Monday, February 07, 2022

Identity Across the Multiverse

guest post by Amy Kind

Philosophical thinking about personal identity often focuses on identity across time. What makes the baby named Dwayne, born to Ata and Rocky Johnson in May 1972, the same person as the WWE wrestler known as The Rock? And what makes them both the same person as the actor who voiced the part of the shapeshifting demigod Maui in the 2016 animated film Moana? Confronted with an ordinary case of aging like this one, we might naturally think that the answer lies in a combination of facts about biological and psychological continuity. Unfortunately, however, the situation is complicated by the fact that the biology and the psychology facts can come apart.

Examples arise in various real-life situations, such as when an individual in a persistent vegetative state has biological continuity with an earlier individual without having any psychological continuity with them. Or to take an even more mundane example: Consider a college student who wakes up after a night of such heavy partying that they had a complete blackout. Though they remember nothing of the events of the previous evening, they are nonetheless biologically continuous with the person who imbibed all that alcohol. An even vaster variety of such cases have been depicted in science fiction. When a Star Trek character is beamed from the USS Enterprise to the planet the starship is orbiting, they are dematerialized and sent to the planet as an energy beam. The planetary individual has all the thoughts and memories as the individual who stepped onto the transporter pad, but none of the same atoms. So, does that make transporting a quick means of travel, or should it instead be viewed as a quick means of death?

Unsurprisingly, philosophers have split primarily into two different camps on the issue of personal identity over time – with one camp following in a tradition associated with John Locke that focuses on psychological facts and the other camp instead focusing on the biological facts. (A third camp offers a theory based on the soul.) Though various considerations can be advanced in favor of each position, that’s not my interest here.[1] Rather, I want to explore how our thinking about personal identity becomes further problematized when we turn from the question of identity across time to the question of identity across worlds.

Cases of identity across worlds don’t seem to arise in real life (or at least not yet!). But just as identity across time has been insightfully treated in a variety of SF works – in Star Trek episodes like TNG: “Second Chances”, Robert Sawyer’s Mindscan, Philip K. Dick’s “We Can Remember it for You Wholesale,” and Arkady Martine’s A Memory Called Empire, to give just a few examples – science fiction also provides us with some interesting explorations of identity across worlds. In some works of science fiction, multiverse travel proceeds via something like a consciousness transfer. To travel to another world, one’s Earthly consciousness inhabits (or, one might say, takes over) the consciousness of one’s cross-world counterpart. This is how multiverse travel was imagined in Matt Haig’s 2020 novel The Midnight Library. But in other works, travel to other worlds operates more like travel to other places, though the mode of transportation is not a typical airplane or even spaceship. In Black Crouch’s Dark Matter, for example, the relevant vehicle is some kind of mysterious metal cube.

On either of these models, however, an interesting philosophical question arises: How should we view the relationship between a person in one world of the multiverse and their counterpart in another world of the multiverse?

On the one hand, there are good reasons to deny that the counterparts are identical to one another. Counterparts exist in different places at the same time. Their bodies may be qualitatively similar to one another, and perhaps even indistinguishable from one another, but they are not numerically identical to one another. Moreover, though counterparts may have very similar psychological make-ups to one another, there is no shared consciousness between them. Someone from one world cannot introspectively access the thoughts and feelings of their counterpart on another world. All in all, the relationship between an individual and their counterpart is more like a relationship between twins or clones than it is like the relationship between an individual and their past or future selves.

But here it’s worth noting that science fiction depictions of clones frequently sometimes the relationship between clones as one akin to something like identity and, moreover, identity in a non-metaphorical sense. SF clones sometimes seem to think of their own personal identity as unified across clones into a single self. In Ursula LeGuin’s short story “Nine Lives,” for example, when a group of genetically identical clones reports for a mission on the planet Libra, they introduce themselves as a single entity: “We’re a tenclone. John Chow’s the name.” Moreover, after nine of the ten die in an earthquake, the one remaining clone wants to die as well: “I am nine-tenths dead. There is not enough of me left alive.”

So that brings us to the other hand: There may well be good reasons to accept that cross-world counterparts also share personal identity. And this is how science fiction often presents the matter. One particularly compelling example comes in Micaiah Johnson’s The Space Between Worlds. (For another, see Greg Egan’s short story “The Infinite Assassin” from the collection Axiomatic.) In Johnson’s 2020 novel, the Eldridge Institute employs cutting-edge technology to explore the multiverse and bring information and resources back to their own world, what they call Earth Zero. But there’s one important catch. The technology prevents anyone from travelling to a world in which their counterpart is still alive.

Caramenta, the novel’s protagonist, is an especially useful “traverser” for the company. Since her counterparts have died in 372 of the 380 worlds to which travel is technologically possible, she has a greater capacity for world travel than other traversers. It’s hard to tease out exactly how we’re to understand Caramenta’s relationship with her remaining counterparts. She sometimes refers to a counterpart as “her,” sometimes as “me,” sometimes as “another me.” After one of her counterparts dies, her emotions are complicated. When she tells her sister that she and the counterpart weren’t close, her sister disagrees: “You are as close to her as anyone can ever be. You are her.”

When Caramenta does reflect explicitly on the matter, she notes that while she has always believed that her selves are separate, and that “they – we – exist independently,” in quiet moments she can feel her other selves and their experiences. In describing this feeling, she says something especially revealing: “I can feel it all happening. Not just my selves collapsing, but time collapsing, because past and future are other selves just as surely as those on different worlds.”

How should we take this suggestive remark? Is it meant to carve out more distance between our different temporal selves – and more disconnect in our personal identity over time – than we typically recognize? Or is instead meant to encourage us to think of our counterpart selves throughout the multiverse no differently from the way we think of our past and future selves throughout time? Ultimately, I’m not sure. But whichever way Caramenta’s analogy should be taken, it seems clear that our philosophical reflection about personal identity across time could benefit from more philosophical reflection about personal identity across worlds. To understand what makes us who we are, we need to understand not just who we were and who we will be, but also who we could have been.


[1] I discuss this debate in some detail in my book Persons and Personal Identity.

[image source]


Daniel Polowetzky said...

My crude test to determine self versus other is to consider whether I could feel the other’s pain.
If I cannot feel it, then it is not my experience in a very meaningful sense. Of course, there may be things going on that I am unaware of, that could still be said are happening to me.
But the equivalent state occurring in someone else, certainly isn’t that of one of my experiences, in any sense I care about, except insofar as it bears a causal relationship to my experiences.
In that case, the other person could be considered a neuron of mine.

Arnold said...

Very interesting overview. In Caramentas collapses is experience still possible?

Nat Lamb said...

Incredibly disappointing that a post discussing identity across the multiverse would ignore Michael Moorcock. Not only does he explicitly discuss the idea in many of his books, but he was the first writer to use the term "multiverse" outside of esoteric mathematics and in the way it is now commonly used.

chinaphil said...

One of the ways in which fiction may complicate or bias this question is the issue of memory. One of the common suggestions for identity is continuity of memories, and one of the most important features of fiction is the way authors build on what the reader does and doesn't know (remember) and what the characters know (remember) and don't know. So I worry that the mechanics of fiction may be an overlay that could affect the way the question plays out.

Philosopher Eric said...

This seems like Eric Schwitzgebel’s favorite variety of philosophy, or the kind which opens. Nevertheless my own favorite is the kind which attempts to close. I yearn for the existence of a respected community of philosophers that’s able to provide scientists with metaphysical, epistemological, and axiological insights from which to potentially grasp more than than they’re currently able to.

It seems to me that John Locke had things relatively straight here — the self only exists continuously by means of psychological dynamics. But that shouldn’t mean biology doesn’t matter as well. Psychology merely supervenes upon biology, which is to say that it resides at a higher level of biological processes.

I consider self to ultimately exist instantaneously, or to have no inherent connection with earlier or later selves. Evolution seems to have added two things to its conscious creations which help make consciousness feel temporally continuous however. One of them is memory. This tends to join a present self with selves that are at least somewhat remembered. Observe that to have this effect memories needn’t even be true.

Evolution’s means of connecting the present self with future selves is less established. I consider this to exist through present hope (which feels good) and present worry (which feels bad) regarding the future that it contemplates. Thus a person with no hopes or worries should feel no bond with who he/she will progressively become given this connection void.

I suspect that this theory is consistent with self dynamics distributed over time and space, and even a hypothetical multiverse in which virtually exact copies exist of someone. Though each subject may effectively be considered exactly the same psychologically and biologically, feeling in one does not in itself evoke feeling in the other. Thus there should be no inherent self connection. This situation may be contrasted with situations where there is such a connection, as in memory of the past and anticipation of the future.

Amy Kind said...

Thanks for the comments thus far! Some very quick thoughts in response...

Dan -- I like the pain test, and there's something very intuitive about the suggestion, but it's a tricky thing to really specify. The current AK-time-slice cannot feel the pain of yesterday's AK-time-slice -- the current one didn't exist then, and the pain doesn't exist now. So we have to figure out a way to specify the test, and to do so in a way that doesn't presuppose personal identity (since that's what we're trying to explain).

Arthur -- I do think experience is still possible in that case, but obviously, there's a lot of things to think about here!

Nat -- Though I have read a lot of SF, I confess to not having read any Moorcock. I will add him to my reading list. Do you have a favorite work by him that you would recommend?

chinaphil -- You raise an interesting worry about the way that the mechanics of fiction may confound things here. I'll have to think more about it, but one of my first thoughts is that there are all sorts of things we know and don't know (and remember or don't remember) about one another, so I'm not sure there's as much of a disanalogy as you fear -- though of course there is the disanalogy due to the involvement of an author.

PhilosopherEric -- I guess I like both open philosophy and closed philosophy, in your sense, and I try to do both. As for the theory of the self that you're laying out, I'm a little puzzled -- on the one hand, you say that a self exists instantaneously, but on the other hand you reference self dynamics being distributed over time and space. I'm not sure how to make sense of that.

Again, thanks all for your engagement with the piece!

Daniel Polowetzky said...

A tangential issue: Is the question as to whether you survive the Star Trek transporter an instance of a meaningful but untestable hypothesis?
Of course, just as you can test the hypothesis that you will survive eating a tuna sandwich by eating it and then introspecting that “yes, I’m not dead”, you could undergo the transporter and engage in the same introspection.
Well, even if that means of testing it is adequate from a first-person perspective, it clearing isn’t from a third-person perspective. “He seems normal. He says he feels fine.”, is hardly enough.
If the specifics are truly spelled out, that every atom in the body undergoing transport will be replaced within a very short time, then I don’t think ANYTHING would count as verification.
This is because whatever the criteria for “personal identity” are, unless they guarantee survival, which from a first-person perspective isn’t exactly “personal identity” from a third-person perspective, then they are inadequate.
My vague intuition as to what my survival is, subjectively, is clearer than my intuition as to what constitutes personal identity, the latter being similar to identity conditions for rocks, trees, cars.

The thing is, before stepping in the transporter I’m asking myself, “Am I going to die?”, not will the same person stepping in it be the same person transported?

Arnold said...
This comment has been removed by the author.
Philosopher Eric said...

I suppose what I’m suggesting may seem a bit paradoxical. Let me try to clarify.

First I should say that I define “self” essentially as a value dynamic, or feeling good/bad itself. I don’t consider consciousness (in Schwitzgebel’s innocent sense) otherwise possible. And yes I do consider self inherently instantaneous, though evolution also seems to have added things which can bond them so that the present one tends to feel connected with both past and future selves. I’m suggesting that memory bonds the present self with past selves, which seems fairly well documented since people with memory loss seem less bonded with who they were. Furthermore I’m suggesting that we try to advance the interest of our future selves, not because we are future selves, but rather because our engineering tends to give us hopes and worries about what we perceive will happen to them. I’m not sure that the field of psychology has quite worked this out yet. You might test my theory however. Regarding your future do you think that you’ve ever consciously decided to do something that wasn’t incited by means of your present hope or worry about that future person’s welfare?

I’ll continue to believe that instant selves are joined through memory of the past and anticipation of the future until there is good reason to doubt this. Still this seems like a temporal connection rather than spatial I only said that my theory should account for a bonding in space as well given the sci-fi theme here. It wasn’t to suggest that evolution had worked out a way for something to feel its sentience in two places at the same time like some kind of human superposition. I guess for that the physics which create a given example of sentience would need to transpire in two separate places. Still perhaps I should be liberal about this since I don’t consider the temporal connection to be exactly true either. Thus for example a self on a zoom call might be said to be in two places at once.

In any case if there is a person in another universe who essentially lives a mirror existence of my life, though my experiences aren’t his and his experiences aren’t mine, then I don’t consider us to share a self even in the restricted ways that I’ve mentioned. This seems consistent with the first comment here that Dan P made when he proposed a “Do I feel its pain?” test.

Philosopher Eric said...

Actually upon further reflection I should revise the way I was treating time and space. I shouldn’t have said that my proposal addresses changes in time rather than space because it actually applies to both. If I’m at an amusement park watching people on a thrill ride and contemplating trying it out myself (or technically “myselves”), I’m saying that it’s the decisions of countless instant selves fueled by their present hopes and worries about that potential future that should determine what’s decided. Those future selves should not only have temporal coordinates but spatial coordinates — in this case either on or not on the ride. Thus an apathetic person should lack any reason to decide one way or the other, and indeed, perfect apathy in all things should render a person non-conscious, or the elimination of any selves regarding associated time/space.

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Nat Lamb said...

If you wait a bit, his Hawkmoon books are being developed by BBC. Elric and Storm ringer are his most famous creations, but I think the most approachable (and up front multiverse) are the Oswold Beatable books, starting with Warlord of the Air.