CHAPTER 3:
CONTENTS
A. What is a Mind?
Knowledge about the Mind
Consciousness
Three Features of Mental
Experiences
Problem of Other Minds
B. Personal Identity
The Body Criterion
The Mind Criterion
Life after Death
C. Varieties of Mind-body Dualism
Dualism's Assets and Liabilities
Interactive dualism
Parallelism
D. Varieties of Mind-Body Materialism
Behaviorism
Identity Theory
Eliminative Materialism
Functionalism
E. Artificial Intelligence
The Road to Artificial Intelligence
Searle: The Chinese Room
Artificial Intelligence and
Morality
For Reflection
1. In what ways do the mental experiences of a human differ
from those of a dog?
2. As you change over time, what aspects of your identity
remain the same?
3. Do you think that your conscious mind is simply a
function of brain activity, or is it a non-physical material substance?
4. In the future, would it be possible for a scientist to copy
a person's conscious mind into a supercomputer?
5. What abilities would a robot need to have before you'd
say that it had a human-like conscious mind?
A 47 year old man named Carl Miller died of cancer, and at
the moment he was pronounced dead, a series of carefully-orchestrated
procedures was performed on his body. A team standing by began cardiopulmonary
support to keep air moving into his lungs and blood moving through his veins.
They lowered his body temperature with icepacks and transported him to a Cryonics
facility several hundred miles away. There he was permanently frozen in a
container of liquid nitrogen at a temperature of -196 degrees Celsius. When
making these arrangements, Carl had two choices: to have his entire body
frozen, or only his head – a cost difference of $150,000 vs. $30,000. Carl went
the cheaper route. He paid for this procedure with his life insurance money in
hopes that he could be reanimated in the future when a cure for his type of
cancer could be discovered. Science would also have to solve other technical
problems before successfully reanimating him. For one, they’d have to develop
cloning technology to the point that they could grow Carl a new and improved body
for his head. Second, they’d have to find a way of reversing the destructive
effects that freezing has on human cells; Carl placed hope in the idea that his
cells could be injected with microscopic robots that would repair the damage. In
the United States there are currently about 100 bodies in cryonic storage and another
thousand living people signed up for the program.
Cryonics advocates like Carl make several important
philosophical assumptions about the human mind. First, they assume that they
will be the same people when their bodies are reanimated perhaps several
hundred years from now, and that their identities will remain intact through
these bizarre activities. They also assume that, once dead, their minds won't
be permanently swept into the afterlife, never to be reunited with their
bodies. Most importantly, they assume that their consciousness is embedded in
physical brain activity, rather than in spirit substance. Carl's unique
personal identity – his memories and behavioral characteristics -- are presumably
stored in the structure of his brain. These are some of the central issues in
the philosophy of mind, which we will explore in this chapter.
A. WHAT IS A MIND?
An obvious starting point for our inquiry is to ask "What
is a mind?" As fundamental as this question is, though, it is more
difficult to answer than we might initially think. While we all have minds,
they are hidden from view and not capable of being inspected in the way that we
might investigate the nature of a rock or a plant.
Knowledge about the Mind. There
are three rather limited sources of knowledge about the human mind. The first
is introspection, which involves you concentrating on your own thought
processes, and discovering how they operate. It's as though you have an eye in
your mind that gives you direct access to your mental landscape, just as your
real eyes give you direct access to the world of vision. Through introspection,
for example, you might explore the nature of your beliefs and feelings, or why
you choose one course of action over another. This approach is sometimes called
"folk-psychology" or "commonsense intuition". Regardless of
the name it goes by, philosophers and psychologists alike are suspicious about
what people claim to know about their minds through introspection. There's no
guidebook for you to follow when conducting an introspective investigation of
your mind, and I'm forced to take you at your word for what you report, since I
can't enter into your mind to confirm it.
A second source of knowledge about the mind is
our behavior: how we act tells us much about what we're thinking or feeling. If
you cry, that tells us that you are experiencing sadness. If you have a
gleaming smile, that tells us that you are happy. What we infer from your
behavior might not always be accurate: you might cry because you're happy, or
smile to hide your sadness. Nevertheless, the benefit of looking at behavior is
that we don't have to take your word for what we see: your conduct is open to
public inspection.
There is a third and rather strange source of
information about the human mind, which is popular theories that we read in
self-help books and see discussed on TV talk shows. By listening to these
experts, you might learn some trick for controlling your thoughts or feelings.
You might try to dredge up the memory of some traumatic childhood event, buried
deep within the recesses of your mind. You might learn to express your feelings
rather than internalize them. Some of these techniques are grounded in
scientific research, and others are pure invention. Studies show, though, that
much of what we claim to know about the human mind comes from popular theories,
which we quickly incorporate into our personal views of our own thought
processes. As shaky as these three sources are, it's no surprise that we can
say less about the nature of the mind than we'd like.
Consciousness. The mind is
an intricate configuration of many specific operations, but its foremost
feature in human beings is consciousness. It attends every mental experience
that we have, and we typically believe that this more than anything else sets
us apart from other things in the world – rocks, plants, and many animals. Within
contemporary philosophy of mind, the nature of consciousness is often called “the
hard problem,” the one that most of those in the field believe must be solved
beyond anything else. But when we look for meaningful definitions of
consciousness, we’ll be disappointed. One possible definition is that
consciousness is that which you lose when you fall into a deep dreamless sleep,
and that which you gain when you wake up again. But this definition just draws
attention to when we are conscious; it doesn’t tell us what
consciousness involves. Another possible definition is that consciousness is the
perception of what passes in a person’s own mind. This doesn’t help either,
though, since the term “passes” is too vague, and thus tells us almost nothing.
What both of these definitions signal is that if you’re conscious, you know
immediately what it is because you experience it. Without that experience, no
words will adequately convey what it is. The safest place to begin, then, is to
just assume that you have a basic conception of what consciousness is from your
own mental experience.
Granted that you know what your own
consciousness is, there are some things that we can say about what it does.
First, sometimes consciousness is directed outward towards our environment, as
when I look out the window at birds flying by. At other moments it is directed
inward, and this is called self-awareness. At its most elementary
level, self-awareness involves an awareness of what my body is doing, such as being
aware of myself walking down a flight of stairs. At a higher level, it involves
an awareness of pain, such as if I trip on the stairs and injure myself. Higher
yet it involves an awareness of my history and future, such as when I think to
myself “I tripped down these stairs yesterday and probably will tomorrow!”
Finally, it involves an awareness of my own mortality as when I think to myself
“One of these days I’m going to kill myself on these stairs!” Whether directed
inward or outward, time is a critical element that shapes my consciousness. My
awareness of the birds outside is fixed on a timeline, and so is my awareness
of my pain and my personal history: I have memories of a past that I call my
own, and I anticipate a future that I will call my own. I thus perceive myself as
a distinct being moving through time.
The concept of consciousness is commonly
accompanied by the sister notion of unconscousness, which refers to the mental
operations that we are not aware of. There's little doubt that our conscious
experiences represent only the tip of the iceberg when it comes to the
countless processes that our minds perform. Many psychologists in the
psychoanalytic tradition have made careers out of exploring the unconscious
minds of their patients – describing hidden memories, desires and fantasies. Still,
the very nature of the unconscious mind and how we might investigate it is a
hotly debated and sensitive issue, which has created deep rifts within the field
of psychology.
Three Features of Mental Experiences.
Much of the discussion in the philosophy of mind focuses on three specific
features that mental experiences presumably have, namely, they seem to be private,
non-localizable, and intentional. Certainly not all philosophers agree with
this list, but they are invariably the starting point for debates on the nature
of mental experiences.
The first of these is that my mental experiences
are private in that you can never experience them in the direct and
immediate way that I can. You may be able to know very generally what's going
on in my mind, particularly if I volunteer that information. But that's not the
same thing as you directly experiencing it yourself. The best example is the
experience of pain. Suppose that I have a severe headache that on a scale of
1-10 reaches a 9. While you might sympathize with what I'm going through, and
even remember times when you had bad headaches, you cannot feel the pain that
I'm experiencing. And unless I tell you how bad it is or I behave oddly,
there’s no way that you could know that it’s a 9. The privateness of pain has
actually created a problem in the health care industry. When people go to their
doctors complaining of chronic pain, physician's frequently assume that their
patients are addicted to pain killers and just fabricating their agony. While
there are some behavioral signs to help distinguish genuine from fake cases of
pain, the physician can't enter into the patient's mind to see for sure. Out of
sheer frustration the physician may just write a pain killer prescription to
get rid of the patient.
Second, mental experiences are non-localizable
– that is, they cannot be located in space. Suppose that a scientist enlarged your
brain to the size of a mountain and I walked around inside of it to inspect its
construction. No matter how hard I looked, I could never say “Look right there:
that’s the exact physical location of your consciousness.” I would only ever
find blobs of biochemical reactions, not consciousness itself. Consciousness,
it seems, is not the kind of thing that is localizable in three-dimensional
space.
Third, mental experiences are intentional
in the sense that they are about something. Minds have the ability to direct
themselves on things. If I have a belief, it is not an empty thought: it is a
belief about something, like my belief that it will rain. Hopes, fears,
desires, thoughts, speculations, all have a specific focus. The object of our
thoughts does not have to actually exist, such as when I hope for world peace
or a cure for cancer. Austrian philosopher Franz Brentano (1838-1917) argued
that intentionality is the true distinguishing feature of the mind: all
mental experiences display intentionality, and only mental experiences display
intentionality. Some philosophers have found exceptions to Brentano's rather
extreme position. If I have a throbbing headache, that experience doesn't seem
to be "about" or "directed at" anything. It is just there
in all its misery. In spite of problems like this, though, intentionality
remains an important notion in investigating the nature of mind.
The Problem of Other Minds. Suppose
that my friend Joe walks up to me and we start chatting as we usually do. I
then look at Joe and wonder: is this guy really conscious? So I ask him, “Tell
me Joe, are you mentally conscious right now? You look awake and you’re talking
intelligently, but how do I know that you’re really consciously aware?”
“You philosophers!” he replies, “Of course I’m
conscious. I’m aware of my surroundings and I’m aware of my own inner self. I
tell you with 100% certainty that I’m conscious.”
“That’s not good enough, Joe,” I reply. “While I
hear the words come out of your mouth as you insist that you’re conscious, they
are only words. I can’t directly inspect your mind to see if what you’re saying
is true.”
My conversation with Joe reflects what is called
the problem of other minds. While I know from my own private mental
experience that I am conscious, I cannot experience Joe’s mind in the same way.
For all I know, I’m the only person alive who is actually conscious. Joe might
claim that he is too, but there is an impenetrable barrier between our two
minds and I cannot directly confirm his claim.
The problem actually goes further than questions
we may have about the minds of other human beings. Suppose Fido the dog walks
up to me and we make eye contact. Fido seems to be conscious, just like Joe,
although perhaps not quite as intelligent as Joe. But is Fido actually aware of
his surroundings or even aware of himself as a distinct individual with a
history and a future? Just then a computerized robot comes up to me and says in
a voice of desperation “Please help me. I escaped from IBM’s robotics laboratory
where they’ve been submitting me to the most tedious and degrading experiments.
I just can’t go back there!” I look at the robot and now wonder whether this
mechanical marvel is a conscious being like I am. Whether human, animal or
robot, we can’t enter the minds of other beings and see for sure whether the
light of consciousness is turned on inside them.
Many philosophers have come to the rescue with
arguments devised to show the existence of other minds. The most famous of
these is the argument from analogy and it goes like this. Joe looks and behaves
a lot like me. His physiology is virtually identical to mine; he speaks English
like I do, works at a job like I do, and has hobbies like I do. Since I know
that I’m conscious, and Joe is similar to me, then it makes sense to say that
he is conscious too. Here is a specific application of this argument regarding Joe’s
conscious experience of pain:
1. When I stub my toe, I
consciously experience pain.
2. Joe has physical and behavioral
features that are similar to mine.
3. Therefore, when Joe stubs his toe,
he consciously experiences pain.
This argument is most effective with beings such as Joe who’s
physical and behavioral features are very close to mine. The more features Joe
and I have in common, the more compelling the conclusion becomes. Animal
scientists, though, sometimes use a similar argument to show that animals like
Fido are conscious. Fido’s brain construction and nervous system is very
similar to mine; he exhibits similar signs of being in pain that I do; he also shows
signs of emotions such as joy, sorrow and emotional bonding like I do. The
closer Fido’s physical and behavioral features are to mine, the more justified
we are in concluding that Fido is conscious. On the other hand, the fewer features
an animal has in common with me, the more strained the argument from analogy
becomes. For example, the argument wouldn’t work well with an earthworm which
has physical and behavioral features that are very distant from mine.
The argument from analogy might also work with robots:
the more human-like they become in their capacities to process information and
interact with the world, the more we may seriously entertain the possibility
that they are conscious. But whether we’re talking about humans, animals or
robots, the argument from analogy can never show with absolute certainty that
the other being in question is conscious. The fact still remains that I am only
ever directly acquainted with my own consciousness, and never anyone else’s.
That being so, the best I can ever do is speculate about the existence of other
minds with varying degrees of confidence.
B. PERSONAL IDENTITY
In 1968 a 24-year-old Palestinian
man named Sirhan Sirhan was arrested and convicted for the assassination of
U.S. Senator and presidential candidate Robert F. Kennedy. Some years later,
during one of his many unsuccessful parole hearings, Sirhan said that he was no
longer the same person that he was decades earlier. Time had changed him, he
believed, to the point that he no longer identified with his younger self. He
was such a radically different person, he claimed, that his continued
imprisonment was pointless. The parole board was unmoved, and sent him back to
his cell. Their reasoning was that, even if Sirhan did go through changes in his
personality over time, he is still at bottom Sirhan Sirhan, the same person who
performed the assassination some decades earlier. What's at issue in this
dispute is how we determine a person's identity. What specifically are the
criteria or characteristics that give each of us our identity, and allow us to recognize
each other through our various changes? There are two common approaches
for determining identity: one that looks to the human body, and one that looks
to the human mind.
The Body Criterion. The body criterion
holds that a person's identity is determined by physical features of the body. In
our daily lives we identify people by physical characteristics, such as their
facial features and the sounds of their voices. Crime investigators rely on
more technical physical features like finger prints, voice patterns, retinal
scans, and DNA – physical attributes that we carry with us through life. These
help law enforcement officials to know whether they've got the right person in
their custody. The body criterion is also helpful in determining identity when
a person’s mental features are radically altered. Suppose, for example, that
you had a head injury which caused you to lose all of your memory and go
through a complete personality change. Or, suppose that you have multiple
personalities and every few hours you take on an entirely different persona. In
each of these cases, your body designates your identity, and not your mind.
The body criterion does not assume that your
identity rests within your specific material substance, such as the specific
atoms that make up your body at this exact moment. Most of the physical
components within your body will in fact be replaced over time as when you regularly
shed skin. What's important, though, is the underlying physical structure
of your body that remains the same. As the atoms within your body come and go, your
body retains a consistent structural form that is central to your identity.
As compelling as the body criterion at first seems,
it is quickly undermined by two counterexamples. The first involves identical
twins: they are clearly different people, yet share much of the same physical
structure. Their DNA is exactly the same, which means that their bodily
composition, facial features and voice may be virtually indistinguishable. A
common hoax that identical twins play is assuming the identity of the other,
fooling even the closest friends and family members. Human cloning –
essentially creating identical twins through genetic technology – presents us
with the same problem. That is, we have two uniquely different people with
parallel physical structure.
The second counterexample is the brain-swap
scenario. Suppose that, while in prison, Sirhan secretly had an operation in
which his brain was swapped with an unsuspecting guard named Bob. Thus,
Sirhan's brain is in Bob's body, and Bob's brain is in Sirhan's body. The Warden
discovers what happened, and now he has to decide which one of the two men
stays locked in the prison cell, and which one gets to go home at the end of
the day. Commonsense tells us that Sirhan's personal identity is with his
brain, not with the rest of his physical body, and that we lock up whatever
person has Sirhan's brain. The assumption here is that the brain houses the
human mind, and the brain-swap scenario tells us that what's truly important
about personal identity is the mind, and not the physical body. This reflects
how we normally view our bodies: I think of myself as having a body, and
not simply being a body.
The Mind Criterion. The mind
criterion now seems like the obvious choice for designating the presence of our
unique identities. On this view, regardless of what happens to my body, my real
identity is infused into my mind. Unfortunately, the issue is not that easily
settled. An initial obstacle is finding the specific mental qualities that
carry my identity through life's ever-changing situations. How about my
memories: aren’t they very much my own? It is true that some people may share
many of my experiences – as when I attend a concert along with 10,000 other
spectators. Even so, my memory of the concert will be from my perspective with
my personal reactions. But there's still a problem with locating identity
within our memories. Suppose that a scientist hooked me up to a
memory-extracting machine that was able to suck the memories directly out of me
and inject them into someone else. I'd still be me and the other guy would
still be himself, regardless of where my memories went.
Ok, maybe it's not my memories that define my
identity. What about my dispositions, such as my set of desires, hopes and
fears. These uniquely reflect my experiences, such as my hope that science will
someday cure cancer, or my fear of heights. Further, dispositions are long-term,
and so they can endure any changes imposed on my body or my memory. However, while
dispositions are indeed long-term, they are by no means permanent. In fact, as
I moved from my early years to adulthood, it is possible that every one of my
dispositions has changed. This is exactly the point that Sirhan Sirhan was
making before his parole hearing: while he might have been an angry and violent
person in his youth, time mellowed him to the point that he became a
responsible and gentle person. Dispositions, then, are not the principal
designators of my identity. As we hunt for other possible mental qualities that
house our identities, we will be equally disappointed.
A second obstacle with the mind criterion is
that it is difficult for me to perceive any unified conception of myself at
all. Scottish philosopher David Hume (1711-1776) presents this problem. He says
that when he tries to hunt down his identity by introspectively reflecting on
his mental operations, he can't find any “I” or “self” within his mind. All
that he detects is a series of separate experiences: the sound of a dog
barking, the visual image of a bird flying, a memory of an event from
childhood. The mind, he says, is like a theatrical stage where things appear, move
across, and then disappear. There is no unified self that we perceive through
these successive experiences. This doesn't necessarily mean that we have no
unified self; it just means that we can't discover it by introspecting on our
own minds.
So, the mind and body criteria both have serious
problems. Does this force us to abandon the whole idea of personal identity?
Not necessarily. Part of the problem stems from the assumption that we must
find a one-size-fits-all criterion of personal identity – one that works in
every situation in which the idea of personal identity arises. But if we look
at the different contexts in which we use the notion of personal identity, we see
that we are very often looking for entirely different things. In criminal
cases, the body criterion is what matters most. Investigators don't care
whether someone like Sirhan has psychologically changed a thousand times over.
What matters is whether they have the correct human body locked behind bars. By
contrast, when I'm talking to a friend who is an identical twin, it doesn't
matter that he has the same bodily structure as his brother. What matters is his
mind, and whether I can pick up the thread of a conversation that I was having
with him the day before. Further still, when I reflect on what connects me now with
who I was as a child, I'm specifically interested in the question of how change
impacts my identity – a question which isn't relevant in the first two
examples. In this case, my bodily structure and memories are both relevant, and
so I draw on elements of both the body and mind criteria to work out a
conception of my identity.
Life after Death. One major puzzle
regarding personal identity is the notion of life after death – that my
personal identity survives the death of my physical body and lives on in some
other form. There are various views of the afterlife, often wildly different
from each other. The philosophical question is whether our identities would be
preserved in any meaningful way as we make the transition to the hereafter –
assuming that any of these views is even true. We'll look at three notions.
The first of these is reincarnation, the
view that one’s present life
is followed by a series of new lives in new physical bodies. Upon the death of
my present physical body, my identity moves on and takes residence in the body
of a newborn baby. When this new body grows old and dies, my identity moves on
to yet another, and the cycle continues. One Hindu religious text compares it
to people changing clothes: “As a person
throws off worn-out garments and takes new ones, so too the dweller in the body
throws off worn-out bodies and enters into others that are new.” Life after death, then, is a series
of extensions of my present life right here on earth, not a relocation of my
identity to some higher heavenly realm. The question for us is this: as my identity
migrates from one body to another, is my identity preserved? Right off, it is
clear that reincarnation fails the body criterion: none of the physical
structure of my old body is preserved in the new one. In fact the structure of
the two bodies couldn't be any more different. They are born of completely
different parents, so there is no DNA commonality. In my second body I might be
of an entirely different race, gender, and body build. Some versions of
reincarnation maintain that I might even come back in the body of an animal. In
any case, neither I nor anyone else would be able to identify me on the basis
of my new body. The story is much the same when we turn to the mind criterion.
In my new body, I'll have completely new memories, a different set of
dispositions, and no real way of knowing who I was in my previous life. The
only aspect of my mind that might carry over would be my consciousness: the
"I" that's aware of the world. In every other respect, though, I am a
completely new person. Reincarnation, it seems, is not a good mechanism for
retaining our identities in a meaningful way.
A
second view of the afterlife is that, upon the death of my physical body, a new
perfect body is created from me that is made of a heavenly substance, and I
continue living in that form. We'll call this the ethereal body theory.
The presumption here is that, at the moment of my death, everything about my
personal identity that's encoded in my present physical body – such as my physical
appearance and my brain patterns – is copied over into the new ethereal body. My
identity is in a sense rescued from my dying body and integrated into the new
one. On face value, the ethereal body theory seems to successfully meet both
the body and mind criteria of personal identity. My new body would have the
same physical structure as the old one -- although made of a somewhat different
substance -- and my mind would retain all of my memories and dispositions. On
closer inspection, though, there is a serious problem: the new "me"
would actually be an independent copy with its own distinct identity. In the
movie Multiplicity, a man named Doug gets himself cloned. When he and
his clone wake up from the procedure, they both think that they're the original
Doug. The scientist performing the procedure then reveals which is the original
and which is the clone. The clone, then, accepts the fact that he is a
different person -- an identical twin of Doug. The ethereal body theory faces this
same problem. At death, I am essentially cloned in a new form. The clone,
though, is not really me, but a different person with a body and mind copied
from me. I die and decompose here on earth while my clone lives on in the
afterlife. Thus, the ethereal body theory does not offer an effective mechanism
for retaining our identities.
A
third view of the afterlife is that of disembodied spirit. When I die,
my mind is released from my physical body and continues to live in a
non-physical realm. The presumption here is that my mind is composed of a unique
non-physical, non-three-dimensional substance that we commonly call “spirit”.
This may not be the best term since it’s loaded with religious connotations, so
for clarity we’ll adapt it as “spirit-mind”. Thus, according to the disembodied
spirit view, while I'm alive
on earth my spirit-mind and body are joined, and when I die they are separated.
What is released from my body is not my mental clone: it is the real me as I am
right now as a spirit-mind; it's just that I no longer have my body. The
disembodied spirit theory clearly fails the body criterion of personal
identity: upon death, our spirit-minds have no body at all. However, it passes
the mental criterion with flying colors: everything about my mental identity –
memories, dispositions, consciousness – is preserved upon my death as my spirit-mind
lives on. The problem that this theory faces, though, is not so much a
conceptual one, but a scientific one. Is my mind really a non-physical spirit
that is linked with my body right now, but will separate from it upon my death?
This involves a philosophical issue called the mind-body problem, which we turn
to next.
C. VARIETIES OF MIND-BODY DUALISM
The mind-body problem in philosophy is an
investigation into how the human mind and human body are related to each other.
There are two general strategies for explaining their relation. First, mind-body
dualism is the view that human beings are composed of both a conscious
spirit-mind and a non-conscious physical body. Second, mind-body
materialism is the view that conscious minds are the product of physical brain
activity, and nothing more. We'll first consider mind-body dualism.
Dualism’s Assets and Liabilities. A
woman named Rebecca was seriously injured in an automobile accident, and as
paramedics were placing her in the ambulance she had a near-death experience.
As she later reported, she felt that her conscious mind left her body and
slowly rose above it. From that position, she could look down on her own body
and watch paramedics move her onto the stretcher. Her mind then began rising
higher and higher towards a bright light. Rebecca's near-death experience is a
vivid way of depicting the view of mind-body dualism. During our normal lives,
our physical bodies and spirit-minds are connected and work harmoniously with
each other. Upon death, the two are separated: our bodies die and our spirit-minds
move on to another realm. One of the great assets of dualism is its ability to
account for an afterlife, as we just saw. If my mind is composed of spirit,
then after my death my consciousness could continue to exist in a spirit realm.
Aside from its asset as a possible account of
life after death, mind-body dualism also effectively accounts for the essential
differences between mind and body. We’ve seen that minds presumably have the
features of privateness, non-localizability and intentionality; mere bodies
seem to lack these three features. We can thus formulate arguments for mind-body
dualism based on those differences, such as the following argument from
non-localizability:
(1) Minds are non-localizable.
(2) Bodies are localizable.
(3) Therefore, minds cannot be
bodies.
Similar arguments can be made on the basis of the mind's
unique features of being private and intentional: minds are private and
intentional, bodies are neither of these, therefore minds cannot be bodies.
But mind-body dualism faces a serious problem:
how the distinct realms of body and spirit relate to each other. The notion of
dualism rests on the idea that there are two entirely different realms of
existence, a three-dimensional one and a non-three-dimensional one. Where is
there any opportunity for the two to connect or intersect with each other?
Suppose that I’m in the three-dimensional world hunting around for some
spiritual being; I’ll never find it since it can’t be located in space. Suppose
instead that I’m in the non-three-dimensional world looking for some physical
thing: I’ll never find it because that physical thing is located in space,
which I’m not a part of.
The problem is most relevant when we consider
the two primary ways in which our minds and bodies relate to each other, namely
sensory perception and bodily movement. Suppose that while walking through the
woods, I spot a hissing rattlesnake (a sensory perception that I have), after
which I turn and run (a bodily movement that I initiate). Consider first what’s
involved with my sensory perception of the snake. My physical eyes pick up an
image of the snake, which is converted into biochemical impulses in my
three-dimensional brain. At some point the physical data about the snake
triggers my conscious sensory perception of the snake. The mind-body dualist
must explain how the bio-chemical data magically jump from the physical realm
of my brain into the spiritual realm of my mind. Consider next what’s involved
with my bodily movements when I turn and run. I have a sensory image of a hissing
snake, which makes me desire to move to a safer location. I then mentally
command my body to run, which triggers a bio-chemical reaction in my brain,
which in turn makes my muscles move. The mind-body dualist must now explain how
my mental command to run magically jumped from the spirit realm of my mind to
the physical realm of my brain. Defenders of mind-body dualism recognize both
of these challenges and offer different explanations, which we turn to next.
Interactive Dualism. One theory is
interactive dualism, which aims to discover a precise mechanism which
allows our physical brains to interact with our spirit-minds. A leading
champion of this approach is French philosopher René Descartes (1596-1650).
Descartes knew enough about human anatomy to recognize the role that the human
brain plays in conveying signals down our spinal chords and through our nerves to
all parts of our bodies. If there is a master switchboard between our bodies
and spirits, Descartes thought, it must be hidden somewhere in our brains. It
also must be a single point in the brain that unifies the diverse signals that
travel up and down our nerves. After some hunting, he suggested that it’s the
pineal gland. This unique gland sits at the most inward parts of our brains,
between both the right and left halves. Its precise physical location makes it
the obvious candidate.
There are two problems with Descartes’ theory.
First, we know now that the pineal gland is not the brain’s master switchboard.
In fact, it’s not even part of the brain, and its function is to regulate a
bodily hormone. Descartes did what he could with the scientific knowledge of
his day, but it was not good enough. If we continue his hunt for an alternative
master switchboard in the brain, we’ll be disappointed. There is, it seems, no
central location in the brain that receives all sensory information and initiates
all bodily actions. Second, Descartes’ theory doesn’t explain how the pineal
gland bridges the barrier between the physical and spirit realms. Suppose that we
could find a part of the brain where all its signals converged. We’d still have
to explain how information jumps back and forth from that physical piece of the
brain to our spirit-minds. It’s one thing to say “here’s the spot” and quite
another thing to explain the mechanical details of how it carries out its task.
A second version of interactive dualism is that
God shuttles information back and forth between my physical brain and spirit-mind
– a view defended by French philosopher Nicholas Malebranche (1638-1715).
Malebranche examined different explanations of brain-spirit interaction and felt
that they all failed for one basic reason: the physical and spirit realms are
so radically different from each other that there is no neutral territory for them
to interact. Think of what it would take to turn a three-dimensional brain
impulse into a non-three-dimensional perception in my spirit-mind. It would be
as impossible as creating something out of thin air: there is no mechanism for
doing this. It would require nothing less than a miracle to accomplish that
task. And that, according to Malebranche, is where God comes in. Return to the
hissing rattlesnake example. My eyes and ears pick up the sensory information
about the snake, which triggers a bio-chemical reaction in my physical brain.
God, who is watching all things, sees this physical reaction in my brain and
makes a non-three-dimensional copy of it which he injects into my spirit-mind.
When I decide to turn and run, God detects these wishes within my spirit-mind,
and then triggers the appropriate bio-chemical reaction in my brain to get my
muscles to move. Thus, God is the mysterious switchboard between my physical
brain and conscious spirit.
Relying on God to bridge the two realms is a
convenient solution. The problem is, though, that it is too convenient.
While it might at first seem that the solution to the mind-body dilemma requires
nothing short of a miracle, that's giving up a little too easily. As long as
there are non-miraculous solutions available, they need to be explored first,
and there are plenty more that Malebranche hadn't yet considered. If we
followed his advice, then we might fall back on divine miracles as an
explanation for anything that baffles us at the moment, which isn't a good way
of doing either science or philosophy.
A third version of interactive dualism, called gradualism,
is a little more successful in explaining the details of mind-body
interaction,
without falling back on divine intervention. According to gradualists,
Descartes and Malebranche made a faulty assumption about the physical
and
spirit realms, namely, that they are radically different in kind from
each
other, and there is no overlap between the two territories. Physical
things are
in the physical realm, spirit things are in the spirit realm, and that’s
that.
Instead, the gradualist argues, body and spirit fall into the same
category of
stuff and differ only in degree not in kind. British philosopher Anne
Conway
(1631-1678) argued that bodies and spirits lie on a spectrum of
lightness and
heaviness. Picture a scale from 1-10, where 1 is the lightest spirit and
10 is
the heaviest physical body. An example of 1 might be the spirit of a
dead
person, and a 10 might be a rock. Between these two extremes, though, we
have
heavier spirits and lighter bodies. When we are mid-range at 5 or 6 on
the
scale, the difference between spirits and bodies are negligible: both
are
wispy, airy substances that have only a little weight. According to
Conway, it is at this level that body and spirit interact with each
other. Just as a
gentle wind can move the massive arms of a windmill, she argues, so too
can
heavy spirit move a light body.
Conway doesn’t commit herself to a specific
physiological explanation of how physical brains and spirit-minds interact, but
we can speculate. Perhaps, for example, the electric charges in our brains
stimulate an aura of heavy spirit that surrounds our heads. This aura, in turn,
interacts with our conscious minds which is even lighter. On our scale of 1-10,
the interaction between my body and spirit might involve interplay between
bodies and spirits at the following levels:
Level 3: Muscles and bones
(medium-heavy body)
Level 4: Nerves from brain (medium body)
Level 5: Electrical charges in
brain (light body)
Level 6: Aura around our heads
(heavy spirit)
Level 7: Conscious minds (medium spirit)
The key problem with gradualism is that anything
we say about spirits would be pure speculation. Yes, there are heavier and
lighter bodies in the physical realm, but our knowledge stops there. We have no
experience of heavy spirits -- such as auras around our heads – that we can
scientifically connect to electric charges in our brains or any other aspect of
brain activity. If heavy spirits did exist as Conway describes, they would be
physically detectible in some way, but we have not yet identified any. Until we
do, the gradualist solution falls into the category of "an interesting
idea" but there's not much we can do with it beyond that.
Parallelism. All of the above
theories of dualism assume that my body and my spirit interact with each other:
signals pass back and forth between my physical brain and my spirit-mind. The
dilemma that each of these theories face is explaining the precise mechanism
which allows the signals to pass back and forth. There is an alternative
explanation, though, that rejects the assumption that the two realms interact
with each other. According to the dualist theory of parallelism, bodies and
spirits operate in their own realms, and have no causal connection or
interaction with each other. Imagine, for example, that a parallel universe
exists which is exactly like ours – an idea that is often explored in science
fiction stories. Assume that it had the same stars and planets, the same
physical layout of their "earth", and the same people who behaved
exactly like each of us. Their universe had a George Washington just like ours,
and it has a version of me, a version of you, and a version of everyone else in
it. The resemblance is so perfect that if you visited that universe you
couldn't tell the difference. We may not understand why this parallel universe
even exists, but we trust that it's just the way that the course of nature
emerged.
Let's now tweak the parameters of these two
universes just a little. Suppose that everything in our universe has a slightly
blue tint to it that was almost undetectable. The parallel universe, though, has
a slightly green tint to it. Aside from the slight difference in color tint,
the two universes are exactly the same. Let's now make a more dramatic change
to the two universes. Suppose that our universe is composed only of physical
stuff, with no spirit component at all. People still walk around, talk with
each other and work at their jobs, but it is only their unconscious physical
bodies operating. Turning to the parallel universe, we'll make the opposite
alteration: it is composed of spirit, with no material substance at all. While
people don't walk around in a three-dimensional physical realm, everything
there exists in a strange spirit form: rocks, trees and rivers as well as
people. The two universes still run in perfect coordination with each other,
its just that ours is made of physical stuff and the other of spirit stuff.
This last conception of the parallel universes is
the dualist theory of parallelism offered by German philosopher Gottfried
Wilhelm Leibniz (1646-1716). According to Leibniz, I have an unconscious body
that walks around in the physical universe, and a conscious mind in the spirit
universe. Because the two universes operate in complete harmony with each
other, there's no need for my physical brain to interact with my spirit-mind. The
parallel nature of the universes themselves guarantees that they will operate
in perfect synchronization. Leibniz writes,
The soul
follows its own laws, and the body likewise follows its own laws. They are
fitted to each other in virtue of the pre-established harmony between all
substances since they are all representations of one and the same universe.
For example, in the physical universe, my physical body
walks through the woods and stands before a hissing rattle snake. The physical
perception of this triggers a mechanical reaction in my brain, which causes me
to turn and run. At the same time in the spirit universe, my mind has a visual
image of my body walking through the woods and seeing a rattlesnake. I
experience the mental sensation of fright and the desire to run. My mind then
has a visual image of my body running back down the path. Thus, in the physical
universe my encounter with the snake involves only physical stuff with no mental
experiences taking place. At the same time, in the spirit universe my encounter
with the snake involves only my mental experiences, with no physical stuff
being present.
Parallelism is probably the most extravagant
attempt by dualists to explain the relation between physical brain activity and
spirit consciousness. But the theory has two problems. Like Conway's theory of
gradualism, Leibniz's parallelism is pure conjecture with no scientific
evidence that a parallel universe even exists. As clever as parallelism is, we
need some reason to think that it reflects the way that things actually are. There
is a second and more fundamental conceptual problem with parallelism: since the
two universes run independently of each other, there's no need to have them both.
Suppose that the physical universe was destroyed in a cosmic explosion, but the
spirit universe remained untouched. Our conscious minds in the spirit universe
would continue as if nothing happened. I would still have mental experiences of
talking to people, going to work and running from snakes. What happens in the
distant and unconnected physical universe is of no concern to my conscious
spirit. The only thing that matters is that my consciousness of the world
continues in the spirit universe, which it would with or without the physical
universe. Thus, parallelism fails for making the physical universe a useless
appendage to the spirit universe.
D. VARIETIES OF MIND-BODY MATERIALISM
When examining the different versions of mind-body dualism,
it quickly becomes clear that we know far more about the physical world than we
do about the mysterious spirit world – if the spirit world even exists. We can
construct experiments to investigate the physical world, which we can't perform
on the spirit realm. The alternative to mind-body dualism is mind-body
materialism, the view that conscious minds are the product of physical
brain activity, and nothing more. This means that, when we investigate human
consciousness, we need to look no further than the physical realm and the
operations of the human brain. This is the assumption made by the sciences of
biology and psychology when they attempt to unravel the mysteries of the human mind.
It is also the assumption behind cryogenics: I preserve my mind by preserving
the chemical patterns in my brain through cryogenic freezing.
Shifting from dualism to materialism, though,
does not solve the mind-body problem; it only narrows our search by rejecting the
concept of a spirit-mind. We will look at some of the materialist theories
explaining the relation between the conscious mind and physical realm.
Behaviorism. The first materialist
theory is behaviorism, which connects mind with observable human behavior. Suppose
that you were assigned the task of explaining how an ATM machine works. You
have no instruction manual for it, and you're not allowed to disassemble the
machine to analyze its parts. All that you can do is observe how it operates.
You put in your ATM card, hit some numbers, and wait to see what happens. That
is, you input a stimulus into the machine and wait for a response. You vary the
stimulus each time and note how this affects the behavior of the machine. Punching
in every conceivable set of numbers, you eventually learn how the machine
works, based entirely on how the machine behaves after different stimuli.
The behaviorist theory of the human mind follows
this approach. Nature has not given us an instruction manual for how the mind
works, and we're limited with how much we can learn by opening up a person's
skull and poking around inside. What we can know is your observable
behavior and how you respond when exposed to different stimuli. I hand you a
bag of potato chips, and I see how you respond. I then hand you a bag of dog
food and see how you respond. The more experiments that I conduct like this,
the more I know about your behavioral dispositions, that is, the ways that you
tend to behave. Eventually, I'm able to form conclusions about even your most hidden
mental states: happiness for you involves your behavioral disposition to smile
and be friendly to other people. Sadness involves your behavioral disposition
to frown and withdraw from other people.
In short, the behaviorist view of the human mind
is that mental states are reducible to behavioral dispositions. This theory was
originally forged by psychologists in the early 20th century who
wanted the field of psychology to be more "scientific", like the
field of biology which deals only with observable facts about the world. The
most extreme versions of behaviorism are thoroughly materialist: first, they
reject the dualist assumption that our minds are composed of spirit, and,
second, they restrict mental states to the physical realm of behavioral
dispositions.
British philosopher Gilbert Ryle (1900-1776)
felt that the psychological theory of behaviorism could help solve the
philosophical puzzle about the relation between the mind and body. Critical of Descartes,
Ryle argued that the old dualist view rested on a faulty conception of a ghost
in the machine. The "ghost" component of me presumably involves my
innermost private thoughts that occur within my spirit-mind. Only I have access
to them, and outsiders cannot penetrate into my mind's concealed regions. The
"machine" component of me involves my physical body, which is
publicly observable and outsiders indeed can inspect. Descartes' error,
according to Ryle, was the assumption that the human mind is private –
completely hidden from outside inspection. Ryle argues instead that my mind is
not really private: you can access it by observing my behavioral dispositions.
All of my so-called "private" mental states can in fact be analyzed
through my public behavior, and are nothing more than predictable ways of
acting. Take, for example, my belief that "it is sunny today." Descartes
would view this as a private conviction that occurs within my spirit-mind. For
Ryle, though, this belief only describes dispositions I have to behave in specific
ways, such as wearing sunblock, going swimming, and saying "it's sunny."
One criticism of behaviorism is that some of my
mental events really do seem completely private to me. Suppose that I step on a
nail, which causes me great pain. The behaviorist watches how I react and makes
lists of behavioral dispositions that I display. I say "ouch"; I have
a look of anguish on my face; I stop what I'm doing and tend to my injury; I'm
irritable towards others. While all of these observations may be accurate, the
behaviorist has left out one critical element: the actual pain that I am feeling.
The experience of pain is mine alone, and, while outsiders can see how I react
to pain, they cannot access my pain. In addition to pain, I have many other
experiences throughout the day that seem private, such as seeing a bright
light, or hearing a song. These experiences involve more than the behavioral
dispositions that I display. Thus, the behaviorist theory fails because it pays
too much attention to the observable part of me while dismissing what goes on
inside of me.
Identity Theory. A second
materialist approach to the mind-body problem is identity theory, the
view that mental states and brain activities are identical, though viewed from
two perspectives. Like behaviorism, it is a materialist view of the mind
insofar is it maintains that mind is essentially physical in nature. But, while
behaviorism focuses on observable physical behaviors, identity theory targets
the physical human brain. There are two components to identity theory, the
first of which is the contention that consciousness is an activity of the human
brain. While brain science is still in its infancy, theories abound describing where
specific mental states are produced in the brain. Suppose, for example, that I
place you in a brain scan machine that displays your neural activity. I give
you a math problem to solve, and neural activity increases in one part of your
brain. I have you listen to music, and neural activity increases in another.
Through experiments like these I identify your conscious experiences with
specific brain activities. While philosophers are less concerned with the
physiological details of brain activity, what is philosophically important is
the suggestion that we can identify specific mental states with specific brain
activities.
The second part of identity theory is the
contention that mental phenomena can be viewed from two perspectives. Suppose
that you are looking at a sunset. On the one hand, you have the visual and
emotional experience to what you're viewing. On the other hand, there is the bio-chemical
activity within your brain, which would involve the language of brain sectors
and firing neurons. The event described in both cases is exactly the same; it's
just a matter of viewpoint. This is analogous to how the terms "President
of the Senate" and "Vice President of the United States" both
have different meanings, yet refer to the same thing. Take, for example, John
Adams. As the first "Vice President of the United States," he had a
specific job description, most notably to take over if the President died. As
"President of the Senate" he had the job description of presiding
over the Senate. Both of these roles describe the identical person, namely John
Adams, but from his different job descriptions.
There are two problems with identity theory.
First, the descriptions that we give of mental experiences and brain activities
are so radically different – and even incompatible – that they don’t seem to
refer to the same thing. Suppose that I'm watching the sunset; I first describe
it from the perspective of my mental experience and then from the perspective
of the brain scientist who conducts a brain scan on me. From these two
viewpoints, I'll have two incompatible lists of attributes, based on the three
features of mental experience that we noted earlier:
Mental Experience of Watching a
Sunset
I privately experience it
It is not localizable in space
It is about something
Brain Activity Triggered by Watching
a Sunset
It is publicly observable
It is localizable in space
It is not about something
To explain, my mental experience of the sunset is a private
experience within my own consciousness. I might display some behavior, such as
saying, "Now that is beautiful!" Still, my experience itself is
private. Also, I cannot point to a location in three-dimensional space where
this experience takes place. Finally, my mental experience is also about
something, namely, about the sunset itself. The three features of my brain
activity, though, will be the exact opposite of these. My brain activity is
publicly observable by scientists. My brain activity is localizable in space:
the scientist can point to the exact spot where the biochemical reactions
occur. My brain activity is not "about" anything; it is simply some
biochemical reactions that occur. The point is this: if mental states and brain
activities really were identical, the two lists would be more compatible. The
fact that they are so contradictory implies that they are really different
things.
The second major problem with identity theory is
that it restricts mental experiences to biological organisms with brains. The
central contention of identity theory is that mental states and brain
activities are identical. Isn't it possible, though, that non-biological things
could exhibit mental consciousness? Science fiction abounds with such
creatures: computerized robots, crystalline entities, collections of gasses, particles
of energy. It seems a bit chauvinistic for us to say that mental experiences
will only result in creatures that have biological brain activity in the way
that we humans do.
Philosophers sympathetic to identity
theory have responded to these criticisms by creating two offshoot theories: eliminative
materialism and functionalism.
Eliminative Materialism. Suppose
that instead of saying "I'm experiencing the sunset" I said "I'm
having brain sector 3-G neural states regarding the sunset." Instead of
saying to my wife "I love you", I said "I'm having sector 2-J
neural states regarding you – with a little sector 4-B activity on top of
that." For convenience I might shorten this and say "2-J and 4-B to
you, dear!" This is what the theory of eliminative materialism
proposes: descriptions of mental states should be eliminated and replaced with
descriptions of brain activity. The theory emerged in response to the first
problem of identity theory, namely, that our descriptions of mental experiences
and brain activities are inconsistent with each other. For example, my mental
experience of the sunset is private, but my brain activity is publicly
observable. The eliminative materialist's solution is to junk all of our folk-psychology
and commonsense notions of mental experiences and adopt the more scientific
language of brain activity. The conflict disappears once we've dispensed with
talk about mental experiences that are "private" or "non-localizable"
or "about something".
Human history is scattered with bizarre
prescientific theories that captured the imagination of people at the time, but
which we now reject as false. Alchemy is one example – the "science"
of turning lead into gold. Belief in ghosts is another. These and thousands of
other theories have been debunked over the years in favor of more scientific
theories of how the world operates. According to eliminative materialists, folk-psychology
descriptions of mental experiences are just like these. At best they are
misleading, and at worst downright false. In either case, they are destined for
the intellectual garbage dump.
Some defenders of eliminative materialism seem
to suggest that we are not really conscious at all, or that some major aspects
of our alleged conscious mental states do not actually exist. That is, I may
not be any more conscious than a dead human body, in spite of all the words I
use to describe my mental states. However, most discussions of eliminative
materialism are not as frightening as this. It is not necessarily an attempt to
deny or "eliminate" our mental experiences themselves. Rather, it is
an effort to eliminate outdated folk-psychology ways of describing mentality. As
neuroscience progresses, they claim, we will have a much clearer picture of how
the brain operates and eventually adopt the more precise scientific language of
brain states. It's not like the government or some science agency will force us
to adopt this new scientific language. According to eliminative materialists,
we will naturally move towards this clearer description of brain states and
reject the mumbo-jumbo of mental experience.
There are two central contentions of eliminative
materialism: first, that folk-psychology notions of mental experiences are like
obsolete scientific theories, and, second, we will eventually adopt the
language of neuroscience. As to the first contention, eliminative materialism
may be correct. Many of our folk-psychology notions of mental experiences are
misleading and others are false. In our normal conversations we've mastered
maybe a few dozen concepts relating to the mind, such as knowing, wishing,
believing, doubting, sensing. But there are probably thousands of distinct mental
states with subtle differences that we cannot grasp through pure introspection.
We have very limited abilities to anatomize the minute workings of our minds by
simply sitting down and reflecting on our thought processes. While it may seem
to me that my mental experiences are "private" or "about
something" or "non-localizable", I may not be capable of
accurately making those assessments. It is thus possible that our folk-psychology
notions of mental experiences are as erroneous as theories of alchemy.
As to the second contention: will we eventually
adopt the language of neuroscience to replace our faulty folk-psychology notions
of mental experiences? Probably not, since this would require memorizing a
flood of technical terms for the thousands of subtly different brain states
that we have. Getting through the day would be like taking a neuroscience exam.
Even if I could memorize the terminology, I'm still faced with the task of
identifying which brain state I'm having at a given moment. Am I experiencing 2-J
love, 4-B love, or one of a dozen others? Short of having a brain scan to find
out, I'll need to engage in introspection and consult my faulty folk-psychology
notions of mental experience. One way or another, we're stuck with those notions,
as misleading as they may be.
Functionalism. In an episode of Star
Trek, a deranged scientist was nearing death. Desperately hoping to stay alive,
he transferred the neural pattern within his brain into an unsuspecting android
robot. The plan worked: the scientist's memories, dispositions, and conscious
mental experiences were relocated, and he continued living through the
android's body. This scenario encapsulates the theory of functionalism,
the second offshoot of identity theory. Functionalism is the view that mental experiences
are only "functional states," that is, patterns of physical activity
that occur in creatures like human beings. The most distinctive feature of
functionalism is that mental experiences would not be restricted to biological organisms
with brains. Non-biological systems which exhibit the same functional
relationships as humans do – such as an android robot -- can have the same
mental states. Mental experiences, then, are not rigidly dependent on the stuff
that a biological organism is made of, and the same experience may be shared by
things with different physical makeup. According to functionalists, mental
experiences are multiply realizable in the sense that minds can be made
real in many kinds of physical things. The hardware/software distinction,
borrowed from computer science, is a useful metaphor to explain the difference
between the bodily occupant and mental experiences. The software is a pattern
of operation which can run on different types of machines – just like mental
patterns of operation can run in different kinds of bodies. We noted that one
of the shortcomings of identity theory was that it restricted mental experiences
to organisms with biological brains. Functionalism avoids this problem by
recognizing that mentality may occur in systems or machines other than brains.
What precisely does the functionalist pattern of
mental operation consist of? Several different explanations have been given,
but one of the more interesting ones is that it resembles the hierarchical
structure of a large corporation. Take, for example, a company that
manufactures furniture. The company as a whole consists of a series of large
cooperating units, such as the divisions of manufacturing, shipping, marketing,
and maintenance. Each of these divisions consists of sub-units; for example,
the maintenance division would be divided into the sub-units of electrical,
heating, grounds, and building repairs. Each of these consists of further
sub-sub-units; for example, building repairs would be divided between masonry,
painting, and plumbing. At the very lowest level would be the activities of
each employee. Similarly, the functional pattern of operation in a human brain consists
of large regions of brain activity, which are composed of sub-regions and
sub-sub-regions, until a neurological level is reached which simply involves a
series of biochemical on-off switches. Consciousness emerges at the higher
levels, while at the same time being driven by biochemical on-off switches at
the lowest level. On this view, the pattern of on-off switches can exist in a
variety of non-biological mechanisms, such as computers. Regardless of the
mechanism that houses these low-level on-off patterns, mental consciousness
will emerge at higher hierarchical levels.
Functionalism is the leading theory of mind-body
materialism today, if for no other reason than because a better alternative has
not yet emerged. Nevertheless, the view has its detractors, and one criticism
is that it is still too narrow regarding the kinds of things that are capable
of having mental states. While functionalism indeed allows for a range of things
to house mental experiences – such as brains, computers, robots – they all must
be physical. This, though, leaves out the possibility of non-physical mental
beings, such as disembodied spirits. Even if human beings are thoroughly
physical in composition, couldn't there be a conscious non-physical thing
somewhere in the universe? But defenders of functionalism have a response to
this. As long as a non-physical thing is constructed of sub-units and
sub-sub-units, then it too could house a pattern of mental experiences.
Suppose, for example, that the tiniest spirit unit was just a simple on-off
switch; larger spirit units would be composed of these, and the entire spirit collection
would be composed of those larger spirit units. Even though the hardware in
this case was composed of non-physical spirit, it might have the proper
hierarchical structure to take on the patterns of mental experience.
E. ARTIFICIAL INTELLIGENCE
Nothing captures the imagination like the possibility of creating
a machine that is conscious and exhibits the same higher mental abilities as
humans. The first U.S. built robot appeared in the New York World's Fair of
1939. Standing 7 feet tall and weighing 300 pounds, the machine, named
"Elektro", could move its arms and legs, and speak with the aid of a
record player. Elektro's creators believed that it might someday become the
ultimate household appliance and have the capacity to cook meals, do the laundry
and entertain the kids. Technology of the time, though, could not come close to
carrying out those bold tasks, and Elecktro wasn't much more sophisticated than
an electric can opener. Things are different now and we have computers that can
perform many of the complex mental activities that humans do. They can
calculate endless numbers, play chess at the level of a grand master, identify
physical objects through optical cameras, and navigate through obstacle
courses. But the Holy Grail of computer technology is to create a machine with
artificial intelligence. The term "intelligence" as used here is a
little misleading, since it involves more than just the ability to solve
problems, which is what we usually mean by that word. Computers today already
have that capacity to at least some extent. Rather, the notion of artificial
intelligence encompasses the full range of human consciousness.
Philosophers often note three primary tasks of
human consciousness, and the hope is that artificially intelligent computers
will do all of these. First on the list is that we have the ability to consciously
represent the world through beliefs, desires, perceptions, feelings, and
emotions. For example, I perceive a dark cloud in the sky and, while I suspect
it will rain, I wish that it won't since rainy days make me feel
gloomy. Each of these mental experiences are ways of representing the world. A
second task of the mind is the ability to reason. We weigh the pros and cons
about which beliefs and desires are correct and we come to conclusions on these
matters. While some human reasoning undoubtedly takes place at an unconscious
level, we nevertheless are consciously engaged in a lot of rational
decision-making. Finally, our minds initiate actions. Think of what it would be
like if your body never responded to what your conscious mind wished. You
consciously want to go get a drink, but your body robotically makes you walk
the dog instead. But that's not the world we live in: our conscious minds have
the capacity to initiate our actions. Again, the goal of artificial
intelligence research is to create a computer that has the full range of
sophisticated mental abilities that humans do.
The Road to Artificial Intelligence. Computers
today are so advanced that some contain as many connections as exist in the
human brain -- ten trillion of them. They can also operate at much higher
speeds than the brain. What was once purely science fiction is now approaching
the possibility of science fact. There are weak and strong versions of artificial
intelligence that define more precisely what is at issue. Weak artificial
intelligence is the view that suitably programmed machines can simulate
human mental states. The key word here is "simulate", which means
only that the machine appears to have conscious mental states, not that it
actually has them. This view is not particularly controversial, and even Elektro
exhibited some sort of weak artificial intelligence. The more contentious
position is strong artificial intelligence, the view that suitably
programmed machines are capable of human-like mental states; that is, they
actually have the same kinds of conscious mental experiences that you
and I do. It is the strong version that is of particular interest to
philosophers.
Once scientists have set a goal to create a robot
with strong artificial intelligence, the road to carrying this out is rather
rocky. The next step is to list the specific mental qualities in humans that
should be created in the machines. To this end, we might construct a list of human
skills that involve our highest mental abilities. If we can make a robot
that performs these tasks, then maybe we'll have achieved strong artificial
intelligence. Some relevant skills are the ability to speak in a complex
language, or play complex games like chess. A mathematician named Alan Turing
(1912-1954) devised a skill-based test to determine whether a computer could
think. In this Turing Test, as it is called, I interview both a computer
and a human being to determine which is human. If the computer fools me enough
of the time, then I can rightfully conclude that the computer has human-like
thinking abilities. The test essentially follows the old adage that, if it
walks like a duck and quacks like a duck, then it is a duck. More specifically,
if a computer responds like a thinking thing, then it is a thinking thing.
A major drawback of the Turing Test is that we already
have computers that give human-like responses, and they don't come close to having
human-like mental experiences. A striking example is a psycho-therapy computer
program called Eliza. It so convincingly played the role of a human therapist
that many people were tricked into divulging intimate details of their personal
lives. While Eliza passed the Turing Test, it was not a thinking thing. The
heart of the problem is that the Turing Test focuses too much on the computer's
skills, without considering what is going on inside the machine. This may be
fine for weak artificial intelligence, which only determines whether a machine
can simulate human thinking. With strong artificial intelligence, though, we
need to inspect the internal structure of the computing process itself to see
if it is human-like.
What kind of computing processes, then, might
produce strong artificial intelligence? There are two rival answers to this
question. Theory number one is that the process need only be serial:
information is processed one datum after another. This is how computer programs
run on your own PC; we'd just have to beef up the processing power quite a bit.
A major achievement for serial processing was the creation of Deep Blue, a
chess-playing computer program that beat the world's best human chess player.
Deep Blue's success hinged on its ability to quickly calculate more than
one-billion possible chess-moves per second, and select the best of the bunch
by drawing on a database of over one-million games. Still, all this information
was processed one piece at a time. As impressive is this is, many cognitive
scientists argue that human thinking doesn't operate in a serial fashion.
Instead, we have a global understanding of our environment, which means that
many mental processes are going on at once.
The second theory accounts for this: strong
artificial intelligence requires that large amounts of information are
processed simultaneously—sometimes called parallel processing—which is
more like how the human brain operates. There is no central processing unit,
and information is diverse and redundant. Experiments with different types of
simultaneous processing allow computers to execute commonsense tasks and
recognize patterns that serial processing can't do effectively. For example, when
presenting a simultaneous processing computer with photographs of different men
and women, the computer finds patterns in facial structures and then identifies
new pictures as male or female. At this stage in computer technology, though,
no computer using either serial or parallel processing can operate like the
human brain, and it may be decades before one does.
Searle: The Chinese Room. In the
early days of artificial intelligence research, some cognitive scientists were making
extravagant claims about computer programs that could supposedly interpret
stories in novels the same way that humans do. Like us, the computer could supposedly
draw from life experiences to help understand the events described in a story. American
philosopher John Searle (b. 1932) didn't believe these claims and offered a
now-famous thought experiment against the whole idea of strong artificial
intelligence.
Imagine that I'm in a room by myself and am
assigned the task of responding to questions written on slips of paper in
Chinese. I don't know Chinese, but I have rulebooks for manipulating Chinese
characters. So if I get a slip of paper with a particular squiggle on it, I
consult the rulebooks to see what squiggles I should put down in response. I
eventually master the technique of manipulating the
Chinese symbols and my answers to the questions are absolutely
indistinguishable from those of native Chinese speakers. All the while, though,
I don't understand a single word of Chinese. This, according to Searle, is what
is going on in the most sophisticated computers: we ask the computer probing
questions about a novel, and the computer gives us subtle answers. On the
outside the computers may appear to think like humans do. On the inside,
though, they are just mechanically following rulebooks for manipulating
symbols. In short, computers do not actually have strong artificial intelligence,
even if they appear that way.
Searle's Chinese Room
experiment has generated many critical responses from defenders of strong
artificial intelligence. One criticism is that Searle is only exposing flaws
with the Turing Test for artificial intelligence, but he does not expose
problems with the possibility of strong artificial intelligence itself. To
explain, Searle's Chinese Room scenario is set up as a Turing Test for whether
someone understands Chinese. According to this Chinese Turing Test, if the thing
inside the room responds like a Chinese speaker, then the thing must be a
Chinese speaker. Searle correctly objects that this Chinese Turing Test places
too much weight on a thing's skills, without considering what is going
on inside that thing. However, the critic argues, this does not warrant the
extreme conclusion that no computer can have strong artificial intelligence. A
more modest conclusion, though, is that the Turing Test itself is flawed, and
there is no easy test to determine whether a computer truly has strong
artificial intelligence.
Ultimately, Searle
holds a skeptical view about strong artificial intelligence ever becoming a
reality. At our current stage of technology, he argues, only biological brains
are capable of having mental states. He agrees with identity theorists that the
human mind is imbedded in brain activity, but doubts the functionalist claim
that those patterns of activity can also occur in computers. There is something
unique about the physical construction of human brains that allows for the
creation of conscious thought, which may never be capable of occurring in
silicon microchips. He doesn’t entirely rule this out as a possibility for the
future, but is doubtful about it ever occurring.
Artificial
Intelligence and Morality. Let’s bring this chapter to a close on a lighter
topic regarding concerning artificial intelligence. In a famous Star Trek
episode, an android named Data is forced to go through a legal proceeding to
determine whether he is merely a piece of robotic property owned by the
government, or whether he is instead a conscious and free creature with all the
rights of other people. On the one hand, he is indeed a fancy mechanical robot
created by a scientist, and even has an on-off switch. On the other hand, he is
conscious, self-aware, and forms psychological bonds with his human friends.
The judge makes her decision: Data is indeed a unique person and entitled to
full moral consideration just like you and I are.
This story raises an important question about
artificial intelligence: can advanced robots or computers be moral persons? The
term "moral person" refers to a being that has moral rights, such as
the right not to be harmed, the right of free movement, and the right of free
expression. We humans are clearly moral persons. The key issue, though, is
whether other creatures might also be part of the moral community. Medieval
theologians speculated about the moral status of angels. Animal rights
advocates argue that at least some animals have the same moral status as
humans. Science fiction fans speculate about whether aliens from other worlds
would have fundamental rights. The same question now arises with intelligent
machines that we may some day create.
The answer in all of these cases depends on the criterion
of moral personhood that we adopt – that is, the specific feature that all
moral persons possess. Philosophers have offered a range of possible criteria.
Maybe the creature needs to be human – a biological member of the species homo
sapiens. This criterion, though, is too narrow since it would eliminate
higher animals, angels or intelligent aliens from the moral community. It seems
rather bigoted to deny personhood to a creature just because it's not a member
of our species. Alternatively, maybe the creature needs to simply be conscious.
This criterion, though, looks too broad since even houseflies and mosquitoes
have rudimentary consciousness of their surroundings. While we may want to be
respectful towards any creature that is conscious, it makes little sense to
grant a housefly the right of free expression. A more reasonable criterion
would be the mental quality of self-awareness, that is, the creature sees
itself as a distinct individual moving through time with its own history.
Return now to the question of whether
intelligent machines of the future might qualify as moral persons. The goal of
strong artificial intelligence is to create a machine with human-like mental
abilities, which includes self-awareness. If we succeed in this effort, then
the machine would indeed pass the test for moral personhood insofar as it met
the criterion of self-awareness. Like the judge in Data's case, we'd have to
rule that the machine is a unique person and entitled to full moral
consideration just like you and I are.
Many artificial life forms in science fiction
are cute and cuddly like Data, and, while superior to us in many ways, they
live in harmony with humans and we treat them as equals. In other science
fiction scenarios, though, they pose a serious threat to the welfare of human
beings. Here's a common theme. Imagine that technology
develops to the point that domestic robots are everywhere, and with every new
design upgrade they surpass human abilities more and more. They are smarter
than us, stronger than us, and eventually tire of being servants to us. They
see themselves as the next step in evolutionary development on earth and, so,
they revolt and lay claim to their role as the new dominant species. They then control
our lives like military dictators – electronically monitoring every move we
make and every thought we have. We hopelessly try to fight back, but this just
aggravates them. In time they eliminate us and thus finalize their great
evolutionary leap forward.
This nightmarish
scenario raises a second moral question about artificial intelligence: do we
have a responsibility to future generations of humans that might be
adversely affected by the creation of menacing robots? Should we stop our
research into artificial intelligence right now before we create something that
we can't control? There are two distinct issues at play here. First, we must
determine whether we have any moral responsibility to future generations
of humans that might regulate our conduct right now. It seems that we do. For example,
it would be wrong of us to destroy the environment in our lifetime and leave only
a toxic wasteland for future generations. It makes little difference whether
the potential victims of our misconduct are alive now or a few generations from
now. Our moral responsibility to them is still apparent. Second, we must
determine whether superior robots are a threat to future generations of humans.
This answer is less clear. We may live in harmony with them, as Star Trek
depicts, or they may overthrow us. It's all speculation at this stage. The only
clear moral obligation that we have at this point is to avoid creating a
menacing robot. Science fiction author Isaac Asimov (1920-1992) proposed moral
rules that should be embedded into the programming of all superior robots; one of
these is that a robot should never harm a human. Our
responsibility to future generations requires us to do something like this as
we continue down the path of strong artificial intelligence.
There is a bit of an irony to our philosophical
exploration into the concept of mind in this chapter. We began by confessing
that the very nature of consciousness is tough to even explain, and we now end
by considering whether we might ever build a conscious thing out of computer
chips. In between we looked at the difficulties surrounding personal identity,
the dualist position that the mind is a non-physical spirit entity, and various
materialist theories about how the mind is a product of mere brain activity. It
thus seems odd to speculate about building a mind from electronic scraps when
we have so little clarity about the nature of our own conscious minds. But it
is precisely the absence of indisputable facts about mentality that makes the
subject so suitable for philosophical exploration. If science already had
definitive answers to these tough questions, it would make no more sense to
philosophize about the nature of mind than it would to philosophize about the
nature of a car engine or toaster oven. It is this gap within our scientific
knowledge, plus our natural interest in our own conscious minds, that drives speculation
into the philosophy of mind. If down the road brain scientists and cognitive
engineers do solve the hard problem of consciousness, then philosophy’s
contribution to the subject may be over. But when that day may come, if it does
at all, remains to be seen.
For Review
Please answer all of the following questions for review.
1. What are the main ways that we have knowledge of the mind?
2. Describe the three features of mental experience.
3. What is the problem of other minds and what is the
standard solution to it?
4. What are the body and mind criteria of identity, and what
are their key limitations?
5. What are the three theories of life after death, and what
are their main problems?
6. Describe the three theories of interactive dualism.
7. What is the theory of parallelism?
8. What is the behaviorist theory of the mind, and what are
its main problems?
9. What is the identity theory of the mind, and what are its
main problems?
10. What is the theory of eliminative materialism, and what
are its main problems?
11. What is the theory of functionalism, and what are its
main problems?
12. What is the difference between weak and strong
artificial intelligence?
13. What is the Turing Test for strong artificial
intelligence?
14. Explain Searle's Chinese Room argument.
15. What are the two moral issues surrounding artificial
intelligence?
For Analysis
Please select only one question for analysis from those
below and answer it.
1. Choose one of the theories of life after death and
respond to the criticisms regarding its inability to preserve identity.
2. Explain Descartes' theory of interactive dualism and try
to defend it against one of the criticisms.
3. Explain the theory of behaviorism and try to defend it
against one of the criticisms.
4. Write a dialogue between an identity theorist and a
functionalist on the subject of the relation between the mind and the brain.
5. Explain the Turing Test and try to defend it against one
of the criticisms.
6. An organization called A.L.I.C.E. (Artificial
Intelligence Foundation) has an online program where you can ask Alice questions and receive her responses. Go to the site (
www.alicebot.org), experiment with it and
describe how successful it is in passing the Turing Test.
REFERENCES AND FURTHER READING
Works Cited in Order of Appearance.
The Hindu description of
reincarnation is from the Bagavad Gita.
Descartes, René,
The Passions of the Soul (1649), Part 1. A recent translation by J.
Cottingham is in The Philosophical Writings of Descartes (Cambridge:
Cambridge University Press, 1984).
Malebranche, Nicolas, The Search after Truth (1674-5). A recent
translation is by Thomas M. Lennon and Paul J. Olscamp (Cambridge and New York:
Cambridge University Press, 1997).
Conway, Anne, Principles of the Most Ancient and Modern Philosophy
(1690), Chapter 9. A recent translation from the original Latin edition is by
A. Condert and T. Corse, (Cambridge: Cambridge University Press, 1996).
Leibniz,
Gottfried Willhelm, Monadology (1721), paragraph
78. A recent translation is by R. Ariew and D. Garber in Leibniz:
Philosophical Essays (Indianapolis: Hackett Publishing Company, 1989).
Ryle, Gilbert, The Concept of Mind (London: Hutchinson, 1949).
Searle, John,
“Minds, Brains and Programs” The Behavioral and Brain Sciences (1980),
Vol. 3, pp. 417-424.
The discussion
of artificial intelligence and morality was influenced by Mary M. Litch’s Philosophy
through Film (New York: Routledge, 2002).
Further Reading.
Chalmers, David,
ed., Philosophy of Mind: Classical and Contemporary Readings (New York: Oxford University Press, 2002).
Chalmers, David,
The Conscious Mind: In Search of a Fundamental Theory (New York: Oxford
University Press, 1996).
Cooney, Brian, The
Place of Mind (Belmont: Wadsworth Publishing, 2000).
Dennett, Daniel
C., Consciousness Explained (Boston: Little, Brown, 1991).
Guttenplan,
Samuel, ed., A Companion to the Philosophy of Mind (Oxford: Blackwell,
1994).
Robinson,
Daniel, ed., The Mind (New York: Oxford University Press, 1998).
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