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A peer-reviewed electronic journal published by the Institute for Ethics and ISSN 1541-0099 22(1) –November 2011 |
Personal Identity and Uploading
Mark Walker
Richard
L. Hedden Chair of Advanced Philosophical Studies
Department
of Philosophy
Journal of Evolution and Technology - Vol. 22 Issue 1 – November 2011 - pgs 37-51
Abstract
Objections to uploading may be parsed into substrate issues,
dealing with the computer platform of upload and personal identity. This paper
argues that the personal identity issues of uploading are no more or less
challenging than those of bodily transfer often discussed in the philosophical
literature. It is argued that what is important in personal identity involves
both token and type identity. While uploading does not preserve token identity,
it does save type identity; and even qua token, one may have good reason to think
that the preservation of the type is worth the cost.
1. Uploading: prospects and perils
You arrive at
one of the thousands of kiosks run by the late twenty-first century’s largest
corporation: U-Upload. With some trepidation you step into the superscanner.
There is a slight hum as it inventories the molecular building blocks of your
brain. Your brain is destroyed in the process, but you are not dead – or so the marketing
materials from U-Upload claim. For information about the building blocks, along
with a general program that describes the fundamental laws of molecular
interaction, is uploaded to the shiny new robotic brain you purchased (Sandberg
and Boström 2008). For your friends and family, a few terrifying moments pass
before the robotic body stirs. To their relief, your first words are: “It’s me.
I made it.” You then go on to crack a joke – just as your family and
friends have come to expect of you. Of course you have changed in some
respects: gone is your human carbon-based body. Now you experience the world
through camera eyes and microphone ears, you dance the fandango with robotic
legs and speak through a voice synthesizer. But it is still you. You have
migrated to a silicon substrate: you have been uploaded.
At least that
is one interpretation of these events. The contrary construal is that although
a robot was created that acts and talks like you used to, claims to have your
memories, and indeed, claims to be you, this robot is not you. You are dead. You
died when your brain was destroyed during the scanning process.
If, like me,
you think that uploading is possible (at least in principle), and so you hold
that the first interpretation of these events is correct, then you must hold
true the following three theses:
[1] Computers are
capable of supporting the important properties constitutive of personal
identity, e.g., thought and consciousness.
It is clear
that uploading will not preserve all properties we associate with Homo sapiens, e.g., basic facts about
the human digestive system are not likely to be preserved in uploading to a
robotic body. But these facts are not typically thought to be important for
personal identity. Candidates for important properties include thought,
consciousness, emotions, creativity, aesthetic experience, sensory experience,
empathy and so on. For the most part, the question of which properties are
important is not as serious as it may first seem, since uploading promises to
preserve the essential aspects of the brain and nervous system, which overlap
with the usual lists of important properties for identity.
A famous
challenge to thesis [1] is made in Searle’s
Chinese Room argument (Searle 1980). It is beyond the scope of this paper to
explore this argument; suffice it to say that if Searle is correct, then [1] may be false. For Searle thinks that
a computer can never consciously think merely in virtue of instantiating a
computer program, and the uploading process seems to be one of merely
instantiating a computer program (Agar 2010, 2011).
[2] It is possible to
capture the information necessary to emulate the important properties of
individual humans.
The technical
challenge of thesis [2] is to capture
the information in all parts of the brain in a manner that preserves the
relevant information. Clearly this won’t be easy. If we slice off layers of
your neurons, and record the information of each layer, the lower layers will
change (due to trauma or death).1 If we flash freeze your brain, we
may destroy some essential information. Philosophical questions arise as to whether
the information encoded in the brain is sufficient to account for all the relevant
properties. For example, consider a dualist who believes that we have souls in
addition to brains, and much of what is morally important (e.g., conscious
thought) resides in the soul. If the dualist is right, then scanning your brain
could never be sufficient, for it would be necessary to scan your soul to
access at least some of what is important. If it is unlikely that we will be
able to scan souls, there will be an insurmountable obstacle to uploading.
Notice how theses [1] and [2] may differ on this point: a dualist
could consistently hold that a computer might have a soul; it is just that if
computers have souls, it is not because we obtained the soul-building information
from humans. (Perhaps God implants souls in humans and computers.)
[3] It is possible to
survive the uploading process.
To see how [3] differs from [1] and [2], imagine that
at some point in the future we have created computers of sufficient complexity
that it is agreed that they have the same morally relevant properties as humans:
these advanced computers think and are conscious, they are accorded rights, and
the scanning problem has been solved so that we are able to scan the brain in
such a way that we are not worried about loss of information. None of this
answers the question of whether you have been preserved during uploading or
whether uploading merely makes a very good copy of you. The worry that only a
copy is created is often fueled by this thought: the information about the
building blocks of an individual human brain could be uploaded to multiple
computers with robotic bodies. The number of copies of a person is limited only
by the available computing power. If an individual can be uploaded once, then
it seems the same individual could be uploaded twice into separate computers,
and indeed, billions of the same individual all embodied in separate robotic
bodies could be created.
This quick
survey of the conceptual terrain suggests that there are substantial
philosophical (not to mention technical) obstacles to uploading. To make the
discussion manageable, I will focus on thesis [3], and assume without argument that [1] and [2] have been
resolved in favor of uploading. So our question is this: assuming that
computers can be conscious, have memories, and (robotic) bodies, and assuming
that it is possible to scan and capture all the information of a human brain,
does uploading preserve personal identity?
I will argue
that uploading does preserve personal identity; at least identity of a certain
sort.
2. The equivalency thesis
The fact that
we are assuming that computers are capable of embodying all the same type of
properties necessary for personal identity means that we can make use of the
equivalency thesis:
Equivalency thesis: If it is
possible for an individual to survive migration from a carbon to a carbon body,
then it is possible for individuals to survive migration from a carbon to a silicon
body.
To spell this
out, I’ll say first what I mean by occupying different human bodies, and then
say what use the equivalency thesis will serve for us.
Let us start
by considering a familiar fictional example of people switching human bodies,
i.e., carbon-to-carbon transfers. One of my personal favorites is a schlocky
episode in the original Star Trek
series. Captain Kirk finds himself in the body of his jilted ex-lover, Dr.
Janice Lester, after an alien “personality swapping” device is used on him.
She, jealous of his power, takes control of his body, and, what is worse, his
spaceship. This plot device has been used numerous times since, including in
the movie Freaky Friday where a
mother finds herself in her teenage daughter’s body and vice versa. These works
of fiction are premised on the idea that whatever makes individuals the
individuals they are is only contingently related to the bodies that they find
themselves in. Captain Kirk grew up in a male body, but we are asked to believe
that, at least for a short while, he inhabited a female body.
In Kirk and
Lester’s body swap, the idea is helped along by the visual effects (such as
they were in the 1960s) that showed what apparently we are to understand as
soul swapping. (A soul, it turns out, looks much like a translucent version of
one’s body. Who knew?) We do not need to have recourse to the idea of souls,
however. Imagine the scanner used to encode all the relevant biochemical
information from a brain was used to scan both Kirk’s and Janice’s brains.
Nanobots – nanoscale
robots – then rearrange
the biochemicals in each brain to encode the relevant memories, personality and
intellectual abilities and so on. This differs then from brain swapping,
because each brain is reorganized using nothing but the locally available
biochemicals. Here the information is uploaded to a different human body rather
than a computer. Using this procedure, it makes perfect sense why Captain
Kirk’s body would act much like we would expect Dr. Janice Lester to act, and
vice versa.
There are a
couple of reasons for invoking the equivalency thesis. The first is so that we
are not misled by a new form of racism: substratism (Walker 2006). Substratism
is the view that one’s substrate is inherently superior to that of other
substrates along the lines that racists think their race is inherently superior
to some other race. In the present case, it would suggest the idea that carbon-based
humans are inherently more morally worthy than silicon based beings. Consider the
fact that we would not accept this argument: it is not possible for persons to
migrate from one body to another because then it would be possible for people
of skin color X to move to bodies of skin color Y, and Y skin color is morally
inferior. We want to avoid the same bad argument in considering moving from one
substrate to another. Notice that this does not beg the issue at hand, since it
is possible to say that having a certain substrate (or even skin color) is
constitutive of my identity; it merely prohibits saying that this property in
itself makes for moral superiority.
The second is
that it makes directly relevant an enormous amount of philosophical effort that
has gone into exploring the possibility of carbon-to-carbon transfers. The
question of carbon-to-silicon transfers thus may piggyback on this effort.
3. Personal identity: psychological and somatic
accounts
Historically,
there are two main schools of thought about what is required for personal
survival; the psychological and somatic approaches (Olson 2002). Derek Parfit’s
famous thought experiment may serve as illustration:
I enter the Teletransporter. I have been to Mars before, but
only by the old method, a space-ship journey taking several weeks. This machine
will send me at the speed of light. I merely have to press the green button.
Like others, I am nervous. Will it work? I remind myself what I have been told
to expect. When I press the button, I shall lose consciousness, and then wake
up at what seems a moment later. In fact I shall have been unconscious for
about an hour. The Scanner here on Earth will destroy my brain and body, while
recording the exact states of all of my cells. It will then transmit this
information by radio. Travelling at the speed of light, the message will take
three minutes to reach the Replicator on Mars. This will then create, out of
new matter, a brain and body exactly like mine. It will be in this body that I
shall wake up. (Parfit 1987, 199)
Those that
hold the psychological account of personal identity will tend to endorse the
view that one survives teletransportation. For the psychological account says
that what is essential for survival is continuity of psychological states such
as memory, beliefs, desires and personality. John Locke, an early proponent of
this view, famously described personal identity in terms of psychological
continuity, within an analysis of personhood as consisting in existence as “a
thinking intelligent being, that has reason and reflection, and can consider
itself as itself, the same thinking thing, in different times and places...” (Locke
1975). The person on Mars who awakens will claim to remember being Derek
Parfit, and to have memories and a personality that are psychologically
indistinguishable from the person on earth whose body was destroyed. Locke,
then, would say that Parfit survived teletransportation.
Somaticist
accounts suggest the survival of a particular body is critical for personal
identity over time. Since the body on Earth is destroyed during the scanning
process, Parfit ceases to be. A different person will awake on Mars. This
person will of course have psychologically indistinguishable memories and
personality to those of the late Parfit, but this person will not be Parfit. The
new person will be but an infant in terms of chronological age: only a few
minutes old.
We will think
of “somaticism” as the view that continuity of one’s body is necessary for
personal identity from one time to the next.2 There are two ways
that one might be a somaticist: one can believe that bodily continuity is
necessary but not sufficient, or that it is necessary and sufficient. One easy
case to distinguish these two is as follows: a piano falls on your head, and
causes you to go into a permanent vegetative state. Your relatives discuss
whether to “pull the plug.” Those who think that bodily continuity is necessary
but not sufficient may say that you no longer exist, but your body continues to
exist. Those who think that bodily continuity is necessary and sufficient will
say that you continue to exist, albeit your cognitive capacities are
non-existent. Both views qualify as “somaticism” in our sense.
In my
extremely limited and informal survey of students and friends, most would be
unwilling to step into Parfit’s Teletransporter.3 The usual response
is that it is equivalent to committing suicide: the person here is killed, and
a new duplicate is created. Nothing of the original survives. Locke and others
who endorse the psychological account would retort that this is just an
irrational attachment to a certain set of molecules. If a molecule-for-molecule
identical copy is made, then it seems irrational to prefer one set of molecules
to another. Parfit compares this to an attachment to a wedding ring: there may
be sentimental value in having the original rather than a molecule-for-molecule
identical copy, but such attachments are “merely sentimental” and have nothing
to do with personal identity.4
The
reluctance to use the transportation device seems hard to explain other than by
the fact that people hold, at least implicitly, to somaticism. This provides a
robust challenge to psychological accounts in general, and a challenge to
uploading in particular. In the next three sections I will offer arguments
against somaticism.
4. Against somaticism: the big stroke
The Vorlons,5
a mysterious and intellectually advanced alien species, make this offer: you
can have an original undiscovered play by Shakespeare written in his hand, or a
copy of the play made by one of his lackeys. You salivate at the joy this will
bring to the world (not to mention the fame and fortune it will bring you
personally). Since you can have only one, the choice, it seems, is a
no-brainer. You should opt for the one written by the bard’s hand. But now consider
this variant: the Vorlons tell you that the text written in Shakespeare’s hand
is missing the last two pages, while they assure you the copy written by the
lackey is a perfectly faithful reproduction of all the words in the original. While
it would be great to have both, you reason that the most important thing is the
play itself be preserved, not Shakespeare’s handwriting. The copy here is in
some sense better than the original because the original has been damaged. This
tips the scales in favor of the copy, because while being written by the bard’s
own hand is good, having the whole play is even better.
We can apply
this lesson to thinking about personal identity. The Vorlons, with their
ability to see into the future, say the news is grim. In less than twelve hours
you will have a massive stroke that will cause you to lose many of your
memories and some mobility, and impair your intelligence. Your stroke will not
be as bad as some: the damage from the stroke will not leave you completely
cognitively impaired, but you will no longer be able to work as an academic. You
will have to find some relatively mindless job befitting your new level of
intelligence, perhaps in academic administration. Friends and family will say
that your once keen memory has been dulled such that your memory is now fuzzy,
and you seem to remember the most superficial things. It is a shame, and
totally unexpected at your young age. Even with their immense power, there is
nothing the Vorlons can do to prevent the stroke. They provide a radical
alternative: creating a perfect replica of you – down to the molecular
level – with the
exception that the problems with the arteries to your brain will be fixed in
the body replica. They insist, however, that only one body can survive. You
must choose tonight whether the replica or your current body survives.
Most people
I’ve asked about this would rather see the replica survive, for the replica
best embodies what is most important about you: your memories, your
personality, your beliefs and desires. None of this is to say that the loss of
one’s body is trivial. One can be quite attached to one’s body; but, when given
this tragic choice, more of what is essential to you as a person survives in
the replica.
Obviously, this
example is structurally similar to Parfit’s, but with one big exception: what
is gained by having the replica survive is much more significant in this case
than in the Teletransporter to Mars case. Parfit offers the incentive of
avoiding three weeks of space travel. (We might not even sacrifice our original
wedding ring for an exact replica if the benefit is merely avoiding three weeks
in a spaceship). Here the incentive is the possibility of not having one’s life
radically altered by the stroke. The attachment to one’s body does not seem
worth the cost in this case.
Perhaps it
might be remonstrated thus: “If I survived in a brain damaged state, I would be
a terrible burden on my family and the world. It would be better for my family
and the world that I died and a replica replaced me.” To avoid this objection
we can simply stipulate that the decision is to be entirely selfishly
motivated, and that we know this about your preferences: you would rather
survive a stroke than not survival at all. So, if the Vorlons did not offer you
a chance to survive as a replica, you would rather live after the stroke than
die. If the choice is still to have your present body die (the one with the bad
arteries), then this can only be explained by thinking that you will survive as
a replica.
It may be
thought that even the most selfish person might prefer death if it meant
something else he or she valued might result, e.g., you value the finishing of
your novel more than you value your own life. If a replica of you can better
realize this project, then it is consistent with selfishness to prefer death to
oneself for the sake of the great unfinished novel. Again, we may simply
stipulate around this objection. We may say simply that what you want most is
for you to finish writing the novel,
not someone else. If you die, you would rather it remain the “great unfinished
novel” than be finished by someone else. If this is your most important desire,
then preferring the stroke body’s death cannot be explained away by the thought
that what you wish for is the completion of your projects.
It is worth
noting that not all somaticists are likely to be convinced by this example.6
But it should convince a few, and points out one of the heavy costs of
somaticism.
5. Against somaticism: retrospective replicas
In this
section we will examine an alternative explanation to somaticism for why people
might be reluctant to use Parfit’s Teletransporter, namely, fear of the
unknown. Notice that Parfit’s case is prospective: he asks us to imagine the
decision to walk into the scanner with the hopes of being teletransported. The
thought is that fear of the unknown may be muddying the waters here. That is, perhaps
it is this fear of the unknown, rather than a commitment to somaticism, that
explains the reluctance to use the Teletransporter. We can test this thought by
considering a retrospective rather than a prospective version of a replication
scenario.
Suppose that
every night when people sleep their bodies (including their brains) are scanned
by a swarm of nanobots and a molecule for molecule identical body is beamed
from a hidden alien spaceship in orbit; the old body is vaporized in a manner
that is undetectable by the human eye. Scientists discovered this fortuitously:
physicists noticed a spike in neutrino levels every time psychologists in the
adjoining lab conducted sleep experiments. Intrigued, scientists built a
chamber to isolate subjects from neutrino influences and then had test subjects
sleep in the chamber. Once the experiment was initiated, a hologram of a Vorlon
appeared in the lab and spoke thusly:
We are an ancient race known as the “Vorlons.” We battled
another species, the “Shadows,” just as your species was beginning to evolve on
this planet. One of the toxic effects of our war was a type of radiation that
kills all higher intelligences within three days. We have no way of eliminating
the radiation, but we have left advanced technology to recreate your bodies
from different molecules every day so that the radiation will not harm you. We
left the galaxy eons ago. You are hearing this message now because you have advanced
technologically to the point where you can detect our technology. If you
interfere with our replicator technology, you will quickly die of radiation
poisoning.
What should
we make of this? It is clear that dismantling it is out of the question since
all humans will die within three days. If you are a somaticist, you must
conclude that you have been alive only for a very short while. In fact, you
have existed only since last night. After all, the physical continuity of one’s
body has lasted only this length of time. However, most of us, I think, would
conclude the opposite. That is, that we have existed for years: that we do not
cease to exist every night and a new person comes into being.
This example
may not be a decisive refutation of somaticism, but it does at least pull out
one pillar of support. Somaticists ask why so many would be reluctant to step
into the Teletransporter that Parfit describes, intimating that our reluctance
has to do with the fact that our bodies will not survive. The retort, suggested
by this example, is that the reluctance is explained more simply as a fear of
the unknown. Contrariwise, the somaticist must now explain how so many people
could be mistaken about their own identity retrospective case; after all, it
seems very likely that, upon learning about the Vorlons’ technology, most would
conduct their lives as if they hadn’t just come into existence that day. Who is
going to say such things as: “I do not have to look after these children you
call mine: how can I have children if I myself was born today. I can’t use this
driver’s license, it is someone else’s – I was just born today. I’m not qualified
to teach any classes: a postgraduate degree is required, which takes years to earn,
and I was just born today?”
6. Against somaticism: practical ethics
Many of the
problems of personal identity are simply extensions of the more general problem
of identity; for example, a meteor falls on a family dining room table smashing
exactly half of it beyond repair. The other side is virtually unscathed. Expert
carpenters are brought in to fix the missing half. Has the table survived? Most
say yes. Here is a variant on the story: siblings fight over who gets to
inherit the family dining room table. In the end they saw it exactly in half and
each sibling hires expert carpenters to replace the missing half. Did the
original table cease to exist when it was cut in half by the siblings? If we
say yes this seems to conflict with the original intuition that a table can
survive the loss of half of its material. If we say no, then it seems we have
the impossible situation where numerically distinct tables (each owned by one
of the siblings) are not in fact numerically distinct. As intimated above, we
can construct parallel cases for personal identity. My point here is that there
are complex metaphysical issues of which at least some personal identity issues
look to be merely specific instances of more general problems.
Since issues
of personal identity are acknowledged by all to be deeply contested, and since
they may be intimately intertwined with the more general and equally contested
issue of identity, it looks like we won’t be able to resolve these issues
anytime soon. Hence, we are left in a quandary about how to proceed. To
emphasize, let us suppose that despite the fact that the preponderance of
reasons seem to be against somaticism, imagine that the metaphysical reasons
for and against somaticism are exactly balanced.
Does this imply that we should be neutral on
the issue? I think not. It may be that there is a further court of appeal to
decide the issue, specifically, practical ethics. That is, the suggestion is
that if our metaphysical arguments and intuitions cannot decide the
metaphysical issue of personal identity, it is permissible to decide the issue
on non-metaphysical grounds. I won’t argue for this claim here, as it will take
us too far into the meta-philosophical issue of how different areas of
philosophy, in this case, metaphysics and practical ethics, are related. Suppose,
for the moment, it is true that practical ethics can tell us something about
metaphysical issues, it is then reasonable to ask: What does practical ethics
tell us about the issue of personal identity?
Imagine two
persons, McCoy and Hatfield, who want to kill one another. They are
co-inventors of the first replicating machine. McCoy thinks it should be used
on humans, Hatfield believes that it never should be so employed. McCoy believes
in the psychological continuity thesis of personal identity, whereas Hatfield believes
in somaticism. How should we reason about personal identity in terms of what is
good for society? We can imagine two possibilities: society adopts for social
and legal purposes (its “public norm” for short), somaticism or psychological
continuity. Which is better for society?
Consider
first using somaticism as the public norm. McCoy could kill Hatfield and then
hop in the replicating machine. We would be forced to say, because we have
adopted somaticism as our public norm, that McCoy is dead and the replica of
McCoy (call this person “McCoyson”) is a different person. Since McCoyson was
born after the crime, McCoyson cannot be responsible for the crime. (We have
long abandoned the idea that one can inherit personal responsibility for the
sins of one’s ancestors). This crime would be ruled a murder-suicide in a
somaticist jurisdiction. Of course McCoy then has every reason to commit the
crime, as he does not believe in somaticism. We can easily imagine that the
number of murder-suicides would greatly increase. Indeed, mass murder hardly
seems out of the question. If you are looking for a job in philosophy, you
could plant a bomb at the American Philosophical Association conference and
kill off hundreds of philosophers at once. Before the police capture you, you
could hop into the replicator. The person created by this process, according to
the public norm, died by replication. The new person is not responsible for the
crime, having just been born. Now this new person can apply for one of the many
philosophy jobs that have suddenly become available.
If
psychological continuity is the public norm, then neither Hatfield nor McCoy will
have reason to commit the crime based on replication. As before, Hatfield will
not because he will consider this equivalent to suicide. McCoy will not because
the public norm says that McCoy will survive the replication and be subject to
criminal sanctions. Since a public norm of somaticism is more likely to lead to
negative social consequences, this gives us some reason to reject somaticism.
(There are
other policy options we might explore, e.g., we could simply shoot anyone who
is not a somaticist, or ban replicating technology. For some, these two
policies might be very similar in terms of their practical effects. Imagine,
similar to the stroke case, that without replication someone will die. Banning
replication technology will end his or her life just as surely as being shot
would. Obviously the two policies are not morally equivalent. Rather, it is to
point out that banning such technology would come with some huge costs for
some.)
7. No branching
Debates about
identity preservation and uploading invariably get hung up on the “branching”
problem, and this probably provides the strongest support for somaticism. The
problem is that it seems there is only one of me. But uploading seems to allow
the possibility that there could be hundreds, if not millions, of “me.” But if
there can be only one of me, then uploading does not preserve my identity. It
is clear how this problem arises given our previous discussion of the uploading
process. Imagine my brain is scanned and the relevant information is recorded.
Instead of being uploaded to a single computer with robotic body, imagine a
thousand robot brains are encoded with the information. Of course it seems
possible that thousands of robots could awaken in the same instant, all
claiming to be Mark Walker. (And what a wonderful world this would be!)
Using the
equivalence thesis we can see how this is exactly the same problem as the
problem of branching that philosophers discuss in connection with
carbon-to-carbon transfers. Parfit extends his Teletransporter case in exactly
this way:
Several years pass, during which I am often Teletransported.
I am now back in the cubicle, ready for another trip to Mars. But this time,
when I press the green button, I do not lose consciousness. There is a whirring
sound, then silence. I do not lose consciousness. I leave the cubicle, and say
to the attendant: “It’s not working. What did I do wrong?”
“It’s
working,” he replies, handing me a printed card. This reads: “The New Scanner
records your blueprint without destroying your brain and your body. We hope that
you will welcome the opportunities which this technical advance offers.”
(Parfit 1987, 199)
Of course
there is no reason to stop at one replica. Using Parfit’s Teletransporter
thousands of organic molecule-for-molecule identical persons could awaken in
the same instant, all claiming to be Mark Walker. (And what a wonderful world
this would be!)
Notice that I
did not say that any of the thousand persons claiming to be Mark Walker are me.
Somaticism will deny that any of the thousand replicas are me; only the
original is me. If the original is destroyed, and a thousand replicas are made,
then somaticism will claim that I did not survive.
What does the
psychological account have to say about multiple replicas? Here opinions
differ. On the one hand, it seems that if there are multiple replicas, and they
are all psychologically indistinguishable from the original, then each of them
has as good a claim to be me, and so they are all me. The contrary “no-branching”
view is that at most one replica is me, for there can be only one me (Shorter
1962).
The question
then is whether there can be “branching”: more than one of me. I will argue
that both sides of the debate are correct; there is a sense in which there
can’t be more than one of me, and a sense in which there can be multiple
versions of me. The first step in our argument is to get a little clearer about
the no-branching argument, which may be schematized as follows (where “P” stands for “premise” and “C” for “conclusion”):
The
No-branching Argument
P1: Multiple replicas
X, Y, Z…. of an individual O (the original) are numerically non-identical with
each other, that is, X is not identical with Y or Z, Y is not identical with X
or Z, and so on.
P2:
Preservation of personal identity requires preservation of numerical identity.
C: Therefore,
not all replicas X, Y, Z… preserve personal identity of O.7
It is worth
distinguishing this argument from a similar but less serious objection. The
less serious objection is that if there are a thousand replicas, then they will
quickly have psychologically distinguishable properties. All thousand replicas
will not fit in the same cab, for example, and so will have different
experiences leaving the replicating center. Their psychological states will
only diverge further over time. Riffing on Parfit’s example, we can imagine a replica
waking on Mars, the Moon, and Pluto all at the same time. Each will almost
immediately have different experiences, and so quickly will be psychologically
different.
Even if this
is conceded, it does not answer the question of the status of the replicas at
the moment they are created. Imagine the thousand replicas are all created at
the same instant, and each awakes in a separate but identical room. At the
instant of awakening, there will not be any psychological divergence8
and so the argument from diverging experience tells us nothing about the
identity of the thousand replicas at this moment.9
I want to
suggest that the problem with the no-branching argument is that there is a
critical ambiguity. To explain the ambiguity it will be helpful to review the
type/token distinction.
8. Types and tokens
The
nineteenth century philosopher Charles Peirce is credited with first making the
type/token distinction. Pierce’s own example involving the individuation of
words is as instructive as any:
A common mode of estimating the amount of matter in a
manuscript or printed book is to count the number of words. There will
ordinarily be about twenty the’s on a
page, and of course they count as twenty words. In another sense of the word
“word,” however, there is but one word “the” in the English language. (Peirce
1906)
There are
twenty tokens of the word the, but a
single type of the word the. The
argument to be canvassed is that if we think of personal identity as ambiguous
between types and tokens, then the no-branching argument may be rejected.
We may
approach the issue by recasting the previous argument by reference to a work of
literature; so let us consider the no-branching argument applied to Shakespeare’s
Hamlet. We may reconstruct the
argument first as about tokens, and then about types.
No-branching
Token Argument
P1’: Multiple replicas
X, Y, Z…. of an individual O (the original Hamlet
penned in Shakespeare’s hand) are numerically not (token) identical with each
other, that is, X is not (token) identical with Y or Z, Y is not (token)
identical with X or Z, and so on.
P2’:
Preservation of play-identity requires preservation of (token) numerical
identity.
C’: Therefore,
not all replicas X, Y, Z… preserve play-identity of O.
It is pretty
clear where this argument goes wrong: P2’
is false. The original token of Hamlet,
written in Shakespeare’s hand on paper created over four hundred years ago, is
now long lost. But the same play that Shakespeare wrote can be read today. The
no-branching token argument fails.
No-branching
Type Argument
P1’’: Multiple replicas
X, Y, Z…. of an individual O (the original Hamlet
penned in Shakespeare’s hand) are numerically not (type) identical with each
other, that is, X is not (type) identical with Y or Z, Y is not (type)
identical with X or Z, and so on.
P2’’:
Preservation of play-identity requires preservation of (type) numerical
identity.
C”: Therefore,
not all replicas X, Y, Z… preserve play-identity of O.
It is pretty
clear where this argument goes wrong: P1’’
is false. I may have bought my copy of Hamlet
at a different bookstore than you, but still, we are reading the same play. At
least in the case of plays, the type version of the no-branching argument
fails. Thus, the no-branching argument, in both its token and type formulation,
does not look the least bit plausible when applied to literature.
9. The type/token solution to personal identity
In this
section I will say a little about the type/token (TT) account of personal
identity10 and then see whether the no-branching argument has any
traction against it. In the case of literature, the tokens of Hamlet are individuated according to the
physical implementation: my Hamlet is
in a different spatial location from your Hamlet.
The Hamlet type is an abstract entity,
which particular tokens of Hamlet embody.
Similarly, the TT solution to personal identity says that tokens of a person
type are individuated in terms of physical implementation: each replica will
have a different spatial location. The person type is the abstract entity,
which the various tokens are all embodiments of.
We previously
rejected somaticism, but this is because we had yet to survey the type/token
distinction. The version of the type/token view that we should adopt says that
somaticism is correct about tokens, and the psychological account correct about
types. Consider then the case where the original Mark Walker is scanned and
destroyed and a thousand replicas are created. Somaticism, as a theory about
tokens, says that the original token was destroyed, and a thousand new tokens created.
The psychological account applied to types says that the Mark Walker type
continues to exist, and indeed, is multiply instantiated.
The ontological status of abstract entities is
a perplexing and contested issue (Wetzel 2009), but there is no reason to think
that it is more perplexing in the case of persons rather than literature, and
we are committed to types in the case of literature.11
Can the
non-branching argument be deployed against TT? Assuming that types can have
more than one token, non-branchers cannot allow the notion of types to have a
role in personal identity. So, to disambiguate the original non-branching argument,
it must be about tokens:
The
No-branching Argument in terms of Tokens
P1’’’: Multiple replicas
X, Y, Z…. of an individual O (the original) are numerically [token] non-identical
with each other.
P2’’’:
Preservation of personal identity requires preservation of numerical [token]
identity.
C’”: Therefore,
not all replicas X, Y, Z… preserve personal identity of O.
There are two
problems with this argument. First, it is question begging. The entire issue is
whether personal identity can be explained in terms of preservation of type
identity, and so P2’’’ prejudges the
issue.12
The other
problem is that it is difficult to see how one can insist on non-branching
without collapsing into somaticism. To see this, consider the case where the
original Mark Walker’s body, O, is destroyed when three replicas X, Y, and Z
are created. Either O is not identical with any of X, Y, Z, or O is identical
with one of X, Y, Z. If the former, then non-branching is simply somaticism in
disguise. If it is asserted that O is identical with exactly one of X, Y, Z,
then any choice would be arbitrary in the sense that choosing one among the
thousand to be The Mark Walker would
not be choosing based on any intrinsic differences. We could, for example, have
all the replicas draw a number out of a hat and designate the winner of the
lottery The Mark Walker. But an
appeal to a lottery shows that precisely no intrinsic properties are used to
individuate: it is the process (the lottery) that does the individuating. We
could do the same for Hamlet. We
could assign a number to every extant copy of Hamlet and have a lottery to find out which is The Hamlet, and which are mere copies. But, of course, no one would
be impressed by this.13
Criticizing
the non-branching argument is not a positive argument for TT, but it does
suggest that TT need do little to prove itself more plausible than
non-branching. However, in terms of a positive argument for TT, the fact that
it provides a number of intuitively plausible consequences speaks in its favor:
i.
The TT solution explains why people might be
reluctant to enter the Teletransporter in Parfit’s original example. It requires
sacrifice of their token identity, for little compensatory gain (three weeks in
a space craft). In other words, it can explain how we might survive (as a
type), even though we may regret some loss of identity (since the original
token is now dead).
ii.
The TT solution explains why it would be
rational to sacrifice one’s token identity in the stroke case: the loss of
token identity is not inconsiderable, but the replica is type identical, and
the new token replica will be in better shape than the original token.
iii.
The TT solution explains why, in the Vorlon
radiation case, we are not likely to feel much threat to our identity: the type
survives destruction of each token, and each token is only a day old.
Analogously, other things being equal, I would feel more upset about having my
copy of Hamlet from my undergraduate
days stolen, and less worried about a copy just acquired yesterday. In both
cases, of course, the same play type is stolen.
iv.
The TT solution explains why in Parfit’s
modified transporter case – where a replica is created on Mars, but the
original on Earth is not destroyed – the person on Earth has more claim to being Parfit
than the replica on Mars. The person on Earth is both type and token identical
with Parfit from the previous month (assuming he hasn’t used the Teletransporter
in the meantime). The replica on Mars is merely type identical.14
v.
The TT solution explains in a satisfactory
manner what happens when the original is destroyed to make multiple replicas.
Each replica is type identical with the original, but none of the replicas is
token identical with the original. This avoids the embarrassment of having to
say which of the indistinguishable replicas is identical with the original.
10. Should I upload?
I have tried
to strike some compromise between saying that there is no loss of identity in
replication (and by our equivalency thesis, uploading), and the position that
survival is impossible. Still, it may look as though this is tantamount to an
argument against uploading: if there is any loss in uploading, even if it is
only token identity, why would anyone want to sacrifice some identity? The
answer is that there are considerable advantages (or at least purported
advantages) to being uploaded, including immortality and enhancement.
Except for
the completely reckless, forgetful or lazy (ahem), everyone backs up his or her
valuable computer files. But once we see that people too can be backed-up, it
appears that virtual immortality is assured. For so long as there are operating
computers, one can simply transfer the files that comprise oneself from
computer to computer. If the hardware on one computer fails, you simply move to
another computer. Suppose a piano falls on your robotic body. No problem. A new
robotic body is brought out of the closet and a backup copy of you is uploaded.
What formerly would have meant certain death is now only a small inconvenience.
As Freeman Dyson long ago realized, the question of how long one might live
quickly resolves to how long the universe will remain habitable (Dyson 1979), hence,
the term “digital immortality” is sometimes used to refer to this prospect.
As for
enhancement, one possibility is that our senses could be radically enhanced:
robots presently make use of a sensory apparatus that detects light in parts of
the spectrum not available to (unaided) human vision (e.g., infrared, x-rays,
etc.), sounds that are beyond normal human auditory range, and so on. In terms
of enhancing cognition consider that it is a relatively routine matter to add
memory or computing power to today’s computers. If one is uploaded to a
computer, then it seems that it would be a relatively routine matter to enhance
one’s memory or cognition: just add more computer memory or processing power. The
sky is literally the limit here. Anders Sandberg (1999) has done some
preliminary calculations to suggest that planetary scale computers,
“Jupiter-sized brains” might be possible. How powerful and how smart would such
brains be? It is, obviously, hard to say. Certainly they would eclipse us by a
greater margin than we eclipse the cognitive powers of your typical lab rat.
Along with such enhanced cognition would come awesome powers to manipulate the
physical world, for there is some truth to the saw that knowledge is power. In
short, and without too much hyperbole, those who upload may well be on their
way to godhood.15
It is beyond
the scope of this paper to argue that these purported benefits of uploading
really are benefits, but, if they are, the temptation to upload is clear. And just
as in the stroke case, it is clear why
it might be rational to forgo token identity survival for these advantages.
Acknowledgments
I
would like to acknowledge the following persons for their assistance: Nick
Agar, Russell Blackford, Jamie Bronstein, and Tim Cleveland.
Notes
1. Hans
Moravec (1988) discusses ways around this challenge.
2. There are
many problems for the bodily criterion of personal identity that I will not
discuss here. See Williams (1973) and Olson (2006).
3. Parfit has
found similar reactions to the case. He even concedes that he has some residual
doubt that he would survive teletransportation (Parfit 1987, 279).
4. Moravec
(1998, 117) suggests that this is like being attached to “jelly.”
5. From the
television series:
6. The
protagonist and somaticist in John Perry’s fun little dialogue accepts death
rather than ceding ground to the psychological account (Perry 1978).
7. See
Williams (1973). Thomas Reid seems to have had a similar argument in mind: see
Perry (2008) and Martin and Barresi’s editors’ introduction (Martin and Barresi
2003).
8. At least
where psychological states are narrowly construed (Putnam 1981).
9. Even
Nozick’s (1981) closest continuer theory would not be able to choose one among
the many.
10. Williams
(1973, 80-81) considers something analogous to the present proposal.
11. This is
not to argue, à
12. Patrick
Hopkins has an argument that seems to show that the type construal is not
possible: “The relationship of ‘identity’ is a very strong, and necessarily
strong, concept that strictly refers to literal sameness – not similarity. When
we use ‘identical’ in this sense, we are not saying that two things are just
very like each other (‘identical twins’), or even exactly similar (‘identical
cars’), we are saying that ‘two’ things are actually one and the same specific
thing” (Hopkins n.d.). I’m not sure what Professor Hopkins would say about Hamlet: are he and I reading exactly
similar plays or are we reading the same play? The former sounds perverse to
these ears. But even granting this is the correct description, it seems that “exact
similarity” is all the identity we may want in certain cases (such as the
stroke case).
13. Indeed,
we could solve every paradox – a set of statements that are individually
equally plausible, but mutually inconsistent – by assigning a number to each
statement and rejecting the loser of a lottery. Obviously, this is no way to
solve a paradox.
14. Parfit
(1987, 293-97) discusses the possibility of individuating in terms of types and
tokens. He argues that it is the type that matters, not the token. As noted
above, I disagree: both type and token are important.
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