Max
Velmans, Department of Psychology, Goldsmiths, University of London, New Cross,
London SE14 6NW, England.
Journal of Consciousness Studies, 9(11), 2002, pp.3-29. (Target Article for
Special Issue)
In everyday life we take it for granted that we
have conscious control of some of our actions and that the part of us that
exercises control is the conscious mind.
Psychosomatic medicine also assumes that the conscious mind can affect
body states, and this is supported by evidence that the use of imagery,
hypnosis, biofeedback and other ‘mental interventions’ can be therapeutic in a
variety of medical conditions. However,
there is no accepted theory of mind/body interaction and this has had a detrimental
effect on the acceptance of mental causation in science, philosophy and in many
areas of clinical practice. Biomedical accounts typically translate the effects
of mind into the effects of brain functioning, for example, explaining
mind/body interactions in terms of the interconnections and reciprocal control
of cortical, neuroendocrine, autonomic and immune systems. While such accounts are instructive, they
are implicitly reductionist, and beg the question of how conscious experiences could have bodily effects. On the other hand, non-reductionist accounts
have to cope with three problems: 1) The physical world appears causally
closed, which would seem to leave no room for conscious intervention. 2) One is
not conscious of one’s own brain/body processing, so how could there be
conscious control of such processing? 3) Conscious experiences appear to
come too late to causally affect the processes to which they most obviously
relate. This paper suggests a way of
understanding mental causation that resolves these problems. It also suggests
that “conscious mental control” needs to be partly understood in terms of the voluntary operations of the preconscious mind, and that this allows
an account of biological determinism that is compatible with experienced free
will.
What
needs to be explained.
The assumption that we have a conscious mind that
controls our voluntary functions and actions is taken for granted in everyday
life and is deeply ingrained in our ethics, politics and legal systems. The potential effect of the mind on the
body is also taken for granted in psychosomatic medicine. But how the conscious mind exercises its
influence is not easy to understand. In
principle, there are four distinct ways in which body/brain and
mind/consciousness might enter into causal relationships. There might be
physical causes of physical states, physical causes of mental states, mental
causes of mental states, and mental causes of physical states. Establishing which forms of causation are
effective in practice is important,
not just for a deeper understanding of mind/body interactions, but also for the
proper treatment of some forms of illness and disease.
Within conventional medicine, physicalÕphysical causation is taken for granted. Consequently, the proper treatment for
physical disorders is assumed to be some form of physical intervention. Psychiatry takes the efficacy of physicalÕmental causation for granted, along with the
assumption that the proper treatment for psychological disorders may involve
psychoactive drugs, neurosurgery and so on.
Many forms of psychotherapy take mentalÕmental
causation for granted, and assume that psychological disorders can be
alleviated by means of "talking cures", guided imagery, hypnosis and
other forms of mental intervention.
Psychosomatic medicine assumes that mentalÕphysical
causation can be effective ("psychogenesis"). Consequently, under some circumstances, a
physical disorder (for example, hysterical paralysis) may require a mental
(psychotherapeutic) intervention. Given the extensive evidence for all these causal interactions (cf.
readings in Velmans, 1996a), how are we to make sense of them?
Clinical
evidence for the causal efficacy of conscious mental states.
The problems posed by mentalÕphysical causation are particularly acute, as
reductionist, materialistic science generally takes it for granted that the
operation of physical systems can be entirely explained in physical terms. Yet there is a large body of evidence that
states of mind can affect not only subsequent states of the mind but also
states of the body. For example, Barber (1984), Sheikh et al. (1996), and the
readings in Sheikh (2001) review evidence that the use of imagery, hypnosis,
and biofeedback may be therapeutic in a variety of medical conditions.
Particularly puzzling is the evidence that under
certain conditions, a range of autonomic
body functions including heart rate, blood pressure, vasomotor activity, blood
glucose levels, pupil dilation, electrodermal activity, and immune system functioning
can be influenced by conscious states. In some cases these effects are
striking. Baars & McGovern (1996)
for example report that,
“The global influence of consciousness is
dramatized by the remarkable phenomenon of biofeedback training. There is firm evidence that any single neurone or any population of neurons can come to be
voluntarily controlled by giving conscious feedback of their neural firing
rates. A small needle electrode in the
base of the thumb can tap into a single motor unit - a muscle fibre controlled
by one motor neurone coming from the spinal cord, and a sensory fibre going
back to it. When the signal from the
muscle fibre is amplified and played back as a click through a loudspeaker, the
subject can learn to control his or her single motor unit - one among millions
- in about ten minutes. Some subjects
have learned to play drumrolls on their single motor units after about thirty
minutes of practice! However, if the
biofeedback signal is not conscious, learning does not occur. Subliminal feedback, distraction from the
feedback signal, or feedback via a habituating stimulus - all these cases
prevent control being acquired. Since
this kind of learning only works for conscious
biofeedback signals, it suggests again that consciousness creates global access
to all parts of the nervous system.” (p75)
The most well accepted evidence for the effect of
states of mind on medical outcome is undoubtedly the "placebo effect"
- well known to every medical practitioner and researcher. Simply receiving treatment, and having
confidence in the therapy or therapist has itself been found to be therapeutic
in many clinical situations (cf Skrabanek & McCormick 1989; Wall,
1996). As with other instances of
apparent mind/body interaction, there are conflicting interpretations of the
causal processes involved. For example,
Skrabanek & McCormick (1989) claim that placebos can affect illness (how
people feel) but not disease (organic disorders). That is, they accept the possibility of mentalÕmental causation but not of mentalÕphysical causation.
However, Wall (1996) cites evidence that placebo
treatments may produce organic changes.
Hashish et al. (1988) for example, found that use of an impressive
ultrasound machine reduced not only pain, but also jaw tightness and swelling
after the extraction of wisdom teeth whether or not the machine was set to
produce ultrasound. Wall also reviews
evidence that placebos can remove the sensation of pain accompanying well-defined
organic disorders, and not just the feelings of discomfort, anxiety and so on
that may accompany it.
As McMahon and Sheikh (1989) note, the absence of
an acceptable theory of mind/body interaction within philosophy and science has
had a detrimental effect on the acceptance of mental causation in many areas of
clinical theory and practice.
Conversely, the extensive evidence for mental causation within some
clinical settings forms part of the database that any adequate theory of
mind/consciousness - body/brain relationships needs to explain.
Some
useful accounts mental causation.
The theoretical problems posed by mental
causation are nicely illustrated by studies of imagery. According to the evidence reviewed by Sheikh
et al (1996), imagery can be an effective tool in exercising mental control
over ones own bodily states (heart rate, blood pressure, vasomotor activity and
so on). It can also affect other states
of mind, playing an important role in hypnosis and meditation. But, how could
ephemeral images affect the spongy material of brains? And by what mechanism
could conscious images affect other conscious states?
In clinical practice, the effects of imagery on
brain, body and other conscious experience are often explained to patients in
terms of refocusing and redirection of
attention, linked where plausible to the operation of known biological
mechanisms. For example, in their pain
control induction programme, Syrjala & Abrams (1996) explain the
effectiveness of imagery to patients in terms of the gate-control theory of
pain:
“Even though the pain message starts in your leg,
you won’t feel pain unless your brain gets the pain message. The pain message moves along nerves from
where the injury is located to the brain.
These nerves enter the spinal cord, where they connect to other nerves,
which send information up the spinal cord to the brain. The connections in the
spinal cord and brain act like gates.
These gates help you to not have to pay attention to all the messages in
your body all the time. For example,
right now as you are listening, you do not notice the feelings in your legs,
although those feelings are there if you choose to notice them. If you are
walking, you might notice feelings in your legs but not in your mouth. One way we block the gates to pain is with
medications. Or we can block the gates
by filling them with other messages.
You do this if you hit your elbow and then rub it hard. The rubbing fills the gate with other
messages, and you feel less pain.
You’ve done the same thing if you ever had a headache and you get busy
doing something that takes a lot of concentration. You forget about the headache because the gates are full of other
messages. Imagery is one way to fill
the gate. You can choose to feel the
pain if you need to, but any time you like you can fill the gate with certain
thoughts and images. Our goal is to
find the best gate fillers for you.” (p243)
While this account is nicely judged in terms of its practical value to patients, it does not give much detail about the actual mechanisms involved. Nor does it serve as a general account of mental causation in situations that seem to demand a more sophisticated understanding of the intricate, reciprocal balance of mind/brain/body relationships. The evidence that involuntary processes can sometimes be brought under voluntary control, for example, appears to blur the classical boundary between voluntary and autonomic nervous system functions, and extends the potential scope of top-down processing in the brain. And the evidence that imagery can sometimes have bodily effects that resemble the effects of the imaged situations themselves suggest that the conventional, clear distinction between “psychological reality” and “physical reality” may not be so clear in the way that these are responded to by body and brain. As Kenneth Pelletier (1993) puts it,
“Asthmatics sneeze at plastic flowers. People with a terminal illness stay alive until after a significant event, apparently willing themselves to live until a graduation ceremony, a birthday milestone, or a religious holiday. A bout of rage precipitates a sudden, fatal heart attack. Specially trained people can voluntarily control such “involuntary” bodily functions as the electrical activity of the brain, heart rate, bleeding, and even the body’s response to infection. Mind and body are inextricably linked, and their second-by-second interaction exerts a profound influence upon health and illness, life and death. Attitudes, beliefs, and emotional states ranging from love and compassion to fear and anger can trigger chain reactions that affect blood chemistry, heart rate, and the activity of every cell and organ system in the body - from the stomach and gastrointestinal tract to the immune system. All of that is now indisputable fact. However, there is still great debate over the extent to which the mind can influence the body and the precise nature of that linkage.” (P19).
One
productive route to a deeper understanding of such linkages is the traditional
biomedical one, involving a fuller understanding of the interconnections and
reciprocal control between cortical, neuroendocrine, autonomic and immune
systems. These have been extensively
investigated within psychoneuroimmunology.
Following a detailed review of this research, Watkins (1997) concludes
that
“It
is apparent that the immune system can no longer be thought of as
autoregulatory. Virtually every aspect
of immune function can be modulated by the autonomic nervous system and
centrally produced neuropeptides. These
efferent neuroimmunomodulatory pathways are themselves modulated by afferent
inputs from the immune system, the cortex and the limbic emotional
centers. Thus the brain and the immune
system communicate in a complex bidirectional flow of cytokines, steroids and
neuropeptides, sharing information and regulating each other’s function. This enables the two systems to respond in
an integrated manner to environmental challenges, be they immunological or
behavioral, and thereby maintain homeostatic balance.” (p15)
So why
does mental causation remain a problem?
Such innovative findings and their practical
consequences for the development of “mind-body medicine” demand careful
investigation. It is important to note however that such explanatory accounts
routinely translate mind-body interactions
into brain-body interactions. Unless one is prepared to accept that mind
and consciousness are nothing more
than brain processes[1] this
finesses the classical mind/body problems that are already posed by normal
voluntary, “mental” control. How imagery
might affect autonomic or immune system functioning is mysterious, but how a
conscious wish to lift a finger makes that finger move is equally
mysterious. Why? There are many
reasons, but I will focus on just three:
Problem 1. The physical world appears causally closed. As noted above, it is widely accepted in science that
the operation of physical systems can be entirely explained in physical
terms. For example, if one examines the human brain from an external
third-person perspective one can, in principle, trace the effects of input
stimuli on the central nervous system all the way from input to output, without
finding any “gaps” in the chain of causation that consciousness might fill.
Indeed, the neural
correlates of consciousness would fill any “gaps” that might potentially be
filled by consciousness in the activities of brain. In any case,
if one inspects the operation of the brain from the outside, no subjective
experience can be observed at work. Nor
does one need to appeal to the existence of subjective experience to account
for the neural activity that one can
observe. The same is true if one thinks of the brain as a
functioning system described in information processing terms rather than neural
terms. Once the processing
within a system required to perform a given function is sufficiently well
specified in procedural terms, one does not have to add an “inner conscious
life” to make the system work. In
principle, the same function, operating to the same specification, could be
performed by a non-conscious machine.[2]
2. One
is not conscious of one’s own brain/body processing. So how could there be conscious control of such processing? How
“conscious” is conscious, voluntary control?
It is surprising how few people bother to ask.[3]
One might be aware of the fact that
relaxing imagery can lower heart rate, but one has no awareness of how it does so, nor, in biofeedback,
does one have any awareness of how consciousness might control the firing of a
single motor neurone. One isn’t even
conscious of how to control the
articulatory system in everyday “conscious speech”! Speech production is one of the most complex tasks humans are able to
perform. Yet, one has no awareness
whatsoever of the motor commands issued from the central nervous system that
travel down efferent fibers to innervate the muscles, nor of the complex motor
programming that enables muscular co‑ordination and control. In speech, for example, the tongue may make
as many as 12 adjustments of shape per second ‑ adjustments which need to
be precisely coordinated with other rapid, dynamic changes within the
articulatory system. According to
Lenneberg (1967), within one minute of discourse as many as 10 to 15 thousand
neuromuscular events occur. Yet only the results
of this activity (the overt speech) normally enters consciousness.
Preconscious
speech control might of course be the result of prior conscious activity, for example, planning what to say might be conscious,
particularly if one is expressing some new idea, or expressing some old idea in
a novel way. Speech production is commonly thought to involve hierarchically
arranged, semantic, syntactic, and motor control systems in which communicative
intentions are translated into overt speech in a largely top-down fashion. Planning
what to say and translating nonverbal
conceptual content into linguistic forms requires effort. But to what extent is
such planning conscious? Let us see.
A number of
theorists have observed that periods of conceptual, semantic and syntactic
planning are characterized by gaps in the otherwise relatively continuous
stream of speech (Goldman‑Eisler, 1968; Boomer, 1970). The neurologist John Hughlings Jackson, for
example, suggested that the amount of planning required depends on whether the
speech is “new” speech or “old” speech.
Old speech (well-known phrases, etc.) requires little planning and is
relatively continuous. New speech
(saying things in a new way) requires planning and is characterized by
hesitation pauses. Fodor, Bever &
Garrett (1974) point out that breathing pauses also occur (gaps in the speech
stream caused by the intake of breath).
However, breathing pauses do not generally coincide with hesitation
pauses.
Breathing
pauses nearly always occur at the beginnings and ends of major linguistic
constituents (such as clauses and sentences).
So these appear to be coordinated with the syntactic organization of
such constituents into a clausal or sentential structure. Such organization is
largely automatic and preconscious. By contrast, hesitation pauses tend to
occur within clauses and sentences and appear to be associated with the
formulation of ideas, deciding which words best express one’s meaning, and so
on. If this analysis is correct, conscious
planning of what to say should be
evident during hesitation pauses - and a little examination of what one
experiences during a hesitation pause should settle the matter. Try it.
During a hesitation pause one might experience a certain sense of effort
(perhaps the effort to put something in an appropriate way). But nothing is revealed of the processes that formulate ideas,
translate these into a form suitable for expression in language, search for and
retrieve words from memory, or assess which words are most appropriate. In short, no more is revealed of conceptual
or semantic planning in hesitation pauses than is revealed of syntactic
planning in breathing pauses. The fact
that a process demands processing effort
does not ensure that it is conscious. Indeed, there is a sense in which one is
only conscious of what one wants to say
after one has said it!
It is
particularly surprising that the same may be said of conscious verbal thoughts. That is, the same situation applies if one formulates one’s
thoughts into “covert speech” through the use of phonemic imagery, prior to its
overt expression. Once one has a
conscious verbal thought, manifested in experience in the form of phonemic
imagery, the complex cognitive processes required to generate that thought,
including the processing required to encode it into phonemic imagery have already operated. In short, covert speech and overt speech
have a similar relation to the planning processes that produce them. In neither case are the complex antecedent
processes available to introspection. It should be clear that this applies equally to the processes that
generate the detailed spatial arrangement, colours, shapes, sizes, movements
and accompanying sounds and smells of an imaged visual scene.
3. Conscious experiences appear to come too late
to causally affect the processes to which they most obviously relate. In the production of overt speech and
covert speech (verbal thoughts) the conscious experience that we normally
associate with such processing follows
the processing to which it relates.
Given this, in what sense are
these “conscious processes” conscious?
The same question can be asked of that most basic of conscious voluntary
processes, conscious volition itself.
It
has been known for some time that voluntary acts are preceded by a slow
negative shift in electrical potential (recorded at the scalp) known as the
“readiness potential,” and that this shift can precede the act by up to one
second or more (Kornhuber
& Deeke, 1965). In itself, this says nothing about the relation
of the readiness potential to the experienced
wish to perform an act. To address
this, Libet (1985) asked subjects to note the instant they experienced a wish
to perform a specified act (a simple flexion of the wrist or fingers) by
relating the onset of the experienced wish to the spatial position of a
revolving spot on a cathode ray oscilloscope, which swept the periphery of the
face like the sweep-second hand of a clock. Recorded in this way, the readiness
potential preceded the voluntary act by around 550 milliseconds, and preceded
the experienced wish (to flex the wrist or fingers) by around 350 milliseconds
(for spontaneous acts involving no preplanning). This suggests that, like the
act itself, the experienced wish (to flex one’s wrist) may be one output from
the (prior) cerebral processes that actually select a given response. If so, “conscious volition” may be no more
necessary for such a (preconscious) choice than the consciousness of ones own
speech is necessary for its production.[4] And the same is likely to apply to more
complex voluntary acts, such as the voluntary control of autonomic functions
through imagery and biofeedback discussed above.[5]
As noted, there is extensive experimental and
clinical evidence that conscious experiences can affect brain/body processes,
and the importance of conscious experience is rightly taken for granted in
everyday life. In one sense this can be
explained by a more sophisticated biomedical understanding of mind/brain/body
relationships. But in a deeper sense,
current attempts to understand the role of conscious experience face an
impasse. How can experiences have a
causal influence on a physical world that is causally closed? How can one consciously control something
that one is not conscious of? And how
can experiences affect processes that precede
them? Dualist-interactionist accounts of the consciousness-brain relationship,
in which an autonomously existing consciousness influences the brain, do not
even recognise these “how” problems let alone address them. Materialist reductionists attempt to finesse
such problems by challenging the accuracy, causal efficacy and even the
existence of conscious experiences.
This evades the need to address the “how” questions, but denies the validity
of the clinical evidence and defies common sense. I have given a detailed critique of the many variants of dualism
and reductionism elsewhere and will not repeat this here.[6] In what follows I suggest a way through the
impasse that is neither dualist nor reductionist.[7]
Ontological
monism combined with epistemological dualism
How can one reconcile the evidence that conscious
experiences are causally effective with the principle that the physical world
is causally closed? One simple way is
to accept that for each individual there is one
"mental life" but two ways of knowing it: first-person
knowledge and third-person knowledge. From
a first-person perspective conscious experiences appear causally
effective. From a third-person
perspective the same causal sequences can be explained in neural terms. It is not the case that the view from one
perspective is right and the other wrong.
These perspectives are complementary. The differences between how things
appear from a first- versus a third-person perspective has to do with
differences in the observational
arrangements (the means by which a subject and an external observer access
the subject's mental processes).
Let’s see how this
might work in practice. Suppose you
have a calming image of lying in a green field on a summer’s day, and you can
feel the difference this makes in producing a relaxed state, slowing your
breathing, removing the tension in your body and so on. You give a causal account of what is going
on, based on what you experience. From my external observer’s perspective, I
can also observe what is going on – but what I observe is a little
different. I can measure the effects on
your breathing and muscle tension, but no matter how closely I inspect your
brain, I cannot observe your experienced image. The closest I can get to it are
its neural correlates in the visual system, association areas and so on.[8] Nevertheless, if I could observe all the
neurophysiological events operating in your brain to produce your relaxed
bodily state, I could give a complete, physical account of what is going on.
So, now you have a first-person account of what is going on that makes sense to
you and I have a third-person account of what is going on that makes sense to
me. How do these relate? To understand
this we need to examine the relation of your visual image to its neural
correlates with care.
The
neural correlates of conscious experience. Although we know little about
the physical nature of the neural correlates of conscious experiences, there
are three plausible, functional constraints imposed by the phenomenology of
consciousness itself. Normal human
conscious experiences are representational
(phenomenal consciousness is always of
something).[9]
Given this, it is reasonable to assume that the neural correlates of such
experiences are also representational states.
Although this
assumption has not always been made explicit in theories of consciousness it is
largely taken for granted in psychological theory. Psychophysics, for example, takes it for granted that for any
discriminable aspect of experiences (a just noticeable change in brightness,
colour, pitch and so on) there will be a correlated change in some state of the
brain. It follows from this that the
information encoded in experience (in terms of discriminable differences) will
also be encoded in the brain. The same is true for the more complex contents of
consciousness, in the many cognitive theories that associate (or identify) such
contents with information stored in primary (working) memory, information at
the focus of attention, information in a global workspace and so on.
A representational
state must, of course, represent something,
that is it must have a given content. For a given physical state to be the
correlate of a given experience it is plausible to assume that it represents
the same thing (otherwise it would
not be the correlate of that
experience).
Finally, for a
physical state to be the correlate of a given experience, it is reasonable to
suppose that it has the same “grain”.
That is, for every discriminable attribute of experience there will be a
distinct, correlated, physical state. As each experience and its physical
correlate represents the same thing it follows that each experience and its
physical correlate encodes the same information about that thing. That is, they are representations with the
same information structure.[10]
[11]
If
these assumptions are well founded, your experience and
the neural correlates that I observe will relate to each other in a very
precise way. What you experience takes the form of visual or other imagery
accompanied by feelings about lying on the grass on a summery day. What I
observe is the same information
(about the visual scene) encoded in the physical correlates of what you
experience in your brain. The
information structure of what you and I observe is identical, although it is
displayed or “formatted” in very different ways. From your point of view, the only information you have about your
own state of mind is the imagery and accompanying feelings that you
experience. From my point of view, the
only information you have (about your own state of mind) is the information I
can see encoded in your brain. The way your information (about your own state)
is displayed appears to be very different to you and me for the reason that the
“observational arrangements” by which we access that information are entirely
different. From my external,
third-person perspective I can only access the information encoded in your
mind/brain by means of my visual or other exteroceptive systems aided by
appropriate equipment. With these means I can detect the information displayed
in the form of neural encodings, but not in the form of accompanying
experiences. While you maintain your
focus on the imaged scene, you cannot observe its neural correlates in your own
brain (you would need to use my equipment for that). Nevertheless, the information in those correlates displays
‘naturally’[12], in the
form of the imaged scene that you experience.
But what is your mind really like? From my “external observer’s perspective,” can I assume that what you experience is really nothing more than the physical correlates that I can observe? From my external perspective, do I know what is going on in your mind/brain/consciousness better than you do? No. I know something about your mental states that you do not know (their physical embodiment). But you know something about them that I do not know (their manifestation in your experience). Such first- and third-person information is complementary. We need your first-person story and my third-person story for a complete account of what is going on. If so, the nature of the mind is revealed as much by how it appears from one perspective as the other. It is not either physical or conscious experience, it is at once physical and conscious experience (depending on the observational arrangements). For lack of a better term we may describe this nature as psychophysical.[13], [14] If we combine this with the representational features above, we can say that mind is a psychophysical process that encodes information, developing over time.
An initial way to make sense of the causal interactions
between consciousness and brain.
This brief analysis of how first- and
third-person accounts relate to each other can be used to make sense of the
different forms of causal interaction
that are taken for granted in everyday life or suggested in the clinical and
scientific literature. PhysicalÕphysical causal accounts describe events from an
entirely third-person perspective (they are “pure third-person accounts”).
MentalÕmental causal accounts describe events entirely
from a first-person perspective (they are “pure first-person accounts”).
PhysicalÕmental and mentalÕphysical
causal accounts are mixed-perspective
accounts employing perspectival switching
(Velmans, 1996b). Such accounts start
with a description of causes viewed from one perspective (either first- or
third-person) and then switch to a description of effects viewed from the other
perspective. To understand such
accounts, one first has to acknowledge that a perspectival switch has taken
place.
PhysicalÕmental causal accounts start with events viewed
from a third-person perspective and switch to how things appear from a
first-person perspective. For example,
a causal account of visual perception starts with a third-person description of
the physical stimulus and the visual system but then switches to a first-person
account of what the subject experiences. MentalÕphysical
causal accounts switch the other way.
From your subjective point of view, for example, the imagery that you
experience is causing your heart rate to slow down and your body to relax
(effects that I can measure). If I could identify the exact neural correlates
of what you experience, it might be possible for me to give an entirely
third-person account of this sequence of events (in terms of higher order
neural representations having top-down effects on other brain and body
states). But the mixed-perspective
account actually gives you a more immediately useful description of what is
going on in terms of the things that you can do (maintain that state of mind,
deepen it, alter it, and so on).
In principle, complementary first- and third-person sources of information can be found whenever body or mind/brain states are represented in some way in subjective experience. A patient might for example have insight into the nature of a psychological problem (via feelings and thoughts), that a clinician might investigate by observing his/her brain or behaviour. In medical diagnosis, a patient might have access to some malfunction via interoceptors, producing symptoms such as pain and discomfort, whereas a doctor might be able to identify the cause via his/her exteroceptors (eyes, ears and so on) supplemented by medical instrumentation. As with conscious states and their neural correlates the clinician has access to the physical embodiment of such conditions, while the patient has access to how such conditions are experienced. In these situations, neither the third-person information available to the clinician nor the first-person information available to the patient is automatically privileged or “objective” in the sense of being “observer-free.” The clinician merely reports what he/she observes or infers about what is going on (using available means) and the patient does likewise. Such first- and third person accounts of the subject’s mental life or body states are complementary, and mutually irreducible. Taken together, they provide a global, psychophysical picture of the condition under scrutiny.
Conscious
experiences are current, global representations formed by the mind/brain.
The above, I hope, gives an initial indication of how one can reconcile the evidence that conscious experiences appear causally effective with the principle that the physical world is causally closed. But there are two further, equally perplexing problems. How can conscious experiences be causally effective if they come too late to affect the mind/brain processes to which they most obviously relate? And how can the contents of consciousness affect brain and body states when one is not conscious of the biological processes that govern those states?
I
suggest that to make sense of these puzzles, one has to begin by accepting the
facts rather than sweeping them under some obscuring theoretical carpet. Why do
experiences come too late to affect the mind/brain processes to which they most
closely relate? For the simple reason that
experiences relate most closely to the processes that produce them. Visual perception becomes “conscious” once visual
processing results in a conscious visual experience, cognitive processing
becomes “conscious” once it produces the inner speech that forms a conscious
thought and so on. Once such
experiences arise the processes that have produced them have already taken
place. Given this, what is consciousness
actually contributing to conscious perception, to conscious speech, to
conscious thought, to conscious voluntary control, and so on?[15]
As
noted above, I am proceeding on the assumption that conscious experiences are
representations. Some experiences
represent states of the external world (exteroceptive experiences), some
represent states of the body (interoceptive experiences), and some represent
states of the mind/brain itself (volitions, thoughts about thoughts, etc.).
Experiences can also represent past, future, real and imaginary events, for
example in the form of thoughts and images.
Whatever their representational content, current experiences also tell one something important about the current state of one’s own mind/brain - that it currently has percepts, feelings, thoughts, images, etc., of a given type, and that it has formed current representations with that particular content, as opposed to any others. For example, the thoughts that enter consciousness at a given moment “represent” the current state of one’s own cognitive system in that they reveal which of many possible cognitions are currently at the focus of attention in a reportable form. If your thoughts are conscious, and I ask you what you are thinking about, you can tell me. Likewise, your visually imaged peaceful world and your conscious feelings about it represent a current, voluntarily produced representational state (and affective responses to it) within your own visual, cognitive and affective systems - and if I want to know what that is like, you can tell me.
Why don’t we have more detailed experiences of the processes which produce such conscious experiences, or of the detailed workings of our own bodies, minds and brains? Because for normal purposes we don’t need them! Our primary need is to interact successfully with the external world and with each other – and for that, the processes by which we arrive at representations of ourselves in the world, or which govern the many internal, adaptive adjustments we have to make are best left on “automatic.” This is exemplified by the well-accepted transition of skills from being conscious to being nonconscious as they become well learnt (as in reading or driving a car). The global representations that we have of ourselves in the world nevertheless provide a useful, reasonable accurate representation of what is going on.[16]
How to
make sense of the causal role of the contents of consciousness.
As noted above, normal experiences are of something i.e., they represent entities, events and processes in the external world, the body and the mind/brain itself. In everyday life, we also behave as “naïve realists.” That is we take the events we experience to be the events that are actually taking place, although sciences such as physics, biology and psychology might represent the same events in very different ways. For everyday purposes, the assumption that the world just is as we experience it to be serves us well. When playing billiards, for example, it is safe to assume that the balls are smooth, spherical, coloured, and cause each other to move by mechanical impact. One only has to judge the precise angle at which the white ball hits the red ball to pocket the red. A quantum mechanical description of the microstructure of the balls or of the forces they exert on each other won’t improve one’s game.
That
said, the experienced world is not the world in itself - and it is not our experience of the balls that governs the movement of the balls themselves.
Balls as-experienced and their perceived interactions are global representations of autonomously existing
entities and their interactions, and conscious representations of such entities
or events can only be formed once they exist, or after they have taken place.
The same may be said of the events and processes that we experience to occur in
our own bodies or minds/brains. When we withdraw a hand quickly from a hot
iron, we experience the pain (in the hand) to cause what we do, but the reflex
action actually takes place before the experience of pain has time to
form. This can also happen with
voluntary movements. Suppose, for
example, that you are required to press a button as soon as you feel a tactile
stimulus applied to your skin. A typical reaction time is 100 ms or so. It takes only a few milliseconds for the
skin stimulus to reach the cortical surface, but Libet, et al. (1979) found
that awareness of the stimulus takes at least 200 ms to develop. If so, the
reaction must take place preconsciously, although we experience ourselves as responding after we feel something touching the skin. The mind/brain requires
time to form a conscious representation of a pain or of something touching the
skin and of the subsequent response.
Although the conscious representations accurately place the cause (the
stimulus) before the effect (the response), once the representations are
formed, both the stimulus and the response have already taken place.[17]
Just as the
interactions amongst experienced billiard balls represent causal sequences in
the external world, but are not the events themselves, experienced interactions
between our sensations, thoughts, images and actions represent causal sequences
within our bodies and brains, but are not the events themselves. The thoughts,
images, and feelings that appear in our awareness are both generated by processes in our bodies and mind/brains and represent the current states of those
processes. Thoughts and images
represent the ongoing state of play of our cognitive systems; feelings
represent our internal (positive and negative) reactions to and judgements
about events (see Mangan, 1993, and the discussion above).
In sum, conscious representations of inner, body and
external events are not the events themselves, but they generally represent
those events and their causal interactions sufficiently well to allow a fairly
accurate understanding of what is happening in our lives. Although they are only representations of events and their causal interactions, for
everyday purposes we can take them to be
those events and their causal interactions. When we play billiards we can line
up a shot without the assistance of physics. Although our knowledge of our own
inner states is not incorrigible, when we experience our verbal thoughts
expressed in covert or overt speech, we usually know all we need to know about
what we currently think - without the assistance of cognitive psychology. When
we experience ourselves to have acted out of love or fear, we usually have an
adequate understanding of our motivation - although a neuropsychologist might
find it useful to give a third-person account of emotion in terms of its neural
substrates in the neocortical, subcortical, diencephalic, midbrain and
pontine-medullary brainstem systems (Watt, 2000). And when we image ourselves in green grass on a summer’s day and
feel relaxed we are usually right to assume that the mental state that is
represented in our imagery has produced a real bodily effect. For everyday life, it doesn’t matter that we
don’t understand how such imaged scenarios are constructed by preconscious
mental processes or exercise top-down control in the mind/brain/body system. It
is not the case that a lower level (microscopic) representation is always
better than a macroscopic one (in the case of billiard balls). Nor are third-person accounts always better
than first-person ones (in describing or attempting to control our thoughts,
images and emotions). The value of a
given representation, description or explanation can only be assessed in the
light of the purposes for which it is to be used.
Who’s in control?
The difference between voluntary and involuntary bodily functions is accepted wisdom, enshrined in the voluntary/autonomic nervous system distinction in medical texts. As we have seen above, some processes that are normally involuntary can also become partly voluntary once they are represented in consciousness (via biofeedback, imagery and so on). But if we don’t have a detailed conscious awareness of the workings of our own bodies and brains and if consciousness comes too late to affect the processes to which it most closely relates how can this be? Consider again the dilemma posed by Libet et al’s (1979) experiments on the role of conscious volition described above. If the brain prepares to carry out a given action around 350 milliseconds before the conscious wish to act appears, then how could that action be “conscious” and how could it be “voluntary”? Doesn’t the preceding readiness potential indicate that the action is determined preconsciously and automatically by processing in the mind/brain?
Let us consider the
“conscious” aspect first. The decision to act (indexed by the readiness potential)
is taken preconsciously but it becomes conscious at the moment that it
manifests as a wish to do something
in conscious experience. The wish then becomes conscious in the same way that
your perception of this WORD is conscious. Like the wish, once you become
conscious of this WORD, the physical, syntactic and semantic analyses required
to recognise it have already taken place. Nonetheless, once you become
conscious of the wish or the WORD the mental/brain processes make a transition
from a preconscious to a conscious state – and it is only when this happens
that you consciously realise what is going on.[18]
But
how could an act that is executed preconsciously
be “voluntary”? Voluntary actions imply the possibility of choice, albeit
choice based on available external and internal information, current needs and
goals. Voluntary actions are also
potentially flexible and capable of being novel. In the psychological literature these properties are
traditionally associated with controlled rather than automatic processing or
with focal-attentive rather than pre-attentive or non-attended processing.[19]
Unlike automatic or pre-attentive processing, both controlled processing (in
the execution of acts) and focal-attentive processing (in the analysis of
input) are thought to be “conscious.” None of the above argues against such
traditional wisdom. In Libet’s
experiments the conscious experience appears around 350 milliseconds after the
onset of preconscious processes that are indexed by the readiness potential. This
says something about the timing of the conscious experience in relation to the
processes that generate it and about its restricted role once it appears.
However, it does not argue against the voluntary nature of that preconscious
processing. On the contrary, the fact that the act consciously feels as if it
is voluntary and controlled suggests that the processes which have generated
that experience are voluntary and
controlled, as conscious experiences generally provide reasonably accurate
representations of what is going on (see above). This applies equally to the
voluntary nature of more complex, mental processing such as the
self-regulating, self-modifying operations of our own psychophysical minds
evidenced by the effects of conscious imagery, meditation and biofeedback. In short, I suggest that the feeling that we
are free to choose or to exercise control is compatible with the nature of what
is actually taking place in our own central nervous system, following processes
that select amongst available options, in accordance with current needs, goals,
available strategies, calculations of likely consequences and so on. While I
assume that such processes operate according to determinate physical
principles, the system architecture that embodies them enables the ability to
exercise the choice, flexibility and control that we experience – a form of
biological determinism that is compatible with experienced free will.
So who’s
in control? Who chooses, has thoughts,
generates images and so on? We habitually think of ourselves as being our conscious selves. But it should be clear from the above that
the different facets of our experienced, conscious selves are generated by and
represent aspects of our own preconscious minds. That is, we are both
the pre-conscious generating processes and
the conscious results. Viewed from a
third-person perspective our own preconscious mental processes look like
neurochemical and associated physical activities in our brains. Viewed introspectively, from a first-person
perspective, our preconscious mind seems like a personal, but ‘empty space’
from which thoughts, images, and feelings spontaneously arise. We
are as much one thing as the other - and this requires a shift in our sensed
“centre of gravity” to one where our consciously experienced self becomes just
the visible “tip” of our own embedding, preconscious mind.
APPENDIX:
IS CONSCIOUSNESS NOTHING MORE THAN A STATE OF THE BRAIN?
It has long been suspected that there is a causal relation between mind or consciousness
and brain. For example, Hippocrates of
Cos (460‑357 B.C.) wrote that,
“Man ought to know that from the brain and from
the brain only, arise our pleasures, joys, laughter and jests, as well as our
sorrows, pains, griefs and fears.
Through it, in particular, we think, see, hear, and distinguish the ugly
from the beautiful, the bad from the good, the pleasant from the unpleasant, in
some cases using custom as a test, in others perceiving them from their
utility. It is the same thing which
makes us mad or delirious, inspires us with dread and fear, whether by night or
by day, brings sleeplessness, inopportune mistakes, aimless anxieties, absent‑mindedness,
and acts that are contrary to habit” (from Jones, 1923, cited in Flew, 1978,
p32).
However, the claim that mind or consciousness is nothing more than a state of the brain
is far more radical. If this claim can be justified, then the fundamental
puzzles surrounding the mind-body relationship, and (in its modern form) the
consciousness-brain relationship would be solved. Clearly, if consciousness is nothing more that a state of the
brain (a C-state say), it should be possible to understand it within the
existing framework of natural science.
Causal relations between consciousness and brain would translate into
the causal relations between C-states and other brain states - and the
functions of consciousness would simply be the functions of C-states within the
global economy of the brain. The
methods for investigating consciousness would then be third-person methods of
the kind already well developed in neurophysiology and cognitive science. With
such a potential prize in view, philosophical and scientific theories of
consciousness over the last 30 years have in the main assumed, or tried to show
that some form of materialist reductionism is true.
How
could conscious experiences be brain states?
Given the apparent differences between the
“qualia” of conscious experiences and brain states it is by no means obvious that they are one and the same!
Physicalists such as Ullin Place (1956), and J.J.C. Smart (1962) accepted that
these apparent differences exist. They
also accepted that descriptions of mental states and descriptions of their
corresponding brain states are not identical in meaning. However, they claimed that with the advance
of neurophysiology these descriptions will be
discovered to be statements about one and the same thing. That is, a contingent rather than a logical
identity will be established between consciousness, mind and brain.
Smart (1962) summarises this position in the
following way:
“Let us first try to state more accurately the
thesis that sensations are brain‑processes. It is not the thesis that, for example, “after‑image” or
“ache” means the same as “brain‑process of sort X” (where “X” is replaced
by a description of a certain brain process).
It is that, in so far as “after‑image” or “ache” is a report of a
process, it is a report of a process that happens to be a brain process. It follows that the thesis does not claim
that sensation statements can be translated into statements about brain
processes. Nor does it claim that the
logic of a sensation statement is the same as that of a brain process
statement. All it claims is that in so
far as a sensation statement is a report of something, that something is a
brain process. Sensations are nothing over and above brain processes”. (p163 - my
italics)
In short there is a distinction to be drawn
between how things seem, how we describe them, and how they really are.
It is important to remember that no discovery
that reduces consciousness to brain has yet been made. Physicalism, therefore, is partly an
expression of faith, based on precedents in other areas of science - and
arguments in defence of this position have focused on the kinds of discovery that would need to be made for reductionism to
be true.
C.D. Broad noted in 1925 that materialism comes
in three basic versions: radical, reductive and emergent. Radical
materialism claims that the term “consciousness” does not refer to anything
real (in contemporary philosophy this position is usually called
“eliminativism”). Reductive materialism accepts that consciousness does refer
to something real, but science will discover that real thing to be nothing more
than a state (or function) of the brain. Emergentism also accepts the reality
of consciousness but claims it to be a higher-order property of brains; it
supervenes on neural activity, but cannot be reduced to it.
While it is not the purpose of this Appendix to
give a full appraisal of these positions (I do this elsewhere, in Velmans,
2000, chapters 3, 4 and 5) it may be useful to indicate why I do not adopt
them. So, by way of illustration, I list some of problems that physicalism must
solve, some of the more plausible physicalist solutions to these, and a few of
the problems with the solutions below.
What
non-eliminative reductionism needs to show.
Let us assume that, in some sense, our conscious
experiences are real. To each and every one of us, our conscious experiences
are observable phenomena
(psychological data) which we can
describe with varying degrees of accuracy in ordinary language. Other people's experiences might be
hypothetical constructs, as we cannot observe their experiences in the direct
way that we can observe our own, but that does not make our own experiences
similarly hypothetical. Nor are our own conscious experiences “theories” or
“folk psychologies.” We may have
everyday theories about what we
experience, and with deeper insight, we might be able to improve them, but this
would not replace, or necessarily improve the experiences themselves.
In essence then, the claim that conscious
experiences are nothing more than brain states is a claim about one set of
phenomena (first-person experiences of love, hate, the smell of mown grass, the
colour of a sunset, etc.) being nothing more than another set of phenomena
(brain states, viewed from the perspective of an external observer). Given the
extensive, apparent differences between conscious experiences and brain states
this is a tall order. Formally, one
must establish that despite appearances, conscious experiences are ontologically identical to brain
states.
Instances where phenomena viewed from one
perspective turned out to be one and the same as seemingly different phenomena
viewed from another perspective do occur in the history of science. A classical example is the way the “morning
star” and the “evening star” turned out to be identical (they were both found
to be the planet Venus). But viewing consciousness from a first- versus a
third-person perspective is very different to seeing the same planet in the
morning or the evening. From a third-person (external observer's) perspective
one has no direct access to a
subject's conscious experience.
Consequently, one has no third-person data (about the experience itself)
which can be compared to or contrasted with the subject's first-person
data. Neurophysiological investigations
are limited, in principle, to isolating the neural correlates or antecedent
causes of given experiences. This would
be a major scientific advance. But what
would it tell us about the nature of consciousness itself?
Common
reductionist arguments and fallacies.
Reductionists commonly argue that if one can find
the neural causes or correlates of consciousness in the
brain, then this would establish consciousness itself to be a brain state (see for example, Place 1956; Crick
1994). Let us call these the “causation
argument” and the “correlation argument”.
I suggest that such arguments are based on a fairly obvious
fallacy. For consciousness to be
nothing more than a brain state, it must be ontologically
identical to a brain state.
However, correlation and causation do not establish ontological identity. These relationships
have been persistently confounded in the literature. So let me make the differences clear.
Ontological identity is symmetrical; that is, if A is identical to B, then B is identical
to A. Ontological identity also obeys Leibniz's Law: if A is identical
to B, all the properties of A are also properties of B, and vice-versa (for
example all the properties of the “morning star” are also properties of the
“evening star”).
Correlation is also symmetrical; if A correlates with B, then B correlates with A. But
correlation does not obey Leibniz's Law;
if A correlates with B, it does not follow that all the properties of A and B
are the same. For example, height in
humans correlates with weight, but height and weight do not have the same set
of properties.
Causation, by contrast, is asymmetrical; if A causes B, it does not follow that B causes
A. If a rock thrown in a pond causes
ripples in the water, it does not follow that ripples in the water cause the
rock to be thrown in the pond. And causation does not obey Leibniz's Law (flying rocks and pond ripples have very
different properties).
Once the obvious differences between causation,
correlation and ontological identity are laid bare the weaknesses of the
“causation argument” and the “correlation argument” are clear. Under
appropriate conditions, brain states may be shown to cause, or correlate with
conscious experiences, but it does not follow that conscious experiences are
nothing more than states (or, for that matter, functions) of the brain. To demonstrate that, one would have to
establish an ontological identity in which all the properties of a conscious
experience and corresponding brain state are identical. Unfortunately for reductionism, few if any
properties of experiences (accurately described) and brain states appear to be
identical.
In short, the causes and correlates of conscious
experience should not be confused with their ontology. As it happens,
various nonreductionist positions
such as dualist-interactionism, epiphenomenalism and modern dual-aspect theory agree that consciousness (in humans) is
causally influenced by and correlates with neural events, but they deny that consciousness is nothing more
than a state of the brain. As no
information about consciousness other
than its neural causes and correlates is available to neurophysiological
investigation of the brain, it is difficult to see how such research could ever
settle the issue. The only evidence
about what conscious experiences are like comes from first-person sources,
which consistently suggest consciousness to be something other than or
additional to neuronal activity. Given
this, I conclude that reductionism via this route cannot be made to work (cf Velmans, 1998).
False
analogies.
Faced with this difficulty, reductionists usually
turn to analogies from other areas in science, where a reductive, causal
account of a phenomenon led to an understanding of its ontology, very different
to its phenomenology. Francis Crick (1994), for example, makes the point that
in science, reductionism is both common and successful. Genes for example turned out to be nothing
but DNA molecules. So, in science, this is the best way to proceed. While he recognises that experienced
(first-person) “qualia” pose a problem for reductionism, he suggests that in
the fullness of time it may be possible to describe the neural correlates of such qualia.
And, if we can understand the nature of the correlates we may come to
understand the corresponding forms of consciousness. By these means science will show that “You're nothing but a pack
of neurones!”
It should be apparent from the above that finding
the neural correlates of consciousness won't be enough to reduce people to
neurones! The reduction of consciousness to brain is also quite unlike the
reduction of genes to DNA. In the
development of genetics, “genes” were initially hypothetical entities inferred
to exist to account for observed regularities in the transmission of
characteristics from parents to offspring.
The discovery that genes are DNA molecules shows how a theoretical
entity is sometimes discovered to be “real.”
A similar discovery was made for bacteria, which were inferred causes of
disease until the development of the microscope, after which they could be
seen. Viruses remained hypothetical until the development of the electron
microscope, after which they too could be seen. These are genuine cases of materialist reduction (of hypothetical
to physical entities).
But it would be absurd to regard conscious experiences as “hypothetical entities”, waiting for their neural substrates to be discovered to make them real. Conscious experiences are first-person phenomena. To those who have them, they provide the very fabric of subjective reality.