Professor Shelly
Kagan: We've distinguished
three different views as to the
secret or key to personal
identity across time.
There's the soul view,
the body view,
and the personality view.
Putting aside,
for the most part,
the soul view,
because I've argued that there
are no souls--although
occasionally I bring it out just
for the sake of comparison and
contrast--the main question we
want to ask ourselves is how to
choose between the body view and
the personality view.
The body view says follow the
body.
If somebody around in the
future's got my body,
that's me.
The personality view says
follow the personality,
that is, the set of beliefs,
desires, memories,
goals, ambitions,
and so forth.
Somebody around in the future
that's got my memories,
my beliefs, my desires,
that's me.
How should we choose between
these two views?
As I mentioned at the end of
last lecture,
what I want to do is offer us a
set of thought experiments.
They've got to be thought
experiments, because in real
life, bodies and personalities
go hand in hand.
But by doing some science
fiction experiments,
we can take them apart and ask
ourselves, "Which one do I think
is me?
When my body goes one way and
my personality goes another way,
where do I go?"
Again, just to remind you,
in order to get the intuitions
actually flowing,
what I'm going to do once I've
separated the body and the
personality this way,
is torture one of the end
products.
So I'm going to be asking you
to put yourself in the first
person.
Imagine this is happening to
you.
And ask yourself,
"Which one do I want to be
tortured?
Or which one do I want to not
be tortured?"
Because that will give you some
kind of evidence as to which one
you take to be you.
And think about this in that
special first person
ego-concerned way that comes
naturally to us.
Just bracket any moral concerns
you may have about torturing
other people or agreeing that
somebody else should be
tortured.
For our purposes,
right now, if I brought up a
volunteer from the class and I'm
asking you--here's you,
there's the other
volunteer--which one do you want
to be tortured?
it's, "Let that one be
tortured.
Don't let it happen to me."
That's how we know this is
me speaking.
All right, so that's the
question I'm going to ask you.
I'll probably slip into talking
about this experiment as though
it's being done to me.
But to get it vivid,
you should think of it as
though it's being done to you.
I'll mention,
just in passing,
that these thought experiments
that I'm about to give,
I'm going to give a pair of
them, come from Bernard
Williams, who's a British
philosopher.
All right, so case number one.
Here you are.
The mad scientist has kidnapped
you and he says:
I've been working on mind
transfer machines.
And what I'm going to do is
I've got you and I've also
kidnapped somebody else over
here, Linda.
And I'm going to hook you up to
my machines and swap your minds.
And what that means is,
I'm going to read off the
memories and the beliefs and the
desires from your brain and read
off the memories and desires and
beliefs from Linda's brain.
And then I'm going to
electronically transfer Linda's
memories and beliefs and so
forth over here and implant them
onto this brain.
And take your memories and
beliefs and so forth and implant
them onto Linda's brain.
First, we'll put you to sleep
when we do all this procedure.
Then when you wake up,
you will wake up in Linda's
body."
There'll be something here
that, you'll wake up and you'll
say, "What am I doing in this
new body?
What happened to my beard?
How come I'm speaking in this
high female voice?"
Whatever it is,
but you'll think to yourself,
"Well, here I am,
Shelly Kagan.
I seem to be inhabiting Linda's
body.
Don't know how that happened.
Oh yes, the mad scientist
kidnapped me and he transferred
us, he swapped us.
He swapped our bodies,
swapped our minds.
I guess the whole thing works."
So the mad scientist explains
all of this to you,
but in order to give it a
little kicker,
because he's also an evil mad
scientist--that may be evil
already, but because he's an
evil mad scientist--he says,
"And then when I'm done--" So
over here we've got Shelly's
body but Linda's personality.
So Linda thinking "What am I
doing?"
and "What am I doing in
Shelly's body?
How did I get a beard?"
So over here,
Linda, in Shelly's body.
Over here, Shelly,
in Linda's body.
"I'm going to torture one of
these.
But because I'm a generous evil
mad scientist,
I want to ask you which one
should I torture?"
Now, when I think about this,
and again, I'm inviting you to
think about this in the first
person, so this is happening to
you.
When I think about this,
I say "Torture the one over
here."
I'm going to be over
here in Linda's body,
horrified at what's been going
on,
horrified that she's being
tortured, but at least it's not
happening to me.
That's the intuition I've got
when I think about this case.
When the mad scientist asks me,
"Which one of these two should
I torture?"
I say, "Torture this one."
Because if I were to say
"Torture this one" and
then he does it,
think about what's going to
happen.
I'll be thinking "I'm Shelly
Kagan.
Oh, this is what a horrible
situation.
Oh, the pain, the pain!
Stop the pain!
Make it go away!"
I don't want that to happen to
me.
If this one's being tortured,
nobody's thinking to himself,
"Oh, I'm Shelly Kagan in
horrible pain."
So I want this one to be
tortured.
All right, that's the intuition
I've got about the case.
Now, if you've got that same
intuition, think about the
implications of that intuition.
You're saying that I,
Shelly Kagan,
ended up over here.
But that's not my body.
This is Linda's body.
Shelly Kagan's old body is over
here.
But this is the one that's me,
because this is the one that I
don't want to have tortured.
So the body isn't the key to
personal identity.
Personality is the key to
personal identity.
This has got my personality,
my memories of growing up in
Chicago, becoming a philosopher,
my thoughts about what I want
to have happen to my children,
my fears about how I'm going to
explain what's going on to my
wife.
Whatever it is,
this is the Shelly Kagan
personality over here.
This is me.
That follows then that this
intuition suggests that what I
find intuitively plausible is
the personality theory of
personal identity.
Now, let's tell a different
story.
Both of these stories,
as I say, come from Bernard
Williams.
Bernard Williams says here's
another example we can think
about.
Mad scientist,
again, kidnaps you,
kidnaps Linda.
And he says,
"Shelly, I've got some news for
you."
I'm switching between you and
me.
He says, "Shelly,
I've got some news for you.
I'm going to torture you."
I say, "No, no!
Please don't do it to me!
Please, please,
don't torture me!"
He says, "Well,
you know, I'm in the mad
scientist business.
This is what I do.
I'm going to torture you."
He says, "But because I'm a
generous mad scientist,
before I torture you,
what I'm going to do is give
you amnesia.
I'm going to completely scrub
clean your brain so that you
won't remember that you're
Shelly Kagan.
You won't have any memories of
growing up in Chicago.
You won't have any memories of
deciding to become a
philosopher.
You won't remember getting
married or having children.
You won't remember the--you
won't have any desire.
The whole thing wiped clean,
complete perfect amnesia before
I torture you.
Don't you feel better?"
No, I don't feel better.
I'm still going to be tortured
and now we've added insult to
injury.
I've got amnesia as well as
being tortured.
No comfort there.
"Well," he says,
"Look, I'll make the deal
sweeter for you.
After I give you amnesia,
before I torture you,
I will drive you insane and
make you believe that you're
Linda.
I've been studying Linda.
There she is.
I've been reading her
psychology by looking at her
brain waves and so forth and so
on.
And so I'm going to delude you
into thinking that you're Linda.
I'm going to make you think
‘Oh, I'm Linda.'"
You won't talk like that.
"Oh, I'm Linda."
"And you'll have the memories
of Linda growing up in
Pennsylvania and you'll remember
Linda's family and,
like Linda, you'll want to be
an author, or whatever it is
that Linda wants to be.
And then I'll torture you.
Are you happy now?"
No, I'm not happy now.
First of all,
I'm being tortured.
I was given amnesia.
And now you've driven me crazy
and make me--deluded me into
thinking that I'm Linda.
No comfort there.
He says, "Okay,
last attempt to make--you're
not being very reasonable," he
says.
"Last attempt,
I'm going to,
after I drive you crazy and
make you think you're Linda,
I'm going to do the
corresponding thing for Linda.
I'm going to give her amnesia
and then I'm going to drive her
crazy and make her think that
she's Shelly.
Give her all of your memories
and beliefs and desires.
Now is it okay that I'm going
to torture you?"
No.
It hardly makes it--it was bad
enough I was being tortured and
given amnesia and driven insane.
It doesn't really make it any
better that you're also going to
give amnesia and drive insane
somebody else.
Don't torture me!
If you've got to torture
somebody, I say in my nonethical
mood, if you've got to torture
somebody, do it to her.
Don't do it to me.
When I think about this second
case, that's my intuition.
Now, think about the
implications of this second case
for the theory of personal
identity.
If I don't want this thing over
here to be tortured,
that must be because I think
it's me.
But if it's me,
what's the key to personal
identity?
Well, not personality,
because after all,
this doesn't end up with Shelly
Kagan's personality before the
torture.
Shelly Kagan's personality is
over there.
This is Shelly Kagan's body and
that suggests if I don't want
this to be tortured,
it's because I believe in the
body theory of personal
identity.
Follow the body,
not follow the personality.
Even though he swapped our
personalities,
it's still me he's torturing.
That's the intuition I've got
when I think about Bernard
Williams' second case.
Now, we're in a bit of a pickle
here, from the philosophical
point of view.
Because when we've thought
about the first case,
the intuition seemed to be,
ah, personality's the key to
personal identity.
But when we thought about the
second case, the intuition seems
to be, huh, body is the key to
personal identity.
That's bad, right?
Two different cases give us two
different, diametrically
opposed, answers on the very
same question.
One sec.
And it's worse still--Of
course, if you don't share the
intuitions that I just--I was
being honest with you.
Those really are my intuitions
when I think about these cases.
If you're with me,
you're in a philosophical
problem.
If you're not with me,
if you didn't have the same
intuitions, then maybe you don't
have a problem.
But I've got a problem.
And it's worse still because
it's not really,
if we're careful and think
about it,
it's not really as though we
have two different cases and
intuitively we want to give
different answers to those two
different cases.
Really, all we've got there is
just one case.
It's the very same case,
the very same story,
that I told two different
times.
In both cases,
before the torturing ends,
goes in, there's Shelly Kagan's
body over here with Linda's
personality and there's Linda's
body over here with Shelly
Kagan's personality.
And we're asking,
"Which one do you want to be
tortured?"
It's the very same setup.
I just emphasized different
elements in a way to manipulate
your intuitions.
But it's the very same case.
It can't be that in one of
them, follow the body and the
other one, follow personality.
So it's very hard to know what
moral should we draw.
The appeal to intuition,
thinking about these cases
doesn't seem to take us very
far.
There's a question back there.
Yeah?
Student: [inaudible]
Professor Shelly Kagan:
Nice suggestion.
So the suggestion was this.
When the mad scientist put my
personality, Shelly Kagan
personality, onto Linda's body,
he had to modify Linda's brain.
And in modifying Linda's
brain--this was the question
that was just raised--hasn't he
actually made that brain more
like Shelly Kagan's brain than
Linda's brain?
And if that's right,
shouldn't we say--Remember,
the best form of the body view,
I argued previously,
was the brain version.
So if this is really Shelly
Kagan's brain over here,
then this isn't a problem for
the body view.
We were deceived when we said
the body view said this is
Shelly Kagan.
Really, the body view,
to wit, the best version of the
body view, that is the brain
version,
now has to say,
"Oh, we moved Shelly's brain
and put it here."
Well, if you're prepared to say
that, then indeed you will be
able to say, yeah,
it's the body view.
The body view says,
"Do it to this one."
Rather, "Don't do it to this
one, because this is Shelly
Kagan."
I don't actually find myself
though inclined to agree with
you that this has become Shelly
Kagan's brain.
If you ask me,
"Where's Shelly Kagan's legs?"
They're still here.
"Where's Shelly Kagan's heart?"
It's still here.
"Where's Shelly Kagan's brain?"
It's still here.
It's not as though what the
scientist did was open up my
skull, take the brain out.
At least, if that's the way
we're imagining it,
don't imagine that!
This is all electronic transfer.
It's not as though he took the
brain out and literally moved
that hunk of tissue over here.
All he's done is reprogram
Linda's brain.
Analogy here that might be
helpful.
Think of the difference between
the computer and the programs
and files saved on the computer.
Personality is a little bit
like a program that's running on
the computer.
Though we have to have not just
the generic program,
but the specific data files and
databases and so forth.
What the mad scientist did,
in effect, was wipe out the
hard drive, put in the other
programs from the Shelly Kagan
computer,
but it's still the very same
computer.
It's still the same central
processing unit,
or so it seems to me.
Of course, it's true that now,
in a certain way,
Linda's brain will be similar
to the way that Shelly Kagan's
brain had been before.
In terms of how,
as it were, the floppy drives
are set up.
But still where's,
literally speaking,
Shelly Kagan's brain?
I want to say it's over there,
not over here.
There was another question or
comment.
Yeah.
Student: [inaudible]
Professor Shelly Kagan:
I'm not quite sure what the
question is.
So the thought is,
look, over here we've got
Shelly Kagan's body with Linda's
personality.
If we torture this one,
this thing, whoever it is,
is going to think to itself,
"I'm Linda.
I'm in horrible pain.
I wish it would stop.
I wonder whether I'll ever see
Linda's husband again."
Over here we've got Linda's
body, Shelly Kagan's
personality.
If we torture this one--of
course to torture,
you cause pain to bodies,
but the pain gets felt in the
mind.
So over here,
we've got something that's
going to think to itself,
"I'm Shelly Kagan.
I'm in horrible pain.
I wonder whether I'll ever see
Shelly Kagan's wife again."
Yes, of course,
we're torturing bodies.
By torturing the bodies we
cause pain to the minds,
the personalities,
who have beliefs about who's
hurting.
What I'm inviting you to think
about is which one,
if you had to choose between
these two gruesome scenarios,
which one would you rather
save?
Which one would you rather
protect?
Which do you care more about?
Making sure that your lump of
flesh doesn't have its neurons
hurt?
Or making sure that the person
who's thinking to yourself,
"I'm Shelly Kagan" or whatever
your name is,
that "I'm in pain."
You don't want to be thinking,
"I, Shelly Kagan,
am in pain."
Or if your name is Mary,
"I'm Mary.
I'm in pain."
That's what we're trying to get
straight on here.
The trouble though is that you
tell the very same story two
different times and I find
myself sometimes being pulled
this way,
sometimes being pulled that way.
So I can't use thinking about
the Williams cases as a method
of deciding what do I really
believe, the body view or the
personality view?
I find, myself,
you spin the story one way and
I follow the body.
You spin the story another way,
and I follow the personality.
If we're going to have a way to
decide between these two
theories, it seems as though we
need some other kind of
arguments.
At least, I need some other
kind of arguments,
because of the intuitions I've
got about the cases.
So let me turn to a different
approach to solving the
question, answering the
question, which one should we
believe?
It starts by raising a certain
philosophical objection to the
personality theory.
It's going to say,
look, the personality theory of
personal identity has an
implication that we cannot
possibly accept.
So we have to reject the view.
And then become body theorists,
if there are no souls.
Here's the objection.
It's a common enough objection.
It's probably occurred to some
of you.
According to the personality
theory, whether somebody is me
depends on whether he's got my
beliefs.
For example,
the belief that I'm Shelly
Kagan, professor of philosophy
at Yale University.
Well, I'm a not an especially
interesting fellow.
So let's make it more dramatic
and think about Napoleon.
You've probably read about this
thing.
Every now and then there are
some crazy people who think
they're Napoleon.
So imagine that there's right
now somebody in an insane asylum
in Michigan who's got the
thought, "I am Napoleon."
Well, the objection says,
clearly this guy's just insane,
right?
He is not Napoleon.
He's David Smith who grew up in
Detroit or whatever.
He just insanely believes he's
Napoleon.
Yet, the personality theory,
the objection says,
would tell us that he is
Napoleon because he's got the
beliefs of Napoleon.
He's got Napoleon's personality.
Since that's obviously the
wrong thing to say about the
case, we should reject the
personality view.
But not so quick.
The personality view doesn't
say anybody who has any elements
at all of my personality is me.
One belief in common is
obviously not enough.
Look, we all believe the earth
is round.
That's not enough to make
somebody else me.
Of course, the belief,
"I am Napoleon" is a much rarer
belief.
I presume that none of you have
that belief.
I certainly don't have that
belief.
Napoleon had it and David Smith
in Michigan's got it.
But so what?
One belief, even one very
unusual belief's not enough to
make somebody Napoleon,
according to the personality
theory.
To be Napoleon,
you've got to have the very
same overall personality,
which is a very big,
complicated set of beliefs and
desires and ambitions and
memories.
David Smith doesn't have that.
David Smith in the insane
asylum in Michigan does not
remember conquering Europe.
He doesn't remember being
crowned emperor.
He doesn't remember being
defeated by the British.
He doesn't have any of those
memories.
He probably doesn't even speak
French.
Napoleon spoke French.
He doesn't have Napoleon's
personality.
So the David Smith case isn't
really bothersome.
It's not really a
counterexample to the
personality theory.
The personality theory says,
to be Napoleon,
you've got to have Napoleon's
personality.
But David Smith doesn't.
So, of course,
we can all agree David Smith,
despite thinking he's Napoleon,
is not Napoleon.
No problem here for the
personality theory.
But we could tweak the case.
We could revise the case.
Some foe of the personality
theory could say,
"Okay, imagine that this guy in
Michigan does have
Napoleon's personality.
He's got the memories of being
crowned emperor and being
defeated, conquering Europe.
He's got all of those memories."
And, remember we want him to
have Napoleon's personality.
He doesn't have any David Smith
memories.
He doesn't have any memories of
growing up in Detroit.
How could Napoleon have
memories of growing up in
Detroit?
Napoleon grew up in France.
The objection then says even if
this guy had all of Napoleon's
memories, beliefs,
desires, personality,
still wouldn't be Napoleon.
So the personality theory's got
to go.
Well, when I think about this
example, I think,
now we've got it right.
That is, that is what
the personality theory has to
say about that case.
But I'm not so confident
anymore that it's the wrong
thing to say.
So think of this,
as it were, from the point of
view of Napoleon,
right?
So there was Napoleon in the
1800s conquering Europe and
being crowned emperor,
being defeated by the British,
being sent to exile on,
was it Elba,
right?
And I forget where Napoleon
actually dies,
but he's got memories of
getting sick and ill and the
light begins to fade and he goes
unconscious.
And then--well,
we'll at least try to describe
it this way--he wakes up.
And he wakes up in Michigan.
And he thinks to himself,
"Hallo.
Je suis, Napoleon!
What am I doing in Michigan?"
I don't speak French,
so I'm going to drop that,
right?
"But the last thing I remember
I was going to bed from my fatal
illness on the Isle of Elba.
How did I get over here?
I wonder if there's any chance
of reassembling my army and
reconquering the world."
If he had all of that,
it's not so clear to me that it
would be the wrong thing to say
that, by golly,
this is Napoleon.
I mean, it would be totally
bizarre.
Things like this don't happen.
But of course,
we're doing science fiction
stories here.
So we'd say to ourselves,
wouldn't we,
somehow Napoleon has been
reborn or reincarnated,
taking over,
by some sort of process of
possession, the body of the
former David Smith,
but now it's Napoleon.
I find myself thinking maybe
that would be the right thing to
say.
Yeah?
Student: [inaudible]
Professor Shelly Kagan:
All right, so the thought was,
look, this guy over here,
David Smith's body with
Napoleon's personality--And
let's be clear about this.
There's no underlying David
Smith personality still there,
to have the counterexample or
the example that we're after.
It can't be that he's got mixed
together memories of growing up
in France and memories of
growing up in Detroit.
He never thinks to himself,
"I'm David Smith.
How did I become Napoleon?"
If you got that junk,
you don't have Napoleon's
personality.
He's just got Napoleon's
personality through and through.
Well, the question then was,
maybe that's not so.
After all, he doesn't really
have Napoleon's experiences,
did he?
Napoleon had the experience of
being crowned emperor.
But this guy didn't have the
experience of being crowned
emperor.
Maybe what we should say is he
thinks he remembers the
experience of being crowned
emperor, but it's a fake memory.
It's an illusion,
or a delusion,
but he didn't really have the
genuine memory.
To have the genuine memory,
he has to have been crowned
emperor.
And he wasn't crowned
emperor;
Napoleon was crowned emperor.
Well, that's what we could say,
but we can't say that until we
decide he's not Napoleon.
After all, if the personality
theory is right,
since he does have all of these
memories,
or semi-memories,
or quasi-memories,
or whatever we should call
them.
If that's the key,
then it is Napoleon.
So he is remembering being
crowned emperor.
If you want to say,
no, no, no, those memories are
illusions, it must be because
you don't think he's really
Napoleon.
In which case,
what you're discovering is you
don't really believe the
personality theory.
Why isn't he Napoleon?
It's not his body.
The body of Napoleon is not
this body and to be Napoleon,
you've got to have Napoleon's
body.
It's a possible position.
That's the thought that the
body theorists are trying to
elicit in you when they offer
these Napoleonesque
counterexamples.
You could match the personality
as much as you want,
but it's still not Napoleon.
Don't you agree?
That's what they say.
And if you do agree,
that shows you don't really
accept the personality theory.
I'm not going to try to settle
this here.
Who should we believe?
The personality theory or the
body theory?
I'm trying to invite you to
think about the implications and
the differences between these
views so as to get clearer in
your own mind about which of
these you accept.
In many moods--at least,
when I think about not the
simple, the ordinary David Smith
case with a single belief or
two,
but the full bodied--that's a
bad term--the full blown
Napoleon case with all the
memories,
all the beliefs.
Suppose David Smith there
thinks, "I remember.
I remember."
I can't say it in a French
accent.
"I remember playing as a lad in
France burying my little toy
saber."
Some memory that Napoleon never
wrote down in his diaries.
And we go and we dig up in
France and there is the saber,
right?
This guy remembers things that
Napoleon would remember.
I find myself thinking,
well, maybe that's Napoleon.
Imagine a slightly different
version of this case.
Napoleon dies on his death bed,
wakes up in heaven saying "Je
suis Napoleon.
I was emperor of Europe and now
I have come to my due reward.
I am here in heaven."
Well, it seems like what we
would want to say is,
"Yeah, that's Napoleon."
It's Napoleon even if it
doesn't have Napoleon's body.
Napoleon's corpse is rotted in
France.
God gives Napoleon some new
angelic body.
It seems straightforward.
If it's got Napoleon's
memories, beliefs,
desires, goals,
and so forth and so on,
wouldn't we say it's Napoleon?
Imagine that--back to this
earth--this Napoleon type of
case happened all the time.
We might have a term for this
sort of thing--possession.
Every now and then,
people's bodies get possessed.
They become this other person
who's, now, personality has
taken over.
If this happened frequently
enough, instead of just a little
science fiction story like with
the David Smith case,
maybe we'd say,
yeah, possession is one of
these things that needs to be
explained.
How is it the personality
travels?
Well, maybe there'll be some
sort of physical explanation for
it.
Still, maybe we'd say,
yeah, the people have been
taken over.
They've become somebody else.
So speaking personally,
I don't find the Napoleon
objection a telling one.
It doesn't give me a reason to
reject the personality theory.
But we can now tweak the worry
in a slightly different way.
Okay, so here was Napoleon back
in France with his memories and
his beliefs and so forth and so
on.
Death bed, goes to sleep,
goes unconscious,
whatever it is.
I told you a story in which he
wakes up, or his personality
wakes up, however we should put
it, in Michigan.
But if it could happen in
Michigan, I suppose it could
also happen in New York.
And if it could happen in New
York and it could happen in
Michigan, I suppose it could
happen in New York and Michigan.
So right now,
let's imagine two people with
Napoleon's personalities,
complete personalities,
one of them in Michigan,
one of them in New York.
Whoa.
What should we say now?
What is the personality theory
going to say about this case?
So I don't know how to draw
personalities very well on the
board, so I'll draw little stick
figures of bodies,
but I mean these to be the
personalities.
So here we've got the
continuing, evolving over
time--this is all taking place
in France--the personality of
Napoleon in France.
There's the deathbed scene.
Now, up here we had somebody
with Napoleon's personality
continuing.
Of course, he's going to change.
He's going to evolve.
Just like the actual historical
Napoleon kept having new beliefs
and new desires,
if this really was Napoleon in
Michigan, he'll start having
some new desires and beliefs
about Michigan,
which perhaps Napoleon never
gave any thought to at all.
Who knows?
So this is Michigan over here.
And I said I was willing to
entertain the possibility that
this is all Napoleon.
Napoleon, if you think of it,
Napoleon's a person extended
through space and time.
According to the personality
view, what makes somebody in the
future the same person as
somebody in the past is if it's
part of the same ongoing
personality.
So maybe that's what we've got
going on in the Michigan case.
Now, we imagine in our new
version of the worry somebody
with Napoleon's personality over
here in New York.
Now, if the Michigan guy hadn't
been there, what I would have
done, if I believed in the
personality theory or when I
believe in the personality
theory,
is say "Oh look,
Napoleon--reincarnated in New
York."
That's what the personality
theory should say and I said it
doesn't seem like a crazy thing
to say if we only had the guy in
New York.
Just like it wasn't a crazy
thing to say if we only had the
guy in Michigan.
The trouble is,
imagine the case where we've
got one guy who's got all of
Napoleon's personality in
Michigan,
one guy who's got all of
Napoleon's personality in New
York.
Now what should we say?
What are the choices here?
Well, I suppose one possibility
would be to say the guy in New
York is Napoleon.
The guy in Michigan isn't.
He's just an insane guy who's
got Napoleon's personality.
You could say that.
The reason that it seems
difficult to say though is
because it seems like it would
be just as plausible to say the
reverse.
Say no, no, no.
It's not the New York fellow
who's Napoleon.
It's the Michigan fellow who's
Napoleon.
Well, we could say that,
but the difficulty is there
seems to be no good reason to
favor the Michigan fellow over
the New York fellow.
Just like there was no good
reason to favor the New York
fellow over the Michigan fellow.
Saying that one of them is
Napoleon and the other one isn't
seems very hard to believe.
Well then, what's the
alternative?
Well, I suppose another
possibility is to say,
at least another possibility
worth mentioning,
is to say they're both
Napoleon.
Somehow, bizarrely enough,
Napoleon split into two.
But when splitting into two,
he split on to two bodies,
but they are both Napoleon.
Now, it's very important to
understand how bizarre this
proposal would be.
The claim is not now we've got
two Napoleons who are,
of course, not identical to
each other.
No, no, we've got a single
Napoleon.
A Napoleon who was in one place
in France and is now
simultaneously in two places in
the U.S.
That seems very hard to believe.
It seems to just violate one of
our fundamental notions about
how people work,
metaphysically speaking.
People can't be in two places
at the same time.
Well, maybe that metahphysical
claim I just made should be
abandoned.
Maybe we should say,
oh, under normal circumstances,
people can't be in two places
at the same time.
But if you had something like
this, by golly,
this guy would be,
Michigan dude is Napoleon and
he's the very same person,
the very same person as
New York dude.
New York dude and Michigan dude
are a single person,
Napoleon, who is bilocated.
It doesn't happen.
But if it did happen,
it could happen.
Well, maybe that's what we
should say.
But again, all I can tell you
is, I find that too big a price
to pay.
People can't be in two places.
It's one thing to say people
are space-time worms extended
through space and extended
through time.
It's another thing to say that
they are Y-shaped space-time
worms.
It seems to violate one of the
fundamental metaphysical things
about how people work.
All right, I've got to remind
you though, none of the options
here are all that attractive.
So when I say,
you don't want to say that,
you don't want to say that,
we're going to run out of
possibilities.
So maybe this is what you'll
want to say.
All right, saying that Napoleon
is in Michigan but not New York
doesn't seem very attractive.
Saying he's in New York but not
Michigan doesn't seem very
attractive.
Saying he's in both places at
the very same time doesn't seem
very attractive.
But what other possibilities
are there?
If he's not one but not the
other, and if he's not both,
the only other possibility is
that he's neither.
Given this situation,
neither of these guys is
Napoleon.
You've got separate people.
There's the person Napoleon,
a space-time worm that came to
an end in France.
And there's some space-time
worm taking place in Michigan,
some space-time person worm
taking place in New York.
But neither of them are
Napoleon.
That seems to me to be the
least unattractive of the
options we've got available.
But notice that if we say this,
if we say neither of these
guys, despite having Napoleon's
personality,
neither of these guys is
Napoleon, then the personality
theory of personal identity is
false.
It's rejected.
We're giving up on it.
Because the personality theory,
after all, said if you've got
Napoleon's personality,
you're Napoleon.
But now we've got people that
are not Napoleon but they've got
Napoleon's personality.
So the personality theory,
follow the personality,
is wrong if we say neither of
these guys is Napoleon.
But that does seem to be the
least unacceptable of the
options.
At least that's how it seems to
me.
So the personality theory's got
to be rejected.
Now, I think that's right.
I think, in fact,
the personality theory's got to
be rejected.
But that doesn't mean we
couldn't revise it.
We could try to change it in a
way that keeps much of the
spirit of the personality
theory,
but avoids some of the problems
we've just been looking at.
Here's what I think is the best
revision available to fans of
the personality theory.
They should say we were
simplifying unduly.
We were simplifying it,
getting it wrong,
when we said,
"Follow the personality.
If you've got Napoleon's
personality, that's enough to
make you Napoleon."
That's not true.
We need to throw in an extra
clause to deal with branching,
splitting cases,
of the sort that I've just been
talking about.
We need to say,
if there's somebody in the
future who's got my personality,
that person is me,
as long as there's only
one person around in the
future who's got my personality.
If you have multiple examples,
duplications,
splittings and branchings,
nobody, none of them is me.
So where the original
personality theory said,
same personality,
that's good enough for being
the same person,
the new version throws in a
no-competitors clause,
throws in a no branching
clause.
It says, same personality's
good enough, as long as there's
no branching.
If there is branching,
neither of the branches is me.
Now, if we say that,
if we throw in the no branching
clause, then we're able to say,
look, in the original story I
was telling, where there was the
Michigan guy who had Napoleon's
personality but no New York guy,
that really would be Napoleon,
because it would have the same
personality with no competitor.
Similarly, had we had somebody
with Napoleon's personality in
New York and nobody with the
personality in Michigan,
that guy would have been
Napoleon, because we would have
had the same personality with no
branching,
with no competitor.
But in the case where we've got
branching, where we've got
somebody with Napoleon's
personality both in Michigan and
New York,
that violates the no branching
rule, and we just have to say
nobody's Napoleon in that case.
As I say, that seems to me to
be the best revision of the
personality theory available to
them.
So what we now need to ask is,
can we possibly believe that
revision?
Can we possibly accept the no
branching rule?
The no branching rule seems
rather bizarre in its own right.
Think about the ordinary
familiar cases that we're trying
to make sense of.
I'm the same person as the
person that was lecturing to you
last time.
According to the personality
theory or the revised
personality theory,
that's because I've got the
same personality.
The guy last time thought he
was Shelly Kagan,
believed he was professor of
philosophy.
I think I'm Shelly Kagan.
I believe I'm the professor of
philosophy.
He's got all sorts of memories
of his childhood.
I've got the same memories.
He's got desires about
finishing his book.
I've got those desires about
finishing my book.
Same personality, it's me.
That's what the personality
theory says.
So I conclude, hey, it's me.
I know you were all worried
whether I'd survive over the
break a couple days.
Came back, it's still me.
I made it through Wednesday.
Or did I?
Or perhaps I should ask,
"Or did he?"
Yeah, there was somebody there
on Tuesday and yeah,
there's somebody here on
Thursday,
and yeah, this person here now
has got the same personality as
the guy who was there on
Tuesday.
But according to the no
branching rule,
we can't yet conclude that I'm
the same person as the person
that was lecturing to you on
Tuesday.
We can't conclude that until we
know that there aren't any
competitors, that there isn't
anybody else right now who also
has the same personality.
If I'm the only one around
today who's got Shelly Kagan's
personality, then I'm the same
person as the person who was
lecturing to you on Tuesday.
But if, unbeknownst to me,
and I presume unbeknownst to
you, there's somebody in
Michigan right now who's got
Shelly Kagan's personality,
then we have to say,
huh, it turns out I'm not
Shelly Kagan after all.
Neither is he.
Neither of us are Shelly Kagan.
Shelly Kagan died.
So am I Shelly Kagan or am I
not Shelly Kagan?
Can't tell until we know what's
going on in Michigan.
Whoa!
That seems very,
very hard to believe.
Whether I am the same person as
the person who was lecturing to
you on Tuesday presumably should
turn on facts about that guy who
was lecturing to you on Tuesday,
and facts about this guy who's
lecturing to you today on
Thursday, and maybe some facts
about the relationship between
that guy and this guy--or that
stage and this stage,
if we prefer to talk about it
that way.
We can see how whether it's the
same person or not has to turn
on the relations between the
stages.
But how could it possibly turn
on what's happening in Michigan?
How can whether or not I am the
same guy as the guy who was
lecturing to you on Tuesday
depend on what's happening in
Pennsylvania or Australia or
Mars?
To use some philosophical
jargon, the nature of identity
seems like it should depend only
on intrinsic facts about me or
perhaps relational facts about
the relations between my stages.
But it shouldn't depend on
extrinsic, external facts about
what's happening someplace else.
But if we accept the no
branching rule,
we're saying whether or not
we've got identity depends on
what's happening elsewhere.
With the no branching rule,
identity ceases to be a
strictly internal affair.
It becomes, in part,
an external affair.
That's very,
very hard to believe.
And if you're not prepared to
believe it, it looks as though
you've got to give up on the
personality view.
Last thought.
During all of these problems
for the personality theorist,
the body theorist,
the fans of the body theorist,
is standing there laughing.
"Ha!
You poor fools.
Look at all the problems you've
got adopting the personality
theory.
See how easy it is to duplicate
personalities,
leading to these totally
implausible no branching rules.
We can avoid all of that if we
become body theorists."
What we'll ask ourselves next
time is whether or not the body
theorist is in a better
situation.
