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Chapter 1
Thinking About Thinking
This is a book about the biology
of mind, and it is very tempting just to get on with the evolutionary story
outlined in the first section of the book. However, before we can do this,
it is necessary both to discuss some definitions of mind and consciousness
and to ask how we might approach a scientific understanding of them. Before
we can study whether or how the operations going on in our brain might explain
consciousness, we have to begin to attempt a description of what it is that
we are trying to explain. We must do some "thinking about thinking."
How Do We Define Mind and Consciousness?
One of the problems we face is
that sometimes there seem to be as many definitions of words such as "mind" and "consciousness" as
there are people using them. Each of these words refers not to a single entity,
but rather to an array of phenomena. Webster's dictionary gives more than five
definitions of the word "mind." These definitions are offered mainly
with reference to humans. We need to consider also that other animal species
besides ourselves have their own distinctive versions of mind.
Let's begin by thinking about experiences
that we all share. You probably can remember moments of daydreaming or being
lost in thought while driving a car and then noting with a start that you have
been completely unaware of traveling the past several blocks. During all of
this time, your brain was still processing all the relevant information, directing
steering, watching the road. An unexpected occurrence, like a child running
into the road, would have immediately snapped your attention back to your driving.
As another example, you can probably recall an occasion when you have focused
on the verbal content of a discussion with someone and have realized only after
some time that you have become annoyed, an emotional reaction that grew out
of your awareness as your body reacted to signals sent by the other person's
posture and tone of voice. Such simple experiences tell us that much more is
usually going on than we choose to be aware of.
*********
DESIGN NOTE: IMPORTANT POINT
Our consciousness can include much
more than we are aware of at a given moment.
*********
Awareness
What we are aware of does not necessarily
depend on its importance to us. We can be aware of trivial things and unaware
of very important things. Reading these words might be most important to you
right now, but you might also be partially aware of many things not relevant
to this task---perhaps the sound of machinery in the next room, or your leg
rubbing against the side of your chair. By the same token, you might be able
to remember an occasion when you were walking down the street taking in random
sights and smells and were unaware, until after the fact, of something very
important: that you quickly dodged to the side after a shadow suddenly appeared
in your path that might have been caused by a falling object.
In such cases we can, if we choose,
switch the focus of our attention to what we have not been aware of. Underlying
what we can be aware of, however, are many unconscious or implicit operations
that may not be accessible to our introspection. These can occur, for example,
in the fraction of a second just after we encounter new sensory stimuli. Current
inputs are matched with past experiences of similar events to generate our
perceptions. These unconscious processes can sometimes make mistakes that fool
us. This happens in a well-known experiment in which subjects are shown a brief
view of an impossible playing card such as a red ace of spades. Many report
seeing what their experience leads them to expect, either a black ace of spades
or a red ace of hearts. The brain has edited the actual stimulus and reported
something else. You may also have experienced another kind of biasing when,
on meeting someone, you immediately liked or disliked that person, for no obvious
reason. Perhaps the individual resembled someone from your past, who was loved
or feared? Emotional memories can act as filters to give a slight positive
or negative "spin" to encounters in the present.
*********
DESIGN NOTE: IMPORTANT POINT
We can be oblivious to unconscious
or implicit mechanisms that bias our conscious awareness.
*********
Thus our current focus of awareness
is just a part of our consciousness, which in turn is a small fraction of the
vast number of implicit or unconscious operations going on in our brains. Our
minds are something larger than our consciousness, and they involve operations
that extend beyond our brains. These brains are constantly involved in an array
of interactions with other parts of our nervous systems: the spinal cord and
autonomic nervous system, as well as muscular, endocrine, and immune systems.
This whole ensemble is what carries out actions upon and within the physical
and social environment to which we humans have adapted. We can change this
environment, and this environment can change our minds. The fact that our minds
exist in the context of such complex interactions makes it difficult to offer
a precise definition of their boundaries. Probing
these relationships is one of the goals of this book.
*********
DESIGN NOTE: IMPORTANT POINT
The nature and the bounds of our
minds are quite fuzzy. A neat boundary between the thinker and the thinker's
world doesn't exist.
*********
Think of your stream of conscious
awareness from moment to moment. Does it always feel the same? Although our
awareness seems smooth and continuous, you will probably agree that it can
be of several different kinds, and also built in stages of increasing complexity.
To start at the more simple ends of things, you probably have experienced some
quiet moments during which your mind felt quite empty, or blank. The simplest
notion of awareness is one that is devoid of the content of specific sensing
and acting---the state of "just being" that is described by mystical
traditions and meditators. At a next level, we all are familiar with various
phenomenal states of awareness, such as what it is like to taste an orange
or what it is like to feel pain when your forearm is pinched. This is what
we mean by having sensations: a simple, direct, and unreflective experience.
Behavior experiments raise the possibility that animals and human babies might
have such phenomenally conscious states without any concept of a self.
Introspection and Reflection
A next stage is being "conscious
of" our feelings and thoughts, having introspective or reflective access
to them. At this point we become selves, the "I" observing ourselves,
and can do things like think about how it feels to taste an orange. A further
twist is that our conscious awareness can be intentional: related to an object,
action, or goal in the outside world. These latter forms of consciousness are
clearly observed in higher primates as well as humans. However, talking to
ourselves in our heads and talking to others---the narrative self consciousness
based on grammatical language---seems to be unique to our human species.
The stages listed here are crudely
drawn, and professional philosophers and psychologists would wish to make further
functional distinctions. Their efforts to define the functional correlates
of these and other phenomenal states of consciousness are very important, because
we can't hope to address effectively the nerve activities in the brain that
correlate with consciousness unless we have described what they are supposed
to be doing.
How Does Consciousness Emerge from
a Brain/Body
How do we set about explaining
our conscious experience? How do we connect our two different worlds, the inner
one of our subjective experience---how we feel, our emotions, what it is like
to be somebody---and the objective world "out there" of objects that
obey lawful relationships? The book you are holding is "out there";
your experience of it is "what is happening to me." Any complete
description of mind or consciousness has to unify these into one whole and
describe how they depend on one another. We don't yet know how to relate our
subjective experiences to what our brains and bodies are doing, even though
most practicing neuroscientists take it as an article of faith that we someday
will. This current lack of understanding is generally called the explanatory
gap, and it is the subject of intense debate and speculation among philosophers
and scientists.
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DESIGN NOTE: SELF-EXPERIMENT
The issue of an explanatory gap
can be posed with a simple exercise: Take a moment to pinch your forearm gently.
Take time to notice how it feels. Now increase the pressure until you just
begin to feel pain. At a distinct time and place, you have just had a subjective
feeling of mild pain that goes with a particular emotional tone. Now suppose
that during this experiment, some super-neuroscientist with access to the interior
of your head had measured and accounted for all the nerve messages that occurred
during your experience. How much would this explain?
*************
Defining the Problem
Some in the field of consciousness
studies insist on making a distinction between the "easy" problem
and the "hard" problem of consciousness. The easy problem is said
to be explaining the neural basis of things like attention, memory, and sensory
motor coordination. These people say that no matter how much neuroscientists
discover about these things, it won't crack the hard problem: They still won't
be able to tell us why we experience the color and smell of a rose as we do.
Third-person science will never get us to first-person experiences. There has
to be something else, some really radical solution beyond the province of conventional
psychology and neuroscience.
One response to this position,
however, is to argue that the objective and the subjective refer to different
ways of knowing rather than different bodies of knowledge. Why should translating
between them be required for theories of consciousness? If we are materialists
who take mind to be based on matter, any theories of consciousness must blend
with neurobiological and psychological theories and descriptions. The
hard problem, then, is being addressed by current experiments that are revealing
neural correlates of conscious subjective experiences such as vision, attention,
and memory. The really hard problem is to find a unified or integrated description
of all of these. (Approaches to this problem are the subject of Chapter 12.)
Once we have assembled enough of the pieces, the supposedly hard problem
of consciousness may evaporate, just as the concept of phlogiston disappeared
when the true nature of fire was illuminated, the mystery of light yielded
to the discovery of electromagnetic waves, and the mystery of life (how each
organism replicates itself) was clarified by the discovery of DNA.
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DESIGN NOTE: IMPORTANT POINT
The debate over the "easy" versus
the "hard" problems of consciousness remains to be resolved.
*********
This argument takes the view that
there are no questions concerning the physical basis of consciousness that
differ in principle from other ordinary problems about the physical and functional
basis of genes, inheritance, or solidity and liquidity. However, it is also
possible that at this point, we could be in the position of a person ignorant
of relativity theory who is informed that matter is a form of energy but does
not understand the physical concepts that link quantum phenomena to matter
and energy alike. Future theory might provide the scientific concepts we need
to close the explanatory gap.
Problems with Words
Note: this section was not included
in published book
As we get into the thicket of thinking
about minds, consciousness, and brains, we bump into some major quandaries
in dealing with our language. I frequently find
myself thinking: "I know what I mean, or feel, but I just can't put it
into words." As an example, the French translation of the title of an
article "What is it like to be a bat." must be rendered as "What
effect (or impression) does it make to be a bat." French
speakers surely have the concept of "what it is like to be...." but
no clear, concise expression for it. Different cultures develop different systems
of description. An opposite problem occurs when a word or phrase seems to represent
something but in fact does not. A well known example is " phlogiston",
coined in the eighteenth century to refer to the hypothetical material with
negative mass that was supposed to be released from burning bodies. Other examples
are "elan vital", "animal magnetism" and "telepathy".
So, there can be a double jeopardy, words playing hard to get or easy to get
and meaning nothing. Language also is made ambiguous by the existence of multiple
belief systems that use the same words in different ways, so that language
and thought have to be studied the same way that ecologists study multi-species
communities.
Imposing words are used in talking
about mind: concept, attribution, intention, affect, representation, strategy,
consciousness, cognition, phenomenology. The traditions of ethology, psychology,
philosophy and cognitive science differ over how to use these mental terms.
I am going to proceed as simply as possible, adopting an evolutionary and ecological
perspective, noting what animals and humans do in their natural habitats, and
then asking what sorts of underlying mental operations might account for this
behavior. One mental operation that can bias our insights, frequently outside
our awareness, is the use of metaphors (words
for one object or idea being used for another to suggest a similarity between
them, but without an explicit comparison). In our common sense, or folk,
psychology we often describe our mental states and processes using metaphors.
Someone saying to you "I don't want to put ideas in your head" is
taking mind to be a container. If you say "Part of me doesn't want to
do that" you are using the metaphor of mind parts as persons. "John
saw that Jim could not be trusted" is making believing like seeing. This
sort of process is pervasive in our lives. As another example, consider how
the fundamental physical verticality schema of
up and down - relevant to any animal moving against gravity - is usually metaphorically
projected to a whole array of oppositions: happy is up, sad is down; health
is up, sickness is down, rational is up, emotional is down.
Assembling an Explanation
How, then, do we set about assembling
an explanation for anything as complicated as our consciousness? We might start
with some design principles that we know something about. We know that our
bodies are hierarchical systems built up from smaller subunits and components,
as shown in Figure 1-1. The ultimate particles of atomic physics make up our
atoms and molecules. Our molecules then organize themselves into cells. Systems
of nerve cells form our nervous systems and brains. The entities at each level
are building blocks of those at the next level. The description can be expanded
beyond our individual selves, as our minds become components of the larger
entities of societies and cultures. Each level of this hierarchy has its own
laws and theories, which armies of academic specialists study.
Figure 1-1
A hierarchy diagram depicting
how complicated structures are built up from simpler ones.
This book takes the tack of sidestepping,
or bypassing, the issue of relating our brain operations to our subjective
feelings (bridging the explanatory gap mentioned above), and suggests instead,
as indicated by the solid arrows to the left of the dashed ones in Figure 1-1,
that mind is what brain/body does---in the same sense that digesting our food
is what the gut does. We can trace up through the lower levels in the hierarchy
to observe that in practice, each level of organization, built up of simpler
ones, has its own laws and that its members in turn serve as the building blocks
for the next level of organization. We then ask what rules are working at this
next level, what new operating environment we are in.
We tend to visualize the assembly
of our component molecules into cells, of our cells into tissues, and so on
as being like working with building blocks or a simple erector set where things
come together in an intuitive, linear fashion. This
can be a misleading vision, for in fact, all complex entities, whether organisms
or thunderstorms, are nonlinear systems. They emerge from their simpler components
in a way that cannot be predicted by merely summing their components. Examples
of nonlinear processes include schools of fish and flocks of birds, whose grouping
is aided by attractive energies arising because the surrounding fluid moves
with them, and groups of lipid molecules that organize themselves into a biological
membrane by minimizing the repulsive forces between lipid chains and water
molecules.
We might view consciousness as
a higher-level or emergent property of the brain in the simple sense that solidity
is an emergent property of water molecules when they are in a lattice at low
temperatures. In this view, consciousness might be taken as a physical property
of the processes of the brain in the same sense in which solidity is a property
of the molecules in an oak table or an icicle. The perspective that brain processes
cause consciousness, but also that consciousness is a feature of the brain,
avoids both the extreme of making mind separate from body and the excessively
reductive materialistic view that mind is "nothing but" a group of
molecules organized into nerve cells. In our present state of knowledge we
can observe, in the brain, neuronal activity that correlates with, but does
not explain, consciousness. We eventually hope to have a causal theory that
explains why consciousness and neuronal activities are correlated, just as
we now have causal theories that explain why the solidity of a substance correlates
with its molecular structure, or why thunder and lighting are correlated during
a storm.
*********
DESIGN NOTE: IMPORTANT POINT
We can think of our "mindstuff" as
different from our "nervestuff" without edging back toward a dualism
that separates body and mind, because we are talking about the same kind of
distinction we make when we say that DNA is different from the elementary particles
of atomic physics of which it is ultimately composed.
*********
It is important to avoid some potential
confusion about explanations. We appreciate that more complex entities can
be explained in terms of simpler components. Knowing what we do about nerve
cells, we can see how the laws governing a nerve signal follow from the laws
of chemistry and electricity, and in this sense we can "reduce" it
to them. But this is a very peculiar relationship. Under other conditions,
the same laws of chemistry and physics explain liquid crystal displays of wrist
watches, clouds forming over the ocean, thunder and lightning, and sugar dissolving
in our coffee. Those laws of chemistry and physics in turn follow from the
laws of quantum mechanics, which the physicists call fundamental, but only
under the conditions where we normally find matter. Quantum mechanics has very
different consequences in particle accelerators ("atom smashers")
and at the edges of black holes than it does in your kitchen. To propose a
genuine explanation, we must be armed with knowledge of both the lower-level
laws and the conditions under which they act. Those conditions are so variable
that we could never hope to have the higher-level laws just "fall out" (as
the physicists say) of the quantum equations. If we were to restart the universe,
would everything happen in just the same way? Perhaps there would eventually
be clouds and quartz crystals, but what about mushrooms and animals with nerve
cells and action potentials---and, in particular, us, puzzling over consciousness?
These are not all entities whose appearance anyone could have predicted just
from the equations of quantum mechanics: There are simply too many different
ways in which things could have been fit together by evolution.
Figure 1-1 shows arrows pointing
in both the upward and downward directions. The up arrows indicate simpler
things coming together to make more complicated things, such as lipid molecules
making cell membranes or the organ systems of our bodies constructing a skin
or epidermis that encloses us. The downward arrows show that emergent entities
can constrain and direct the components that built them up. A cell membrane
is a physical compartment, or bag, that contains and exerts some control over
all of its smaller components, just as on a larger scale our skins establish
the context for what our muscles and other tissues can do. By the same token,
if a whole organism constrains and regulates its component tissues, it should
not surprise us that an emergent property like our subjective consciousness
can organize, monitor, or direct the nerve assemblies of which it is constructed.
And as we will see in later chapters, there is good evidence that this really
happens. There doesn't have to be anything mystical about it. Our self conscious
behavior can affect and shape the nerve and muscle physiology in our bodies. Finally,
the consciousness or mind that each of us experiences is not the final step
in the causal chain, for it is strongly influenced and organized by the particular
human culture in which we grew up.
Organism and Environment
The hierarchy drawing in the previous
section looks tidy, but it can give the false impression that complicated things
build themselves in isolation. The building is instead a historical process
that depends strongly on the environment in which it occurs. In the hubris
that accompanied the early days of molecular biology, one could hear scientists
say, in effect, "Give me the structure of human DNA and I will compute
you a human." Today this is recognized as nonsense, and few now take that
extreme sort of reductionism very seriously. DNA is expressed only in a complex
environment, first in the egg and then in different tissues as they form. As
the fertilized eggs that generated you and me started dividing to generate
the trillions of cells in our bodies, they were partners in an exquisite series
of interactions with other cells. Each of these cells contained all of our
genes, yet only particular subsets of their progeny turned on the genes that
were needed to specify a liver cell, kidney cell, or nerve cell. Their fate
was instructed by their particular surroundings in the embryo, surroundings
that contained a rich broth of growth factor molecules. If taken away from
this broth and placed in a minimal solution of nutrients just sufficient to
sustain life, these cells might live, but they would probably return to an
undifferentiated state. Not only do cells within a developing embryo regulate
each other, but the hormones in the embryo's intrauterine environment influence
its sexual development and behavior. Embryos exposed to higher levels of testosterone,
for example, emerge as more aggressive individuals.
The wiring connections in our brains---the
specific circuits formed during development---depend on features of the sensory
and motor environment in which we grow up after birth. If those environments
are absent or abnormal, the brain develops differently. Just as the differentiated
state of every cell in our body is maintained by constant flux and interaction
with its environment (including other cells), so the differentiated state of
our brains is maintained by unique details of our own environment. The brain
we grow, the self we generate, the language we speak---all are functions of
our unique history and culture. Language, thought, and ways of experiencing
the world can be culturally relative and very different for those living in
Western industrial cultures and those belonging to isolated Stone Age tribes
in Borneo. None of us can claim to have a "God's eye" view of an
objective external reality.
*********
DESIGN NOTE: IMPORTANT POINT
Our development is shaped by the
very environment we try to describe scientifically. Thus there is an inevitable
circularity to our knowing.
*********
This can lead us to an uncomfortable
confrontation with our common-sense belief that the way things seem to us is
the way things really are. Of course, we all know that we make mistakes, and
sometimes we are fooled by tricks and illusions, but the problem goes deeper
than that. Each of us develops in a tight interaction with a particular part
of the external world, in a particular human culture and language, and all
our beliefs and ways of describing things are shaped by that interaction. We
are one part of an interacting whole trying to understand other parts. The
distinction between subjects and objects is not so simple as we commonly think.
It is with a slightly dizzy sensation that we realize we are using our instrument
of analysis (the brain) to analyze that very instrument of analysis (the brain),
like asking an eye to see itself or a mirror to reflect its own image. Figure
1-2, a reproduction of the famous illustration by the Dutch artist M.C. Escher
showing two hands shaping each other, illustrates the quandary. Which
is the "real" hand? It sometimes can be useful for us to put aside
our tendency to stamp a seal of certainty on our experience, as though it perfectly
reflected the world. The experience of anything "out there" is validated
by the human structure, which makes possible "the thing" that arises
in the description. This is not to deny that there is an objective world but
only to say that our ability to describe it is shaped by our history of interactions
with it. (We will consider the issue of the relativity of our knowledge a bit
further in Chapter 7.)
Figure 1-2
Which is the real hand? Both. We
shape our environment, and our environment shapes us.
Where Is the "I"?
We still haven't faced head-on
the question of where the "I" is in the space between our ears. Who
is watching inside when you recall how the Mona Lisa looks? What is this consciousness
or mindstuff? Perhaps you can imagine the "I" in your head as shown
in Figure 1-3, corresponding to an array of purposeful little agents scrambling
around inside, some watching the movie screen of what is going on in the outside
world, others operating the levers on the control panels that direct our movements.
But this just takes the problem back another step, like opening the Russian
wooden doll toy that has another doll nested inside. Opening that doll, you
find the next. The hunt for purposeful agents somewhere down in there becomes
fruitless. As we look further inside the brain, we become increasingly convinced
that there doesn't appear to be anyone at home. We don't find a specific place
where there is a thinker or a feeler or an actor. Rather, there are billions
and billions of nerve cells wired together in complex arrays. We search in
vain among all the specialized areas of our brain to find one that is the president.
Is it in the frontal lobes? (We will take up this question in more detail in
Chapter 12.)
Figure 1-3
Where is the I? It can't reside
in other little humans inside our heads, as suggested here, even though such
a picture perhaps corresponds most closely to our subjective experience.
It might be helpful at this point
to peek at the sort of answer that is outlined in subsequent chapters. The
best idea seems to be that the brain isn't like a classical top-down corporation
or a computer run by a master central processor. Our consciousness is mechanically
implemented by a process more analogous to an economy or an ecosystem---a distributed
system without any central authority. There is no central place from which
a puppeteer pulls all the strings. Our brains are a collection of semi-independent
subsystems designed to perform specific jobs. They are not general-purpose
problem solvers that invoke the same distributed, common processes for all
tasks. They are more like a Swiss Army knife that has special gadgets for different
tasks. Large computational problems (such as vision, audition, movement, and
language generation) are split into a collection of parts processed by specific
brain regions. These parts can be revealed when they are damaged by brain lesions
or genetic mutations. And they can sometimes be directly visualized in living
brains via imaging techniques or electrical recordings. The specialized modules
are not isolated but interact extensively with each other. In Chapter 8 we
consider one of the best-known examples of this, the different areas of the
brain that process different aspects of a visual image, such as form, motion,
distance, and color.
We seem to be a society of mind,
built up of a hierarchy of agents referred
to by different authors as simpletons, stable
subassemblies, multiple drafts, component
selves, and so on (the words vary more than the ideas). The modules are not
what an engineer starting from scratch would have designed (supposing there
were an engineer who could design a brain) but rather a hodgepodge of evolutionary
adaptations and accidents piled one on top of the other, with some components
possibly duplicated and adopted for uses and tricks quite different from their
original "purpose." Consciousness,
at least in part, was natural selection's way of endowing us with thoughts
that helped us survive in the world of our ancestors, not necessarily thoughts
that are consistent or true. These
last points bring us to the subject of the first main section of this book,
how biological evolution has shaped the minds we use today.
*********
DESIGN NOTE: IMPORTANT POINT
Just as we are stuck with the QWERTY
keyboard---an awkward design that slows typing speed, devised in 1872 to avoid
jamming of type bars that vanished long ago---so the modern brain makes do
with modules designed to solve ancient problems.
*********
Summary
This chapter has spelled out a
number of positions and attitudes adopted by most of those who study the scientific
basis of mind. A working assumption is that mind has its origin in physical
stuff, just like the rest of the universe that we know about. Mind is what
our brain/body does. Consciousness arises from the activity of neurons. What
it is for---its function---needs to be described, as well as the hardware that
carries out its activities. For the purposes of this book, mind is very broadly
defined as the sum of the vast number of operations that proceed as our nervous
system interacts with other body systems and with the world to generate cognitions,
only a fraction of which are accessible to our awareness. The book takes take
the optimistic view that we are not blocked, in principle, from understanding
how our conscious awareness works. The "hard problem" of explaining
what it is like to be someone may be resolved as we learn more from descriptions
of what humans do and from experiments in cognitive psychology and neuroscience.
We can use what we already know
about how our complex bodies are built up hierarchically, from simpler components,
as a model for thinking about how consciousness might arise from groups of
nerve cells. We have to admit that our processes of knowing are somewhat circular,
because they are shaped and formed by the very environments they are trying
to describe. But we are certain that the "I" of our subjective awareness
is not like a little human, the 16th century's homunculus, residing somewhere
inside our heads as a master puppeteer pulling all the strings. Rather, our
consciousness is a distributed process that involves many semi-independent
assemblies and agents whose activities are coordinated. One of the goals of
this book is to sketch out the many components of our perceiving, acting, emotional,
and linguistic minds that make us a society of mind. It is the origins of these
components that we now want to consider by going back to the beginning and
starting to tell the story of how our minds evolved over millions of years.
Questions for Thought
1. Several levels of conscious
awareness were discussed at the beginning of this chapter, levels that culminate
in the internal narrative made possible by human language. Some psychologists
have argued that without language there can be no conscious awareness. Do you
agree or disagree with this? Why?
2. Given what you have read here
about definitions of consciousness, awareness, and mind, how would you respond
if someone asked you, "How do you define mind?"
3. Rene Descartes's famous formulation, "I
think, therefore I am" posited a clear dividing line between the mind
and the brain, assigning the former to a nonphysical or spiritual realm and
the latter to the physical world. Perhaps the central point of this chapter
is the contrary assertion that mind has a physical basis, just like the rest
of the world we know about. What is your opinion on this question? (This is
an issue we discuss further in Chapter 12.)
Suggestions for Further General
Reading
Churchland, P.M. 1995. The Engine
of Reason, the Seat of the Soul: A Philosophical Journey into the Brain. Cambridge,
MA: M.I.T. Press. A discussion of computational models of the brain based on
modern findings in neuroscience and psychology.
Dennett, D.C. 1991. Consciousness
Explained. Boston: Little, Brown. A controversial and engaging introduction
to philosophical and technical issues involved in explaining consciousness.
Scott, A. 1995. Stairway to the
Mind. New York: Springer-Verlag. A discussion of how mind might emerge from
assemblies of simpler components.
Clark, A. 1997. Being There. Cambridge,
MA: M.I.T. Press. This book emphasizes how mind and body are defined by their
participation in an extended physical and social environment.
Reading on More Advanced or Specialized
Topics
Flanagan, O. 1992. Consciousness
Reconsidered. Cambridge, MA: M.I.T. Press. A more advanced discussion of issues
in the philosophy of mind, including naturalistic explanations of consciousness.
Hardcastle, V.G. 1996. Ways of
knowing. Consciousness and Cognition 5:359--367. A discussion of how mind and
consciousness are defined that suggests how the "explanatory gap" might
be closed.
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