorb them later. Conversely, could I function as such an entity? How long would I need to diverge before I became a truly separate entity in my own mind?
The book “Accelerando”, by Charles Stross plays with this. He refers to them as eigen-minds. A collection of minds overlapping within a single identity. How liable is a diverged eigen-mind from its alternates, when it comes to contracts and debts?
But none of them are continuity, only replication.
Continuity of material, you mean? The paradox disappears when you understand there are multiple types of continuity.
He’s more machine now than man; twisted and evil.
You already are a ship of theseus that is sentient. Every cell in your body is replaced around every 7-12 years.
Except the ones in your brain, they’re very rarely if ever replaced. And I think most people would agree that your brain is the most important part of your body for your identity
I think the ‘point’ of the ship of thesius is often missed. Grouping things together to be one entity is thought process done in our brains for ease of understanding, but it doesn’t exist in the real world.
I think the ship of thesius thought experiment is there to show that there are times where things can’t be distinctly grouped. When things don’t fit nicely into groups we shouldn’t force them, but abandon the that grouping as it isn’t applicable to the situation.
I’m not even convinced I wake up the same me that fell asleep.
And we are fully dependent on things like bacteria too. Some of which affects us through the gut-brain pathway.
There should be a Black Mirror where uploaded people get hungrier and hungrier.
¯\_(ツ)_/¯ and oddly enough I feel profoundly different every decade or so. Wouldn’t almost recognize my younger self.
Isn’t the human body exactly that
I’m pretty sure I’m not my 10 year old self. Even though i have since off their memories
Apart from specific non-proliferating cells, statistically all of your entire body’s cells will have been completely replaced every 7 years*.
So we’re all exactly like that… just over such a long period of time we don’t notice it.
*For the quickest proliferating cells in your body, like your skin cells, this is a matter of just weeks.
iirc nerve cells basically live forever. So I’m the end, you’ll completely regenerate, except for your nerve cells
Yeah but those cells still have proteins making new parts.
And new neurons are being made all the time, just more slowly and in specific places that then migrate to where they’re needed, so as not to disrupt too much of the neural mesh (and thus completely derail memories or other models).
Some of the atoms/molecules in your body have probably already cycled through the entire food web and come back to you … probably multiple times, especially if you don’t move around a lot and you eat locally produced food.
But do the molecules and atoms in each cell stay the same?
Probably not, even in non-proliferating cells. They do still have to repair damage after all.
But I have no idea of what the timescale is for the complete replacement of every atom in your body
With consciousness not being fully understood it’s possible you’re a different person every time you wake up or just randomly between thoughts or maybe you’re everyone and you just quickly round robin context switch or maybe you don’t have a consciousness and I’m the only one who has one?
Put the weed down /s
Oh no, is it sick?
Or at least post the strain
Pretty much, yeah. Though the amount of self-awareness varies wildly.
This is my view: Your body ages and regenerates. You are a living ship of theseus, you are a different person at different stages of life. Yet, you retain the memory of your past life.
The ship of theseus is an entirely different ship, but it retains the memory of a self.
So if a brain injury causes you to lose your memories, you are an entirely different person?
People with Alzheimer’s usually are totally different people. Though they do tend to retain some long-term memories or skills.
People with Alzheimer’s usually are totally different people.
Are they, though? They certainly aren’t treated as such socially. We don’t start calling them by different names, they remain married to the same partners, they don’t lose ownership of all their stuff, they’re still considered the same person for tax and government benefit purposes…
That’s just everyone around them not letting go (not saying we should). In the context of memories making us who we are, they’re totally different people.
living beings isnt a matter thing, and more of a wave of matter that propagates by getting more matter and shedding old one.
I’m taking bids for a contract: what’s the minimum rate of surgeries per year you can offer to make me immortal. I offer a perpetual fraction of my lifetime earnings, to be agreed upon later.
I can make you immortal with zero surgeries per year! Just sign right here for 20% of your lifetime earnings in perpetuity.
Sure, sure, I know that sounds like a scam, but don’t worry – it’s guaranteed! If you ever die (thus discovering that you have not, in fact, been made immortal), you’re entitled to a full refund of everything you’ve ever paid into it, plus interest!
I reject this proposal based on similarly zero scientific merit.
Time to add that to my kids’ bookcase next to The Fable of the Dragon-Tyrant.
That whole universe is horrifying. Remember when they closed off that one guy behind a brick wall because he wouldn’t work hard enough?
It’s worse than that - he wasn’t being lazy, he was convinced that if he came out of the tunnel, the rain would ruin his paint. Even after it stopped raining, he still wouldn’t come out just in case it started raining again.
Basically he had a mental illness, and his punishment was to be bricked up and forced to watch the other trains going past. One is friendly, one says it serves him right. Because he has no steam, he’s unable to communicate. And all the time his paint is slowly getting ruined anyway because he’s stuck in the tunnel.
As someone who’s had a breakdown, it really resonates in a different way than it did when I was a kid.
It’s not punishment, it’s allegory for the walls mental health issues puts up.
I agree with your lesson, just not the wording.
It’s neither, its a real incident that happened on the railways. All Awdry’s Railway Series stories are.
Mate I don’t think real trains can get depression.
Look up shed 17, the real story of Thomas the tank engine.
That was pretty horrifying.
If they made a spare of each of Thomas’s parts, replaced them one at a time, and then reassembled all his original parts, would there be two Thomases with all his thoughts and memories?
Yes but the other would have to go by Will instead so that we can tell them apart
Couldn’t we just do Tom?
Why not just assemble all of Thomas’ spare parts immediately, without dismantling the original? Same end result, should be indistinguishable.
So with a human, if you could make all the parts and assemble them, it wouldn’t result in the result having all the memories because the brain part doesn’t work that way - it stores memories and experiences that the fresh parts wouldn’t have. We know Thomas is sentient, but as far as we’ve seen, all his parts are just train parts (maybe face notwithstanding); we have never seen that there’s a brain part.
So I’m going to postulate that there’s some essence of Thomas that persists through the part swaps. What’s unclear is whether or not those individual pieces that are swapped out retain the essence of Thomas and would be recreated if they were reassembled.
it stores memories and experiences that the fresh parts wouldn’t have
What if we place the human fresh parts in the exact molecular state, that the original is in ? If my understanding is correct, our memories are somehow encoded with whatever chemical biology is happening in the brain, and if we suppose we can imitate those chemical states with the fresh parts, shouldn’t we get the same memories/consciousness ?
Maybe so, but does Thomas have a brain someplace?
Good question. I’d postulate they have some equivalent for a brain : if not a chemical one, maybe a very intricate mechanical one. Anyway, if it has something that works as a brain, we could theoretically recreate it. But this is only hypothetical of course. We could also say it has just a soul, and then your theory would be back on tracks (pun intended)
Or it could be magic? I mean, what’s the explanation in the Cars universe for the sentient cars? I’m not sure I’ve seen any of the movies, do they explain it?
I mean, ideally the repair would fail and you’d have two dead trains. Anything else is vaguely sickening
Or maybe - just maybe - we’re more than the sum of our parts.
I don’t have time for an existential crisis
