Does Altered Carbon show any ambiguity about the idea of personalities being stored and downloaded into new bodies being the same person? Or it's completely assured they are the same person? I mean, I dont know if it's a good comparison, but if I take the hard drive from a computer and put it into another, even when I'll have the same softwares and files (which might run or not by the way), it isnt the same computer. Does Altered Carbon play with this idea or it's assured through the whole story than the personalities being stored and downloaded into new bodies are the same persons? If I recall correctly, other sci fi stories which used a similar idea (passing one person's memories from one body into another) like "The 6th day", created new persons, not the same one.
In my mind that's a paradox, because "double-sleeving" is a deal breaker for the same-person argument. If you can double-sleeve that means the process is just copying. On the other hand, people are needle-casting to different sleeves and saving themselves to remote backups and dying all the time as if the newly spun up copy is still "them".
You could say the show just ignores the dilemma.
This is one of many ignored concepts in the show. I lost count of plot-holes, unscientific or plain illogical things in it.
tl;dr version: Everyone seems to treat them as the exact same person, with the sleeves just being...sleeves. No more you than your shirt is. That's why they call them sleeves. Changing bodies is just a natural fact of life for them now. It's not special or strange or confusing, and nobody thinks about any of these matters beyond certain religious beliefs. You simply are your DHF. There appears to be a degree of adjustment needed when young children are involved, however. And there are some mostly academic issues hinted at in personality fragmentation.
Here are ways the show addresses the identity matters:
Double sleeving is a crime
The impression is that this isn't because it is "immoral", as no one seems to think Dimitry is disgusting or what have you for doing it, nor do any of Tak's new friends seem to care much when he does it, or even the UN negotiators he talks with at the end. Rather this just seems to be an issue of governance and accountability. It becomes significantly more complicated to resolve and punish crimes if there are duplicates. Inheritance is harder to figure out if you have a dozen copies of the same family members. Who holds copyright on a creative work when there's five of you? If modern day punishments like life in prison and the death penalty are in part because some people are seen as an unchangeable danger to society, what would you do when there are two copies of such a person but only one of them actually killed someone? What if the one that killed people made another copy of themselves? Etc.
The only thing suggesting an immoral aspect to double sleeving is that it is punishable with real death. This, however, seems to be more a consequence of the limits of punishment in the face of stack technology. There are basically only two real forms of punishment available under the law: being de-sleeved and stored as a stack for a period of time, or being real death'd. Given that double sleeving creates a lot of troublesome issues, it stands to reason it would need the more severe punishment. Every other punishment is effectively nullified by having extra copies of yourself.
The Neo Catholic movement, while not really interacted with directly by Kovacs or the others, is really the primary vehicle for getting the plot moving (via motion 653 and religious encodings of stacks). They have a religious belief that re-sleeving and winding back up a stack is a sin. They feel this taints the soul of the person and consigns them to hell. Therefore they implicitly feel that the stack carries the soul, or at least has some attachment to it, and that there is only one soul shared across copies.
Ortega winds up her deceased grandmother to celebrate a holiday, as she had renounced the religious encoding that the rest of her family seems to have. Her friends and family all seem to think of this as the same person, even as she inhabits an adult male delinquent's body. Ortega gets chided a bit that this might be inappropriate to her more religious family. While there is a bit of tension about that, everyone (other than her own daughter and Ortega's mother, Alazne) seems to be having a good time with her and has a friendly, familial attitude towards her. The children in particular.
While (Vernon) Elliot is initially a bit disconcerted by Ava being in a man's body, it doesn't take long before he sees her as Ava and talks with her as he would his wife.
Ava and Elliot's daughter ultimately opts to live in a synthetic, silicone body that came from a sex dungeon. Her choice to stay in that body rather than have a proper sleeve is depicted as a little strange, but we also see her and her family happily living together. Suggesting, again, that nobody really cares that much and that Lizzie is Lizzie.
There are several other identity issues centered around Lizzie—she recognizes her mom in the guy's body pretty much immediately, which surprises and confuses her dad; she was described as having been broken, driven insane, and she kind of had to be rebuilt—but they start getting a little complex as they give her a sort of Cassandra Curse thing, and it's not clear if she's just (still) a bit insane or an actual seer.
The fighting husband and wife
Laurens Bancroft holds a party with an extreme organic damage event that features a husband and wife who fight to the sleeve death. Both Ortega and Kovacs seem a bit shocked at this arrangement, while the couple seems to think it's a sensible thing. When the couple reveals they have children who are ages 5 and 7 and claims that they are used to them regularly coming home in strange new sleeves, both Ortega and Kovacs say "they're not used to it."
In the first episode we see a husband and wife made distraught when their slain young daughter is brought back in a worn down adult woman's sleeve. They are indignant about it, but the employee says they can either pay for an upgrade or put her back on the slab, as that's what they get for free. The child begs not to be put "back in the dark" (one of the few indicators we have that a disembodied DHF may have some sort of sense of their situation and the passage of time). Ortega tells Kovacs that that's how the system works, as the good sleeves (like his) get rented out for profit while the busted up junk ones go to the rest. The parents do seem to accept this as their child, but it is very difficult to handle it when they've been given a sleeve with an extra 30+ years on it.
So all of the above examples indicate that adults don't seem to have any issues with considering resleeved adult people as the same person, having only religious compunctions about whether it is sinful or not. But it is not something children are universally expected to deal with easily when done frequently to people they are close to. On the other hand, at least some of them seem to be able to handle a one-day-a-year visit from great-grandma in a new body without it being unsettling.
But a curveball at the end:
As a scientific matter that's only really relevant to Meths and well-connected criminal types, inhabiting a succession of different sleeves tends to have a cumulative deleterious effect on the person.
Kovacs at one point tries to dismiss his apparent attraction to Ortega as the result of "residual sleeve memory" and hormones. In the Envoy training scenes we are led to believe that there is something of a battle between the person in the DHF and the sleeve. The CTAC use reacclimation drugs, while the Envoys use some sort of psychological training to rapidly take control of the sleeve. Presumably the Envoys are less susceptible to the problem of personality fragmentation. Quell refers to the sleeve as a tool, and that she, the mind, is in control of it.
We also see various issues concerning how people see themselves. Dimi himself in VR has difficulty maintaining a single appearance, with his face instead often oscillating between those of the various sleeves he has inhabited. Also recall that when Kovacs was first decanted into Ryker's body that one of the first things he demands is a mirror. When he gets a makeshift mirror, he looks into it, sees the image of his previous face, and then seemingly forces himself with great effort (and some screaming) to see his new face. This seems to reflect the idea that it is difficult for the mind to adjust to a radically new appearance without it affecting their mind; that one's "self" in a mental way is intimately link to one's physical self. Perhaps Kovacs's forced recognition of his new self is even one of the Envoy techniques for rapid acclimation.
It turns out you can avoid the fragmentation issue if you are jumping into (clones of) your own body, and that's how Meths survive and stay "stable" for as long as they do. If Kovacs's claim about "residual sleeve memory" is to be given any weight (so not just a transparent bit of b.s.), these things would seem to suggest that personality fragmentation is caused (in part) by the psychological stress of adapting to a completely new sleeve having a semi-permanent effect combined with some aspect of the "original person" remaining in the sleeve that can seep its way into the DHF in some fashion. The mind begins to lose track of who they "really" were/are.
This seems to be the most serious way in which the idea that a resleeved person is the same person is undercut within the show. However the only people that are actually going to experience this problem seem to be criminal elements like Dimi. Normal Meths can afford clones and backups, and normal people are lucky to be able to afford even a second body on more than a short rental basis. So for most people the implications of personality fragmentation aren't relevant.
I think the show deliberately ignores the issue. However, I think of it like this: As long as the stack is being moved from body to body I accept the premise that it is the same person. To use your computer analogy, I think of a "person" not as files, etc. (i.e. their memories) but as a "process" that runs on the stack. When a body dies the process simply hibernates and resumes when inserted into a new body.
The trouble begins with remote backups. Here I would no longer consider them the same person since it is a new "process" simply created from the same (or usually, slightly older) "files". On a computer this process would get a new
pid (process id) and would thus be a completely new but similar process.
My understanding of the way that DHF/Stacks worked is that they've essentially found a way to capture and manipulate "brain states" of people, allowing them to be transferred, stored, and/or copied into new minds. I think what's important here is what you consider as a "person"; then you can explore how this concept applies in Altered Carbon. For this, I would consider someone to be the same person if they have exactly the same thoughts, memories and feelings, because they would consider themselves the same person, and would behave as such.
If you operate under the assumption that a person, and life itself, is just a naturally occurring physical process, then it appears that the DHF is able to completely capture and transfer the entire state of thinking between sleeves without any losses. Through this process, needlecasting your DHF to a new sleeve would be still considered the same person, by the metrics I'm using.
This means that for any new copies made (double-sleeved or not), they will always feel like the same person at the exact point that the DHF copy was taken from. As far as that particular DHF copy is concerned, they have lived their entire life up until that point, and are continuing to live in the new sleeve. For all intents and purposes, they are the person that they were when the DHF was copied. When you double sleeve using the same DHF, at the point of copying, the DHF represents the exact same person, because all the thoughts are the exact same up until that point.
What makes a person is their own thought process, which is highly affected by past life events. This means that the idea of an individual person is inherently temporal. The person I am right now is not the same person I was 20 minutes ago; if I double sleeved myself 20 minutes ago, the second version of myself would no longer be the same me as I am now. They would be an altered copy of me due to different experiences diverging from my current personality, thus changing the "person" that the copy is.
Basically, for all intents and purposes you're the same person because you would perceive yourself as being the same person you were copied from, at the time you were copied, and your actions towards everyone else would also reflect that.