JOHN SEARLE’S NYRB ARTICLES ON CONSCIOUSNESS
Anil Mitra PHD, COPYRIGHT © 1996, REFORMATTED May 2003
Document status: May 21, 2003
No further action needed for Journey in Being
No action needed for studies in consciousness since this document is superseded by Review of works by John Searle and David Chalmers
Maintained out of interest
CONTENTS
Observations
and quotes with comments
From the Philosophical Preliminary
Definition of consciousness is simple
The body image and the idea of a functional brain
On the on-off nature of consciousness
On the identity of brain processes with
consciousness and with mental processes
Partition of the problem of consciousness into a
philosophical problem and a scientific problem
Arguments about strong and weak artificial intelligence
John Searle’s
The article outlines philosophical issues that surround the putative biological problem of explaining how consciousness arises in the brain - and then reviews recent books by Francis Crick, Daniel Dennett, Gerald Edelman [two books], Roger Penrose, and Israel Rosenfield. The following books are reviewed:
The
Astonishing Hypothesis: The Scientific Search for the Soul, Francis Crick
Consciousness
Explained, Daniel C. Dennett
The Remembered Present: A Biological Theory of Consciousness, Gerald Edelman
Bright Air, Brilliant Fire: On the Matter of the Mind, Gerald Edelman
Shadows of the Mind: A Search for the Missing Science of Consciousness, Roger Penrose
The Strange,
Familiar, and Forgotten: An Anatomy of Consciousness,
Quotes 1 through 7, which follow, are from the philosophical preliminary. The remaining Quotes 8 through 12 are from the review portion of Searle’s essay. Interwoven with the quotes and comments are my observations. They are numbered 1 thruugh 7 in approximate correspondence with the Quotes 1 through 7
“The most important problem in the biological sciences is... How exactly do neurobiological processes in the brain cause consciousness.”
A number of approaches lead to the conclusion that brain processes cause consciousness: the effects of injury to specific parts of the brain; the correlates between mental activities [such as perception, thought, emotion] and neurobiological activities; and the formation by the brain of “the body image”. The following quote occurs later in the second part of the article in reviewing Rosenfield [and will be repeated in its place in the sequence of quotes]:
“The brain forms an image of the entire body. And when we feel pains or any other sensations in the body, the actual occurrence of the experience is in the body image
“That we experience bodily sensations in the body image is most obvious in the case of phantom limbs... a patient may continue to feel pain in his toe even after his entire limb has been amputated.”
Now, I do not want to deny the
importance of the idea that consciousness or experience arises in the brain [or
is “caused” by the brain]. There are two reasons that I regard this stark form
of materialism as important: [1] it provides clues to the whole picture and [2]
it challenges me to sharpen my own views which include but are not restricted to
alternate ways of thinking. Here, however only some brief challenges to the
idea that mind or mental processes or mental function is caused by or arises in
or is ontologically secondary to matter and material processes
Anything that is empirical is contingent: matter as the seat
of mind, death... therefore even if mind is seen to arise in matter, it does
not follow, except in pragmatic materialism, that all mind arises in matter
Ultimately: if we consider the claim “mind, consciousness
arises in the brain”, we can ask: what causes brains to exist and body images
to form: ontogenetically, proximately in epigenesis and from the relatively
immediate and local environment and phylogenetically
and ultimately [in the biological sense] from the
earth and its history and even from existence... and all of this within a
standard material or cosmological framework
In the here and now: from the
diffusion of consciousness among the elements of being [see my essay for
details]... is not this diffusion the trace of the ultimate in the present, and
if it is vague, is this not only so relative to the stark elements of
consciousness but not to the primal ground: the body and its unconscious
including the mental: including the “seen but not recognized”
The existence of alternate points
of view: idealism, realism and realistic idealism [including graded realism]...
programmatically and have some clear-headed thinking to do before I define my
position
Now, the idea that the occurrence of all experience - sensations, stream of consciousness, etc. - occurs in the body image and that the “brain forms an image of the entire body” is a powerful argument for the thesis that “neurobiological processes in the brain cause consciousness”
Therefore I propose to drive a
wedge into any absolute and final notion of the two-part idea [1] the brain
creates the body image, and [2] all experience occurs in the body image. Of
course this is not to deny the utility of this idea as an important component of
any complete explanation of the source of consciousness
Preliminarily, let us consider
“phantom” pain. Suppose the source of such pain occurs at some point between
the limb-stub and the brain. Something causes a tweaking of the nerve or an
excitation of a neuron. Physically a neural impulse is received or occurs in
the brain. There is the experience of pain... and no doubt interpretation of
the “sensation” also enters into the registration of pain
Searle will say:
“It might sound as if phantom limb pains were some extremely peculiar oddity, but in fact, many of us have a version of the phantom limb in the form of sciatic pains... what exactly is going on in [a patient’s] leg that corresponds to his pain? Exactly nothing! ... the sciatic nerve in the spine is stimulated and this triggers neuron firings in his brain which give him the experience of feeling a pain in his leg...” and
“in a sense all our bodily sensations are phantom body experiences, because the match between where the sensation seems to be and the actual physical body is entirely created in the brain.”
Thus, while phantom limb
phenomena and sciatica reinforce arguments for the body image, they also show
that the body image can be mistaken. This is not a serious problem, nor is it
an objection to the body image; but it needs to be noted. The body image itself
is one source of somatic hallucination
More seriously: consider [1] the
reflex arc and [2] the separation of consciousness within the individual “I”
leading to multiple but diffuse and apparently discrete centers of
consciousness within the person. This is the wedge. The concept
of multiple centers of consciousness in the individual in total or partial
separation stand against the completeness of brain-body image as the
source-manifold of all experience. Or, we could perhaps say that the brain
itself is more distributed than we think it to be... or, more precisely, we
could talk of a functional-conceptual Brain vs. the organic brain
“All of our conscious life is caused by these lower level processes but we have only the foggiest idea of how it all works... why don’t the relevant specialists... figure out how it works? Why should it be any harder than finding out the causes of cancer? But there are a number of problems raised by the brain sciences even harder to solve. Some of the difficulties are practical.”
Searle now comments on the number of neurons [estimated 1011] and the number of interconnections per neuron [100 to many 10-thousands] and the difficulty of experimenting on live subjects: you and me. He adds:
“In addition to the practical difficulties, there are several philosophical and theoretical obstacles and confusions that make it hard to pose and answer the right questions. For example, the commonsense way in which I have just posed the question: How do brain processes cause consciousness? is already philosophically loaded.”
He wants to set the stage before discussing the latest work, “by clarifying some of the issues and correcting what seem to me to be the worst historical mistakes.”
Consciousness so defined switches off and on.”
“One issue can be dealt with swiftly. There is a problem that is supposed to be difficult but does not seem very serious to me and that is the problem of defining ‘consciousness’ “... and:
“It does not seem to me at all difficult to give a commonsense definition of the term: ‘consciousness’ refers to those states of sentience and awareness that typically begin when we awake from a dreamless sleep and continue until we go to sleep again or fall into a coma or die, or otherwise become ‘unconscious’. Dreams are a form of consciousness, though of course quite different from full waking states. Consciousness so defined switches off and on.”
This is an example in which the
contingent is made necessary...This is legitimate from some practical points of
view, useful in terms of providing a necessary practical philosophical
complement to scientific-empirical brain research. But we need to have in the
back of our minds - at least - that the ultimate may be quite different. This
is valuable of course from metaphysical, personal and religious-spiritual
perspectives that some practical persons minimize; but: even the ultimate has
practical implications. See my essay for details on relations between immediate
and ultimate issues
“The first serious problem derives from intellectual history... Descartes and Galileo made a sharp distinction between the physical reality described by science and the mental reality of the soul..
“...But this dualism has become an obstacle in the twentieth century, because it seems to place consciousness and other mental phenomena outside the ordinary physical world and thus outside the realm of natural science.”
Even scientists who admit
scientific discussion of consciousness may be blocked by the ordinary language
of their intuition, and in which they talk about science... I have for many
years attempted to recognize the traces of dualistic thinking and language in
my own experience and the idea of mind as alien to science and yet, especially
in conversation and other interaction with others - the world of work, I
experience the return of the dualist paradigm
As noted by Searle, the
Cartesian dualism has theological origins and ongoing theological biases. It
also has a socio-economic basis; and of course, through history, the sacred and
the secular mesh in their broad relations
“But even if we treat consciousness as a biological phenomenon and thus as part of this ordinary physical world, there are still many mistakes to avoid. One I just mentioned: if brain processes cause consciousness, then it seems to many people that there must be two different things: brain processes as causes and conscious states as effects, and this seems to imply dualism. This second mistake derives in part from a flawed conception of causation. In our official theories we suppose that all causal relations must be between discrete events ordered serially in time..
“Certainly, many cause and effect relations are like that, but by no means all... think of the solidity of the table: it is explained causally by the behavior of the molecules of which the latter is composed. But the solidity of the table is not an extra event, it is just a feature of the table... By the way, this analysis - that brain processes cause consciousness but that consciousness itself is a feature of the brain provides us with a solution to the traditional mind-body problem, a solution which avoids both dualism and materialism, at least as these are traditionally conceived.”
Now Searle identifies a third
difficulty: that of explaining the subjective, qualitative states that we
possess intimately and privately in terms of the publicly observable, objective
phenomena of brain phenomena. The private, internal, qualitative states are
sometimes called - as Searle notes - qualia. He now states:
The following observations regard partition of the problem of consciousness into [1] the philosophical problem of the origin of qualia in matter, and [2] the scientific problem of how specific qualia and, more generally, the structure and categories of mental process arise in the brain
“Among the interesting differences in the accounts of consciousness given by the writers under review are their various divergent ways of coming to terms - or sometimes failing to come to terms - with the problem of qualia.”
As Searle will point out, the
problem of qualia is sometimes considered to be a side issue, but in fact it is
not: it is the problem of consciousness
Now in fact this problem can be broken
down into two parts: [1] the general problem of the origin of qualia in matter
[assuming of course that qualia do so arise] and [2] how the specific qualia: a
color, a feeling of warmth, perception of a scene, thinking... arise from
specific processes [or sets of processes] in specific parts [or sets of parts]
of the brain. Searle has identified these two parts but I don’t think he
claimed the partition of the problem into the two parts. Part [1] is general,
philosophical. And it is one reason to consider idealist versions of
metaphysics. Part [2] is scientific, neurobiological, detailed
Further along in the article,
toward the end of his review of Gerald Edelman’s work, Searle seems to me to
equate part [2] with the problem of qualia even though, generally, he clearly
and definitely recognizes the difficulty of part [1]
My essay includes further
consideration of what may be called the philosophical problem of qualia. I
argue that matter, by definition, cannot in principle explain qualia. I
consider philosophically and historically what any definition of matter must be
- what is the essence of such a definition [a different question than: what is
the essence of matter?]
However, the philosophical
difficulty in no way limits answers to part [2]. Thus, although the scientific
explanation is far from complete, the difficulties - unless there is some
philosophical issue I have overlooked - are practical. This does not mean that
the practical difficulties can or will be resolved by us, or anyone; nor will a
proximate material explanation end the matter, for we also want ultimate and
mental explanations [and these in turn yield new material issues]
Some of the other authors under
review agree, but for different reasons, that qualia cannot be explained
scientifically. And thus, in some cases, they see some inherent practical
limitation that I don’t see
“A fourth difficulty is peculiar to our intellectual climate right now and that is the urge to take the computer metaphor of the mind too seriously... There are different versions of the computational theory of the mind. The strongest one is...: the mind is just a computer program. There is nothing else there. This view I call Strong Artificial Intelligence [Strong AI for short] to distinguish it from the view that the computer is a useful tool in doing simulations of the mind... This more cautious view I call Weak AI.”
“... Strong AI can be refuted swiftly,..
“... The Chinese Room Argument -
as it has come to be called - has a simple three-step structure
1. Programs are
syntactical
2. Minds have a semantics
3. Syntax is not the same as,
nor by itself sufficient for, semantics
“Therefore programs are not minds. QED
..
“It now seems to me that the
argument, if anything, concedes too much to strong AI, in that it concedes that
the theory was at least false. I now think that it was incoherent, and here is
why
..
“The upshot is that Strong AI,
which prides itself on its “materialism” and on the view that the brain is a
machine, is not nearly materialistic enough.”
Searle’s contention - and I agree within a materialist paradigm - is that the brain is an [organic] machine whereas a computation is an abstract mathematical process that exists relative to conscious observers and interpreters. He continues:
“This is a different argument from the Chinese Room, but it is deeper. The Chinese Room Argument showed that semantics is not intrinsic to syntax; this shows that syntax is not intrinsic to physics
“I reject Strong AI but accept
Weak AI. Of the authors under review Dennett holds a version of Strong AI,
Roger Penrose rejects even Weak AI. He thinks that the mind cannot even be simulated
on a computer. Gerald Edelman accepts the Chinese Room Arguments against Strong
AI and presents some other arguments of his own, but he accepts Weak AI, indeed
he makes powerful use of computer models in his research on the brain, as we
will see
“To summarize the general position, then, of how brain research can proceed in answering the questions that bother us: the brain is an organ like any other. Consciousness is caused by lower level neuronal processes in the brain and is itself a feature of the brain. Because it is a feature that emerges from certain neuronal activities, we can think of it as an ‘emergent property’. Computers play the same role in studying the brain that they play in any other discipline. They are immensely useful devices for studying brain processes. But the simulation of mental states is no more a mental state than the simulation of an explosion is an explosion.”
Searle now turns to review the recent books on consciousness
“The astonishing hypothesis, on which the book is based, is
“that ‘You,’ your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules
“There are two parts to Crick’s astonishment. The first is that all of our mental life has a material existence in the brain - and that is indeed not very astonishing - but, more interestingly, the specific mechanisms, in the brain that are responsible for our mental life are neurons and their associated molecules, such as neurotransmitter molecules. I, for one, am always amazed by the specificity of biological systems, and in the case of the brain, the specificity takes a form you could not have predicted just from knowing what it does. If you were designing an organic machine to pump blood you might come up with something like a heart, but if you were designing a machine to produce consciousness, you would think of a hundred billion neurons?
“Crick is not clear about
distinguishing causal explanations of consciousness from reductionist eliminations
of consciousness. The passage I quoted above makes it look as if he is denying
that we have conscious experiences in addition to having neuron firings. But I
think that a careful reading of the book shows that what he means is something
like the claim that I advanced earlier: all of our conscious experiences are
explained by the behavior of neurons, and are themselves emergent properties of
the system of neurons
“The fact that the explanatory
part of Crick’s claim is standard neurobiological orthodoxy today, and will
astonish few of the people who are likely to read the book, should not prevent
us from agreeing that it is amazing how the brain does so much with such a
limited mechanism. Furthermore, not everyone who works in this field agrees
that the neuron is the essential functional element. Penrose believes neurons
are already too big, and he wants to account for consciousness at a level of
much smaller quantum mechanical phenomena. Edelman thinks neurons are too small
for most functions and regards the functional elements as ‘neuronal groups’
“How does the neuron work? A
neuron is a cell like any other, with a cell membrane and a central nucleus.
Neurons differ, however, in certain remarkable ways, both anatomically and
physiologically, from other sorts of cells. There are many different types of
neuron, but the typical garden-variety neuron has on it a longish, thread-like
protuberance called an axon growing out of one side, and a bunch of spiny,
somewhat shorter, spiky threads called dendrites on the other side. Each neuron
receives signals through its dendrites..
“Now what is astonishing is
this: as far as our mental life is concerned, that story I just recounted about
neurons is the entire causal basis of our conscious life
“Crick is generally hostile to
philosophers and philosophy, but the price of having contempt for philosophy is
that you make philosophical mistakes. Most of these do not seriously damage his
main argument, but they are annoying and unnecessary. I will mention three
philosophical errors that I think are really serious
“First, he misunderstands the
problem of qualia. He thinks it is primarily a problem about the way one person
has knowledge of another person’s qualia..
“Second, Crick is inconsistent
in his account of the reduction of consciousness to neuron firings. He talks
reductionist talk, but the account he gives is not at all reductionist in
nature. Or, rather, there are at least two senses of ‘reduction’ that he fails
to distinguish. In one sense, reduction is eliminative... But in another sense
of reduction we explain a phenomenon but do not get rid of it. Thus the
solidity of an object is entirely explained by the behavior of molecules, but
this does not show that no object is really solid or that there is no
distinction between, say, solidity and liquidity. Now Crick talks as if he
wants an eliminative reduction of consciousness but in fact the direction of
his book is toward a causal explanation..
“The puzzle is that Crick
preaches eliminative reductionism when he practices causal emergentism. The
standard argument in philosophy against an eliminative reduction of
consciousness is that even if we had a perfect science of neurobiology there
would still be two distinct features, the neurobiological pattern of neuron
firings and the feeling of pain, for example..
“Third, Crick is unclear about
the logical structure of the explanation he is offering, and even on the most
sympathetic reading it seems to be inconsistent. I have so far been
interpreting him as seeking a causal explanation of visual consciousness and
his talk of ‘mechanism’ and ‘explanation’ supports that interpretation. But he
never says clearly that he is offering a causal explanation of how brain
processes cause visual awareness. His preferred way of speaking is to say that
he is looking for the ‘neural correlates’ of consciousness. But on his own terms ‘neural correlates’ cannot be the right
expression. First, a correlation is a relation between two different things,
but a relation between two things is inconsistent with the eliminative
reductionist line that Crick thinks he is espousing. On the eliminative
reductionist view there should be only one thing, neuron firings. Second, and
more important, even if we strip away the reductionist mistake, correlations by
themselves would not explain anything. Think of the sight of lightning and the
sound of thunder. The sight and sound are perfectly correlated, but without a
causal theory, you do not have an explanation
“Furthermore, Crick is unclear
about the relation between the visual experiences and the objects in the world
that they are experiences of. Sometimes he says the visual experience is a
‘symbolic description’ or ‘symbolic interpretation’ of the world. Sometimes he
says the neuronal processes ‘represent’ objects in the world. He is even led to
deny that we have direct perceptual awareness of objects in the world, and for
that conclusion he uses a bad argument right out of seventeenth-century
philosophy. He says that since our interpretations can occasionally be wrong,
we have no direct knowledge of objects of the world. This argument is in both
Descartes and Hume, but it is a fallacy... In the standard case, such as when I
look at my watch, I really see the real watch. I do not see a ‘description’ or
an ‘interpretation’ of the watch..
“I believe that Crick has been
badly advised philosophically, but fortunately you can strip away the
philosophical confusions and still find an excellent book..
“What, then, is Crick’s solution
to the problem of consciousness? One of the most appealing features of Crick’s
book is his willingness, indeed eagerness, to admit how little we know. But
given what we do know he makes some speculations. To explain his speculations
about consciousness, I need to say something about what neurobiologists call
‘the binding problem’. We know that the visual system has cells and indeed
regions that are especially responsive to particular features of objects such
as color, shape, movement, lines, angles, etc. But when we see an object we
have a unified experience of a single object. How does the brain bind all of
these different stimuli into a single, unified experience of an object? The
problem extends across the different modes of perception. All of my experiences
at present are part of one big unified conscious experiences [Kant, with his
usual gift for catchy phrases, called this ‘the transcendental unity of
apperception’]..
“Crick says the binding problem
is ‘the problem of how these neurons temporarily become active as a unit’. But
that is not the binding problem; rather it is one possible approach to solving
the binding problem... Neurons responsive to shape, color, and movement for
example, fire in synchrony in the general range of forty firings per second
[forty Hertz]. Crick and his colleague Christof Koch
take this hypothesis a step further and suggest that maybe synchronized neuron
firing in this range [roughly forty Hertz, but as low as thirty-five and as
high as seventy-five] may be the ‘brain correlate’ of visual consciousness..
“Crick has written a good and useful book. He knows a lot, and he explains it clearly. Most of my objections are to his philosophical claims and presuppositions, but when you read the book you can ignore the philosophical parts and just learn about the psychology of vision, and brain science. The limitations of neurobiological parts of the book are the limitations of the subject right now: we do not know how the psychology of vision and neurophysiology hang together, and we do not know how brain processes cause consciousness, whether visual consciousness or otherwise.”
“Of the books under review
perhaps the most ambitious is Penrose’s Shadows of the Mind. This is a sequel
to his earlier The Emperor’s New Mind and many of the same points are made,
with further developments and answers to objections to his earlier book. The
book divides into equal parts. In the first he uses a variation of Gödel’s
famous proof of the incompleteness of mathematical systems to try to prove that
we are not computers and cannot even be simulated on computers. Not only is
Strong AI false, Weak AI is too. In the second half he provides a lengthy
explanation of quantum mechanics with some speculations on how a quantum
mechanical theory of the brain might explain consciousness in a way that he
thinks classical physics cannot possibly explain it. This, by the way, is the
only book I know where you can find lengthy and clear explanations of two of
the most important discoveries of the twentieth century, Gödel’s incompleteness
theorem and quantum mechanics
“I admire Penrose and his books
enormously. He is brash, enthusiastic, courageous, and often original... My
main disagreement is that his use of Gödel’s proof does not seem to me to
succeed, and I want to say why it does not..
“That is, Penrose’s argument
rests on what we can know and understand, but it is not a requirement of
computational cognitive science that people be able to understand the programs
they are supposed to be using to solve cognitive problems
“This objection was made by
Hilary Putnam in his recent review of Penrose in The New York Times, and
Penrose responded with an indignant letter [in New York Times Book Review,
November 20, 1994]..
“Penrose’s discussion is always
about the conscious thought processes of mathematicians when they are proving
mathematical results, and he wants to know whether theorem-proving algorithms
can account for all of their successes. They can’t; but that is not the
question at issue in computational cognitive science, at least not as far as
Weak AI is concerned. The aim is not to get an algorithm that people are trying
to follow, but rather one which accurately describes what is going on inside
them... Nothing whatever in Penrose’s arguments militates against a
computational model of the brain, so construed..
“To summarize this point:
Penrose fails to distinguish algorithms that mathematicians are consciously [or
unconsciously, for that matter] following, in the sense of trying to carry out
the steps in the algorithm, from algorithms that they are not following but
which accurately simulate or model what is happening in their brains when they
think. Nothing in his argument shows that the second kind of algorithm is
impossible. The real objection to the second kind of algorithm is not one he
makes. It is that such computer models don’t really explain anything, because
the algorithms play no causal role in the behavior of the brain. They simply
provide simulations or models of what is happening..
“In the second part of the book,
Penrose summarizes the current state of our knowledge of quantum mechanics and
tries to apply its lessons to the problem of consciousness..
“Here is the hypothesis [Penrose] presents:
“On the view that I am tentatively putting forward, consciousness would be some manifestation of this quantum-entangled internal cytoskeletal state and of its involvement in the interplay... between quantum and classical levels of activity
“...The problem with these speculations is that they do not adequately speculate on how we might solve the problem of consciousness. They are of the form: If we had a better theory of quantum mechanics and if that theory were noncomputable, then maybe we could account for consciousness in a noncomputational way. But how?..
“I have not explored the deeper metaphysical presuppositions behind his entire argument. He comes armed with the credentials of science and mathematics, but in fact he is a classical metaphysician, a self-declared Platonist. He believes we live in three worlds, the physical, the mental, and the mathematical... I will simply assert the following without argument: we live in one world, not two or three or twenty-seven... Admiring Penrose and his work enormously, I conclude that the chief value of Shadows of the Mind is that from it you can learn a lot about Gödel’s theorem and about quantum mechanics. You will not learn much about consciousness.”
“...Similarly, Edelman wants to extend an account of the development of perceptual categories - categories ranging from shapes, color and movement to objects such as cats and dogs - into a general account of consciousness. The first idea central to Edelman is the notion of maps. A map is a sheet of neurons in the brain where the points on the sheet are systematically related to the corresponding points on a sheet of receptor cells..
“The second idea is his Theory
of Neuronal Group Selection..
“The basic point is that the
brain is not an instructional mechanism, but a selectional
mechanism; that is, the brain does not develop by alterations in a fixed set of
neurons, but by selection processes that eliminate some neuronal groups and
strengthen others
“The third, and most important,
idea is that of reentry. Reentry is a process by which parallel signals go back
and forth between maps..
“So the result is that you get a
unified representation of objects in the world even though the representation
is distributed over many different areas of the brain. Different maps in
different areas are busy signaling each other through the reentry pathways...
what Edelman calls ‘global mapping’ and this allows the system not only to have
perceptual categories and generalization but also to coordinate perception and
action..
“When Edelman talks about
perceptual categorization he is not talking about conscious perceptual
experiences
“The question then is, how do we get from the apparatus I have described so far
to conscious experiences? What more is needed?... It
is essential to distinguish between ‘primary consciousness’, which is a matter
of having what he calls imagery, by which he means simple sensations and
perceptual experiences, and ‘higher-order consciousness’, which includes
self-consciousness and language. In order to have primary consciousness in
addition to the mechanisms just described, the brain needs at least the
following:..
“1. It must have memory..
“2. The brain must have a system
for learning. Learning for Edelman involves not only memory but also value, a
way of valuing some stimuli over others..
“3. The brain also needs the
ability to discriminate the self from the nonself..
“To get the full account of
primary consciousness we have to add three more elements
“4. The organism needs a system
for categorizing successive events in time, and for
forming concepts
“5. A special kind of memory is
needed. There must be ongoing interactions between system 4 and the systems
described in 1, 2, and 3, in such a way as to give us a special memory system
for values matched to past categories
“6. We need a set or reentrant
connections between the special memory system and the anatomical systems that
are dedicated to perceptual categorizations..
“The problem is the same one we
encountered before: How do you get from all these structures and their
functions to the qualitative states of sentience or awareness that all of us
have, which some philosophers call ‘qualia’?... His
answer to the problem of qualia in The Remembered Present seems to me somewhat
different from the one in Bright Air, Brilliant Fire, but neither seems to me
to be adequate. In The Remembered Present he says that science cannot tell us
why warm feels warm and we should not ask it to. But it seems to me that is
exactly what a neuroscience of consciousness should tell us: What anatomical
and physiological features of the brain cause us to have consciousness at all,
and which features cause which specific forms of conscious states..
“In Bright Air, Brilliant Fire,
Edelman says we cannot solve the problem of qualia because no two people will
have the same qualia and there is no way that science, with its generality, can
account for these peculiar and specific differences..
“Though Edelman differs from Crick on many issues, they share the one basic conviction that drives their research. To understand the mind and consciousness we are going to have to understand in detail how the brain works.”
“Before discussing Dennett’s Consciousness Explained, I want to ask the reader to perform a small experiment to remind himself or herself of what exactly is at issue in theories of consciousness. Take your right hand and pinch the skin on your left forearm. What exactly happened when you did so? Several different sorts of things happened. First, the neurobiologists tell us that the pressure of your thumb and forefinger set up a sequence of neuron firings that began at the sensory receptors in your skin... A few hundred milliseconds after you pinched your skin, a second sort of thing happened... You felt a pain..
“This unpleasant sensation had a
certain particular sort of subjective feel to it, a feel which is accessible to
you in a way it is not accessible to others around you. This accessibility has
epistemic consequences - you can know about your pain in a way that others
cannot - but the subjectivity is ontological rather than epistemic. That is,
the mode of existence of the sensation is a first-person or subjective mode of
existence whereas the mode of existence of the neural pathways is a
third-person or objective mode of existence; the pathways exist independently
of being experienced in a way that pain does not. The feeling of the pain is
one of the “qualia” I mentioned earlier
“Furthermore, when you pinched
your skin, a third sort of thing happened. You acquired a behavioral
disposition you did not previously have. If someone asked you, “Did you feel
anything?” you would say something like, “Yes, I felt a mild pinch right here.”
No doubt other things happened as well - you altered gravitational relations
between your right hands and the moon, for example - but let us concentrate on
these first three
“If you were asked what is the essential thing about the sensation of pain, I
think you would say the second feature, the feeling, is the pain itself... The
problem of consciousness in both philosophy and the natural sciences is to
explain these subjective feelings. Not all of them are bodily sensations like
pain. The stream of conscious thought is not a bodily sensation and neither are
visual experiences. Yet both have the quality of ontological subjectivity that
I have been taking about. The subjective feelings are the data that a theory of
consciousness has to explain, and the account of the neural pathways that I
sketched is a partial theory to account for the data. The behavioral
dispositions are not part of the conscious experience, but they are caused by
it
“The peculiarity of Daniel
Dennett’s book can now be stated: he denies the existence of the data. He
thinks there is no such thing as the second sort of entity, the feeling of
pain. He thinks there are no such things as qualia, subjective experiences,
first-person phenomena, or any of the rest of it..
“What really happens, according
to Dennett, is that we have stimulus inputs, such as the pressure on your skin
in my experiment, and we have dispositions to behavior, ‘reactive dispositions’
as he calls them. And in between there are ‘discriminative states’ that cause us
to respond differently to different pressures on the skin, to discriminate red
from green, etc., but the sort of state that we have for discriminating
pressure is exactly like the state of a machine for detecting pressure... there
are no such things as ‘inner feelings’. It is all a matter of third-person
phenomena: stimulus inputs, discriminative states, and reactive dispositions..
“The main point of Dennett’s
book is to deny the existence of inner mental states and offer an alternative
account of consciousness, or rather what he calls ‘consciousness’... Dennett,
however, does not begin on page one to tell us that he thinks conscious
states...do not exist, and that there is nothing there but a brain implementing
a computer program. Rather, he spends the first two hundred pages discussing
questions which seem to presuppose the existence of subjective conscious states
and proposing a methodology for investigating consciousness... It is not until
after page 200 that you get his account of ‘consciousness’, and not until well
after page 350 that you find out what is really going on
“The main issue in the first
part of the book is to defend what he calls the ‘Multiple Drafts’ model of
consciousness as opposed to the ‘Cartesian Theater’ model. The idea, says
Dennett, is that we are tacitly inclined to think that there must be a single
place in the brain where it all comes together, a kind of Cartesian Theatre
where we witness the play of our consciousness. And in opposition he wants to
advance the view that a whole series of information states are going on in the
brain, rather like multiple drafts of an article. On the surface, this might
appear to be an interesting issue for neurobiology: where in the brain are our
subjective experiences localized? Is there a single locus or many? A single
locus, by the way, would seem neurobiologically
implausible, because any organ in the brain that must seem essential to
consciousness... has a twin on the other side of the brain. But that is not
what Dennett is driving at. He is attacking the Cartesian Theater not because
he thinks subjective states occur all over the brain, but rather because he
does not think there are any such things as subjective states at all..
“What is his alternative
account? Not surprisingly, it is a version of Strong AI. In order to explain it
I must first briefly explain four notions that he uses: von Neumann machines,
connectionism, virtual machines, and memes. A digital computer, the kind you
are likely to buy in a store today... is called a serial computer, and because
the initial designs were by John von Neumann,... it is
sometimes called a von Neumann machine. Recently there have been efforts to
build machines that operate in parallel, that is with
several computational channels working at once and interacting with each other.
In physical structure these are more like human brains. They are not really
much like brains, but certainly they are more like brains than the traditional
von Neumann machines..
“Another notion Dennett uses is that
of a ‘virtual machine’. The actual machine I am now working on is made of
actual wires, transistors, etc.; in addition, we can get machines like mine to
simulate the structure of another type of machine. The other machine is not
actually part of the wiring of this machine but exists entirely in the patterns
of regularities that can be imposed on the wiring of my machine. This is called
the virtual machine
“The last notion Dennett uses is
that of a ‘meme’. This notion is not very clear. It was invented by Richard
Dawkins to have a cultural analogue to the biological notion of a gene...
According to Dawkins’s definition a meme is..
“a unit of cultural transmission, or a unit of imitation ... Examples of memes are tunes, ideas, catchphrases, clothes fashions, ways of making pots or of building arches. Just as genes propagate themselves in the gene pool by leaping from body to body via sperm or eggs, so memes propagate themselves in the meme pool by leaping from brain to brain via a process which, in the broad sense, can be called imitation
“I believe the analogy between gene and ‘meme’ is mistaken. Biological evolution proceeds by brute, blind, natural forces. The spread of ideas and theories through ‘imitation’ is typically a conscious process directed toward a goal. It misses the point of Darwin’s account of the origin of the species to lump the two sorts of processes together
“On the basis of these four notions, Dennett offers the following explanation of consciousness:
“Human consciousness is itself a huge collection of memes [or more exactly, meme-effects in brains] that can best be understood as the operation of a ‘von Neumannesque’ virtual machine implemented in the parallel architecture of a brain that was not designed for any such activities
“In other words, being conscious is entirely a matter of implementing a certain sort of computer program or programs in a parallel machine that evolved in nature..
“The extreme anti-mentalism of
his views has been missed by several of Dennett’s critics, who have pointed out
that, according to his theory, he cannot distinguish between human beings and
unconscious zombies who behave exactly as if they were human beings..
“His claim is that...there is no
difference between us and machines that lack conscious states in the sense I
have explained... In one of his several discussions of zombies, he considers
whether there is any difference between human pain and suffering and a zombie’s
pain and suffering..
“Why should a ‘zombie’s’ crushed hopes matter less than a conscious person’s crushed hopes? There is a trick with mirrors here that should be exposed and discarded. Consciousness, you say, is what matters, but then you cling to doctrines about consciousness that systematically prevent us from getting any purchase on why it matters. Postulating special inner qualities that are not only private and intrinsically valuable, but also unconfirmable and uninvestigatable is just obscurantism
“The rhetorical flourishes here
are typical of the book, but to bring the discussion down to earth, ask
yourself: When you performed the experiment of pinching yourself, were you
‘postulating special inner qualities’ that are ‘unconfirmable
and uninvestigatable’? Where you being
‘obscurantist’? And most important, is there no difference at all between you
who have pains and an unconscious zombie that behaves like you but has no pains
or any other conscious states?..
“Dennett’s book is unique among
the several under discussion here in that it makes no contribution to the
problem of consciousness but rather denies that there is any such problem in
the first place..
“I regard Dennett’s denial of
the existence of consciousness not as a new discovery or even as a serious
possibility but rather as a form of intellectual pathology. The interest of his
account lies in figuring out what assumptions could lead an intelligent person
to paint himself into such a corner..
“Scientific objectivity,
according to Dennett’s conception, requires ‘the third-person point of view’.
At the end of his book, he combines this view with verificationism
- the idea that only things that can be scientifically verified really exist.
These two theories lead him to deny that there can exist any phenomena that
have a first-person ontology. That is, his denial of
the existence of consciousness derives from two premises: scientific
verification always takes the third-person point of view, and nothing exists
which cannot be verified by scientific verification so construed. This is the
deepest mistake in the book, and it is the source of most of the others, so I
want to end this discussion by exposing it
“We need to distinguish the
epistemic sense of the distinction between the first- and the third-person
points of view [i.e., between the subjective and the objective] from the
ontological sense. Some statements can be known to be true or false
independently of any prejudices or attitudes on the part of observers. They are
objective in the epistemic sense... Some entities, mountains for example, have
an existence which is objective in the sense that it does not depend on any
subject. Others, pain for example, are subjective in that their existence
depends on being felt by a subject. They have a first-person or subjective
ontology
“Now here is the point. Science does indeed aim at epistemic objectivity... But epistemic objectivity of method does not require ontological objectivity of subject matter... Dennett has a definition of science which excludes the possibility that science might investigate subjectivity, and he thinks the third-person objectivity of science forces him to this definition. But that is a bad pun on ‘objectivity’. The aim of science is to get a systematic account of how the world works. One part of the world consists of ontologically subjective phenomena. If we have a definition of science that forbids us from investigation that part of the world, it is the definition that has to be changed and not the world.”
“Israel Rosenfield’s
book is the shortest and apparently the most unassuming of the books under
review, but it is quite ambitious in its aims. On the surface the book consists
mostly of a series of case histories describing various forms of neural damage
that people have suffered and the consequences for their mental life and
consciousness..
“Consciousness arises from the
‘dynamic interrelations of the past, the present, and the body image’..
“The continuity of consciousness
derives from the correspondence which the brain establishes from moment to
moment with events in space and time. The vital ingredient in consciousness is
self-awareness..
“One of the most remarkable
things about the brain is its capacity to form what neurobiologists call ‘the
body image’. To understand this, remember when I asked you to pinch your left
forearm. When you did so, you felt a pain. Now, where exactly does the event of
your feeling the pain occur? Common sense and our own experience tell us that
it occurs in our forearm exactly in the area of the skin that we have been
pinching. But in fact, that is not where it occurs. It occurs in the brain. The
brain forms an image of our entire body. And when we feel pains or any other
sensations in the body, the actual occurrence of the experience is in the body
image in the brain..
“I believe the most important
implication of his book for future research is that we ought to think of the
experience of our own body as the central reference point of all forms of
consciousness
“I said at the beginning of the
first of these two articles that the leading problem in the biological sciences
is the problem of explaining exactly how neurobiological processes cause
conscious experiences. This is not Rosenfield’s
direct concern and none of the books under review provides an adequate answer
to that question; but Crick, Edelman, and Penrose, in their quite different
ways, are at least on the right track. They are all trying to explain how the
physical matter in our head could cause subjective states of sentience or
awareness. We have a long way to go, but with the philosophical ground cleared
of various confusions such as Strong AI, it is at least possible to state
clearly what the problem is and to work toward its solution