This is a summarized version of a long debate I had with Bill Adams on the epistemology of conscious experience, or the debate between Direct Perception v.s. Representationalism in September 2005.
See also the Cartoon Epistemology
SL: Introduction
BA: Very enjoyable thanks. Some missteps & false dichotomy.
SL: Care to elaborate?
BA: What is an image? What is a representation?
SL: Solid volumes with colored surfaces in a spatial void.
Bill Adams' Response to Cartoon Epistemology
BA: My reactions to Cartoon Epistemology
BA: 1: Two frames of reference & how to switch between them.
BA: 2: Pictures are mental judgments. The eye is not a camera
BA: 3: False statement: Sides of road are not straight and parallel.
BA: 4: The appearance diverges from agreed upon reality.
BA: 5: Two realities? How to switch between them?
BA: 6: Our bubbles are synchronized by mind-independent reality?
BA: 7: Mind must be non-causal or it violates conservation of energy.
BA: 8: How do you see discrepancy if you can't see the external world?
BA: 9: How can brain see itself? Capacity for self-reflection?
BA: 10: How to see the discrepancy if you can't see the external world?
BA: 11: Are there three realities? Or four?
BA: 12: The sensorimotor homunculus is not the rational self-reflective homunculus
BA: 13: What kind of "force" is "motivational force?"
BA: 14: What is the other reality? The brain or the world? Contradictions.
BA: 15: Your swipe is not fair. You defeat a straw man.
Steve Lehar's Response to Those Points
SL: 1: The promise was fulfilled!
SL: 2: A photo is an image; The eye is like a camera.
SL: 3: The phenomenal world is both straight and curved.
SL: 4: Phenomenal perspective is not social consensus.
SL: 5: We experience a warped view of an undistorted world.
SL: 6: There is an objective external world.
SL: 7: Experience is causal, not an epi-phenomenon.
SL: 8: We see the world through experience.
SL: 9: We know a dream through its inconstancy. There is no experiencer.
SL: 10: Same as point 5.
SL: 11: There are only 2 realities.
SL: 12: Body-image is not the self-reflective homunculus. There is no need for one.
SL: 13: A mental force moves mental objects.
SL: 14: There are two realities; mental experience is in the brain.
SL: 15: How have I misrepresented?
Bill Adams' Response
BA: Comments on SL's rebuttal.
BA: 1: The duality of phenomenal experience.
BA: 2: Are there images without observers?
BA: 3: On mental synchrony.
BA: 4: The causality of experience.
BA: 5: Kantian duality.
BA: 6: The inner surface of your skull.
BA: 7: Mediated v.s. direct visual experience.
BA: 8: The homunculus.
BA: 9: Representationalism, science, and materialism.
Steve Lehar's Response
SL: Comments on BA's rebuttal.
SL: 1: The duality of phenomenal experience.
SL: 2: Seeing your retinal image.
SL: 3: Images without observers.
Bill Adams' Response
BA: Comments on SL's rebuttal.
BA: Dualism
BA: Immaterialism and Spiritualism
BA: Visualizing Mental and Physical
BA: Causality
BA: Mind and the Laws of Physics
BA: Occam's Razor
BA: Conjectures and Refutations
BA: The Scope of Science
BA: Scientific Observation
BA: An Inconclusive Conclusion
Steve Lehar's Response
SL: Comments on BA's rebuttal
SL: Dualism
SL: Immaterialism and Spiritualism
SL: Visualizing Mental and Physical
SL: Causality
SL: Mind and the Laws of Physics
SL: Occam's Razor
SL: Conjectures and Refutations
SL: The Scope of Science
SL: Scientific Observation
SL: An Inconclusive Conclusion
SL: 8 Final Questions
SL: 1. Is your experience spatially structured?
SL: 2. Where is your visual experience located?
SL: 3. Is there an objective external world?
SL: 4. Do you see the warped ruler as regular and warped?
SL: 5. How would your experience differ from the diorama?
SL: 6. What would subjects say in Hallway Experiment?
SL: 7. Does mind change the state of the brain?
SL: 8. Would this be a scientific hypothesis? [invisible sphere]
Bill Adams' Response
BA: Comments on SL's rebuttal.
BA: 1. Is your experience spatially structured?
BA: 2. Where is your visual experience located?
BA: 3. Is there an objective external world?
BA: 4. Do you see the warped ruler as regular and warped?
BA: 5. How would your experience differ from the diorama?
BA: 6. What would subjects say in Hallway Experiment?
BA: 7. Does mind change the state of the brain?
BA: 8. Would this be a scientific hypothesis? [invisible sphere]
Steve Lehar's Response
SL: Comments on BA's rebuttal.
SL: 3. Is there an objective external world?
SL: 4. Do you see the warped ruler as regular and warped?
SL: 7. Does mind change the state of the brain?
SL: 8. Would this be a scientific hypothesis? [invisible sphere]
Hi Bill,
On the subject of subjectivity, and reflexive examination of experience, I thought you might enjoy this Cartoon Epistemology.
http://cns-alumni.bu.edu/~slehar/cartoonepist/cartoonepist.html
Steve Lehar
Thanks, Steve, very enjoyable. I could show the series to my cogsci
class.
I have defended Gibsonian direct perception in the past. I did a
post-doc with him in the late 70’s. But I drifted away from his
point of view as I discovered that it was not really a single point of
view, but a melange of many incompatible ones.
My theoretical feedback on your cartoon is that it makes a couple of
missteps that lead to a false dichotomy at the end. But it’s a
clever strategy. If you can get the reader to accept the frame of
reference, then you control the kinds of questions that can be asked.
[Note:Underline highlights key points addressed
in the response.]
Would you care to elaborate on the missteps and the false dichotomy?
Most of my anti-representationalist friends agree with most of the
responses of the little fat guy. In fact those responses are modeled
on the many debates I have had with different people over the years,
so I thought I had a pretty good handle on the arguments of the
opposition. But if I have missed something I would be interested to
know about it. As you know, nobody fits exactly into discrete
categories, and there are an infinite variety of variations.
As for alleged missteps, as you know they are in the eye of the
beholder. But I would ask you these three questions:
First, visual experience is (in my view self-evidently and
indisputably) spatially continuous and volumetric. Every point on
every visible surface is experienced simultaneously and in parallel,
and every point is perceived in a specific spatial relation to every
other point in that surface in three dimensions. And all of the points
in a surface are perceived as a spatial continuum within the surface
to a certain spatial resolution, and the surface is perceived to be
embedded in a 3-D volumetric space. In other words, visual experience
takes the form of...
In other words, visual experience is expressed in the form of an
*analogical* representation.
Lets leave point 3 until I hear your reaction to this much.
My reactions [to the Cartoon Epistemology] may be of interest to you.
Husserl identified the “natural attitude” in which the world is
accepted naively as it appears, and the “phenomenological
attitude” in which the world is not as it first seems
(“strange” as you say). To switch from the natural to the
phenomenological, one performed a mental gymnastic called the
“transcendental reduction.” You, apparently, are adept at it.
Husserl never could explain why there should be two apparently
incompatible frames of reference, nor how, exactly, one switches
between them. Your introduction seems to promise that you will
explain. In the end, that promise was not fulfilled.
[Note:Underline highlights key points addressed
in the response.]
There is a picture on the camera’s film only because some human
being says so, just as there is a face on the moon for the same
reason. Do you agree that there is no objective face on the moon? But
you seem to think that there is an objective, mind-independent picture
on the film. Why? There is no face on the moon and there is no
picture on the film.
“Pictures” are mental judgments. The pattern of silver nitrate
precipitates on the exposed film is a consequence of the refractive
properties of the camera lens. We, the visually perceiving humans,
look at the pattern and say, “It looks similar to the scene beyond,
only smaller.”
The difference between the chemicals on a film and the activity on a
retina is that nobody is looking at the retina, least of all
the owner of the retina. Nobody ever says, “It looks similar to the
scene beyond.” Not even the brain can do that.
The analogy between eye and camera is thus unsound.
But they’re not straight and parallel as far as the eye can see.
As far as the eye can see is the horizon, where the curbs converge at
a vanishing point. So the statement is patently not true. Why start
out with a false statement?
What you want to say perhaps is something like, “Despite
appearances to the contrary, we have agreed, by consensus and
intellectual tradition, that the curbs are parallel all the way to the
horizon. The appearance diverges from that agreed-upon reality.”
However, in a surprising move, you suggest instead that we take the
melon rind as the reality.
This suggestion subtly shifts the discussion from reality and its
appearance, to a scenario in which there are two realities, one a
scale model transform of the other. Some perceiving subject perceives
them both and finds a discrepancy.
That’s a huge shift in assumptions and it should have been made explicit.
You simply assume that our bubbles are “synchronized.”
There’s no way you could know that, of course.
But since you assume it, then you have to explain it, and your
preferred explanation is that the mind-independent reality beyond
perception, what Kant called the noumenal world, is causal, while the
bubble world is merely the effect of the external world.
You make an error however when you say that there must be a real house
there to be the common cause of both perspectives.
A “perspective” is a function of the perceiver’s unique
location in time and space. It is not caused by the house, but by the
perceiver.
What you should have said was that the noumenal house is the cause of
each bubble. You don’t know if the bubbles are identical. In fact
we know that they are not, since two individuals cannot occupy the
same space at the same time. They have different perspectives.
Mind would have to be a non-causal consequence of brain
activity (a byproduct), otherwise physical laws of conservation of
energy are violated. So the bubble reality, being mental, is only an
effect, not a cause. So in comparison to WHAT, would mental
experience ever be strange? It simply is what it is.
You seem to assume that the mind can magically bypass brain and have
direct access to the external world. It then compares its “direct
access” to the world with what the brain provides, and finds a
discrepancy. But that is an impossible and illogical scenario.
Well, somebody has to see the external world directly. Otherwise, how
do we know that there is a “strange” discrepancy, and how could
we hypothesize a transform function between the realities?
Your idea here is logically inconsistent (as was Kant’s idea of the
two worlds). If all you know is the bubble reality, how do you know
there is a skull beyond that reality? You can’t know what is
beyond knowledge. You can’t perceive what is beyond perception.
Furthermore, seeing the world “through private conscious
experience” of it, is problematic. The private conscious
experience IS the seeing experience.
When you use the word “through,” you imply that the subjective
locus of seeing is somehow different from the seeing experience. Like
a person going “through” a doorway, or looking “through” a
telescope. What entity is it that sees “through” private
conscious experience? Your proposal here is uninterpretable.
Hallucinations and dreams are only interesting because of the
discrepancy they present between the external and bubble realities.
But how does that discrepancy arise if the mind knows only what the
brain gives it?
Actually, in your thesis, the mind would not even know the bubble
reality. The mind IS the bubble reality. From what point of view
would the mind be able to realize that it is “IN” a bubble
reality?
Self-awareness is required in order to reflect upon the processes and
products of perception. But as an inert byproduct of brain activity,
mind would not be capable of self-reflection. It perceives, but
cannot know that it perceives. There would therefore be no bubble
reality, only “reality.”
Without a homunculus, there is no discrepancy between appearance and
reality and you have no problem to solve.
The brain only processes the activity of the receptors. It knows
nothing of “the world”. Only the mind knows the world. It’s
no good to pretend that the brain is a mental homunculus.
If you are trying to suggest that all we ever perceive, mentally, is
brain activity, then the brain IS the world, as far as perceptual
reality is concerned. But in that case, no discrepancy could ever
arise between appearance and reality.
Are you now suggesting that there are THREE realities: External
world, brain representation, and mental experience?
The phrase “internal replica” is ambiguous. Does it refer to
the brain representations, or to the bubble reality of experience?
If you seriously mean that one “sees the remote external world
THROUGH the medium” of a replica, you would have to invent a FOURTH
reality where some homunculus could sit and view the bubble reality,
and compare it to the other two realities, brain map and external
world.
If, on the other hand, you mean to say that the internal replica is
the brain representations, then the bubble reality is merely a
transform of the brain representations. Mental experience is thus of
the brain and we can forget about the so-called external world.
So, which of these two incredible hypotheses are you endorsing:
There are FOUR realities, and perception involves #4 (the homunculus)
reflecting on the others, or Visual experience is actually perception
of the brain. The world is irrelevant.
Your “perceptual homunculus” is just another brain activity.
That’s fine, although misleading to call it a homunculus. It is
more like a sensori-motor comparator. What brain scientists call the
sensory homunculus is simply a set of cortex areas mapped to
receptors. That’s not what you mean. You are talking about an
active, computational sensori-motor comparator.
But your sensorimotor homunculus it has nothing to do with the mental,
rational, self-reflective homunculus required for you to support the
hypothesis that perception involves viewing the external world *via*
the medium of the bubble world, the way a person might view the world
through rose tinted glasses.
The idea of motor representation in the brain is non-controversial,
and your presentation of it is entertaining, as is your discussion of
sensori-motor coordination. But it doesn’t have much to do with
your thesis. And it does NOT excuse you from accounting for a mental
homunculus. Sensorimotor coordination does not explain WHO sees the
world *through* visual experience.
Indeed, you introduce a second mental homunculus in the motor
discussion when you assert ‘free will’, or perhaps you mean only
to expand the powers of the original mental homunculus (which you do
not acknowledge) from evaluation of visual experience to exertion of
intentionality, or will. Either way, your sensorimotor comparator
does not meet the requirements you need to support your theory.
I will not comment on your theory of motivation until you tell me what
kind of a “force” a “motivational force” is supposed to
be.
Your thesis (as best I can understand it) is that the world we see
is the bubble world, a transform of some other reality. It is unclear
what you think the other reality is.
Sometimes you suggest it is the brain (sensori and motor
representations), and other times you suggest it is the external world
itself. Both hypotheses have internal contradictions.
If mental experience is of the brain, then the external world is
not relevant to your theory of perception (and indeed, cannot even be
known). But in that case, there is no possibility of a discrepancy
between brain operations and mental experience.
If mental experience is a picture of the external world, then you need
a mental homunculus to make the judgment that it is looking at a
picture of the external world, to compare the picture to the external
reality, and say, “This picture is similar to the scene beyond.”
The homunculus would have to magically know about the external world.
Your swipe at the theory of direct perception is not really fair,
since you only presented that point of view as a straw man.
There’s no denying that this is a creative and entertaining way to
present some important concepts in perceptual theory, Steve. Thanks
for doing it, and for making it available to me.
Best regards,
Bill Adams
Response to the many points:
That promise was very much fulfilled, and it was fulfilled with a
unique and original observation: That the phenomenal world is both
straight (Euclidean) and it is curved. The sides of the road
are perceived to be straight and parallel, and yet they are also
perceived to meet at a point, and this is explained by the fact that
our reference scale by which we judge objective size and
straightness is itself bent, or warped. The duality of experience is embodied
in the representation itself. This duality is an observed property of
the experience itself, without regard either to the geometry of the
external world, nor to the neurophysiological mechanism in the
brain. To "switch between them" you attend either to the
shape of the experience itself, which is warped and bulgy, or to the
geometry of the warped and bulgy reference grid, whose curved lines
and shrinking perspective are by definition actually straight
and parallel and equally spaced. If you ignore the curvature of the
visual world, and see the road as straight, and ignore the fact that distant
objects appear smaller, (as we commonly ignore in everyday experience)
then you are perceiving the objective component of the
experience. Both the curved and the straight geometry are observed
properties of the phenomenal world.
If you deny that you see the world as warped and bulgy, check out my Hallway
Experiment and tell me if you would answer the questions any
different than my subjects did.
An image on the photosensor array of a video camera is only a picture
to a human user of the camera, it is not a picture to a computer
that copies and processes that video data. [Paraphrased]
This concept, cleverly disguised as merely a question of definitions,
is actually the key concept behind the Gibsonian view of perception,
and it embodies the key epistemological error of that way of
thinking. This foundational assumption needs to be examined and
justified, rather than presented as a statement of indisputable fact,
because the whole question of the directness of perception (or
otherwise) hinges critically on this "definition".
In the first place the definition of what is or is not a picture is a
matter of consensus, or how people generally understand the concept,
rather than a question of dogma or logical necessity. And most people
would consider the image at the back of your retina to be a "picture",
as they would a pattern of light on the photosensor array of a video
camera, whether or not there is somebody viewing it. The whole field
of digital image processing is based on the notion that it is pictures
or images that are being processed. Image processing operations such
as image convolution are spatial computations with spatial effects on
the spatial properties of the processed image. It would be absurd to
define these as non-images unless or until a user shows up to "see"
them. Wouldn't it be more reasonable to define images as spatial
patterns in some medium contrived to represent the spatial pattern of
something else, like the brightness of light on a picture plane? This
definition would be agnostic to whether it is "viewed" by a human or a
robotic "observer", or by any observer at all.
I agree that there is no objective face in the moon. But would you
agree that there is a face in the moon to a computer image
recognition program that is tuned to detect faces? If given an image
of the moon, it will try to interpret the image in terms of its stored
prototypes or tempates. If there is enough similarity, the face
detector will trigger, and the program "sees" the face in the moon. To
the computer program, there is a face in the moon, and to the
computer programmer it is meaningful to talk of the existence of
objective "faces" in images, as defined by the probability that they
would trigger the face detector, and people can meaningfully talk of
the objective existence of faces in photographs as defined by the
probability of being recognized as faces by other people.
But why does a Gibsonian object so vehemently to what is just a
question of definitions? Why is this very notion pronounced taboo? A
"category error"? Self-evidently false? It is taboo because just
allowing that there are pictures in video cameras, immediately raises
the obvious analogy between the eye and a video camera. Both
have lenses, and adjustable apertures, light-sensitive photosensor
arrays, and wires to transmit an image to a computational
brain. How can one reasonably deny
that the eye works like a video camera in that it records an image and
transmits it to the brain?
Now it may be that the eye works by an entirely different principle,
as Gibson suggests. But until that other principle can be explicitly
described and conclusively demonstrated, (which Gibson did not provide) the
simplest, most parsimonious explanation favored by Occam's Razor, is
that the eye records an image and transmits it to the brain. And if
this first stage of sensory processing already makes use of a
representation, representing a pattern of light with a pattern
of electrochemical activation, then representationalism is at least
workable in principle. In fact the principles of representationalism
have been demonstrated in actual robot models equipped with video
cameras that transmit images to a computer brain for processing.
Gibson's
dogmatic denial of the existence of images in the brain or even on
the retina, all stem from his foundational epistemological assumption
that the spatial structures that we see in our experience are the
spatial structures of the world itself. That there is no
representational entity, the sense data, that stand as
intermediaries between the world and our experience of it. But this
hypothesis must be proven against the more obvious representational
alternative. One cannot simply begin with the assumption that
perception is direct, as an axiomatic fact. This is supposed to be
Science, not dogma. That initial assumption needs to be
justified against the representationalist alternative. And it needs
to explain how perception can be direct when the experience is a
dream, or hallucination, which are definitely "image-like" spatially
structured experiences. Where are those hallucinated images if not in
the brain? How can we experience a spatial structure that does not
exist in the material universe known to science? Is the brain not just
a computational machine?
There is a duality in phenomenal perspective; it is experienced to be
curved like a fish-eye-lens view, with distant objects appearing
smaller, and yet we also perceive the world as undistorted, with
distant objects undiminished in perceived objective size. In everyday
naive perception (natural attitude) the curvature is invisible to us,
we would swear that the sides of the road are straight and parallel
along its entire perceived length, and we can easily tell when the
road actually narrows, as opposed to narrowing due to perspective. In
naive perception the sides of the road are perceived to be
straight and parallel and equidistant, even as they clearly converge
to a point! This may not be true of a two-dimensional
photograph of a perspective scene, but it is certainly true of
a real road viewed in the world.
This statement is not false!
No! That suggests it is some cognitive reasoning process or social
consensus. But the ability to compensate for perspective is far more
pre-attentive and beyond cognitive influence, a more primal and
hard-wired primitive function. No-one could convince you to perceive
the road as converging when you can see that it isn't, or
vice-versa. And yet that judgment is easily fooled by contrivances
like the
Ames' Room, and by perspective
dioramas that engage and deceive that same automatic perspective interpretation mechanism.
Perceptual constancy has been confirmed even in simpler animals. For
example newly hatched chicks who, when trained to peck at the larger
target, even pick correctly when the larger target appears smaller by
perspective. This is a very low-level hard-wired function that must be
common to virtually all visual animals.
I am NOT taking the "melon rind" as "the reality", I am merely
pointing out the observed properties of experience. If you
contest my observation, then please tell me what it is that you
observe. Because what I observe is two sides of the road which
I could swear appear straight and parallel as far as the eye can see,
and yet I also see those two sides meet at a point up ahead and back
behind. They do not appear to be curved like a melon slice, but they
appear straight and parallel along their entire visible length, and
yet paradoxically, they also meet at two points which are well short
of infinity, as if they were curved like a melon slice.
We do not perceive both realities and then notice a discrepancy
between them. Instead, we experience a warped and distorted world,
which we automatically and pre-attentively assume to be a warped view
of a straight world. That "assumption" is embodied literally in the
bulgy reference grid that we automatically perceive invisibly
superimposed on the warped and bulgy experience.
The principle behind this perception can be seen even when
looking at a distorted picture like this one:
Anyone looking at this picture would immediately see that it depicts a
distorted fish-eye lens view of an undistorted world. You can see that
the road is "supposed to" be straight, and that the two houses are
"supposed to" be the same size and shape, even though your direct
experience is of a curved world with distorted houses. Your perceptual
apparatus automatically and pre-attentively interprets the curved and
bulgy world as a warped view of a straight Euclidean world, even
though it has to tolerate a gross violation of Euclidean geometry in
doing so, and allow that parallel lines meet at two opposed points at
a distance well short of infinity.
In the picture the curvature is perfectly apparent, whereas when
standing on a real road, the curvature is virtually invisible, only
the gross violation of Euclidean geometry remains apparent. But the
principle by which you see a straight Euclidean world "through"
a distorted fish-eye lens world in this picture, is the same principle
by which we see the Euclidean geometry of the perceived world through
our warped experience of it.
Yes, I assume different people's experience is automatically
"synchronized" by a common objective external world. That is a core
assumption of science itself. Science assumes the existence of
an objective world, and studying that world is the objective of
science. To propose that our individual experiences are not
coupled veers towards solipsism, which I take to be
self-evidently false. Surely you don't subscribe to Husserl's extreme
phenomenological view that there is no objective reality, all that
exists is our experiences. Do you?
I don't follow your point on the causality
issue. The shape of the experience is a function both of the objective
shape of the house, and of the location of the perceiver. But I
do assume that there is an undistorted Euclidean house out
there that is the cause of the shape of my distorted experience of
it. Is that an error?
I don't subscribe to the notion that experience is non-causal,
that consciousness is an epi-phenomenon with no functional
value. For something as majestically intricate and elaborately
articulated as our conscious experience, to have evolved to such a
high level of sophistication while serving no functional role, seems
vanishingly unlikely in a Darwinean context.
Furthermore, the causality of experience is demonstrated by the fact
that a purely mental thought, such as "I raise my arm" can be made to
have direct causal consequences in the actual movement of my arm. This
is not a violation of the conservation of energy. It merely
states that mind is not some etherial non-physical entity somehow
magically superimposed on the physical brain, but rather, that mind is
itself a pattern of physical energy causally present in the physical
brain, and that is why mind can have direct causal consquences both
directly on the state of the brain, and indirectly on the state of the
body through motor action. This is the basis of identity
theory, that mind is identically equal to certain processes in the
physical brain, rather than an epi-phenomenal byproduct of the brain
with no functional value or causal potency. Although identity theory
cannot be proven to be true, neither can it be shown to be false, as
is commonly but mistakenly assumed. And identity theory provides the
most parsimonious explanation for the existence of consciousness in a
Darwinean world.
The Bubble Reality is therefore both mental and physical. Its mental
component is seen in the patterns that it exhibits in experience, and
its physical component is the physical substance of which experiences
are expressed or represented in the brain.
The mind does not "magically bypass" the brain and does not have
direct access to the physical world, but rather it attains its
information about the world indirectly, through sensory detection and
internal representations, and it plies its causal influence indirectly
through internal motor representations and motor commands.
The discrepancy detected by the mind is not a discrepancy between the
world and its representation, but rather a discrepancy between the
world of experience and our expectations of that experience. We
do not expect physical objects to morph elastically as we view them
from different aspects, our mind finds it more parsimonious to assume
that the morphing experience is a perspective transformation of an
object with fixed size and shape, and it is that fixed or invariant
configuration that we experience in naive perception (natural
attitude) despite the morphing of the actual experience.
As explained above, the discrepancy is not
between the world and its representation, but between the warped
experience and our expectations of an invariant, un-warped
objective world.
This idea is not logically inconsistent, nor is it at variance
with Kant's nouminal and phenomenal worlds. Kant declared that the
only way we can perceive the nouminal world is by its effects in the
phenomenal world. Wherever we see irregularities and inconsistencies
in the phenomenal world, objects zooming unaccountably through different
sizes, objects morphing elastically through different shapes, parallel lines
meeting at two points short of infinity, we try to account for them as
perspective transformations on rigid objects, because that is the most
parsimonious interpretation of our experience.
We do not see the objective world and its properties directly, but
rather we infer its properties from the world of experience
that we do see, by way of the warped reference grid.
As for your complaint about the wording: "seeing the world 'through'
private conscious experience of it." This is not problematic if you
understand that "through" is being used in the sense of "by way of",
the same way that we see the remote world "through" our television set
by way of the medium of glowing phosphors on a glass screen, that
gives us the illusion of seeing the world literally "through"
the television as if through an open window.
As with the television analogy, the subjective locus of seeing is in
the representation, i.e. in the glowing phosphors on a glass screen,
even though the pattern apparent on that screen represents a remote
external scene. According to representationalism, it is possible to
"see" something remote by way of the representational medium in your
brain, without ever actually "seeing" anything beyond your brain.
I understand that your objection to this terminology is rooted in your
objection to the whole notion of sense data as intermediaries in the
act of seeing, which you consider to be impossible in
principle. Although I don't aspire to convince you otherwise, I hope
you will at least concede that the representationalist view of
perception is at least equally plausible as the direct
perception view, and that it is not dogged by insoluable
paradox as is often assumed, or at least no more than the alternative
direct perception view, a view that is in fact dogged by the
insoluable paradox of how something can be experienced that is not
explicitly represented in your brain.
The only way the mind can notice a case of dream or hallucination is
by the inconsistency and inconstancy of the dream or hallucination,
where unlike in waking experience, people and objects can morph
unaccountably into different things, and the plot, or story line of
your experience often takes abrupt and illogical turns.
The way we know of the objective properties of perceived objects is by
their observed constancies. Objects have existential permanence, they
don't tend to appear or disappear unaccountably, as illusory objects
often do. We can usually find them where we last left them unless
somebody else moved them in between. Objects morph by perspective, but return to
the same shape when viewed from the same perspective, as if they had
an objective unchanging shape underneath their changing
appearance. Other people report seeing the same objects we can see,
and the same places in the world, as if we were all living in the same
world that continues to exist even in our absence. We can never be
absolutely certain of the existence of that objective world, because
we can never see it directly. But we can be pretty sure of the
objective existence of the people and objects in our everyday world,
or at least, about as certain as it is possible to be certain of
anything.
How does the mind experience itself in the absence of an "experiencer"
there to experience the experience? This is the old homunculus
objection.
The straight answer is that we don't know how the brain can
experience its own spatial structure, or why it should produce certain
patterns of experience in the process of perceptual computation. We do
however know for a fact that we have experience, that experience exists,
and it exists in the form of a vivid spatial structure, like the
experience of the world you see around you, the one that disappears
whenever you close your eyes. Wherever it is located, and of whatever
it is composed, that experience exists, and it exists in the form of a
volumetric colored structure that comes into existence only when my
brain is engaged in perception. The only question is where is that
structure, and of what is it composed?
Gibson's explanation is that the experience is located out in the
world, on external objects themselves. But he does not explain how
that experience comes to appear on external objects when it is a
product of the brain, nor does he explain what that experience is
composed of, or by what mechanism it is constructed by the brain, or
how it can hold spatial information in the absence of a spatial
representation. So the problem of experience is at least as
mysterious in the Gibsonian view as in the representationalist view.
In fact it is far more mysterious and paradoxical than the
representationalist view. Because according to representationalism,
the patterns of our experience are physically located as patterns of
energy in our physical brain, causally coupled to sensory input and
motor output through nervous pathways. In the Gibsonian view
experience is located out in the world, but is a consequence of
processes in the brain. There is a vital causal link that is missing
in that explanation, the causal link between the brain and the spatial
experience that it projects into the world. The experience, as a
spatial structure, is undetectable by scientific means in the space
where it supposedly exists. It is a structure that is experienced,
but does not exist. Surely it is more parsimonious to assume that
experience is a structure in the brain, constructed in the service of
perceptual computation.
Representationalism begins with the confident assumption that
conscious experience will eventually succumb to a physical, scientific
explanation, as a physical process in the physical brain. The brain is
a computational device that operates on physical principles, so it
must be possible in principle to build a machine that has experience
by the same basic principle. Let us set out to discover the brain
mechanism behind the phenomenon of visuospatial experience, and how it
paints the pictures of our experience, rather than to deny that our
experience is spatially structured, and give up the search before it
has hardly started.
No there are not three realities, nor four (!) only
two, the nouminal world and the phenomenal world. But the
phenomenal world has two manifestations, objective and
subjective. Subjectively the phenomenal world is the spatially
extended volumetric world of our experience. Objectively, the
phenomenal world is a representation in our brain: That is, it is an
actual physical substance or field of energy that is experienced as a
spatial structure whenever it comes into existence, and vanishes into
non-experience when the field breaks down, like the image on a
television screen when the power is turned off.
This is the aspect of representationalism that is the hardest to
swallow. How can a field of energy in your brain become conscious of
its own existence and spatial structure? I admit from the outset that
this seems at first sight to be frankly incredible.
But what is incredible is that we do have experience, and yet we know
for a fact that experience exists. And as a materialist, I would like
to believe that experience must have a physical basis in the brain.
But the Gibsonian "direct perception" view does not escape this
same paradox! If perception were direct, it would
still be a mystery how we come to experience the world. In
fact, in the Gibsonian world view this paradox only deepens
because now we are expected to believe that we can become magically
aware of objects and surfaces outside of our body, out in the
world itself, where there is no computational or representational
hardware available.
It is more parsimonious, and less deeply mysterious, to claim that we
can become aware of patterns of energy in our brain, than of patterns
out in the world beyond our brain.
Quite correct. The body-image homunculus is not the self-reflective
homunculus that "sees" the world of the internal theatre. That body is
a perceived object, composed of the same "substance" as the rest of
the experienced scene, because the picture of the world would be
incomplete without a picture of one's own body in the world.
According to representationalism, you do not need a viewer to view the
internal scene. Patterns of energy in the brain correspond directly to
patterns of shape and color in our experience, just as the pixels in
an image data array correspond directly to pixel brighnesses in an
image.
We do not see the blue sky out there from in here behind our
eyeballs, but rather, we experience the blue sky to exist out there at
the location it is perceived to occupy. If my body-image homunculus
were to disappear, I would have a disembodied experience, like an
invisible ghost, but my experience of the blue sky out there would
continue in the absence of any kind of viewer at the egocentric point.
In physics a force is something that can set objects into motion. In
the mind a force is something that can set mental objects into
motion. The body image homunculus is drawn by a mental force of
attraction that moves it towards attractive stimuli.
But since the body-image homunculus is coupled to the posture of the
external nouminal body, the causal force of mental motivation has its
effects both on the internal model of the body directly, and on the
external physical body indirectly where it is expressed as an actual
physical force that pulls it in the direction of the attractive force
in the mental representation.
Causality can only be transmitted from
mind to brain if mind is a physically measurable entity with an actual
presence in the world known to science.
There are two realities: The physical world known to science, composed
of matter and energy in space, and the phenomenal world that consists
of volumetric colored spatial patterns of experience in phenomenal
space. If mind is to ever succumb to a rational, materialistic
explanation, then the patterns of mind must necessarily correspond to
patterns in some physically measurable medium in the brain. Mind and
brain are not separate, one being physical while the other is pure
experience, but rather mind is a physical pattern explicitly present
in the brain.
Mental experience is in the brain, but the external world is
still relevant, and can be known indirectly through those
representations, because the representations take on the shape of the
external objects they represent, and thus we can see the shapes of the
external world through the medium of their perceptual effigies. There
can indeed be no discrepancy between brain operations and the
corresponding mental experience. But there can be plenty of
discrepancy between mental experiences and the world that those
experiences attempt to represent, especially in the case of dreams and
hallucinations.
Mental experience is indeed a picture of the external world, but you don't need a homunculus to make a judgment that it is looking at the world.
Well please enlighten me as to where I have misrepresented direct
perception, so that I can represent it more fairly.
Thanks very much for your feedback. Hope to hear more from you!
Steve Lehar
Hi Steve,
Thanks for formatting our conversation into HTML, and I presume,
posting it. I think the dialog is stimulating and potentially useful
to others.
I have a few comments on your rebuttals. I will avoid going over old
ground and focus only on the most important points we have disagreed
on, in the interests of mutual understanding.
You say the phenomenal experience is straight (Euclidean) and curved.
I cannot experience both aspects simultaneously. At best it is like
the oscillation of Necker cube aspects. The switching time between the
two modes seems quite fast, but not zero. If you say you can
experience both aspects at once, then our perceptual experience
differs fundamentally.
Your explanation of this duality is, for me, perplexing. If the
reference scale by which we judge objective size and straightness is a
bubble, then how would it be possible to ever experience the bubble
itself? No matter what you looked at, you would get Euclidean
geometry.
One answer might be that you mentally discard the reference scale in
order to experience the bubble world. But if use or non-use of the
reference scale is optional, and apparently under conscious cognitive
control, then all you have done is reassert my proposition that there
are two alternating attitudes for apprehending phenomenal experience.
And we still lack an explanation of how or why, one switches between
modes.
Saying that the duality is an observed property of the experience
itself is misleading. It is a subjective rather than an objective
property of the experience. I think it is an error of reification to
objectify it.
My interpretation of the duality as bimodal is consistent with the
results of your hallway experiment, and, I suggest, more consistent
with the actual questions and answers of the experimental protocol
than the idea that the experience itself is some kind of a hybrid
unity. (Ingenious experiment though!)
This is a fundamental point of difference. Forgive me if my point of
view sounds dogmatic, but I have a hard time seeing any reasonable
alternative.
The image on the back of the retina is a picture, I admit. Image and
picture are almost synonymous terms. I am not trying to split that
hair.
When a doctor looks into your eye, she might see your retinal image.
That’s fine. An image is an interpreted optical pattern. As long
as there is an observer to interpret, there can be an image. So I
accept the common sense view that the retinal image is an image.
However, we know that a person never sees their own retinal image. So
if we are talking about phenomenal experience, that is, first person
experience “from the inside” as it were, how the world appears
to one, it is quite clear that there is no retinal image. That is the
basis on which I say that there is no retinal image involved in the
experience of perception.
What about images in the third-person, scientific, observational
context? Even here, I do not agree that there are any objective
images. You give the example of a computer image recognition device
that is tuned to detect faces, and when pointed at a face or a picture
of a face, gives some appropriate output. This is supposed to
demonstrate the objectivity of images.
The example embodies a common error afflicting AI advocates. I
suffered under it for decades. A computer program or engineered
device is an implementation of the programmer or designer’s
assumptions, values, and rules for pattern recognition. The device
does not literally detect images. Its designer or programmer does, in
deferred execution, through the medium of the device.
When a novel is sitting on your bookshelf, do you think that the
characters are writhing about in the pages all day and all night? Of
course not. The drama represented in the novel is the author’s
story, communicated in an asynchronous mode. The author uses a medium
of deferred message delivery. The author might even be dead by the
time the reader receives the message. But at no time do we believe
that the book itself understands the drama written on its pages.
The analogy holds for the computer program. The programmer tells us
what he or she believes are good rules for pattern recognition.
Strong light usually comes from above. A size gradient indicates
depth of field. Properties of the optic array are such and such.
That’s fine. I admit that the programmer is a human being and can
recognize patterns according to certain rules and interpret some
patterns as representational images.
Writing out the rules for image identification and interpretation, and
storing those rules in a medium for later execution, does not confer
image-recognition powers to the storage device. To believe that it
does is an incredibly naive error to me (Although, as I say, I once
labored under that error. Today, I don’t see how I could have).
You say that objective faces in images can be defined by the
probability that they would trigger the face detector in a device. I
agree that people can meaningfully talk of the objective existence of
faces in photographs using that operational definition. It is
meaningful only in a sort of shop jargon however.
If the face detector is in a spacecraft like Voyager I, traveling
through interstellar space away from Earth, processing pictures
provided for it, and nobody will ever inspect its activity or output,
would you still say it is detecting faces? You might say so, and I
would say, “How do you know?”
You would show me copies of the pictures, which I would look at and
interpret as faces, and say, yes, those are faces.
And you would refer me to the text of the computer program or the
device specifications and I would agree, yes, those describe rules
that I could use to identify faces.
You and I can identify faces and we can even specify some of the rules
we use to do so. But the criterion of a face is still a mental
judgment. It is an error of reification to objectify that judgment,
and a non sequitur to point out that an engineered device can be made
to store a description of the judgment.
I think the reification error is prevalent because of the newness of
computers and robots in human experience. When television first came
out, people would try to peer down the edge of the screen to see what
the newscaster was reading. When the movies came out it was
literally, the magic lantern. We have not yet, as a culture, fully
absorbed information technology so we tend to misinterpret it.
Are there pictures in video cameras? Only in the trivial sense that a
video camera is a device designed expressly to implement certain
pattern recognition principles that capture and later present patterns
that look like images to a person. There are many other patterns it
could capture that we would not recognize as images, but who would buy
a camera that did that? I could say that a video camera contains
potential images, because its designed purpose is to isolate patterns
that a human readily interprets as images.
I do admit that an analogy can be drawn between eye and video
camera. As you say, both have lenses, and adjustable apertures,
light-sensitive photosensor arrays, and wires. But I believe the
analogy quickly becomes misleading rather than helpful.
For example, you say both have wires to transmit an image to a
computational brain. But here is where the analogy becomes invalid.
The wires transmit only signals, not images. Why? Because there is
no image until some human (or other visual observer) says there is.
If no biological visual systems had evolved, do you think there still
would be images in the world? Would a pond form an image of the
clouds above, according to you?
It is no good to say there is an image if there is a point to point
correspondence between A and B, since some visual observer must
identify that correspondence for it to exist.
I believe that Occam’s razor favors the more simple explanation,
that images are a mental judgment, not an objective fact.
I don’t defend the Gibsonian view that locates images in the world.
I locate images in the mind, as mental judgments, or interpretations
of sense data. I am the umpire who says, “It is neither a ball nor
a strike until I call it.”
The history of psychophysics demonstrated that for simple sensory
judgments, humans are remarkably consistent among each other and
within themselves over time. On that basis, we accept that we have
“the same” or within boundary conditions, very similar sensory
experience.
That agreement does not generalize well however, as the
Introspectionist school quickly discovered. For all but the most
simple sensory judgments, there is virtually no consensus on how to
describe a particular mental phenomenon.
I think the facts favor the hypothesis that our mental experiences are
not well coupled, and that we must continually negotiate an acceptable
shared reality. (As we are trying to do here).
In the context of your theory of perception, I accept the assumed
“synchrony” of simple sensory information, but reject the
synchrony of its interpretation as Euclidean or bubble-shaped. I
think our debate here illustrates that point.
I mis-attributed your position, apparently, when I called you an
epiphenomenalist. Sorry. I understand your endorsement of identity
theory, that mind is identically equal to certain processes in the
physical brain, electrical and biochemical processes, presumably.
However, I’m afraid I find that position incoherent. If I make two
lists, one listing the qualities of mental experience, and one listing
the features of the brain, there is virtually no overlap in the lists.
Ideas have no mass or volume. They do not absorb, emit, or transmit
heat, light, electricity, radiation, or any other kind of energy.
Call me dense, but I don’t see how anyone could seriously say that
mental events are physical. It distorts the way language is used.
Furthermore, there is a logical problem. If we grant that mind and
brain are identical, then you have no problem to discuss. Your only
task is the scientific description of the brain. In that case, what
is your cartoon epistemology about?
I realize that identity theory is a well-worn argument and there is no
point in us rehashing the whole history of that debate. I should say
though, honestly, and not as any sort of put-down, that it is my
impression that identity theory has become, if not discredited, then
at least out of favor in contemporary philosophy of mind.
In contrast, epiphenomenalism is a simple thesis: mind is a noncausal
byproduct of brain activity, occurring by mechanisms unknown. That
position conserves the laws of physics and allows the existence of the
mind, but explains nothing.
Every such solution to the mind-brain problem that I have ever
encountered, and there are a lot of them, has one or more fatal flaws.
There is no solution. I myself am a dualist, an interactionist. I
say mind and body are different realities that interact. Each has
causal efficacy. That seems most consistent with common sense
experience. How they interact is a puzzle I am still working out.
I think it is possible that we agree on an important point here. You
say that the discrepancy detected by the mind is not a discrepancy
between the world and its representation, but rather a discrepancy
between the world of experience and our expectations of that
experience. I think that is correct.
Expectations might arise from familiarity, consistency, subjective
probability.
But where we differ is in deciding what is the best inference to draw
from those expectations and their occasional violations.
You say it is more parsimonious to assume that morphing experience is
a perspective transformation of an object with fixed size and shape,
and it is that fixed or invariant configuration that we experience in
naive perception (natural attitude) despite the morphing of the actual
experience.
That is the standard scientific inference. But I don’t think it is
parsimonious, for it leaves unexplained precisely the problem that
interests us most, namely, what is the nature of the transformation?
Objects that recede appear smaller, but they’re not really
smaller. The disjunction between appearance and reality is exactly the
problem to be solved.
I think you have made an honorable confrontation with that problem
with your idea of the spherical frame of reference, but as these
comments indicate, for various reasons I am not satisfied with that
explanation.
You clarify your position when you say that we do not see the
objective world and its properties directly, but rather we infer its
properties from the world of experience that we do see, by way of the
warped reference grid.
I can accept that, and the implication that perceptual “error”
is simply what we call deviations from long term expectations about
phenomenal experience.
However, it is difficult for me to see how you get from those starting
assumptions to the conclusion that visual experience is surrounded by
a skull, except by the unconvincing equation, which I do not accept,
that visual experience is identical with the brain. With that
formula, all you are saying is that the brain rests within a skull.
It’s not clear why any inference is necessary for you. The brain
is its own experience. What more beyond that does it need?
I understand and appreciate your analogy between vision and CCTV. You
want to say that the (metaphorical) phosphors of the brain are the
consequence of a long causal chain of events that began with an energy
event in the world.
You emphasize in your discussion the relationship between the ultimate
phosphors (the representation) and the causally remote world event. I
have no problem with long chains of causality and I understand how a
television image gets on my screen and in what sense it represents a
remote event.
But making that technology analogous to vision results in a confusion
of first and third person points of view. From the first person point
of view, visual experience does not have the quality of being a
consequence of a long causal chain. On the contrary, it has the
quality of being direct, that is, unmediated by a causal chain.
From the third person (e.g., engineering) point of view, you infer
that if visual experience is caused by the brain, and brain activity
is mediated by a long causal chain, then first-person visual
experience must also be so mediated. I think that is an error of
reasoning.
However, I can see where you would not agree, since if visual
experience is the same thing as brain activity, then by definition,
visual experience is mediated.
However, for we dualists, visual experience is not identical with
brain activity, so we can say without contradiction that visual
experience is unmediated, or direct.
Visual experience can be intellectually analyzed into phenomenal sense
data components, such as the Gibsonian invariants, but that is a
different exercise than the direct visual experience itself, which is
Gestalty. Both Gibsons were adamantly anti-associationist, and they
converted me to that view.
However, I do not agree with the Gibsonian idea that visual experience
is direct because the Gestalt patterns are objectively in the world
and “picked up” by osmosis, or whatever. When Gibson got to the
end of his explanatory rope he resorted to the mysterious metaphor of
“resonance” between the experience and the world.
But at least he never made the “error” (as he and I would both
call it) of identifying experience with the brain. His gift was
intuitive phenomenology of visual experience. He knew perfectly well
that the brain has no phenomenology, and in keeping first and third
person points of view distinct, he saw no reason to discuss
third-person phenomena such as brain representations, retinal images,
and so on.
He did, alas, finally confuse first and third person points of view in
his later theory of affordances. His masterwork, in my opinion, was
the 1966 book, The Senses Considered As Perceptual Systems, in which
he did the visual phenomenology without resorting to associationism or
representationalism.
We’ve already been over this, so I’ll be brief. You say that
according to representationalism, you do not need a viewer to view the
internal representation. Patterns of energy in the brain correspond
directly to patterns of shape and color in our experience.
In fact, you should say that patterns of energy in the brain are
patterns of experience. The identity theory has no need of a concept
of correspondence.
My objection is that it does not seem to me that my experience is a
brain. It just doesn’t have any of the qualities of a brain.
You say that mental experience is indeed a picture of the external
world, but you don't need a homunculus to make a judgment that it is
looking at the world.
I understand that for you, “looking” simply is brain activity,
so you can say that no homunculus is needed to look.
But in that case, why not just define brain firings in area 17 as
“looking?” What’s the point of having the picture at all?
I don’t think it is true that representationalism entails
materialism. I can be a non-materialist (e.g., a phenomenologist) and
appreciate that one pattern of experience represents another. Indeed
that is the basis of language.
Science though, necessarily entails materialism, since it depends on
measurement, and only physical things can be measured. In my
dualistic world view, therefore, there cannot be a science of mind,
since the mind is immaterial.
Since I find identity theory incomprehensible, I have no interest in
trying to equate the principles of mind to physical principles.
Rather, I think it will be more productive in the long run to find
ways to adjust the basic principles of science so that it can support
an inquiry into the mind. Some steps in that direction are being
taken by some cognitive psychologists.
I can’t understand why materialists would enjoy reducing their
mentality to atoms and molecules, which have no inherent meaning. What
is human life without meaning?
Not only is material reductionism self-destructive, but success of the
project would negate the possibility of its ever having existed. So it
is paradoxically self-contradictory besides.
I think it makes eminently more sense to accept experience as it
appears, which is directly in the mind, with little evidence of
biological mediation. That’s an empirical starting point, rather
than a doctrine. Figuring out how to connect experience with
biological embodiment is an important question, but unfortunately, one
that is not at the present time susceptible to scientific method.
Best regards,
Bill Adams
Hi Bill,
Thank you once again for your very thoughtful reply. It is a genuine
pleasure to be debating someone who is clear-thinking and without a
hint of defensiveness or insecurity, just an honest seeker after
the truth, even if you are profoundly misguided.
In order to avoid an exponential expansion of our debate into
innumerable parallel threads, I have confined my responses to a few
key central points. I think we are honing in on the central
differences between our viewpoints, even if we are no closer to coming
to any agreement.
Steve
You say in message 8 point 1
Forget about phenomenal perspective, and just take a look at this
warped ruler. (Intended as a 2-D image, not a perspective sketch)
Do you not see both a regular scale, and a distortion applied to it?
Do you not see both the scale and the distortion simultaneously? There
is no Necker-cube instability here, there is just one experience, it
is of a warped scale, and that warped scale appears as a
regular scale under distortion. Perhaps a more primitive creature
would see the lines but never recognize any kind of regularity in
them. They would see only the curved lines and unequal spacing that
are literally present in the stimulus. But to humans, the regularity
appears immediately and pre-attentively as a regularity perceived
in the irregular pattern, just as you can see the cylindrical
shape of a rope even when it is coiled up. As in phenomenal
perspective, one is inclined to say "That is a ruler, and it is
bent!".
When one is in the "natural attitude" one tends to ignore the warping
of perspective, in the same way that you would ignore the warping of
this ruler if you saw it like this through a fish-eye lens where
everything else is similarly warped. You could even use the warped
ruler to measure distances in the warped world through the fish-eye
lens by simply ignoring the warp. But even when you are ignoring it,
you still see the ruler warped, it never becomes straight, even when
we "know" it to be so. Instead, it is our definition of straightness
that warps to match the warped ruler, although it does not un-warp the
ruler by doing so. This is my most profound and significant
observation on phenomenal perspective, that the experience is both
warped and straight, simultaneously. Can you reasonably deny that?
What would you predict if the subjects in the Hallway Experiment were
asked "Do you see the sides of the hallway converging, and parallel,
both at the same time, or do you see only one at a time, alternating in
succession?"
You say in message 8 point 1
It is true you never see your retinal image at the location where you
presume your retina to be located, at the back of your eye. All you
see there is an imageless void, a "window" out of which we seem to be
peering.
But we clearly do see our retinal after-images after
looking at a bright light or camera flash. And when we see them, they
appear not at the back of the eyeball, but out in the world! And in
the world they take the form of an explicit spatially-extended colored
image! Surely this is a direct experience "from the inside" of the
photochemical state of our physical retina. Is it not?
(See my Introspective
Retrogression for an exercise in phenomenology.)
This raises anew a question I asked in an earlier round for which I
have not yet received a response from you.
Is your visual experience spatially structured?
For clarity, I am talking about that component of your experience that
disappears when you close your eyes, that is, distinct from the world
which it is an experience of. I understand that it is an
experience of a spatially structured world. But my question is
a phenomenological one about the experience itself. Is your visual
experience spatially structured?
Here we get to what is really the most central point of our
disagreement, the paradigmatic difference in our views of
perception. This is probably where we will have to agree to disagree.
You state with supreme confidence that a computer program or
engineered device does not literally detect images. Its designer or
programmer does, but not the device. Are you saying here that
no man-made device could ever "see" of its own accord?
Are you hereby stating that vision is a magical mystical process that
cannot ever be reduced to an artificial computational mechanism?
In your point 9 you make the shocking
statement that:
Is this really your view??? So mind is like the immortal soul, in a
separate plane of existence where it is undetectable by scientific
means? You don't believe that there is a physical substrate behind
experience? The brain is not just a physical computational
mechanism?
But then it is your theory that violates the conservation of
energy. Because minds have only ever been observed arising out of the
operation of brains, and brains are composed of physical substance and
they follow physical laws, and mental operations consume energy that
is provided by the brain. Mind is not causally isolated from the
physical brain, the content of mind can be profoundly influenced by
the physical state of the brain, and conversely, the mind can have
causal consequences in the physical world through motor action. If
mind were really causally isolated from the brain, as you suggest,
then it could not possibly serve any adaptive function, being
effectively isolated in a separate universe, and thus it would never
have had any reason to evolve, so its existence in a Darwinean world
would be as profoundly mysterious as its principle of operation and
plane of existence.
The chief objection to your kind of dualism is Occam's razor: it is
more parsimonious to posit a single universe with one set of physical
laws, rather than two radically dissimilar parallel universes composed
of dissimilar substance and following dissimilar laws, making tenuous
contact with each other nowhere else but within a living conscious
brain. But if mind and matter come into causal contact, as they
clearly do in both sensory and motor function, in which both
information and energy are exchanged, then surely they must be
different parts of one and the same physical universe.
But there is another, still more serious objection to your
dualism than the issue of parsimony. Since the experiential, or
mind component of the theory is in principle inaccessible to
science, that portion of the theory can be neither confirmed nor
refuted. This places the mental component of your theory of vision
beyond the bounds of science, and firmly in the realm of religious
belief.
Every aspect of this world which initially seemed deeply mysterious to
our ancestors, from the motions of the planets, to the shining of the
sun, the blowing of wind, and the curse of disease, has succumbed to a
materialistic physical explanation. Even life itself, which was
considered by the vitalists of the last century to be a deeply
mysterious and fundamentally mystical phenomenon, has succumbed to an
explanation in terms of molecules and chemistry. If even life itself
can be explained in purely materialistic terms, surely consciousness
must also eventually succumb to a scientific explanation.
And even if it turns out ultimately that mind cannot be
explained by science, why would we give up the attempt before we have
exhausted the materialist possibilities? If, like the vitalists, we
declare from the outset that experience is a deep dark mystery that
can never be explained in principle, that conclusion would turn into a
self-fulfilling prophecy, and we would never come to understand visual
experience. Thank God the materialists of the last century were not
persuaded by the vitalists into giving up the search for the principle
of life before it had even gotten started!
And how can you say that mind cannot be studied by science when I have
shown quite clearly how it can? Science begins by observation, even
before it has any explanation, and conscious experience is clearly
observable, and that observation can be quantified, as I have
shown. Visual experience is a spatial structure with a certain finite
resolution that is lawfully related to the visual stimulus, with a
specific information content, and with a peculiar geometry unlike
anything in the external world. Even if mind were a mysterious
mystical non-physical entity, it would still be a spatial structure
with the properties we observe it to have, and thus it would be open
to scientific scrutiny.
In conclusion: I admit that representationalism is frankly incredible,
and thus I sympathize with your urgent effort to find a more
reasonable explanation. But as incredible as it may be, it is not
nearly as incredible as the notion of experience as a
mysterious non-physical entity that is undetectable in principle by
scientific means, and yet that somehow comes into existence from the
activation of living brains, while remaining causally disconnected
from those brains. It has spatial extendedness, but not in the space
known to science, but in some other parallel universe or orthogonal
dimension that has no causal connection to the universe known to
science, and yet physical light can make an impression on the mind
through sensory processing in the brain, and volitional thoughts can
have causal consequences in the physical world through motor action,
all without any exchange of energy or information between mind and
brain.
In the end, the real difference between us is that I am committed
almost "religiously", to a materialist explanation of mind: I firmly
believe that science will ultimately triumph over the problem of mind,
as it has already triumphed over mysteries which were at least equally
deep. The theory of direct perception, on the other hand, is an
elaborate rationalization to justify our naive realist intuition that
the world of experience is the world itself, seen directly out where
it lies beyond the sensory surface. Unfortunately it comes at the cost
of abandoning science itself, and introducing magical mystical
entities that are beyond the world known to science.
That is a trade-off that I am not willing to make.
Steve
Hi Steve,
I think our discussion does get at some very fundamental issues and I
am pleased you are posting it. I shall do the same.
However, I really must address some egregious misunderstandings in
your last response.
I don't mind letting you have the last word, since you stimulated the
discussion with your excellent Cartoon Epistemology. Feel free to
edit, or omit entirely, my comments below from your post of the
debate.
I am surprised that you do not comprehend dualism. On the other hand,
I find identity theory incoherent, so maybe I shouldn't be so
surprised. Replying may be like attempting inter-species
communication, but it has to be tried.
My dualistic position is, as I said, that mind is immaterial.
Thoughts and ideas, plans and memories, take up no space, have no
mass, do not emit, transmit or absorb energy. Immaterial means
non-physical, intangible, and consequently, not susceptible to
scientific measurement.
I confess I am confounded at your automatic equation of immaterialism
with spiritualism. Where does that come from? I said nothing about
spirits, religion, or an "immortal soul." Why are you bringing those
concepts into the conversation?
Are you making an error of logic like this?
Anyone can see that is not a valid argument.
You express incredulity at the very idea of an immaterial mind.
The straightforward answers are:
You ask about "a physical substrate behind experience. There is no
"substrate" because there are no "strata." A "substrate" implies some
sort of layered conceptualization, probably with the higher or "upper"
level being causally dependent on the lower. But I do not endorse a
layer cake model so there is no "substrate" for me. A better
visualization would be
No strata, no substrates. Likewise, there is nothing “behind”
and nothing in front. Mind and brain are equal partners in dualism.
But they are also interdependent. Without physical embodiment, there
is no mental experience. And conversely, without mental experience,
physical embodiment cannot be discussed or even known. Its
mind-independent ontological status is therefore moot.
The physical and the mental realms are not causally isolated in my
kind of dualism, the interactionist kind. Common sense experience
supports that. I can choose to raise my arm, and my physical arm goes
up, a clear demonstration of mental causation on physical phenomena.
Conversely, I can drink a tumbler of whiskey to demonstrate physical
causation acting on mental experience. I don’t see how anyone
could deny that mind and body are reciprocally causal.
Science insists that the physical world has absolute claim to
causality. There is no rational basis for that claim. In fact,
common sense proves that it is wrong. Nevertheless, as long as
science insists that causality is limited to the physical world, then
of course, from that point of view, the mind, being immaterial, is
causally isolated from the physical world.
But since I have already said that mental experience is not
susceptible to scientific measurement, there is no reason for me to
accept the artificial, irrational, and counterfactual constraint that
causality is limited to the physical world.
You suggest that dualism violates the conservation of energy.
Strictly, it does not, because “energy” is a concept of physics
that only applies to the physical world.
People like to speak of “mental energy,” but that is only a
metaphor for the mental experience of intentionality. There cannot
literally be any mental energy because energy is physical and the mind
is not physical.
However, within the closed universe of physical science, when I choose
to raise my arm and do so, there is no explanation for the impetus
that initiated the movement. That is precisely why science cannot
allow the existence of a causal immaterial mind. The loss is to
science, because we know from everyday experience that in fact, a
person can raise their arm at will.
I am not highly fluent in quantum physics, but it is my understanding
that there is considerable consensus nowadays that physical phenomena
must depend, in a nontrivial sense, on mental phenomena. It is a
hopeful sign to me that science is finally going to come out of its
19th century cocoon and face the facts of life.
A germane reference is from Richard Conn Henry, physicist at Johns
Hopkins and Director of the Maryland Space Grant Consortium. The
article is "The Mental Universe" in the highly respected journal:
Nature (July 7, 2005 issue).
A copy is at the link below:
http://bj2.netsh.com/bbs/83260/messages/8692.html.
You say “it is more parsimonious to posit a single universe with
one set of physical laws, rather than two radically dissimilar
parallel universes composed of dissimilar substance and following
dissimilar laws.”
But I disagree. It is far more economical to start with the actual
facts as they are given to common sense, namely that we have mental
experience and a physical body. Cutting off half of human existence
to make the facts fit a certain preconception is Procrustean, to say
the least.
You object that “there is another, still more serious objection to
your dualism than the issue of parsimony. Since the experiential, or
mind component of the theory is in principle inaccessible to science,
that portion of the theory can be neither confirmed nor refuted. This
places the mental component of your theory of vision beyond the bounds
of science, and firmly in the realm of religious belief.”
It is true that the immaterial portion of dualism cannot be confirmed
or refuted by science. But science is not the only game in town.
There are many other ways to confirm or refute propositions. For
example, there are consensus, judicial arbitration, hermeneutical
analysis, phenomenology, rhetorical argument, logical inference,
historical interpretation, and many other ways that humans define and
affirm truth. The assumption that only science can define truth is
extremely narrow minded. Science can only refute scientifically
well-formed propositions about the physical world.
And your conclusion, that if a proposition cannot be tested by
scientific means, that it must belong “to the realm of religious
belief,” is so strange that I can’t even respond to it.
You argue that “Every aspect of this world which initially seemed
deeply mysterious to our ancestors, from the motions of the planets,
to the shining of the sun, the blowing of wind, and the curse of
disease, has succumbed to a materialistic physical explanation. Even
life itself…”
Well, depending on who you want to count as our ancestors, I disagree.
In the historical period, some of the most deeply mysterious human
questions have been about the nature of the mind, human values, human
nature, the definition of the good, the foundation of aesthetics, and
the meaning of human existence, just to name a few. On these and
innumerable similar questions, science has been mute.
I am not anti-science. I am trained as a scientist and grateful as a
human being for the remarkable comfort, health and prosperity that
science has brought to me and all people. I am also grateful to
science for holding back (so far) the dark tides of ignorance and
religion.
Of course people want to know what causes crop failures, but equally
so, they want to know why relationships fail. Not all questions are
scientific questions, and there is simply no reason to assume that
every question that can be asked will be susceptible to scientific
method, and certainly no reason to think that the best answers will be
in terms of materialism.
You ask, “how can you say that mind cannot be studied by science
when I have shown quite clearly how it can? Science begins by
observation, even before it has any explanation, and conscious
experience is clearly observable, and that observation can be
quantified, as I have shown.”
On this point we may be closer to agreement than on others. I agree
wholeheartedly that conscious experience is clearly observable. Alas,
those do not qualify as scientific observations, since they are
private, not public, and thus not subject to scientific measurement.
As an example of the problem with introspective observations, I point
to our disagreement over whether visual experience is dual in aspect
(subjective and objective points of view) or a single unified hybrid,
as you suggest. We simply disagree, and there is no scientific method
by which that disagreement could be resolved.
Introspective observations can only be “quantified” in the sense
that you can naively assume that the observations do not differ across
people, and that people all report their mental observations
accurately and completely, and then you can tally the verbal
reports. The assumptions are not well justified and for that reason
the quasi-science that is cognitive psychology is vastly
overinterpreted.
I think solutions can be found for these problems, but they will
require expanding the definition of what counts as empirical
observation, and most scientists are not yet prepared to do that.
Your conclusion attributes views to me that I do not hold. I
understand that you are pre-theoretically committed to materialism,
and thank you for being so frank about that. It hardly needs to be
pointed out that such a “religious” commitment, as you call it,
is not based on empirical fact and is unscientific.
The theory of direct perception you criticize is not familiar to me.
I have never said that mental experience is “out in the
world”. I have also not suggested that science be abandoned, only
modified. Finally, I have not introduced any magical or mystical
entities into the discourse. I infer that your conclusion is
addressed to some audience other than myself.
I appreciate the opportunity to have this discussion and I come away
from it more informed, but just as perplexed as ever.
Best regards,
Bill
Hi Bill,
I wouldn't dream of pruning your response, or insist on having the
last word. As I said earlier, the intent is to present both sides of
the debate as clearly and articulately as we are able to do, in the
interests of getting to the truth behind this most important and
significant issue. I very much appreciate your willingness to follow
this through to wherever it takes us.
Where does this idea come from? What gives you any reason to believe
that thoughts and ideas take up no space, have no mass, and do not
emit, transmit, or absorb energy? Is there anything else in the
universe that has these (non-)properties? If not, then where would
this idea come from?
The closest analog we have to thoughts, are the "thoughts" in a
computer, that can store information and perform computations, as our
mind does (although of course by a completely different
principle). The computations in a computer are blindingly fast because
the medium, electricity, is almost completely massless, and can thus
be shunted around at lightning speed. But electricity is a
physical substance with some mass, and it is necessarily
physically detectable, and it can exert forces on physical things,
otherwise it could never serve as a computational device, because the
output of its computations must be able to drive the display that
presents the results.
By the same token, if mind were really spaceless and massless and
causally disconnected, how could it ever possibly influence the brain
to send motor currents to move our body?
Given the intense and complex electrochemical activity in the brain,
would it not be more reasonable to suppose that mind is made of
patterns of electrical activity, as is the case in "computer brains"?
Is that not the most parsimonious assumption, to be rejected only if
it were positively demonstrated to be false?
Why do I equate immaterialism with spiritualism? Because it has
exactly the same properties as the immaterial soul! You say that mind
takes up no space, has no mass, does not emit, transmit or absorb
energy, it is non-physical, intangible, and not susceptible to
scientific measurement, and it is the basis for conscious experience
and the impetus for deliberate action. Excepting only for immortality,
those are exactly the properties of a spirit or soul!
And like a spirit or soul, this "explanation" neatly avoids explaining
anything about how vision works, how perceptual information is
stored or processed, or how it interacts with the body without having
a causal presence in the physical world. It is tantamount to saying
that vision is a deep dark mystery that will never be understood in
scientific terms!
You say "No, the mind is not like the immortal soul, whatever that
is.". How can you say that? In the first place the only
thing you "know" about mind and soul is that they both share
the properties enumerated above, with the sole exception of
immortality, and you cannot even know that mind is not immortal, since
it is undetectable by scientific means! And what are the properties by
which mind differs from the properties of soul? You don't
know, you can't say, because as with the "theory" of soul, you can't
know anything about its properties. In fact all of the
properties you claim for mind are not known facts, but initial
assumptions which are conveniently unverifiable in
principle!
Every one of the properties that you claim for mind are completely and
totally unobservable and unverifiable. How can you be so certain of
something for which there is not a scrap of evidence? Where does this
idea come from, besides an urgent desire to contrive an explanation to
justify your naive realist intuitions?
Here there is a profound and fatal flaw in your concept of
mind. Causality inescapably involves an exchange of energy. It is
impossible for one thing to cause another without pushing on it in
some manner. The notion of interactionist dualism is a
contradiction in terms! If they interact, then they necessarily
are part of one and the same universe, and thus, mind is detectable in
principle.
If you wish to extend causality beyond the physical world, then
you must begin by redefining the meaning of causality, because until
you redefine it, causality is a physical process defined in the
physical world.
You say that when you choose to raise your arm, "there is no
explanation for the impetus that initiated the movement." Are you
saying that there are physically uncaused events going on in
the brain? If so, then the action of the mind would in fact be
detectable in principle at the point where the impetus from mind
enters the material world. And where that impetus acts on the brain,
it causes a physical change that has no apparent physical cause.
And what exactly are the "facts as they are given to common
sense" that indicate that mind is takes up no space, has no mass,
does not emit, transmit or absorb energy, is non-physical,
intangible, and not susceptible to scientific measurement? Where does
that idea come from???
The facts that are given to my common sense are that visual
experience is spatially extended and volumetric, and that mind is a
function of the physical brain, which is an organ of biological
computation composed of the ordinary matter and energy of the
universe. There would have to be extraordinary evidence to the
contrary for me to believe otherwise. As Karl Sagan said,
extraordinary hypotheses require extraordinary evidence; and in my view,
the existence of immaterial entities that take up no space, have no
mass, are non-phyical, and intangible, and yet lead to spatially
extended experience and causal consequences in a physical body, is
about as extraordinary a hypothesis as I have ever heard!
There are indeed other ways to confirm propositions, such as hunches,
feelings, faith, ancient scriptures, voices in your head, mental
telepathy, Tarot cards, crystal balls, astrology, the I-Ching, ... the
list is endless. The question is which of these other ways can we
trust as a reliable guide to the truth?
Science is indeed not the only game in town, but it is the only
rational and reasonable game in town, and that is why other games
which are vitally important to us, such as the laws of evidence in
legal proceedings, the logic of legal reasoning, rhetorical argument,
logical inference, historical interpretation, and so forth, have all
adopted the methods of science, that is, the method of eternal
and skepticism until verified by hard evidence or reproducible
experiments.
Your assumption of the existence of immaterial mind which has never
been observed or detected, with properties which have never been
demonstrated, simply because it "seems" that way intuitively, is as
close to religious belief as anything I have heard of.
It wouldn't bother me if you just argued that mind might be
immaterial and causally isolated. But you (and all other direct
realists in my experience) are so supremely confident in the truth of
your hypothesis that you cannot even conceptualize the alternative,
let alone consider the mere possibility of it maybe being right, strikes me
as very strange for a "theory" for which there is not a scrap of
evidence.
You may argue that my own position is equally dogmatic. But the only
thing about which I am dogmatic is about the methods of science
and the process of reason. And it is by the process of reason that I
arrive at indirect perception. Specifically, the causal chain
of vision, that goes from world, through the eye, to the brain. If you
could demonstrate to me irrefutably the mere possibility of the
existence of massless, spaceless, immaterial entities, hidden in a
parallel universe inaccessible to scientific scrutiny, which however
can have causal consequences in this world, I would be willing to
entertain that possibility. But your concept of mind is so defined
such that it is impossible in principle to demonstrate. That, in my
view, is a religious belief rather than a scientific hypothesis.
I urge you, just for a moment, to entertain the possibility
that you may perhaps be mistaken, and that perception might be
indirect. Would the world look any different if perception were
indirect? I can tell you that from my perspective, the world
would appear very different phenomenologically if perception
were in fact direct. There would be no dreams or hallucinations,
retinal after-images, phenomenal perspective, or loss of resolution in
peripheral vision. The sky would not be a dome over my head, and the
sides of the road would not converge to a point. All of these, it
seems, are incontestable evidence that perception is in fact indirect,
because they are clearly not part of the world, and many of them are
obviously part of our selves.
There are realms of human knowledge where science does not yet
reign supreme. But that is only because science has not been applied
to them yet. Science, or more generally, the methods of reason,
will ultimately triumph even in those fields, because reason is the
only reliable path toward the truth.
The nature of mind can be investigated in a scientific manner,
as I myself have demonstrated. Human values, human nature, the
definition of the good, the foundation of aesthetics, and the meaning
of human existence, can all be investigated using the methods of
reason, and it is only through reason that any objective truth will
ever be established in those fields.
[I use reason as the more general application of
scientific principles.]
For example ethics and morality, which were originally thought to be
dictated by God, are currently thought by most people to be rooted in
"feelings" of right and wrong, or "conscience"; a mysterious
built-in moral compass that each of us supposedly posess. But then why
do some think that all war is evil, while others think it moral in
some circumstances? Why do some think that human life is sacred, and
even a fetus must be accorded "human rights", whereas others think it
is morally justified to murder innocent civilians by the thousands? We
will never find a universal rule of morality by that route.
The true basis of morality can be found by examining the origins of
morality in our animal ancestors, and the Darwinean reasons behind
their spontaneous emergence in human and animal evolution. All of our
basic moral instincts, abhorance of murder, protection of the weak,
aggression against enemies, duty to King and Country, have their
origins in Darwinean selection — they are the rules that have
been found to work, and the sooner we examine and understand
those pragmatic underpinnings behind our instinctive sense of ethics
and morality, the sooner we will come up with a universal law of
morality whose truth can be objectively verified. Some of this work
has begun in the field of game theory, that uses computer
simulations of synthetic agents endowed with randomized ethical rules,
interacting and reproducing in a synthetic world, to determine which
rules of ethics lead to the most successful strategies for
survival. Not surprisingly, those strategies have been shown to
include fairness and reciprocity, competitive trechery, and
cooperative action, each in different measures depending on the
conditions of the synthetic world.
As for the meaning of human existence, science suggests that there is
no such meaning, the universe is a grand accident that has no global
objective or goal. Our lives have meaning to us because it is
adaptive for us to feel that way. The sense of meaning in our lives
helps us survive and prosper. It may not be the answer we would
like to find, and for that reason most choose to reject that
notion of senseless existence. But all other methods besides reason
have not come up with any better solution, most of them result in
fantastic theories of Gods and angels and devils that assuage our
emotional need to find purpose in our life. But I would rather know
the ugly truth as revealed most reliably by reason, than to indulge in
feelgood fantasies because I can't face the truth.
And even aesthetics can be reduced to reason; their origin lies in the
computational principles by which our brain operates. If you are
interested I can send you material that explains further. (See Lehar
2003 The World In
Your Head, Chapter 11, "A Psycho-Aesthetic Hypothesis". I would be
happy to send you the chapter electronically if you are interested)
All questions are reducible to scientific terms, and science,
or reason, is the only reliable path toward any kind of objective
truth. This is an empiracal fact that has been demonstrated
again and again throughout human history. I am sufficiently convinced
of it that I hold it as an article of faith.
You argue that phenomenolgy does not qualify as scientific observation
because it is private, not public, and thus not subject to scientific
measurement. But all scientific observation comes to us
through the veil of experience. Even a measurement with a ruler, or a
reading on a guage, are performed by subjective observation through
conscious experience. We simply assume that other people would make
the same readings, but that is clearly untrue, for example, for people
suffering from visual agnosia, or psychosis, or people with extreme
theoretical prejudice, who would report different readings from those
of healthy, impartial, and reasonable observers. In fact, our
phenomenological observations of our own experience are
epistemologically more certain and reliable than
anything we can possibly know about objective reality. And
phenomenological observations can be replicated by other
observers. In fact, the science of phenomenology appeals to the reader
to confirm for themselves the recorded observations of the
phenomenological author. That is the most certain and reliable
confirmation possible!
You may tell me that you do not see the sides of the road both
converge and be parallel, or at least not simultaneously. But you will
never shake my faith in how I experience that percept. I
am as certain of my experience as I can be of anything. Fortunately my
observation has been confirmed by enough other people to assure me
that I am not mad, but that others see it that way too, if they can
bring themselves to observe objectively, without bias due to
preconceived theoretical notions about how things ought to
appear. Of course there will always be those who deny that they see
what I see. But then there are also legions of people who insist that
the earth is flat, and that the cosmos is run by an infinitely
intelligent and benevolant immaterial agent who has specific designs
for the detailed conduct of our lives. Even science can't break through
to those people. Phenomenology is no less certain a science than any
other. If anything it is more certain, because we know for a
fact what it is that we experience.
You say that my committment to materialism as an article of faith is
not based on empirical fact, and is thus not scientific. Quite to the
contrary — anything other than materialism is not
scientific. My faith is in science itself as a methodology for
discovering truth, and that is the only faith that is
scientific. In fact, faith in science is a pre-requisite for any
scientist. You have to believe that science is the most reliable path
toward the truth, otherwise you are apt to be waylaid by specious
un-scientific notions such as immaterial minds that are in principle
inaccessible to scientific scrutiny. That is a truly
un-scientific notion by the very definition of science! That is
in fact a magical, mystical entity that you introduce, as you admit,
as a "fact" as "given to common
sense". History has shown that facts "as given to common
sense" are often plain wrong. The earth is round, not flat, as it
appears. The earth rotates around the sun, not the sun around the
earth, as it appears. The ground underfoot does not spin erratically,
as it appears when we are dizzy. And the world that you see around you
in your experience is not the world itself, as viewed directly, but is
in fact a miniature replica of that world in an internal
representation.
You complain that my characterization of your theory of perception is
inaccurate. I have tried to give you ample opportunity to present your
theory yourself. If I continue to misunderstand it, it is probably, as
you say, akin to inter-species communication. We are arguing from
different foundational assumptions, which is always difficult.
I do get the sense however that the debate seems to be winding to a
close, we seem to be converging, as expected, on an agreement to
disagree. I thank you again for an entertaining and informative
exchange. And of course I will be happy to continue as long as we have
anything more to resolve, although barring any new surprises, your
next response is likely to be the last word on this debate.
Before I close, to satisfy my curiosity, would you please be so kind
as to answer a few last remaining questions on which I remain unclear?
Just a brief response on each point would be appreciated.
Hi Steve,
I agree that our discussion is winding down. I don’t see any way
we can overcome our apparently irreconcilable differences in
fundamental assumptions. That itself is disturbing to me. It shakes
my confidence in the power of reason. But it is what it is.
I will try my best to answer your final questions.
Yes and no. It’s an odd question. My visual experience is
certainly not structured around smells or tastes, but around my bodily
experience of distance, volume, and movement. So in that sense, yes,
it is spatial.
In the normal, natural attitude, visual experience is part of
whole-body exploration of an environment, including locomotion,
kinesthesia, touch, audition, and so on. The experience of negotiating
and learning about my environment is not particularly visual, except
that upon reflection, I understand that I use vision predominantly,
and vision, as I said before, is spatial in a bodily sense.
If I’m interested in the blue jays on my bird feeder, my experience
is dominated by color, time, and thoughts about the differences
between humans and birds. The experience is not particularly spatial
in character, but more like a relationship between subjectivity and
objectivity.
When I’m reading a book or playing the piano, I would say that my
visual experience is sub-personal, that is, not apparent to
reflection, and not spatial at all.
I can become reflective and analytic about my visual experience, and
when I do that, I find that it is NOT spatial in character. For
example, as you have pointed out, the curbs of a street seem to
converge in the distance, even though I believe that is not how space
is actually structured. So in phenomenological mode, I would say that
visual experience is structured in a pseudo-spatial way.
This is an improper question, like asking what do numbers taste like?
It doesn’t really make any sense. “Location” is a term
indexed to objectively defined space, whereas visual experience is
refers to subjective mental experience. Logically, I must say that my
subjective experience is attached to my biological individuality, but
that is merely an intellectual deduction.
If you ask me about my experience in its own right, “location”
is not a cogent descriptor. In my mind, experience extends from the
beginning of time to the indefinite future, as I understand it, and
throughout all the corners of the world as I know it, and beyond
myself into all of humanity, as I feel it. It is not physical, and as
such, not located.
Of course, but it is a negotiated reality, not a mind-independent,
self-existent one.
Again, the question itself is not well-formed. What does it mean
“to see A as B?” Assuming veridical perception, one would see A
as A and B as B. To see A as B is to make a perceptual error.
The fundamental confusion behind your “demonstration” of the
warped ruler is that you do not have a theory of pictures. A picture
of a ruler is not a ruler, but a socially agreed-upon set of pictorial
conventions.
If I put a single dot on a piece of paper and say it is a picture of a
horse, am I wrong?
It would differ in the way that pictures differ from reality. As with
trompe d’oeil paintings, all you have to do is move your head
slightly to instantly reveal the difference between a picture of a
window, and an actual window. Same for the Ames room. Pictures
cannot be fully explored by the whole animal the way that reality can
be, and that is always the difference.
However, if I were wearing a virtual reality helmet, and had for some
reason forgotten that I had it on, and if the computer could manage
the visual display to be perfectly coordinated with my eye, head and
neck movements, then I would say that the virtual reality would BE
visual reality, as far as my visual system were concerned.
That is, if the sensory input perfectly matches expectations arising
from the exploratory (motor) intentionality, then that is the
definition of veridical perception. It would not be a “virtual”
reality, but merely “reality,” with respect to the visual
system.
(Of course the VR apparatus would have to be weightless and I would
have to suffer from retrograde amnesia, or, alternatively, be 100%
adapted.)
In a forced choice question like that, with a strong experimenter bias
and plenty of social performance expectations, I don’t know what to
predict. It’s a bad design.
Why not ask them, “How do you describe the geometry of the
hallway?”
People differ in degree of phenomenological skill and I would expect a
range of answers, with high variance, categorizable from parallel
sides, to converging sides.
There is no reason to assume that the causal relationship between mind
and brain is unidirectional and ballistic. According to interactive
dualism, mind and brain are equal partners. Mental intentionality can
be expressed as physical adjustment, and physical changes can become
mental phenomena. It is an ongoing reciprocity. It is an artifice of
the laboratory to talk in terms of “stimuli” and
“responses.”
Visualize a Watt flyball governor operating on a steam boiler. Does
the rising steam pressure cause the balls to fly higher and the valve
to open, or do the balls drop, closing the valve and raising the steam
pressure? It is silly to phrase the question in that way for a
functioning cybernetic. One must take a systems approach.
I would say that mental activity (not all of it conscious)
continuously causes biochemical changes, and vice versa, even during
sleep, as long as the person is alive. Scientists can, in principle,
measure all of the electrical and biochemical changes that take place
in an organism, but none of the mental changes. Without access to the
mind and its role in the functioning of the animal, the scientist is
forced to attribute all electro-biochemical changes to other physical
causes. The success of that project has not been great, to date.
I do not think that we have come even close to a successful scientific
explanation of animal behavior, let alone complex human social
interaction. I am not surprised by that, since one half of the
mind-brain equation has been ignored.
It could be, depending on context. Cosmologists today make almost
exactly the claim you outline above in the hypothesis of dark matter,
which makes up 90% of the mass of the universe but which is utterly
undetectable. Is that a scientific hypothesis? Most people would say
it is, because it connects to the body of established scientific
knowledge and attempts to extend or modify it.
Likewise, my description of an immaterial but causal mind could be
construed as a scientific hypothesis inasmuch as it is linked in an
explanatory way to accepted (social-)scientific observations about how
people report their experience (in psychophysical tasks and surveys,
for example).
I’m sure these are not the answers you would have given, Steve, and
they may not even be comprehensible to you. I don’t understand why
two educated, articulate people with similar training and background
so consistently fail to communicate. It’s a mystery to me.
In any case, I hope I will have a chance to say hello to you at the
Tucson conference in April.
Best regards,
Bill Adams
Hi Bill,
Yes, debate on this issue sure shakes my confidence in the
power of reason! It goes to show that even science is not based on
reason alone, but is itself founded on some underlying paradigmatic
assumptions which are not arrived at by any process of logical
reasoning. Debates on this question are more like religious debates,
it seems that you can never persuade people to change their initial
paradigmatic assumptions. This was Thomas Kuhn's (1970) point in
The Structure of Scientific Revolutions. Kuhn made the point
that different paradigms are kind of like a Gestalt switch, as, for
example, when viewing an ambiguous figure like this one.
In any one interpretation there is just tons of evidence that
it is indeed a young lady, or conversely, an old hag. Every fragment
of the image further confirms whatever interpretation you have
chosen. And when the percept switches, suddenly everything in
the picture changes profoundly into a completely new configuration!
I am fascinated by this phenomenon, and by the question of how it is
that people arrive at their initial assumptions in the first place. We
are all born naive realists. But when we first come face to face with
the causal chain of vision in highschool biology, i.e. how
light is transduced in the retina and a signal is sent up the optic
nerve to the brain, we are suddenly plunged into a paradox, because
the causal chain suggests that all we can experience is the inside of
our own brain. And yet in everyday experience we are convinced that we
see the world itself, out there beyond the sensory surface. Most people
live with this paradoxical Jekyl-and-Hyde view of vision that flips
inside out, depending on whether we consider our own visual
experience from the "inside", or somebody else's from the
"outside". But the two views are inconsistent!
But there are some who simply will not tolerate this paradoxical
situation, and eventually their mind flips into one of two alternative
states. Either they finally accept that the world of experience
is a picture in their head, which requires that they
fundamentally revise their conception of what the brain is capable of,
or they finally accept that the world of experience simply
is the world "out there" beyond the sensory surface. This
requires that they fundamentally revise their notion of the nature of
mind and its place in the world, and the concept of computation and
representation in brains and computers.
The curious thing is that this choice appears to be an unconscious
gut-level choice, because once the choice is made, people tend to be
very dogmatic about their chosen alternative, and they can no longer
seem to entertain the possibility that the other view might be right
instead.
This issue is the closest I have ever seen to being a matter of
religious belief in science.
I guess we must agree to disagree, but I am delighted that we could do
so without being disagreeable. I have a few last comments on some of
your responses to the questions, feel free to ignore or to respond as
you see fit. I think we have a pretty good idea of where the other
stands, even if we remain baffled as to why they choose that
stance.
Thank you once again for an interesting and entertaining exchange,
Steve
This answer is totally ambiguous! If everyone died, would the world continue to exist?
You say: "To see A as B is to make a perceptual error."
No it is not! I can see a pattern of shading in a picture as a
young lady (or an old hag). And when I do, I see both the
pattern of shading and the lady (or hag). I see the lady
in the pattern of shading. Likewise, I can see a series of
irregular spaced lines as a regular grid through some kind of
distortion. I see the irregular lines and I see the regular
grid simultaneously. I can't help feeling that your reasoning here is
a case of argument by conclusion avoidance: You don't want to
concede the point in the clear case of the ruler because it would
undermine your argument in the case of phenomenal perspective.
Again your answer here strikes me as evasive. It is totally irrelevant
whether the causal influence of mind is unidirectional or
interactive. If the Watt flyball governor is attached to a steam
engine, the engine behaves differently, that is, it starts running at
a constant speed, whereas without the governor it would run at
variable speed. If the governor was made of "mind" instead of matter,
then the governor would remain undetectable by scientific means, but
the effects of the governor would still be observable in the
fact that the engine was "mysteriously" running at constant speed.
Likewise, if the physical brain were causally coupled to a mind, then
all of the influence of the mind on the brain would appear as
mysterious "uncaused" events, especially in the case of spontaneous
volitional motor action.
Bad analogy. The reason cosmologists invented the dark matter
hypothesis was to explain an otherwise unexplained property of
galactic behavior. They rotate as if they were much more massive than
their visible parts would suggest. The dark matter is causally
connected with the physical galaxy, and thus, it is a scientific
hypothesis that makes specific predictions.
A hypothesis that makes no predictions is not a scientific hypothesis.
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http://cns-alumni.bu.edu/~slehar/
Date: 8/32/2005 11:49 AM
From: Bill Adams
Subject: A Cartoon Epistemology
Date: August 25 2005 2:14 PM
From: Steve Lehar
Subject: A Cartoon Epistemology
Date: 8/32/2005 4:00 PM
From: Bill Adams
Subject: A Cartoon Epistemology
Date: August 25 2005 10:41 PM
From: Steve Lehar
Subject: A Cartoon Epistemology
Bill Adam's Comments: 15 Points
Date: 8/32/2005 11:49 AM
From: Bill Adams
Subject: A Cartoon Epistemology
Point 1
[Response to Point 1]
Point 2
"There is no mystery in that kind of perspective, it is … a
projection from a 3-D world through a focal point onto a 2-D
surface. And in your eyeball the retina is like the film."
[Response to Point 2]
Point 3
[Response to Point 3]
Point 4
[Response to Point 4]
Point 5
[Response to Point 5]
Point 6
[Response to Point 6]
Point 7
"Mind is nothing more than the operation of the physical brain."
[Response to Point 7]
Point 8
"You cannot see the external world directly. You can only see it
through your private conscious experience of it. So this world you see
around you is the picture in your brain. In other words beyond the
dome of the sky above, and beyond the solid earth underfoot, is the
inner surface of your true physical skull.
[Bill Adams response]
[Response to Point 8]
Point 9
[Response to Point 9]
Point 10
"But whatever else we know about the visual representation, one thing
is plainly obvious by inspection, that the representational strategy
used in the brain is an analogical one. In other words objects and
surfaces are represented in perception not by an abstract symbolic
code, nor by the activation of individual cells, or cell
assemblies. Instead, objects are represented in the brain by
constructing full spatial effigies of them that appear to us for all
the world like the objects themselves."
[Response to Point 10]
Point 11
"Vision is televisual. It lets us see the remote external world through
the medium of an internal replica of it."
[Response to Point 11]
Point 12
"The perceptual homunculus is ... a computational mechanism …[of]
the brain to help it control the body."
[Response to Point 12]
Point 13
"The internal marionette is coupled to the larger body somehow, so that
the posture of the model always exactly mirrors the posture of the
real body that it represents.
[See Response to Point 9]
[Response to Point 13]
Point 14
"Look—if you once just accept the fact that this world we see around
us is a picture in our head, all the rest of it follows by inspection!
Besides, the alternative view, that we can somehow see the world
directly, bypassing the sensory machinery in the eye and brain, is
just plain magic!
[Response to Point 14]
Point 15
[Response to Point 15]
Steve Lehar's Response to 15 Points
[Skip to next message]
Date: September 02 2005
From: Steve Lehar
Subject: A Cartoon Epistemology
Point 1 Response
[Original Point]
[Bill Adams response]
[On to Point 2]
Point 2 Response
[Original Point]
[Bill Adams response]
[On to Point 3]
Point 3 Response
[Original Point]
[On to Point 4]
Point 4 Response
[ Original Point ]
[On to Point 5]
Point 5 Response
[ Original Point ]
[On to Point 6]
Point 6 Response
[ Original Point ]
[Bill Adams response]
[On to Point 7]
Point 7 Response
[ Original Point ]
[Bill Adams response]
[On to Point 8]
Point 8 Response
[ Original Point ]
[On to Point 9]
Point 9 Response
[ Original Point ]
[On to Point 10]
Point 10 Response
[ Original Point ]
[On to Point 11]
Point 11 Response
[ Original Point ]
[On to Point 12]
Point 12 Response
[ Original Point ]
[On to Point 13]
Point 13 Response
[ Original Point ]
[On to Point 14]
Point 14 Response
[ Original Point ]
[On to Point 15]
Point 15 Response
[ Original Point ]
Bill Adam's Response
Date: 9/13/2005 2:57PM
From: Bill Adams
Subject: A Cartoon Epistemology
1. The duality of phenomenal experience.
[Steve Lehar's Response]
2. Are There Images Without Observers?
[Steve Lehar's Response]
[Steve Lehar's Response]
3. On Mental Synchrony
The presumed synchrony of experiences between observers is not
axiomatic to science, but rather a negotiated settlement. It is an
inference supported by ostensive definition. We stand around and
point at the litmus paper and we nod our heads and say, Yes, it is
pink, don’t you think so? Yes, definitely pink.
4. The causality of Experience.
5. Kantian Duality
6. The Inner Surface of Your Skull
7. Mediated Vs Direct Visual Experience
8. The Homunculus
9. Representationalism, Science, and Materialism
[Steven Lehar's Response]
Steve Lehar Responds
Date: September 14 2005 4:10 PM
From: Steve Lehar
Subject: A Cartoon Epistemology
1. The Duality of Phenomenal Experience
"I cannot experience both aspects simultaneously. At best it is like
the oscillation of Necker cube aspects. The switching time between the
two modes seems quite fast, but not zero. If you say you can
experience both aspects at once, then our perceptual experience
differs fundamentally."
2. Seeing your Retinal Image
"a person never sees their own retinal image."
3. Images Without Observers
"In my dualistic world view ... there cannot be a science
of mind, since the mind is immaterial. "
Bill Adams Responds
Date: September 15 2005 5:59 PM
From: Bill Adams
Subject: A Cartoon Epistemology
Dualism
[Steven Lehar's Response]
Immaterialism and Spiritualism
"So mind is like the immortal soul, in a separate plane of existence
where it is undetectable by scientific means? You don't believe that
there is a physical substrate behind experience? The brain is not just
a physical computational mechanism?"
[Steven Lehar's Response]
Visualizing Mental and Physical
[Steven Lehar's Response]
Causality
[Steven Lehar's Response]
Mind and the Laws of Physics
[Steven Lehar's Response]
Occam’s Razor
[Steven Lehar's Response]
Conjectures and Refutations
[Steven Lehar's Response]
The Scope of Science
[Steven Lehar's Response]
Scientific Observation
[Steven Lehar's Response]
An Inconclusive Conclusion
[Steven Lehar's Response]
Steve Lehar Responds
Date: September 16 4:51 PM
From: Steve Lehar
Subject: A Cartoon Epistemology
Dualism
Immaterialism and Spiritualism
Visualizing Mental and Physical
Causality
Mind and the Laws of Physics
Occam's Razor
Conjectures and Refutations
The Scope of Science
Scientific Observation
An Inconclusive Conclusion
Final Questions
Is your visual experience spatially structured?
[Bill Adams Response]
Where is your visual experience located? In your head? In
the world? Or in an orthogonal dimension?
[Bill Adams Response]
Is there an objective external world common to different people's
experiences? Or is experience all that exists, as suggested by
Husserl?
[Bill Adams Response]
Do you or do you not see the scale of the
warped ruler as a regular scale which is warped? In other
words, do you instantly recognize that it is "supposed to" be a
regular periodic scale simultaneously with seeing it as
being warped?
[Bill Adams Response]
Imagine a perspective diorama like THIS
one, or THIS
one, but imagine that you are strangely blind to the convergence
by perspective, i.e. that paradoxically, you perceive the road in
the model to be straight and parallel all the way to the horizon,
even as the sides of the road meet. If you can picture such a
paradoxical self-contradictory percept, how would that experience
differ from your actual experience when standing on a long
straight road?
[Bill Adams Response]
What response would you predict if the subjects in the Hallway
Experiment were asked "Do you see the sides of the hallway
converging, and parallel, both at the same time, or do you see
only one at a time, alternating in succession?" (Stand in a
hallway and take a look yourself)
[Bill Adams Response]
If your mind acts on your brain so as to initiate a movement of
your arm, is there some place in your brain where your mind
changes the electrochemical state of your brain to cause a
movement that would otherwise not have occurred? Could a
neurophsysiologist in principle observe an apparently un-caused
event in your brain at that point?
[Bill Adams Response]
If I claimed that there was a sphere located right here
(some location) in space, made of some invisible massless
substance which is undetectable in principle by any
physical means, including even by possible future technologies:
Would that be a scientific hypothesis?
[Bill Adams Response]
Steve
Bill Adam's Response
Date: 9/19/2005 12:07 PM
From: Bill Adams
Subject: A Cartoon Epistemology
[Steve Lehar's response]
1. Is my visual experience spatially structured?
2. Where is your visual experience located?
3. Is there a [shared] objective external world?
[Steve Lehar's Response]
4. Do you see the scale of the warped ruler as a
regular scale which is warped?
[Steve Lehar's Response]
5. How would your experience differ (from diorama)?
6. What response would you predict if the subjects in the ? [Hallway
Experiment]
7. Does mind change the state of the brain?
[Steve Lehar's Response]
8. Would this be a scientific hypothesis? [invisible sphere]
[Steve Lehar's Response]
Steve Lehar Responds
Date: 9/20.2005 1:09 PM
From: Steve Lehar
Subject: A Cartoon Epistemology
3. Is there a [shared] objective external world?
4. Do you see the scale of the warped ruler as a regular scale which is warped?
7. Does mind change the state of the brain?
8. Would this be a scientific hypothesis? [invisible sphere]