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Professor Paul Bloom: We're going to begin the class
proper, Introduction to Psychology, with a discussion
about the brain. And, in particular,
I want to lead off the class with an idea that the Nobel
Prize winning biologist, Francis Crick,
described as "The Astonishing Hypothesis."
And The Astonishing Hypothesis is summarized like this.
As he writes, The Astonishing Hypothesis is
that: You, your joys and your
sorrows, your memories and your ambitions, your sense of
personal identity and free will are in fact no more than the
behavior of a vast assembly of nerve cells and their associated
molecules. As Lewis Carroll's Alice might
have phrased it, "you're nothing but a pack of
neurons." It is fair to describe this as
astonishing. It is an odd and unnatural view
and I don't actually expect people to believe it at first.
It's an open question whether you'll believe it when this
class comes to an end, but I'd be surprised if many of
you believe it now. Most people don't.
Most people, in fact, hold a different view.
Most people are dualists. Now, dualism is a very
different doctrine. It's a doctrine that can be
found in every religion and in most philosophical systems
throughout history. It was very explicit in Plato,
for instance. But the most articulate and
well-known defender of dualism is the philosopher Rene
Descartes, and Rene Descartes explicitly
asked a question, "Are humans merely physical
machines, merely physical things?"
And he answered, "no." He agreed that animals are
machines. In fact, he called them "beast
machines" and said animals, nonhuman animals are merely
robots, but people are different.
There's a duality of people. Like animals,
we possess physical material bodies, but unlike animals,
what we are is not physical. We are immaterial souls that
possess physical bodies, that have physical bodies,
that reside in physical bodies, that connect to physical
bodies. So, this is known as dualism
because the claim is, for humans at least,
there are two separate things; there's our material bodies and
there's our immaterial minds. Now, Descartes made two
arguments for dualism. One argument involved
observations of a human action. So, Descartes lived in a fairly
sophisticated time, and his time did have robots.
These were not electrical robots, of course.
They were robots powered by hydraulics.
So, Descartes would walk around the French Royal Gardens and the
French Royal Gardens were set up like a seventeenth-century
Disneyland. They had these characters that
would operate according to water flow and so if you stepped on a
certain panel, a swordsman would jump out with
a sword. If you stepped somewhere else,
a bathing beauty would cover herself up behind some bushes.
And Descartes said, "Boy, these machines respond in
certain ways to certain actions so machines can do certain
things and, in fact," he says,
"our bodies work that way too. If you tap somebody on the
knee, your leg will jump out. Well, maybe that's what we are."
But Descartes said that can't be because there are things that
humans do that no machine could ever do.
Humans are not limited to reflexive action.
Rather, humans are capable of coordinated, creative,
spontaneous things. We can use language,
for instance, and sometimes my use of
language can be reflexive. Somebody says, "How are you?"
And I say, "I am fine. How are you?"
But sometimes I could say what I choose to be,
"How are you?" "Pretty damn good."
I can just choose. And machines,
Descartes argued, are incapable of that sort of
choice. Hence, we are not mere machines.
The second argument is, of course, quite famous and
this was the method. This he came to using the
method of doubt. So, he started asking himself
the question, "What can I be sure of?"
And he said, "Well, I believe there's a God,
but honestly, I can't be sure there's a God.
I believe I live in a rich country but maybe I've been
fooled." He even said,
"I believe I have had friends and family but maybe I am being
tricked. Maybe an evil demon,
for instance, has tricked me,
has deluded me into thinking I have experiences that aren't
real." And, of course,
the modern version of this is The Matrix.
The idea of The Matrix is explicitly built upon
Cartesian--Descartes' worries about an evil demon.
Maybe everything you're now experiencing is not real,
but rather is the product of some other, perhaps malevolent,
creature. Descartes, similarly,
could doubt he has a body. In fact, he noticed that madmen
sometimes believe they have extra limbs or they believe
they're of different sizes and shapes than they really are and
Descartes said, "How do I know I'm not crazy?
Crazy people don't think they're crazy so the fact that I
don't think I'm crazy doesn't mean I'm not crazy.
How do I know," Descartes said, "I'm not dreaming right now?"
But there is one thing, Descartes concluded,
that he cannot doubt, and the answer is he cannot
doubt that he is himself thinking.
That would be self-refuting. And so, Descartes used the
method of doubt to say there's something really different about
having a body that's always uncertain from having a mind.
And he used this argument as a way to support dualism,
as a way to support the idea that bodies and minds are
separate. And so he concluded,
"I knew that I was a substance, the whole essence or nature of
which is to think, and that for its existence,
there is no need of any place nor does it depend on any
material thing. That is to say,
the soul by which I am, when I am, is entirely distinct
from body." Now, I said before that this is
common sense and I want to illustrate the common sense
nature of this in a few ways. One thing is our dualism is
enmeshed in our language. So, we have a certain mode of
talking about things that we own or things that are close to us
– my arm, my heart, my child,
my car – but we also extend that to my body and my brain.
We talk about owning our brains as if we're somehow separate
from them. Our dualism shows up in
intuitions about personal identity.
And what this means is that common sense tells us that
somebody can be the same person even if their body undergoes
radical and profound changes. The best examples of this are
fictional. So, we have no problem
understanding a movie where somebody goes to sleep as a
teenager and wakes up as Jennifer Garner,
as an older person. Now, nobody says,
"Oh, that's a documentary. I believe that thoroughly true"
but at the same time nobody, no adult, no teenager,
no child ever leaves and says, "I'm totally conceptually
confused." Rather, we follow the story.
We can also follow stories which involve more profound
transformations as when a man dies and is reborn into the body
of a child. Now, you might have different
views around--People around this room will have different views
as to whether reincarnation really exists,
but we can imagine it. We could imagine a person dying
and then reemerging in another body.
This is not Hollywood invention. One of the great short stories
of the last century begins with a sentence by Franz Kafka:
"As Gregor Samsa woke one morning from uneasy dreams,
he found himself transformed in his bed into a gigantic insect."
And again, Kafka invites us to imagine waking up into a body of
a cockroach and we can. This is also not modern.
Hundreds of years before the birth of Christ,
Homer described the fate of the companions of Odysseus who were
transformed by a witch into pigs.
Actually, that's not quite right.
She didn't turn them into pigs. She did something worse.
She stuck them in the bodies of pigs.
They had the head and voice and bristles and body of swine but
their minds remained unchanged as before, so they were penned
there weeping. And we are invited to imagine
the fate of again finding ourselves in the bodies of other
creatures and, if you can imagine this,
this is because you are imagining what you are as
separate from the body that you reside in.
We allow for the notion that many people can occupy one body.
This is a mainstay of some slapstick humor including the
classic movie, All of Me--Steve Martin
and Lily Tomlin – highly recommended.
But many people think this sort of thing really happens.
One analysis of multiple personality disorder is that you
have many people inside a single body fighting it out for
control. Now, we will discuss multiple
personality disorder towards the end of the semester and it turns
out things are a good deal more complicated than this,
but still my point isn't about how it really is but how we
think about it. Common sense tells us you could