Debate with Bill Adams

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

Steve Lehar


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]

The Debate

Date: August 25 2005 8:02 AM
From: Steve Lehar
Subject: A Cartoon Epistemology

Hi Bill,

On the subject of subjectivity, and reflexive examination of experience, I thought you might enjoy this Cartoon Epistemology.


Steve Lehar

Date: 8/32/2005 11:49 AM
From: Bill Adams
Subject: A Cartoon Epistemology

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.]

Date: August 25 2005 2:14 PM
From: Steve Lehar
Subject: A Cartoon Epistemology

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.

Date: 8/32/2005 4:00 PM
From: Bill Adams
Subject: A Cartoon Epistemology

As for alleged missteps, as you know they are in the eye of the beholder. But I would ask you these three questions:

  1. What is an “image?”
  2. What is a representation of an image?
  3. What kind of a force is a motivational force?

Date: August 25 2005 10:41 PM
From: Steve Lehar
Subject: A Cartoon Epistemology

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.

Bill Adam's Comments: 15 Points

Date: 8/32/2005 11:49 AM
From: Bill Adams
Subject: A Cartoon Epistemology

My reactions [to the Cartoon Epistemology] may be of interest to you.

Point 1

"Did you ever notice that things that are far away look smaller? And things that are nearby look bigger! Do you realize how strange that is?"

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.

[Response to Point 1]

[Note:Underline highlights key points addressed in the response.]

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."

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.

[Response to Point 2]

Point 3

"Well take a look at this. See the two sides of this street? They are straight and parallel as far as the eye can see."

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?

[Response to Point 3]

Point 4

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.”

[Response to Point 4]

Point 5

However, in a surprising move, you suggest instead that we take the melon rind as the reality.

"So we are living in a scale model, and the scale of the model shrinks progressively with depth, just like a museum diorama, or a theatre set."

"If we measure distances, and even straightness itself, using this warped reference grid, we can see that all the houses are the same height and width and depth, and that they are really all straight and vertical, not warped and bulgy as they appear."

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.

[Response to Point 5]

Point 6

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.

[Response to Point 6]

Point 7

"Mind is nothing more than the operation of the physical brain."

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.

[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.

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.

[Bill Adams response]

[Response to Point 8]

Point 9

"The pattern of electrical activation in your brain during a hallucination takes the same shape as it would during a normal perception of the hallucinated scene. So the shape and color that you experience are the shape and color that the world would have if you were perceiving it instead of hallucinating it. They are the shape and color of the world, not of your brain! Even if that world is imaginary!"

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.

[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."

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.

[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."

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.

[Response to Point 11]

Point 12

"The perceptual homunculus is ... a computational mechanism …[of] the brain to help it control the body."

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.

[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.

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.

[See Response to Point 9]

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.

[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!

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.

[Response to Point 14]

Point 15

Your swipe at the theory of direct perception is not really fair, since you only presented that point of view as a straw man.

[Response to Point 15]

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

Steve Lehar's Response to 15 Points

[Skip to next message]

Date: September 02 2005
From: Steve Lehar
Subject: A Cartoon Epistemology

Response to the many points:

Point 1 Response

[Original Point]

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.

[Bill Adams response]

[On to Point 2]

Point 2 Response

[Original Point]

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?

[Bill Adams response]

[On to Point 3]

Point 3 Response

[Original Point]

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!

[On to Point 4]

Point 4 Response

[ Original Point ]

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.

[On to Point 5]

Point 5 Response

[ Original Point ]

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.

[On to Point 6]

Point 6 Response

[ Original Point ]

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?

[Bill Adams response]

[On to Point 7]

Point 7 Response

[ Original Point ]

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.

[Bill Adams response]

[On to Point 8]

Point 8 Response

[ Original Point ]

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.

[On to Point 9]

Point 9 Response

[ Original Point ]

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.

[On to Point 10]

Point 10 Response

[ Original Point ]

See Response to Point 5.

[On to Point 11]

Point 11 Response

[ Original Point ]

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.

[On to Point 12]

Point 12 Response

[ Original Point ]

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.

[On to Point 13]

Point 13 Response

[ Original 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.

[On to Point 14]

Point 14 Response

[ Original Point ]

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.

[On to Point 15]

Point 15 Response

[ Original Point ]

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

Bill Adam's Response

Date: 9/13/2005 2:57PM
From: Bill Adams
Subject: A Cartoon Epistemology

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.

1. The duality of phenomenal experience.

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.

[Steve Lehar's Response]

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!)

2. Are There Images Without Observers?

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.

[Steve Lehar's Response]

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.

[Steve Lehar's Response]

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.”

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.

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.

4. The causality of Experience.

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.

5. Kantian Duality

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.

6. The Inner Surface of Your Skull

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?

7. Mediated Vs Direct Visual Experience

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.

8. The Homunculus

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?

9. Representationalism, Science, and Materialism

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.

[Steven Lehar's Response]

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

Steve Lehar Responds

Date: September 14 2005 4:10 PM
From: Steve Lehar
Subject: A Cartoon Epistemology

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.


1. The Duality of Phenomenal Experience

You say in message 8 point 1

"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."

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?"

2. Seeing your Retinal Image

You say in message 8 point 1

"a person never sees their own retinal image."

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?

3. Images Without Observers

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:

"In my dualistic world view ... there cannot be a science of mind, since the mind is immaterial. "

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.


Bill Adams Responds

Date: September 15 2005 5:59 PM
From: Bill Adams
Subject: A Cartoon Epistemology

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.

[Steven Lehar's Response]

Immaterialism and Spiritualism

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.

"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?"

The straightforward answers are:

[Steven Lehar's Response]

Visualizing Mental and Physical

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.

[Steven Lehar's Response]


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.

[Steven Lehar's Response]

Mind and the Laws of Physics

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:

[Steven Lehar's Response]

Occam’s Razor

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.

[Steven Lehar's Response]

Conjectures and Refutations

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.

[Steven Lehar's Response]

The Scope of Science

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.

[Steven Lehar's Response]

Scientific Observation

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.

[Steven Lehar's Response]

An Inconclusive Conclusion

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.

[Steven Lehar's Response]

Best regards,


Steve Lehar Responds

Date: September 16 4:51 PM
From: Steve Lehar
Subject: A Cartoon Epistemology

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?

Immaterialism and Spiritualism

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!

Visualizing Mental and Physical

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.

Mind and the Laws of Physics

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.

Occam's Razor

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!

Conjectures and Refutations

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.

The Scope of Science

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.

Scientific Observation

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.

An Inconclusive Conclusion

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.

Final Questions

  1. Is your visual experience spatially structured?

    [Bill Adams Response]

  2. Where is your visual experience located? In your head? In the world? Or in an orthogonal dimension?

    [Bill Adams Response]

  3. 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]

  4. 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]

  5. 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]

  6. 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]

  7. 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]

  8. 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]


Bill Adam's Response

Date: 9/19/2005 12:07 PM
From: Bill Adams
Subject: A Cartoon Epistemology

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.

[Steve Lehar's response]

1. Is my visual experience spatially structured?

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.

2. Where is your visual experience located?

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.

3. Is there a [shared] objective external world?

Of course, but it is a negotiated reality, not a mind-independent, self-existent one.

[Steve Lehar's Response]

4. Do you see the scale of the warped ruler as a regular scale which is warped?

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?

[Steve Lehar's Response]

5. How would your experience differ (from diorama)?

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.)

6. What response would you predict if the subjects in the ? [Hallway Experiment]

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.

7. Does mind change the state of the brain?

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.

[Steve Lehar's Response]

8. Would this be a scientific hypothesis? [invisible sphere]

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).

[Steve Lehar's Response]

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

Steve Lehar Responds

Date: 9/20.2005 1:09 PM
From: Steve Lehar
Subject: A Cartoon Epistemology

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,


3. Is there a [shared] objective external world?

This answer is totally ambiguous! If everyone died, would the world continue to exist?

4. Do you see the scale of the warped ruler as a regular scale which is warped?

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.

7. Does mind change the state of the brain?

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.

8. Would this be a scientific hypothesis? [invisible sphere]

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.