By continuity of identity I mean the classic teleportation problem: when you teleport, do you arrive at the destination, or do you die and your clone arrives? The problem being that no-one other than you can tell; and by the time you know, you're dead.

In EP it seems reasonable to assume that no one would ever want to resleeve if it caused their death or if it might do so. That implies that in the setting there is some way in which it was shown, when the technology was invented or before it passed into widespread use, that resleeving is safe. Yet it is not clear what this was or what other effects it had on the setting.

I know this question has been asked before in terms of the soul but this is not the same metaphysical question because it is practical: life or death. Regardless of the philosophical nature of the question noone would want to go through a process that is not proven to have a chance of survival. In fact proving a soul exists might have been the proof of safety.

How do Eclipse Phase citizens know that resleeving does not kill them and create a clone?

Edit: just to clarify, I'm not asking how resleeving works in the setting. Rather, I'm asking this: suppose that one day Professor Q was to demonstrate the first ever resleeving machine. He steps in and then comes out in a new morph. Then a heckler shouts, "That's not Professor Q, it's a clone of him with his memories! The original is dead! He might think it worked, but that's because the clone has his memory of getting into the machine. It might look exactly the same to him and everyone else, but the man who stepped into the machine is now dead forever, and if you use that machine, you'll die too!"

What can Professor Q show the audience to prove the heckler wrong? If the answer is "nothing", why would anyone accept and use the machine? If we assume that he did show them something that proved it, then what was it, and what other implications does its existence have for the setting? As far as I know, none of the books address this, and whichever way it resolves has pretty major implications for the tone of the world.

  • 4
    \$\begingroup\$ Most likely related to Eclipse Phase and... the soul? \$\endgroup\$
    – Ahriman
    Commented Nov 10, 2015 at 14:03
  • \$\begingroup\$ @Ahriman: It is related but I do not think identical enough for a duplicate. \$\endgroup\$ Commented Nov 10, 2015 at 14:09
  • \$\begingroup\$ @sardathrion Yes, I looked at that discussion but it focused too much on the religious concept of a soul, rather than the practical one of life or death. \$\endgroup\$
    – Mark Green
    Commented Nov 10, 2015 at 16:14
  • \$\begingroup\$ Comments are not for chewing on problems that even professional philosophers still haven't solved. \$\endgroup\$ Commented Nov 13, 2015 at 3:57

4 Answers 4


They don't

One of the biggest hurdles to overcome when resleeving is the shock caused by the loss of continuity (p272):

The driving point in this loss of continuity is a sort of existential crisis - they are no longer the original person they once were. This leads some to question whether they are who they think they are, or are they some poor imitation and not a real person at all?

Fortunately, this doesn't always happen. When resleeving under normal conditions, the mind is gradually transferred via an ego bridge (p269). Parts of it "run" in both brains at once as the process goes on, and the person can even be awake at the time. In this case, it can be said that there is no "true" self left behind.

While this particular concern is not mentioned as part of the bioconservative agenda, it seems like that's where it would belong, as they oppose uploading. The beauty of Eclipse Phase is that it encourages you to examine such questions.

  • 2
    \$\begingroup\$ And the side effect is that characters have their own belief about that and can conflict in the same team, which is always nice to have, an interesting group dynamic. \$\endgroup\$
    – Klaim
    Commented Nov 10, 2015 at 17:53
  • 1
    \$\begingroup\$ A arguably-transhumanist novel that vividly depicts such a bridged ego transfer (and the deep existential crisis that it may/may not involve) is John Scalzi's Old Man's War. \$\endgroup\$ Commented Nov 13, 2015 at 4:05

No, there is no proof that the individual that exists after the resleeving process is the same individual who existed before it. If this makes you feel uncomfortable - well, that's actually part of the authors' intention. Resleeving is one of the setting's "transhuman technologies" - which is to say, setting elements that force us to re-examine and revise our answers to the question "what is a human?"

More specifically, resleeving forces us to re-examine our answer to the question "what is an individual?" Is it a pattern, and as long as the pattern exists, so does the individual? Is it continual consciousness, and whenever consciousness ceases, the individual ceases to exist? Is it some immaterial essence that transcends consciousness, and if so, does it transfer from one body to the next as the ego does?

There's no single clear answer given in the setting*, no perfect inarguable definition of what makes an individual and proof that it is conserved during resleeving. There's just subjective definitions, and different opinions on what's important, and what people believe. And people do arrive at conclusions, and act on them, even in the absence of proof - just like they do today, when it comes to questions about the existence of an afterlife; If you were to send out a survey, Joe Citizen of the Jovian Republic and Thomas Atkins the Martian Informorph would have very different views on what resleeving means for the individual, and they will act based on those beliefs. The lack of a One True Answer to your question is entirely deliberate; Exploring these questions is what the game, and the entire transhuman genre, is about.

*Actually, there is a sort-of-answer implicit in the fact that if a player resleeves, they can usually continue playing their ego's new morph as if it were the same individual. That said, I suspect this is is a concession to making the game playable rather than a definite answer to the question.


Let us assume that an identity/person is the sum of their experiences, knowledge, and memories. It is this information that makes them who they are. This is what Eclipse Phase refers to as an ego.

In the absence of a soul or any other metaphysical equivalent, the same person is one that will have the same MD5 hash of their ego. This does mean that a perfect clone is the same person. There is just two (or more) of them. In the same way that copying EverybodyKnows.flac to EverybodyKnows-copy.flac is the same song: there are just two (perfect) copies.

How is resleeving safe? Before the egocasting, you make a MD5 hash of your ego. After, you verify that the resleeved ego matches the MD5 hash. For all intent and purpose, you are the same person. No one can tell who the "original" was. While never directly stated (as far as I can remember) in either Eclipse Phase or other works (Takeshi Kovacs, Glasshouse, etc...) this seems a logical extension of the resleeving meme.

Dying is having your ego, or part of your ego, either erased or altered. This is not (read: should not) happen with egocasting/resleeving as you get a perfect copy. This is more or less cannon from the game setting.

If leaving an ego at the point of origin bothers you, you can say that the copy is a quantum copy: As soon as you read the data, it is erased from the source so that when you write it, the source is in effect gone.

Now, if you decide to fork yourself, then there will be two of you for a Heisenberg uncertainty principle defined time. After that, your egos will diverge slows as new inputs, emotions, and knowledge comes flooding it. This is why merging forks gets harder as times elapses since the fork.

  • \$\begingroup\$ Comments are not for discussion. \$\endgroup\$
    – mxyzplk
    Commented Nov 12, 2015 at 8:09

A further answer which I was pointed to and investigated elsewhere which was so interesting I thought I should also post it here.

In Eclipse Phase, after the TITANs attacked Earth, a large number of people left by egocasting - essentially identity-transfer teleportation. The vast majority of those who stayed behind were killed by TITANs, and many who tried to leave by conventional space travel died on that journey due to supplies running out as they searched for a habitable planet that could accept them.

The effect is that all the people who arrived via egocasting - even if they are clones and the original is dead - remember an egocast having worked and save them, and naturally trust that technology. And those who didn't arrive by egocasting, are probably dead anyway.

It has interesting corollaries for any application of that technology. If you were dying of terminal cancer and had the opportunity to switch your body to one without cancer, on the basis that it might kill you but you would die from the cancer anyway, it'd be tempting to try it. And if you died in the process, your clone thinks it went fine.. and will be happy to have it done again, and to tell others it works. After a few generations of this, you have an entire population who could be sacrificing themselves daily without knowing. Pretty terrifying, but that's a part of EP.

  • \$\begingroup\$ Good point about how most people in the post-Fall setting have actually experience the process firsthand, especially. Even those people may still have philosophical or spiritual disquiet about it, but they understand how it feels directly. \$\endgroup\$
    – Alex P
    Commented May 21, 2018 at 17:28

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