> But there is a tension. In allowing your brain and body to be replaced by synthetic parts, you seemed to be accepting that psychological continuity is what matters, not bodily continuity. But if this is the case, why did you risk the spacecraft instead of taking the teletransporter? You ended up allowing your body to be replaced anyway, so why did you decide to risk everything on the spacecraft instead of just giving up your original body there and then?
The question being posed is "what is the difference between replacing all of your cells, vs all of your neurons over time?".
My logic was that my molecules are being replaced over time, so is that so different than my neurons being replaced over time, whereas a wholesale replacement of my body felt like a break in continuity. I'm no philosopher though :)
Otherwise, if the argument was that the destroyed copy doesn't count because I can "feel no continuity", then any quick and sudden death wouldn't count as a death. That would be absurd. If, on the other hand, you believe the teleporter makes a copy of yourself that isn't you, then you're simply not a genuine psychological reductionist.
In my opinion, it makes sense to avoid a 1/2 death by taking a 1/2 chance of staying 100% alive. If it doesn't bother you to die at the teleporter, then any sudden, quick death shouldn't bother you either, which goes against the explicit instruction to ensure survival. This is also true in general without the instruction. If a perfect copy was made of someone, it would be rational for both copies to desire to survive.
If you think you died when you entered the teletransporter, then you either think bodily continuity or an immaterial soul is relevant. All that matters for psychological continuity is that the person has the same memories, personality, etc. as you.
>What if the copy comes back to Earth via spaceship and shoots you? The end result is the same, but it sure looks like you're dead.
The end result is very different because the memories of the surviving copy will be very different. He will remember killing a copy of himself, which by that point is more like a close family member than an identical self.
This doesn't seem like a good enough reason to kill one of you?
Of course, you don't have to agree with the premise that personal identity is psychological continuity. But I think there are other thought experiments that make the bodily continuity theory counter-intuitive. What if my brain was transplanted in such a way that I experienced going to sleep in my body and waking up in someone else's body, with my memory and personality otherwise unchanged? The bodily continuity theory says I would be a different person, but my intuition is that I would still be the same person, just with a different outward appearance.
The quantum no-cloning theorem says that it's physically imposible to make any copy of a quantum state, for example all of the state which comprises your body. But it is possible to transfer quantum state from one form to another. This is of course only true of the physical world if the assumptions of the no-cloning theorem are true. Let's assume they are.
Teleportation of your body including whatever quantum state you might consider important therefore must involves a process that appears, to an observer outside, to dissolve the state at one end simultaneous with recreating it at the other end. For some fuzzy definition of simultaneous; this is quantum state after all, and time is subject to the uncertainty principle just like position and momentum famously are.
The information transfer is analogous to transferring a box which the teleporter cannot look inside. You know it can't look as looking destroys the delicate contents. The teleporter cannot use non-quantum information to encode the contents. But the no-cloning theorem doesn't rule out translating quantum states to different forms, such as complex molecular states to light pulses and back. This is difficult, after all modest size quantum computers are difficult to build, maybe even impossible in practice, and they are much simpler than quantum teleportation of interesting size objects.
Squint a bit, and from a certain point of view, this is not destroying your body while creating a copy. It is an exotic form of physical movement, a bit like traversing a wormhole with your body retaining its integrity during the movement, except the wormwhole geometry is not spatial as we normally think of wormholes, it is instead a kind of complex state transformation analogous to geometry. But to you, it might appear that the universe around you is dissolved by the teleporter, then a new location of the universe is reformed around you, then you step out. No loss of physical continuity.
> Your three choices show that this is what you see as central to your sense of self, not any attachment to a particular substance, be it your body, brain or soul. However, some would say that you have not survived at all, but fallen foul of a terrible error. In the teletransporter case, for example, was it really you that travelled to Mars or is it more correct to say that a clone or copy of you was made on Mars, while you were destroyed?
because you've suddenly switched to a sort of dualism. If you are a psychological reductionist (from some of your other choices, like say using the artificial brain parts), then you assume that minds are what brains do. There is no consciousness separate from your brain, your brain produces your consciousness. So all that matters for you to be alive is for some brain to be around that produces the same mental states you have. There could even be multiple of you!
But if you hop on the spaceship you threaten that continuity for the sake of your body. In that case you treat your consciousness as distinct from your body and are afraid of 'losing' it or not being able to transfer it should that particular body die. So you don't just care about your psychological state any more, you think your particular body 'carries' your mind around. That's a contradiction.
In both cases, an older version of you is "extinct", meanwhile, the latest version of you does not have any recollection of becoming extinct.
If the ship is completely destroyed and a perfect replica rebuilt elsewhere, is it the same ship? Almost certainly not.
If the ship is slowly replaced over time, is it the same ship? As a matter of form or psychological continuity as posited in the question, almost certainly.
At least in the Ship of Theseus paradox, there is the case where you take the old replaced parts and construct a ship from those parts - which is an interesting question, is it the original ship? In this case, the only thing consistent about the ship is the design. Take mass manufactured goods then - are they the same article because the have the same materials?
If it's a perfect replica (as you said in your original comment) then by what parameters is it different from the original ship? Sure, cooordinates might be different, but cooridnates can change. If the exact replica switches places with the original, then even that difference would disappear.
By the way, I am strictly speaking about this topic in the context of the thread we are in. If a replica is built according to exact blueprints of a snapshot of the original (and assuming no mistakes are made), then why would the result be any different than just replacing one part on the original with an replica part made according to exact blueprints of a snapshot of the original part?
In both cases (gradual and instant replacement), at any given moment, there exists only one entity with your consciousness and self of sense and continuous memories leading up to that moment.
Now the doc is replacing parts of your brain with silicon. It's posited that it makes no difference to your mind. Because of that, is your consciousness still in your body? Very probably.
So I'm not following their logic.
How do you reach this conclusion? The only conclusion I can reach is that an identical consciousness is certainly in both bodies. (And as soon as both bodies are making new memories, you have a "fork", where the two persons stop being identical)
So I will not take the teleporter any more than I will shoot myself.
> What is the difference between slowly replacing your cells a few at a time through biological processes, and instantly replacing all of your cells through the teleporter?
If you believe that you die when your cells are replaced (because you are in the old cells and thus can't be in the replacement), then I understand your point of view. But if you're saying that slowly replacing you is different than quickly replacing you, then I would be super curious to hear the logic for this! (This is a sincere comment, I am not seeing the logic myself and would really like to understand it)
The problem with the teleportation is not even that it's a quick replacement... it's that it's not a replacement at all. You're building a clone somewhere else, and destroying the original. You could build 50 clones at the same time on 50 planets if you wanted - and of course none of them would be you, there's zero chance you're preserved. So, you're dead, even if to the rest of the world it makes no difference.
Is that clearer?
In your first paragraph, you say that we can take for granted that when an original is destroyed, having a replacement will preserve consciousness. Then, in your second paragraph, you say the opposite - that destroying an original would NOT preserve consciousness, even if there exists a replacement.
There must be some key assumption which lets you not see this as a contradiction. Maybe you believe that there is something extra-cellular which wouldn't get replicated in a teleporter?
If both are identical I don't see why both aren't equally me.
> because I am on Earth, and I can't be in both bodies.
Why must there be a single continuation of "me"? I wouldn't necessarily consider this true even under current medical technology - we can split the brain in two and have two parts that do not directly communicate.
What if the process is symmetrical (one body in, some kind of mitosis occurs, two bodies out at equal distance)? Does one get assigned "the real me" at random? If both have the same memories/personality/train-of-thought and experience the process as continuous, why not both?
I'm probing to get a better understanding of your belief system. How does it hold up under symmetrical cloning?
> What magic would transfer your consciousness into this clone?
I'll label:
* PM: Physiological "me" - personality, memories, train of thought, currently instantiated as a brain
* IM: "Immaterial" "me" - a "soul", impacted by the PM. May impact the PM or just be an observer (depending on variant of dualism)
From what I understand, you believe there's an IM controlling a PM, and the IM is a different kind of stuff that would not be cloned. The IM generally follows the same PM, but could be "shaken off" from too-large changes. On cloning of PM you think this happens (at the instant of cloning):
IM New soul
| |
PM PM
IM
/ \
PM PM
PM PM
IM IM
| |
PM PMIf you posit that teleportation is equivalent to spaceship, and that a single consciousness cannot inhabit two bodies, then what is your hypothesis about the more-or-less instant transfer of that quality to a remote planet's newly created clone?
Consider IM to be any immaterial "self" that you believe wouldn't be included in the clone - doesn't have to be a soul as various religions may conceptualize.
> and that a single consciousness cannot inhabit two bodies
I believe there could be two bodies with identical personalities/memories/train-of-thought/etc. (whatever we label as consciousness) at some instant, but they would diverge due to different environments and not have any kind of special link between them.
> what is your hypothesis about the more-or-less instant transfer of that quality to a remote planet's newly created clone?
In my view it's just included in the clone - there's nothing extra that hasn't been cloned that needs to be transferred afterwards. If you totally clone an ocean, it has the same waves.
Which cell is the “real” one when it divides? Which branch of a tree is the true tree?
Both versions of you have equal claim to the past, as long as the copy is truly identical.
Not to be obtuse, but... the speed.
Really this is a shortcoming of the thought experiment. Progressive replacement is subjectively more continuous than complete replacement. A better thought experiment would be to feed it out something like:
* What if we replaced every atom of you body progressively over 24 hours?
* What if we replaced every atom of your body suddenly all at once?
* What if we replaced every atom of your body, but delayed by 1s?
* What if we replaced every atom of your body, but delayed by 1 day?
* What if we replaced every atom of your body suddenly all at once, but moved about 1mm?
* *What if we replaced every atom of your body suddenly all at once, but a day later and moved by thousands of miles?"
For me, personally, it comes down to the risk of copies. While both scenarios make copies possible it seems less likely in the case where you’re simply replacing parts of my brain. I cannot imagine copies not being made in the teletransportation scenario.
It seems to me that it's only illogical in retrospect. I don't know that there's body and brain eating viruses ravaging Mars, or that souls have to be frozen to die, and I have to make a choice about this, or what any of that means. I make that decision with only the knowledge that I have to take a ticket to Mars and that my goal, throughout, is to "stay alive."
Perhaps the ”strict psychological continuity” could be called “psychological+spatiotemporal continuity”, but apparently the author considers the spatiotemporal part to be a component of “strict bodily continuity” and nothing else. If you value temporal continuity independently of bodily continuity, the third question becomes a choice between “dead and soul-destroyed” or “dead but reincarnated”, which is clearly not the author’s intent.