Professor Shelly Kagan:
At the end of last class,
we started sketching an
argument that comes from
Descartes, the Cartesian
argument, that says merely by
the process of thinking,
on the basis of thought alone,
it tends to show that the
mind--We all agree that there
are minds.
What the argument attempts to
show is that this mind must be
something separate from my body.
And what's amazing about the
argument is that it works on the
basis of a pure thought
experiment.
The thought experiment,
you recall, was one in which I
imagine, I tell myself a story
in which what I'm doing is I'm
imagining my mind existing
without my body.
It doesn't seem especially
difficult to do that.
But then, we add this extra
philosophical premise.
If I can imagine one thing
without the other,
then it must be that those are
two things.
So my mind must not be my body.
My mind must not be the same
thing as my body or a way of
talking about my body,
because of course if my mind
just was--talking about my mind
just was--a way of talking about
my body,
then to try to imagine my mind
without my body would be trying
to imagine my body without my
body.
And that, obviously,
can't happen.
Look.
Suppose we try to imagine a
world in which Shelly exists but
Kagan doesn't.
You can't, right?
Because of course,
they're just a single thing,
Shelly Kagan.
And so if you've imagined
Shelly existing then of course
you're imagining that single
thing, Shelly Kagan,
existing.
And if you imagine Kagan not
existing, then you're imagining
that single thing,
Shelly Kagan,
not existing.
So you can't even imagine a
world in which Shelly exists but
Kagan doesn't.
Now, it's important not to be
confused about this.
We can easily imagine a world
in which I don't have the last
name Kagan or perhaps to switch
it around, Shelly's not my name.
Suppose my parents had named me
Bruce.
Nothing would be easier.
Imagine a world in which Kagan
exists, but Shelly doesn't
exist, because nobody in the
world is named Shelly.
The question is not,
"Can you imagine me with a
different name?"
Bruce instead of Shelly,
easy enough.
It's rather,
"Can you imagine a world in
which the very thing that you
really are picking out when you
refer to me by the name
Shelly--namely this thing--can
you imagine a world in which
that thing exists,
but the thing that you're
picking up when you use the word
Kagan does not exist?"
And that you can't do,
because in the real world of
course Shelly and Kagan pick out
just two different names of this
very same thing.
This thing right here.
So imagining a world in which
Shelly exists but Kagan doesn't
or Kagan exists but Shelly
doesn't,
that's trying to imagine a
world in which I exist but I
don't.
And that's, of course,
incoherent.
So if you can--On the other
hand, contrast.
Can I imagine a world in which
my left hand exists,
but my right hand doesn't?
Easy.
Why is it so easy?
Because of course there's two
different things.
Of course, that doesn't mean
that in the real world one of
them does exist and the other
one doesn't.
But it does show that in the
real world they are two
different things.
That's why I could imagine a
world with one but not the
other.
Try to imagine a world in which
somebody's smile exists but
their body doesn't.
You can't do it.
You can't have the smile
without the body.
And of course,
no mystery about that.
That's because the smile isn't
really some separate thing from
the body.
Talking about smiles,
as we've noted before,
is just a way of talking about
either what the body can do or
what a certain area of the body
can do.
You can try to imagine it.
In Alice in Wonderland,
the Cheshire Cat disappears and
all we have left,
the last thing that disappears,
is the smile.
But of course,
when you imagine the Cheshire
Cat only having the smile there,
you're still imagining the
cat's lips, teeth,
maybe tongue,
whatever it is.
If you try to imagine a smile
with no body at all,
it can't be done.
Why?
Because the smile isn't
something separate from the
body.
"Try to imagine my mind," says
Descartes, "without my body."
Easy.
From which it follows that my
mind and my body must not be one
thing.
They must, in fact,
be two things.
That's why it's possible to
imagine the one without the
other.
So this Cartesian argument
seems to show us that the mind
is something separate from,
distinct from,
not reducible to,
not just a way of talking
about, my body.
So it's got to be something
extra above and beyond my body.
It's a soul.
That's what Descartes argued.
And as I say,
to this day,
philosophers disagree about
whether this argument works or
not.
I don't think it does work and
in a second I'll give you a
counter example.
And then, having given the
counter example… That is to
say, what I'm going to give is
an example of an argument just
like it,
or at least an argument that
seems to be just like it where
we can pretty easily see that
that argument doesn't work.
And so something must go wrong
with Descartes' argument as
well.
Well, here's the counter
example.
Some of you,
I'm sure most of you,
maybe all of you,
are familiar with the Evening
Star.
The Evening Star is the,
roughly speaking,
first heavenly body that's
visible in the sky as it gets
dark, at least at certain times
of the year.
And I'm sure you're also
familiar then with the Morning
Star.
The Morning Star is that
heavenly body which is the last
heavenly body that's still
visible as dawn comes in and it
begins to get light.
So as a first pass,
the Evening Star is the first
star that's visible and the
Morning Star is the last star
that's visible at the right
times of the year.
The world that we live in has
both the Evening Star and the
Morning Star.
But try to imagine a world in
which the Evening Star exists,
but the Morning Star does not.
Seems fairly straightforward,
right?
I get up in the morning as
dawn's approaching.
I look around and the Morning
Star is not there.
There is no star where the
Morning Star had been or where
people have claimed it would be
or something.
But the Evening Star still
exists.
When I go out as sun sets and
dusk falls, there is the Evening
Star.
So, as I say,
it's a trivial matter to
imagine a world in which the
Evening Star exists and the
Morning Star does not.
And so we've got a--we could
imagine then a--Descartes-like
argument saying,
"If I can imagine the Evening
Star without the Morning Star,
that shows the Evening Star and
the Morning Star must be two
different heavenly bodies."
But in fact, that's not so.
The Evening Star and the
Morning Star are the very same
heavenly body.
In fact, it's not a star at all.
It's a planet.
It's Venus, if I recall
correctly.
So look, there's only one thing.
The Evening Star is Venus.
The Morning Star is Venus.
So there couldn't be a world in
which the Evening Star exists,
but the Morning Star doesn't,
because that would be a world
in which Venus exists and Venus
doesn't exist.
Obviously, that's not possible.
Of course what you can imagine
is a world in which Venus isn't
visible in the morning.
Still, that's not a world in
which the Morning Star doesn't
exist, given that what we mean
by the Morning Star is that
heavenly object,
whatever it is,
that in this world we pick out
at that time in the morning
looking up at the sky.
So when I refer to the Morning
Star, I'm talking about Venus,
whether or not I realize it's
Venus.
When I talk about the Evening
Star, I'm referring to Venus,
whether or not I realize that
Venus is the Evening Star.
So as long as Venus is around,
well, there's the Evening Star,
there's the Morning Star,
there's Venus.
You can't have a world in which
the Morning Star doesn't exist
but the Evening Star does.
Although you could have a world
in which Venus doesn't show up
in the morning.
Still, from the fact that I can
imagine the world in which I
look around for the Morning
Star--there it isn't.
I look around for the Evening
Star--there it is.
You might have thought that
showed--didn't Descartes prove
to us that that shows--the
Evening Star and the Morning
Star are two different things?
Well no, obviously it didn't.
So let's think about what that
means.
So we've got this argument that
Descartes puts forward.
I can imagine my mind without
my body.
And Descartes says that shows
that, in fact,
my mind is something separate
from my body.
Well, I can imagine the Evening
Star without the Morning Star,
so Son of Descartes,
"Descarteson," has to say,
"Oh, so that shows that the
Morning Star and the Evening
Star are two different things."
But "Descarteson" would be
wrong when he says that.
The Morning Star and the
Evening Star aren't two
different things.
They're just one thing,
namely Venus.
In fact, the sentence,
"They are one thing," is
slightly misleading,
right?
It's just one thing, Venus.
If that argument,
if the argument--If trying to
run the Cartesian argument for
astronomy fails,
yet it seems to be an exactly
analogous argument,
we ought to conclude that the
argument for the distinctness of
the mind and the body must fail
as well.
Now, that seems to me to be
right.
I think the Cartesian argument
does fail.
And I think the example of the
Evening Star and the Morning
Star--which is not at all
original to me--that this
example shows,
this counter example shows,
that Descartes' original
argument doesn't work either.
At least, that's how it seems
to me, though as I say,
there are philosophers that
say, "No, no.
That's not right.
Maybe somehow we misunderstood
how the argument goes and it
doesn't exactly--although these
two arguments seem parallel,
they're not, in fact, parallel.
There's some subtle differences
that if we're not looking
carefully, we'll overlook."
But, as I say,
the debate goes on.
One of the reasons for thinking
it's not clear whether the
argument fails or not is because
it's hard to pin down,
where exactly did it go wrong?
Look, take the argument of the
planets, the Morning Star and
the Evening Star example.
I take it that we all agree
that when we attempt to run the
Cartesian argument in terms of
the Morning Star and the Evening
Star, it fails.
But it's harder to say what
went wrong?
How did it go wrong?
Why did it go wrong?
What are the possibilities?
Well, we said,
look, first claim,
first premise.
I can imagine a world in which
the Evening Star exists,
but the Morning Star doesn't.
Well, I suppose one possible
response would be,
"You know, you couldn't really
do that.
You thought you were imagining
a world in which the Evening
Star exists and the Morning Star
doesn't,
but you weren't really
imagining a world in which the
Evening Star exists and the
Morning Star doesn't.
You misdescribed what it is
you've imagined."
That's not a silly thing to say
about the astronomy case.
Maybe that's the right
diagnosis.
Could we similarly say,
"I didn't really imagine a
world in which my mind exists
but my body doesn't"?
That little story I told last
time, I thought I was describing
a world in which my mind exists
and my body doesn't,
but it wasn't really imagining
a world like that.
That doesn't seem so persuasive
over there.
It did seem as though I was
imagining it.
What else could go wrong with
the astronomy example?
Well, maybe I did imagine a
world in which the Morning Star
exists and the Evening Star
doesn't exist,
but maybe imagining doesn't
mean it's possible.
Normally, we think,
if we imagine something,
it means it's possible.
Here I don't mean,
of course, empirically
possible.
I could imagine a world with
unicorns.
It doesn't mean I think
unicorns are physically
possible.
All we mean here is logically
possible.
I can imagine a world with
unicorns.
It seems to follow that
unicorns are logically possible.
Imagination seems to be a guide
to possibility;
but maybe not always.
Maybe sometimes we can imagine
something that's really
impossible.
Try to imagine--can you do that
or can you not do that?--try to
imagine a round square.
Can you imagine it?
Can you not imagine it?
In certain moods,
I sort of feel I can just begin
to imagine it.
Of course, it doesn't really
mean it's possible.
It seems like it's impossible.
So maybe imagination is a
flawed guide to possibility.
So maybe that's what we should
say about the mind-body case.
"Yeah, I can imagine a world in
which my mind exists but my body
doesn't.
But that doesn't show that it's
really possible,
logically possible to have a
world in which my mind exists
and my body doesn't."
Maybe that's where the argument
goes wrong.
On the other hand,
isn't imagination our best
guide to logical possibility?
Isn't the reason I think
unicorns are logically coherent
is because I can imagine them so
easily?
Another possibility.
Maybe we should say,
the mere fact that it's
possible for A and B to be
separate--for A to exist without
B for example,
that's clearly where they're
separate--the mere fact that
it's possible for them to be
separate doesn't mean that in
the actual world they are
separate.
Maybe the argument goes wrong
by assuming that identity--when
A is equal to B,
it's always equal to B,
no matter what.
Maybe identity,
as philosophers like to put it,
maybe identity is contingent.
Maybe A could be the same thing
as B in this logically possible
world, but we could imagine a
completely different logically
coherent world in which A was
not the same thing as B.
If that's right,
then maybe the conclusion
should be "well,
you know, yeah,
the Cartesian thought
experiment shows that there
could be a world in which there
are minds that are not identical
to bodies.
But that doesn't mean that in
this world the mind is not
identical to my body.
Maybe in this world,
minds and bodies are identical,
even though in other logically
possible worlds the identity
comes apart.
Identity is not necessary,
but contingent,
as the philosophers put it."
It's not clear that that's
right either.
The notion of contingent
identity is very puzzling.
After all, if A really is B,
how could they come apart?
There's only one thing there.
There's nothing to come apart.
There's just A equals B,
that single thing.
What's to come apart?
So where exactly does the
argument break down?
Is it that I'm not really
imagining?
I'm just thinking I'm imagining?
Is it that imagination's not
really a good guide to
possibility?
I just--Often it is,
but not always.
Is it that identity is
contingent?
The interesting thing about
Descartes' argument is that it's
easy to see something has gone
wrong in the case of the Morning
Star and the Evening Star,
but it's difficult to pin down
what exactly went wrong.
Different philosophers agree
that something's gone wrong in
the Morning Star and the Evening
Star case,
but disagree about the best
diagnosis of where the mistake
went in.
Armed with your pet diagnosis
of where the argument goes wrong
there, you've got to ask,
"Does it also go wrong in the
mind and body case?"
Well, we could spend more time,
but I'm not going to.
I think Descartes' argument
fails.
I think the Morning Star,
Evening Star case shows us that
arguments like this,
at the very least,
can't be taken at face value.
Just because it looks as though
we can imagine it and just
because it seems as though from
the fact that we can imagine one
without the other,
it just won't necessarily
follow that we really do have
two things that are separate and
not identical in the real world.
I'd be happy to discuss with
you, outside class,
at greater length my favorite
theories as to where the
argument goes wrong and why I
think it goes wrong in
Descartes' case as well.
But I suggest that the argument
goes wrong.
It's not right.
And so, Descartes' attempt to
establish the distinctness of
the mind, the immateriality of
the mind,
on the basis of this Cartesian
thought experiment,
I think that's unsuccessful.
Well, we've spent--Let's step
back and think of where we've
been.
We've spent the last week and a
half or so, maybe a bit more,
two weeks, talking about
arguments for the existence of
the soul.
And unsurprisingly--since I
announced this was going to be
the result before the class had
barely gotten started--I don't
think any of these arguments
work.
I believe the attempts to
establish the existence of a
soul, an immaterial object,
the house of consciousness
separate and distinct from the
body, I think those arguments
fail.
But I recognize that this is
something that reasonable people
can disagree about.
And so this is,
as will be many times the case
over the course of this
semester, something that I
invite you to continue to
reflect on for yourself.
If you believe in a soul,
what's the argument for it?
Well, what we're about to turn
to is Plato's discussion of
these issues in the dialogue the
Phaedo,
which, as I told you last week,
purports to lay out the final
day's discussion with Socrates
before he is killed by--he kills
himself--by drinking the hemlock
in accordance with the
punishment that's been given to
him.
Now, in the course of this
discussion, Socrates and his
disciples argue about not so
much the existence of the soul,
but the question really is the
immortality of the soul.
After all, even if you believe
in a soul, as I have remarked
previously, that doesn't give us
yet any reason to believe the
soul continues to exist after
the death of your body.
The kind of dualist position
that we are considering in this
class is an interactionist
position, where the soul
commands the body.
That's what makes my fingers
move right now.
And the body can affect the
soul.
If I poke my body,
I feel it in my mind.
So the mind,
the soul, and the body are
obviously very tightly
connected.
And so it could be--even if the
soul is something separate from
the body--that when the body
dies, the soul dies as well.
That's the question that's
driving the discussion in the
Phaedo.
Do we have any good reason to
believe the soul survives the
death of the body?
And more particularly still,
do we have good reason to
believe it's immortal?
Socrates believes in the
immortality of the soul.
And so, he attempts to defend
this position,
justify it to his disciples who
are worried that it may not be
true.
It's important to realize--as
you read the dialogue,
it becomes fairly
apparent--that there isn't so
much any defense of the belief
in the soul.
There's some of it,
but it's not the primary goal.
For the most part,
the existence of the soul is
just taken for granted in the
dialogue.
Plato, as a dualist,
portrays Socrates as being a
dualist and that's just taken
for granted.
The question that the
philosophical discussion turns
on is not, "Is there a soul?"
but rather, "Does it survive
the death of the body?
Is it immortal?"
Now, as I said,
this is Socrates' last day on
earth and you'd expect him to be
pretty bummed.
You'd expect him to be sad.
And one of the just striking
things is that Socrates is in a
very happy, indeed jovial,
mood, joking with his friends.
Why is that?
Well, of course,
it's because he thinks,
first of all,
there's a soul and it will
survive and it's immortal.
But more importantly
still--those are all crucial but
there's an extra ingredient as
well--he thinks he's got good
reason to believe,
when he dies he's going to go,
basically, to what we'd call
heaven.
He thinks there's a realm
populated by good gods and maybe
other philosophical kindred
souls.
And if you got your stuff
together here on life,
you'll get to go to that when
you die.
And so he's excited.
He's pleased.
Why does he think he's going to
go?
Well, in thinking about
Socrates' belief in the
existence of a soul,
it's important to understand,
it's important to notice,
that his take on which stuff
gets assigned to the body,
what are the bodily things
versus what are the soul-like
things, is rather different from
the way,
I think, most of us nowadays
would draw the line.
When I talked about arguments
for the existence of a soul,
I said, "Look,
here's one possible argument.
I see colors.
No physical object could,
no purely physical object could
see colors.
I can taste tastes and have the
smell of coffee and so forth."
But Socrates thinks all those
bodily sensations--that's all
stuff that the body takes care
of.
So unlike those modern dualists
who think we need to appeal to
something immaterial in order to
explain bodily sensations,
Socrates thinks no,
no, the body takes care of all
the bodily sensations,
all the desirings and the
wantings and the emotions and
the feelings and the cravings.
That's all body stuff.
What the soul does--Socrates
thinks--the soul thinks.
The soul, in its essence,
is rational.
It takes care of the thinking
side of things.
What does the soul think about?
Well, the soul thinks about all
sorts of things,
doubtless.
But one of the things that it
can do, one of the things that
sort of provides the
underpinnings,
as we'll see,
for Plato's arguments for the
immortality of the soul is the
soul can think about--;well,
here I'll have to introduce a
word of philosophical jargon.
Sometimes the idea,
sometimes the term is called
"ideas."
Sometimes the term is called
"forms."
But the thought is that the
soul can think about certain
pure concepts or ideas like
justice itself,
or beauty itself,
or goodness itself,
or health itself.
So to explain all this we need
now a sort of crash course in
Plato's metaphysics.
Obviously, this will be rather
superficial.
Those of you who would like to
know more about it,
I recommend reading more
Platonic dialogues or taking a
class in ancient philosophy.
But here's the basic idea.
There's all sorts of beautiful
objects in the world.
Objects can vary in terms of
how beautiful they are.
But Plato's got the idea that
there's nothing in this world
that's perfectly beautiful.
And yet for all that,
we can think about beauty
itself.
Well, we might put it this way.
We might say,
ordinary, humdrum,
everyday, physical objects are
somewhat beautiful.
They're partially beautiful.
As, sometimes,
Platonists put it,
they "participate" in beauty.
They partake of beauty to
varying degrees.
But none of them should be
confused with beauty itself.
Or, take justice.
There are various arrangements,
social arrangements,
that can be just or unjust to
varying degrees.
But we don't think anywhere in
the world there's any society
that's perfectly just.
Yet for all that,
the mind can think about
perfect justice.
And notice how ordinary
empirical social arrangements
fall short of perfect justice.
So whatever perfect justice is,
it's not one more thing in the
empirical world.
It's something we can think
about.
It's something that things in
the empirical world can
participate in or partake of to
varying degrees.
But we shouldn't confuse the
physical things which can be
just, the people who can be
virtuous to one degree or
another,
with perfect virtue or perfect
justice.
That's something that only the
mind can think about,
that we don't actually have in
the world, the empirical world
itself.
Or take being round.
The mind can think about
perfect circularity.
But no physical object is
perfectly circular.
There are only things that are
circular to a greater or lesser
degree.
So, by thinking about it,
by thinking about these kinds
of issues, we can see that the
mind has some kind of handle on
these perfect,
well, we need a word.
And as I say,
Plato gives us a word,
"ideas."
Sometimes it's translated as
"ideas" or "forms."
These things that we can think
about that are the template,
or at least the standard,
or maybe at the very least it's
that which the ordinary humdrum
things can participate in to
varying degrees:
perfect justice,
justice itself,
beauty itself,
goodness itself,
circularity itself,
health itself.
All of these things are,
as philosophers nowadays call
them, Platonic forms.
Ordinary material objects of
this world can partake of the
various Platonic forms,
but they should not be confused
with the Platonic forms.
But we still--even though we
don't bump into the Platonic
forms in this world--we can
think about them.
Our mind has a kind of grasp of
them.
Of course, the problem is,
we're distracted by the comings
and goings, the hurly burly of
the ordinary everyday world.
And so we don't have a very
good grasp of the Platonic
forms.
We're able to think about them,
but we're distracted.
What the philosopher tries to
do--this is Socrates' thought,
or Plato's thought that he puts
in Socrates' mouth--what the
philosopher tries to do is free
himself from the distractions
that the body poses--the desire
for food,
the craving for sex,
being concerned about pain.
All this stuff,
hungering after pleasure,
all this stuff gets in the way
of thinking about the Platonic
forms.
What the philosopher tries to
do, then, so as to better focus
on these ideal things,
is to disregard the body,
put it aside,
separate his mind as much as
possible from it.
That's what Socrates says he's
been trying to do.
And so because of that,
he's got a better handle on
these ideal forms.
And then, he believes,
when death comes and the final
separation occurs of the mind
and the body,
his mind gets to go up,
his soul gets to go up to this
heavenly realm.
Philosophers nowadays call it
"Plato's heaven."
He gets to go up to Plato's
heaven where he can have more
direct contact with these
things, with the forms.
Now, I don't have the time here
to say enough to try and make it
clear why this Platonic
metaphysical view is a view that
not only is worth taking
seriously,
but to this day,
many, many philosophers think
that, at least in it's basic
strokes,
must be right.
But let me at least give you
one example that may give you a
feel for it.
Think of math.
Think of some simple
mathematical claim like 2 + 2 =
4.
When we say that 2 + 2 = 4 or 2
+ 3 = 5, we're saying something
about numbers that our mind is
able to grasp.
But what are numbers anyway?
They're certainly not physical
objects.
It's not as though someday
you're going to open up an issue
of National Geographic
where the cover story's going to
be "At long last,
explorers have discovered the
number two."
It's not as though the number
two is something that you see or
hear or taste or could bump
into.
Whatever the number two is,
it's something that our mind
can grasp but isn't actually in
the physical world.
That's the Platonic take on
mathematics.
There are numbers.
The mind can think about them.
Things can partake of them.
If I were to hold up two pieces
of paper, there's a sense in
which they are participating in
"twohood."
But of course,
this is not the number two
here.
If I were to rip these pieces
of paper, I wouldn't be
destroying the number two.
So the number two,
the numbers,
three, whatever it is,
whatever they are,
are these Platonic abstract
entities that don't exist in
space and time.
Yet, for all that,
the mind can think about them.
That's the idea.
And it's not a silly idea.
It seems like a very compelling
account of what's going on in
mathematics.
What mathematicians are doing
is using their mind to think
about these Platonic ideas of
mathematics.
Except Plato's thought was,
everything is like that.
It's not just math,
but justice itself is like
that.
There are just or unjust things
in the world.
The mind can think about them,
but justice itself--this
perfect, this idea of being
perfectly just--that's something
the mind can think about,
but it's not here in the world.
It's another abstract Platonic
form.
So that's the picture.
Plato's idea is that if we
start doing enough metaphysics,
we can see there must be this
realm of Platonic ideas,
Platonic forms.
And we can see that we are able
to grasp them through the mind.
This can't be a job the body
does, because the body's only
got its bodily capacities,
right?
It's able to do the five-senses
thing.
It's the soul that thinks about
the Platonic forms.
And as Plato's then going to go
on to try to argue,
given this picture of what the
mind can do,
he thinks he can persuade us
that the mind,
the soul, not only survives the
death of your body,
but will last forever.
It's perfect.
It's immaterial and can't be
destroyed.
It's immortal.
So he offers a series of
arguments for that conclusion,
for that position,
and starting next time,
we'll work our way through
those arguments.
 
