What is consciousness? or, alternatively, what is identity?
I'm not asking about the mechanisms behind them (although that is a valid scientific question), rather, I am probing the boundaries of what people define as self and not-self.
A series of thought experiments, if you please.
A destructive teleporter that scans and destroys you at one location and reassembles you at another. Nothing is transmitted from two points except for information. You walk in at one end, are destroyed, and you walk out at the other.
A delayed duplicator, that scans you at one location and duplicates you at another, with a delay in between. Days, months, years later. You walk in at one end, you walk out the same end, and, eventually, you walk out the other end.
Which of the scenarios listed above continue your consciousness, and in which copy of you? Which of the scenarios above end your consciousness, and by extension, your life?
Scenario 1 is the least controversial of the above. Setting
t = tp would be identical to everyday existence, travelling a Planck moment at a time. Setting the delay in terms of hours would be little different from a dreamless sleep. Weeks to years, a coma or suspended animation. And I believe that most people feel that they are the same person when they wake up from a mid-afternoon nap.
(If you don't, I would advise you to seek professional help, as the magnitudes of insanity that one feels from having no continuity in one's life is far beyond the scope of what one can normally deal with.)
Scenario 2 is akin to light-speed travel, and to worry about one's continuity through that would be as irrational to worry about transportation in general. A displacement through space, while travelling through the intervening space (or at least existing throughout the entire journey) should be no more taxing on one's identity as a plane ride.
The third scenario creates a conundrum upon which many stumble. The destruction of the original is often seen as the cessation of consciousness, as people often believe that the consciousness rests in the material of the original.
But assuming that the copy is created identically, subatomic particle by subatomic particle, there is literally no difference between the original and the copy. Thus, the copy is you, no matter if it has been assembled thousands of light years away with atoms far removed from your original body.
However, once the original is no longer destroyed, we run into the problem of having two copies of an individual. And thus, Scenario 4 creates the outcome where two copies of you exist.
Which one of them is the real you, when one cannot be distinguished from the other, for all terms of the word?
Both of them are you.
You will find yourselves localized to one of the bodies, of course, and from that instant on, that body will be the new you; the other body will experience the same thing. However, at the instant of creation, the two versions of you are identical. There is no way of saying which is the original (if that means anything at all). One of you will experience the machine as a duplicator, while the other version of you will experience it as a teleporter. And, given that the two versions are identical, both will be right. There can be no arguing which is the original and which is the copy; both have an equally continuous consciousness which support their argument. And indeed, you are both. Until experience causes your selves to diverge.
As both copies will be you, they will both be responsible for your actions committed before the duplication, but will not be responsible for actions of each other after the duplication. No legal precedent has been set for planning beforehand to use the duplicator to create a disposable version of yourself to commit a crime (although I personally believe the other could be charged with conspiracy with yourself).
(An addendum: If you were to use such a machine, it is probably best to agree with yourself upon naming methods prior to stepping into the duplicator (such as the one displaced in space being -beta), as afterward, both of you have the same claim to identity. But remember that you're going to experience both events, so ensure that you will be satisfied either way. So don't enslave copies of yourself (unless you're absolutely sure that you're okay with being enslaved by a copy of you).)
The delayed duplicator brings up interesting questions.
At a delay of 0, it is identical to Scenario 4, but the longer the delay is, the more different the two copies become. From one point of view, it would be identical to having a personal backup of yourself, while from the other it would be a time machine to the future with the ability to meet yourself.
Both are you (or at least some version of you in spacetime). Both have a fully continuous consciousness. But, upon meeting the other version of yourself, how much are you the same?
In the instantaneous duplication case, both copies of you diverge at the same rate, and thus both are equally similar to the original duplicate, and thus assets should logically be divided equally (unless agreements are made beforehand). However, in the delayed case, one copy of you has diverged more than the other, but the assets continued be in the possession of the living copy, and have changed over time. The delayed duplicate has claim to the identity of the original being who stepped out of the machine, but does it have an equal claim to modified identity (and assets)?
Assets, yes. Identity, no.
It can be argued that half assets were held by the original duplicate as a trust for the delayed duplicate (given the precedent of scenario 4) and thus would be inherited upon appearance (minus fees, which should be agreed to in advance. Remember: prepare before making duplicates of yourself).
However, identity cannot be transferred. Identity is a social construct, and in the society when the delayed duplicate appears, the identity refers to the copy which has experienced the intervening time, rather than the original state.
(There is the aspect of personal identity, but that cannot be transferred. The delayed duplicate's personal identity would be identical to the original duplicate's personal identity upon exit from the machine, but their social identities would vary greatly.
Also, although some aspects of social identity will be transferred (due to some shared experiences and shared name), using that social identity would be identical to posing as an impostor. You can only claim an identity with the experiences that you own (but blame mistaking you for your original duplicate rests on the observer). Even after the death of the original duplicate, you do not have its experiences. You are different.)
Thus, your self can be distributed among multiple individuals until their experiences begin to diverge (which usually happens immediately, unless you are being perfectly predicted). You are whatever body you end up in (assuming there are no others identical to you), and no scenario ends your consciousness if you are awakened in the future.
(However, if your awakening is unpredictable, then does your consciousness cease end upon entering the machine? compare to: dreamless sleep from which one has a probability of never awakening. Almost like every single sleep. I would deem that the consciousness never ends, until it is impossible to reconstruct the consciousness whole. Merely suspended.
And, as there is always the possibility that sometime, somewhere, our consciousness will reappear, we will never die.)