I think “me” is relatively well defined at any instantaneous moment of time.
However, when I try to define “the future me 1 hour later,” it is completely subjective who that refers to. If the quantum multiverse (or any cloning machine) creates 100 copies of my current state, and let them evolve in different ways for the next hour, it is subjective which one is the future me, and whose experiences I should anticipate.
There is no objective rule to decide which ones I become. Suppose 99 of my copies has their memories erased one by one, until 90% of their memories are replaced by pigs’ memories. Should I anticipate a 99% chance of gradually forgetting everything and becoming a pig, or should I anticipate a 100% chance of remaining as a human?
It’s impossible to objectively argue either way. Because if you insist that I do gradually become a pig, then what if that pig then becomes a mouse, and then a fruit fly, and then a bacteria, and then a calculator, and then a rock? Should I anticipate being a rock then? Clearly not since I would be “dead” and hence shouldn’t anticipate such an experience, and should only anticipate the experience of my 1 remaining living copy.
But if you insist that I should not anticipate becoming a pig even if 99 of my copies gradually have 90% of their memories replaced by a pigs memories. Then where do you draw the line? What if only 10% of their memories are replaced by a chimpanzee’s memories? Or a neanderthal man’s memories? Clearly I should continue anticipating their experiences, since they are “still alive” and only experienced a little bit of memory loss.
But there is no objective property in the territory which distinguishes “alive” observers and “dead” observers! Indeed, there is a continuum between living observers and dead observers, e.g. brain damage.
Even if you can objectively define “me” as an observer with the same set of memories M, you have to admit that there is enormous subjectivity deciding who “the me 1 hour later” is. Your decision for which future object you stick the “future me” label on, is a subjective decision. A decision which only affects your map, not the territory.
The theory of quantum immortality depends on the theory of identity which—as you correctly pointed out—is difficult.
There are two objective facts about identity:
I will be in my next observer-moment in the next moment of time. There is an objective process which makes mind states follow one another.
I can recognize myself as me or not.
In your thought experiment, these two properties are deliberately made to contradict each other.
A simple answer here is that you should not anticipate becoming a pig because a pig can’t think about personal identity. Anticipation assumes comparison between expectation and reality. A pig can’t perform such an operation. But this is not a satisfactory model.
It can be solved if we assume that we have two types of identity—informational (me or not me) and continuous. This seems paradoxical. But if we then assume that continuous identity passes through all possible minds eventually, then any pig will eventually become me again in some multiverse timelines, and I can calculate a share of my future copies which have a memory of being a pig.
This thought experiment can be done without any supertechnology, just using dreaming as an example: what if some of my copies will have a dream that they are pigs, and others have a dream about being themselves. The idea of anticipation produces error in that case, as in one way it assumes the existence of a mind capable of comparison, but in another way it assumes natural consequences of mind states.
Even if you restrict yourself to entities which can think about personal identity, I’m not sure you can avoid subjectivity.
I think if you ran the Quantum Mars Teleporter, the result of the experiment is the copies of you on Mars will believe that “see, this proves I do become the copy on Mars,” while the copies of you in the surviving branches will believe that “see, this proves that I won’t become the person on Mars,” and they will believe different conclusions, and it is your subjective choice which one of them you identify with and anticipate the experience of.
No objective process in the real world makes any kind of decision on which copy of you your soul flows to. And there is no secular analogy for soul which lets you say “I don’t believe I have a supernatural soul, but I believe I have this other soul-like thing which does flow from my current copy to one of my future copies in an objective manner.”
I mean, suppose there was an objective answer to which copy of you will experience becoming, after you walk into the teleporter. Suppose the objective answer is that you don’t go to Mars. Then what if I modify the teleporter more and more, such that some of your atoms are not destroyed by the teleporter, and simply moved to Mars on a spaceship, while some of your other atoms are still destroyed by the teleporter and recreated on Mars. In the limit, when all of your atoms are moved to Mars on a spaceship, surely you still remain you, since the teleporter didn’t do anything at all.
Suppose on the other hand, the objective answer is you do go to Mars. Then what if I modify the teleporter more and more, such that instead of creating a copy of you, it creates a copy of you from one second ago? What about a copy of you from one day ago? Or a copy of you from 10 years ago, or when you were a baby?
At some point, you have to admit the objective answer is that you die, and the teleporter created someone else.
But when does the objective answer change from teleporting you to Mars, vs. killing you (and you continue to exist in the quantum branch where you weren’t teleported)?
Is it a sudden change or a gradual change? When does the change occur?
And who the heck decides the objective answer? Is there a strange god which measures how similar the copy on Mars is to you, by counting how many of your memories he has, and if this god feels satisfied he says “okay yes, you can become this person, this person is you?
But if he feels oh, it’s a bit too different, he decides “you know what, this person is only kind of you, he’s a bit too different. So I’ll only allow you to have a 20% chance of becoming him, and a 80% chance of continuing to exist in the quantum branch where you weren’t teleported.”
To me, the simplest explanation is there is no objective answer.
Evolution designed creatures to imagine possible experiences by other creatures. However, evolution designed creatures to distinguish between other creatures which are their “future selves,” and other creatures which are “someone else,” in order to make sure that they only work to make themselves happy, rather than other creatures.
Unfortunately, no objective distinction exists in the real world. After all, your “future self” may be more different than you than “someone else” currently is. So evolution makes us strongly believe there is this objective property of “you-ness” when it doesn’t actually exist in the real world.
Generally, I agree with what you said above—there is no (with some caveats—see below) soul-like identity, and we should use informational identity instead. Informational identity is objective, measurable sameness of memory and allows existence of many copies. It can be used to survive the end of the universe. I just care about the existence of a copy of me in another universe.
The main caveat is that the no-soul view ignores the existence of qualia. Qualia and the nature of consciousness are not solved yet, and we can’t claim that the identity problem is solved without first solving qualia and consciousness.
I guess there are aspects of qualia and consciousness I don’t understand. E.g. suppose the universe was infinite. Then there are infinite copies of me who believe 1+1=2, and infinite copies of me who believe 1+1=3, and these two infinities have the same cardinality. So how come I happen to be one of the copies who believe 1+1=2? And by extension, how come I happen to be one of the copies who observe a universe where probabilities have always obeyed the Born rule?
It almost feels like there actually is an objective infinite measure for the “number of conscious beings,” and this measure weighs them according to the Born rule.
I have to admit that this part confuses me.
That being said, even if there exists an objective measure for the number of observers at one instant of time, I still find it unlikely that there further exists an “objective flowchart,” that dictates which future observer each observer shall experience becoming, and with what probabilities.
I think which future observer each observer experiences becoming is wholly subjective, and only feels objective due to evolutionary instincts. It’s the most elegant solution to these thought experiments, as well as the Anthropic Trilemma (which I learned about while writing this reply).
I think there is more to consider. For example, we can imagine a “qualia rainbow” theory of identity. I don’t necessarily endorse it, but it illustrates why understanding qualia is important for identity.
Imagine that infinitely many different qualia of “reds” could denote one real red. Each person, when born, is randomly initialized with a unique set of qualia for all colors and other sensations. This set can be called a “rainbow of qualia,” and continuous computing in the brain maintains it throughout a person’s life. A copy of me with a different set of qualia, though behaviorally indistinguishable, is not me. Only future mind states with the same set of qualia as mine are truly me, even if my memories were replaced with those of a rat.
Is the qualia rainbow theory a personal choice for deciding which copies to count as “me” and which copies to count as “not me?” Or does the theory say there is an objective flowchart in the universe, which dictates which future observer each observer shall experience becoming, and with what probabilities? If it was objective, could a set of red qualia be observed with a microscope?
I agree that qualia is an important topic (even if we don’t endorse the qualia rainbow theory), I agree that identity is complex, though I still strongly believe that which object contains my future identity is a very subjective choice by me.
The problem with the subjective choice view is that I can’t become Britney Spears. :) If I continue to sit at the table, I will find myself there every next moment even if I try to become someone else. So mapping into the next moments is an objective fact.
Moreover, even a single moment of experience is a mapping between two states of the brain, A and B. For example, moment A is before I see a rose, and moment B is after I see it and say: “A rose!” The experience of a red rose happens after A but before B.
The rainbow of qualia theory is objective but it assumes the existence of a hypothetical instrument: a qualiascope. A qualiascope is a mind which can connect to other minds and compare their experiences. This works the same way as my mind can compare qualia of colors and sounds without being any of them. Whether a qualiascope is physically possible is not obvious, as its observations may disturb the original qualia.
:) what proves that you “can’t become Britney Spears?” Suppose the very next moment, you become her (and she becomes you), but you lose all your memories and gain all of her memories.
As Britney Spears, you won’t be able to say “see, I tried to become Britney Spears, and now I am her,” because you won’t remember that memory of trying to become her. You’ll only remember her boring memories and act like her normal self. If you read on the internet that someone said they tried to become Britney Spears, you’ll laugh about it not realizing that that person used to be you.
Meanwhile if Britney Spears becomes you, she won’t be able to say “wow, I just became someone else.” Instead, she forgets all her memories and gains all your memories, including the memory of trying to become Britney Spears and apparently failing. She will write on the internet “see, I tried to become Britney Spears and it didn’t work,” not realizing that she used to be Britney Spears.
Did this event happen or not? There is no way to prove or disprove it, because in fact whether or not it happened not a valid question about the objective world. The universe has the exact same configuration of atoms in the case where it happened and in the case where it didn’t happen. And the configuration of atoms in the universe is all that exists.
The question of whether it happened or not only exists in your map, not the territory.
Haha but the truth is I don’t understand where “a single moment of experience” comes from. I’m itching to argue that there is no such thing as that either, and no objective measure of how much experience there is in any given object.
I can imagine a machine gradually changing one copy of me to two copies of me (gradually increasing the number causal events), and it feels totally subjective when the “copy count” increases from one to two.
But this indeed becomes paradoxical, since without an objective measure of experience, I cannot say that the copies of me who believe 1+1=2 have a “greater number” or “more weight” than the copies of me who believe 1+1=3. I have no way to explain why I happen to observe that 1+1=2 rather than 1+1=3, or why I’m in a universe where probability seems to follow the Born rule of quantum mechanics.
In the end I admit I am confused, and therefore I can’t definitely prove anything :)
The idea of observer’s stability is fundamental for our understanding of reality (and also constantly supported by our experience) – any physical experiment assumes that the observer (or experimenter) remains the same during the experiment.
I agree that it’s useful in practice, to anticipate the experiences of the future you which you can actually influence the most. It makes life much more intuitive and simple, and is a practical fundamental assumption to make.
I don’t think it is “supported by our experience,” since if you experienced becoming someone else you wouldn’t actually know it happened, you would think you were them all along.
I admit that although it’s a subjective choice, it’s useful. It’s just that you’re allowed to anticipate becoming anyone else when you die or otherwise cease to have influence.
I can also use functional identity theory, where I care about the next steps of agents functionally similar to my current thought-line in logical time.
I think “me” is relatively well defined at any instantaneous moment of time.
However, when I try to define “the future me 1 hour later,” it is completely subjective who that refers to. If the quantum multiverse (or any cloning machine) creates 100 copies of my current state, and let them evolve in different ways for the next hour, it is subjective which one is the future me, and whose experiences I should anticipate.
There is no objective rule to decide which ones I become. Suppose 99 of my copies has their memories erased one by one, until 90% of their memories are replaced by pigs’ memories. Should I anticipate a 99% chance of gradually forgetting everything and becoming a pig, or should I anticipate a 100% chance of remaining as a human?
It’s impossible to objectively argue either way. Because if you insist that I do gradually become a pig, then what if that pig then becomes a mouse, and then a fruit fly, and then a bacteria, and then a calculator, and then a rock? Should I anticipate being a rock then? Clearly not since I would be “dead” and hence shouldn’t anticipate such an experience, and should only anticipate the experience of my 1 remaining living copy.
But if you insist that I should not anticipate becoming a pig even if 99 of my copies gradually have 90% of their memories replaced by a pigs memories. Then where do you draw the line? What if only 10% of their memories are replaced by a chimpanzee’s memories? Or a neanderthal man’s memories? Clearly I should continue anticipating their experiences, since they are “still alive” and only experienced a little bit of memory loss.
But there is no objective property in the territory which distinguishes “alive” observers and “dead” observers! Indeed, there is a continuum between living observers and dead observers, e.g. brain damage.
Even if you can objectively define “me” as an observer with the same set of memories M, you have to admit that there is enormous subjectivity deciding who “the me 1 hour later” is. Your decision for which future object you stick the “future me” label on, is a subjective decision. A decision which only affects your map, not the territory.
The theory of quantum immortality depends on the theory of identity which—as you correctly pointed out—is difficult.
There are two objective facts about identity:
I will be in my next observer-moment in the next moment of time. There is an objective process which makes mind states follow one another.
I can recognize myself as me or not.
In your thought experiment, these two properties are deliberately made to contradict each other.
A simple answer here is that you should not anticipate becoming a pig because a pig can’t think about personal identity. Anticipation assumes comparison between expectation and reality. A pig can’t perform such an operation. But this is not a satisfactory model.
It can be solved if we assume that we have two types of identity—informational (me or not me) and continuous. This seems paradoxical. But if we then assume that continuous identity passes through all possible minds eventually, then any pig will eventually become me again in some multiverse timelines, and I can calculate a share of my future copies which have a memory of being a pig.
This thought experiment can be done without any supertechnology, just using dreaming as an example: what if some of my copies will have a dream that they are pigs, and others have a dream about being themselves. The idea of anticipation produces error in that case, as in one way it assumes the existence of a mind capable of comparison, but in another way it assumes natural consequences of mind states.
In short, a correct identity theory allows one to compute correct probabilities of future observations in the situation of many different copies. See also my post The Quantum Mars Teleporter: An Empirical Test Of Personal Identity Theories.
Even if you restrict yourself to entities which can think about personal identity, I’m not sure you can avoid subjectivity.
I think if you ran the Quantum Mars Teleporter, the result of the experiment is the copies of you on Mars will believe that “see, this proves I do become the copy on Mars,” while the copies of you in the surviving branches will believe that “see, this proves that I won’t become the person on Mars,” and they will believe different conclusions, and it is your subjective choice which one of them you identify with and anticipate the experience of.
No objective process in the real world makes any kind of decision on which copy of you your soul flows to. And there is no secular analogy for soul which lets you say “I don’t believe I have a supernatural soul, but I believe I have this other soul-like thing which does flow from my current copy to one of my future copies in an objective manner.”
I mean, suppose there was an objective answer to which copy of you will experience becoming, after you walk into the teleporter. Suppose the objective answer is that you don’t go to Mars. Then what if I modify the teleporter more and more, such that some of your atoms are not destroyed by the teleporter, and simply moved to Mars on a spaceship, while some of your other atoms are still destroyed by the teleporter and recreated on Mars. In the limit, when all of your atoms are moved to Mars on a spaceship, surely you still remain you, since the teleporter didn’t do anything at all.
Suppose on the other hand, the objective answer is you do go to Mars. Then what if I modify the teleporter more and more, such that instead of creating a copy of you, it creates a copy of you from one second ago? What about a copy of you from one day ago? Or a copy of you from 10 years ago, or when you were a baby?
At some point, you have to admit the objective answer is that you die, and the teleporter created someone else.
But when does the objective answer change from teleporting you to Mars, vs. killing you (and you continue to exist in the quantum branch where you weren’t teleported)?
Is it a sudden change or a gradual change? When does the change occur?
And who the heck decides the objective answer? Is there a strange god which measures how similar the copy on Mars is to you, by counting how many of your memories he has, and if this god feels satisfied he says “okay yes, you can become this person, this person is you?
But if he feels oh, it’s a bit too different, he decides “you know what, this person is only kind of you, he’s a bit too different. So I’ll only allow you to have a 20% chance of becoming him, and a 80% chance of continuing to exist in the quantum branch where you weren’t teleported.”
To me, the simplest explanation is there is no objective answer.
Evolution designed creatures to imagine possible experiences by other creatures. However, evolution designed creatures to distinguish between other creatures which are their “future selves,” and other creatures which are “someone else,” in order to make sure that they only work to make themselves happy, rather than other creatures.
Unfortunately, no objective distinction exists in the real world. After all, your “future self” may be more different than you than “someone else” currently is. So evolution makes us strongly believe there is this objective property of “you-ness” when it doesn’t actually exist in the real world.
Generally, I agree with what you said above—there is no (with some caveats—see below) soul-like identity, and we should use informational identity instead. Informational identity is objective, measurable sameness of memory and allows existence of many copies. It can be used to survive the end of the universe. I just care about the existence of a copy of me in another universe.
The main caveat is that the no-soul view ignores the existence of qualia. Qualia and the nature of consciousness are not solved yet, and we can’t claim that the identity problem is solved without first solving qualia and consciousness.
I guess there are aspects of qualia and consciousness I don’t understand. E.g. suppose the universe was infinite. Then there are infinite copies of me who believe 1+1=2, and infinite copies of me who believe 1+1=3, and these two infinities have the same cardinality. So how come I happen to be one of the copies who believe 1+1=2? And by extension, how come I happen to be one of the copies who observe a universe where probabilities have always obeyed the Born rule?
It almost feels like there actually is an objective infinite measure for the “number of conscious beings,” and this measure weighs them according to the Born rule.
I have to admit that this part confuses me.
That being said, even if there exists an objective measure for the number of observers at one instant of time, I still find it unlikely that there further exists an “objective flowchart,” that dictates which future observer each observer shall experience becoming, and with what probabilities.
I think which future observer each observer experiences becoming is wholly subjective, and only feels objective due to evolutionary instincts. It’s the most elegant solution to these thought experiments, as well as the Anthropic Trilemma (which I learned about while writing this reply).
I think there is more to consider. For example, we can imagine a “qualia rainbow” theory of identity. I don’t necessarily endorse it, but it illustrates why understanding qualia is important for identity.
Imagine that infinitely many different qualia of “reds” could denote one real red. Each person, when born, is randomly initialized with a unique set of qualia for all colors and other sensations. This set can be called a “rainbow of qualia,” and continuous computing in the brain maintains it throughout a person’s life. A copy of me with a different set of qualia, though behaviorally indistinguishable, is not me. Only future mind states with the same set of qualia as mine are truly me, even if my memories were replaced with those of a rat.
Anthropic Trilemma is masterpiece.
Is the qualia rainbow theory a personal choice for deciding which copies to count as “me” and which copies to count as “not me?” Or does the theory say there is an objective flowchart in the universe, which dictates which future observer each observer shall experience becoming, and with what probabilities? If it was objective, could a set of red qualia be observed with a microscope?
I agree that qualia is an important topic (even if we don’t endorse the qualia rainbow theory), I agree that identity is complex, though I still strongly believe that which object contains my future identity is a very subjective choice by me.
The problem with the subjective choice view is that I can’t become Britney Spears. :) If I continue to sit at the table, I will find myself there every next moment even if I try to become someone else. So mapping into the next moments is an objective fact.
Moreover, even a single moment of experience is a mapping between two states of the brain, A and B. For example, moment A is before I see a rose, and moment B is after I see it and say: “A rose!” The experience of a red rose happens after A but before B.
The rainbow of qualia theory is objective but it assumes the existence of a hypothetical instrument: a qualiascope. A qualiascope is a mind which can connect to other minds and compare their experiences. This works the same way as my mind can compare qualia of colors and sounds without being any of them. Whether a qualiascope is physically possible is not obvious, as its observations may disturb the original qualia.
:) what proves that you “can’t become Britney Spears?” Suppose the very next moment, you become her (and she becomes you), but you lose all your memories and gain all of her memories.
As Britney Spears, you won’t be able to say “see, I tried to become Britney Spears, and now I am her,” because you won’t remember that memory of trying to become her. You’ll only remember her boring memories and act like her normal self. If you read on the internet that someone said they tried to become Britney Spears, you’ll laugh about it not realizing that that person used to be you.
Meanwhile if Britney Spears becomes you, she won’t be able to say “wow, I just became someone else.” Instead, she forgets all her memories and gains all your memories, including the memory of trying to become Britney Spears and apparently failing. She will write on the internet “see, I tried to become Britney Spears and it didn’t work,” not realizing that she used to be Britney Spears.
Did this event happen or not? There is no way to prove or disprove it, because in fact whether or not it happened not a valid question about the objective world. The universe has the exact same configuration of atoms in the case where it happened and in the case where it didn’t happen. And the configuration of atoms in the universe is all that exists.
The question of whether it happened or not only exists in your map, not the territory.
Haha but the truth is I don’t understand where “a single moment of experience” comes from. I’m itching to argue that there is no such thing as that either, and no objective measure of how much experience there is in any given object.
I can imagine a machine gradually changing one copy of me to two copies of me (gradually increasing the number causal events), and it feels totally subjective when the “copy count” increases from one to two.
But this indeed becomes paradoxical, since without an objective measure of experience, I cannot say that the copies of me who believe 1+1=2 have a “greater number” or “more weight” than the copies of me who believe 1+1=3. I have no way to explain why I happen to observe that 1+1=2 rather than 1+1=3, or why I’m in a universe where probability seems to follow the Born rule of quantum mechanics.
In the end I admit I am confused, and therefore I can’t definitely prove anything :)
The idea of observer’s stability is fundamental for our understanding of reality (and also constantly supported by our experience) – any physical experiment assumes that the observer (or experimenter) remains the same during the experiment.
I agree that it’s useful in practice, to anticipate the experiences of the future you which you can actually influence the most. It makes life much more intuitive and simple, and is a practical fundamental assumption to make.
I don’t think it is “supported by our experience,” since if you experienced becoming someone else you wouldn’t actually know it happened, you would think you were them all along.
I admit that although it’s a subjective choice, it’s useful. It’s just that you’re allowed to anticipate becoming anyone else when you die or otherwise cease to have influence.
I can also use functional identity theory, where I care about the next steps of agents functionally similar to my current thought-line in logical time.