Lecture 1: Persistent Dualisms or The Furniture of the Universe

René Descartes (1596-1650) Cogito ergo sum. Good sense is mankind's most equitably divided endowment, for everyone thinks that he is so abundantly provided with it that even those with the most insatiable appetites and most difficult to please in other ways do not usually want more than they have of this.

But what am I then? A thing which thinks. What is a thing that thinks? It is a thing which doubts, understands, [conceives], affirms, denies, wills, refuses, which also imagines and feels.

Issues and traditional solutions of the mind-body problem
From Valentine, E.R. (1982) Conceptual Issues in Psychology

Idealism

Esposed by Bishop Berkeley. He claimed that what we think of as our body is merely the perception of mind. Before you reject this too rapidly consider the results of a study recently reported by the Ramachandrans. They asked three hemiplegic stroke victims with damage to the right hemispheres of theri brains about their abilities to move their arms. All three claimed, despite evidence to the contrary in the mirror in fron of them, that they could move their right and left hands equally well. Further, two of the three stroke victims claimed that an experimental stooge who faked paralysis of his left arm was able to move his arm satisfactorily.
Dr Johnson's riposte: "I refute it thus" while kicking a stone.

Materialism

Matter is fundamental.

Epiphenomenalism

Mental states, such as feelings, have no causal efficacy. A position associated with Hodgson who elaborated it using the metaphor of a stone mosaic: the colors on the surface of the stones are epiphenomenal to the structural function of the underlying stones.

Neutral Monism

Also known as dual aspect monism. Espoused by Lewes in the 19th century. The argument runs that there is only one kind of stuff. Mind and body differ only in the arrangement of the stuff or in the perspective from which it is apprehended.

Fechner's curve metaphor

This still leaves us with the translation or interaction problem outlined above. As John Tyndall put it in "Fragments of Science for Unscientific People: A Series of Detached Essays, Lectures, and Reviews":

"the passage from the physics of the brain to the corresponding facts of consciousness is unthinkable. Granted that a definite thought, and a definite molecular action in the brain occur simultaneously; we do not possess the intellectual organ, nor apparently any rudiment of the organ, which would enable us to pass, by a process of reasoning from the one to the other."

Nagel takes up this difficult point in his 1974 article entitled "What is it like to be a bat?". He claims that consciousness is what makes the mind-body problem really intractable. As Kathleen Akins puts it in her response to Nagel:

"The problem of consciousness simply put, is that we cannot understand how a brain, qua gray, granular lump of biological matter, could be the seat of human consciousness, the source or ground of our rich and varied phenomenal lives.

Nagel sought to justify our intuitive sense of mystery when confronted with this question by drawing a distinction between subjective and objective experience. Hence the mind-body dichtomy spawns a need to create other dualisms. He claims that subjective facts - facts about conscious experience - are essentially tied to a point of view. He claims that it is impossible for us to know what it is like to be a bat using the sense of echolocation which we do not possess. We can only imagine what it would be like for us to be a bat. This implies a descent into solipsism: we can only know our own minds and experiences. In her response Akins takes the other route available: she asks what science can say about what it is like to be a bat. Why are bats such an anomaly?

Differences Between Sound and Light

Vision	Audition
single light source of the sun	No single source that bathes the world in sound
short wavelengths (380-780nm) reflected by even very small objects	short wavelengths or low intensity signals are easily absorbed by a medium of propagation (such as air)
the wave property of light allows it to be easily focused through a lens or small hole	subject to high diffraction and diffusion
easily developed from avaliable organic building blocks, many organic molecules are sensitive to electromagnetic radiation	the type of medium that carries a sound wave vibration makes a difference to the signal (the principle of ultrasound)

To deal with these difficulties the bat has a sophisticated signalling and receiving system for echolocation. When a particular bat approaches a target it changes its sonar signal in response to the phase of pursuit. The bat's auditory system is such that the transduction/sensory mechanisms "match" the sonar signals: they act as signal filters to either reduce the noise in the incoming signal or "shape" those sounds in some other beneficial way in order to solve problems inherent in the sound world. Effectively, the bat makes its own sun. From an analysis of how the physics of sound changes over the course of the hunt, we can infer with fair reliability, what information the bat lacks. For example, if we know that a sound signal with a certain frequency can travel only 6 ft then we know that an echo of that frequency does not provide any onformation about objects at a distance of greater than 3 feet (i.e. 6 feet there and back). The closer the bat gets to the target, the smaller becomes its depth of field. In the search phase of the hunt, it is the second harmonic that receives the greatest energy; but as the bat gets closer the energy shifts to the high frequency harmonics, sound waves that are more easily absorbed but also provide more detailed information. The closer the bat gets, the more detail it can discern, akin to human vision.

So what does this tell us about what it is like to be a bat? When the bat flies across the night sky, in all likelihood it does NOT use its sonar system to construct representations of objects around it: it is probably neither imagistic ( a stored representation) nor an experience of a world of objects and properties. Hence the bat might not have a point of view at all. She likens the experience to manning the controls of a plane - different cortical regions of the bat's (asprin sized) brain provide different information: coming into view, direction, beating of insect wings, amplitude of the sound, its speed. No need to attribute to the bat intermediary processing steps nor any of the representational capacities that would be required. The specificity of the bat's cortical neurons raises the possibility that the bat may not even possess, from its sonar information, the necessary building blocks for complex spatial representations. Thus, the subjective world of the bat is entirely different from our own, and we know more specifically how than Nagel allowed us to see. The endpoint fo today's lecture on the mind-body problem is nicely provide by Gerald Edelman's concise statement:

"It is not enough to say that the mind is embodied; one must say how."

Edelman is a Nobel prize winning immunologist who has turned his considerable intellect to the problems of neurobiology. I will discuss his theory of Neuronal Group Selection and Darwin Machines in coming lectures.

Sources used to prepare this lecture

Wozniak, R. (1992) Mind and Body A well illustrated web document on the history of thinking about the mind-body problem.

Edelman, G. (1992) Bright Air, Brilliant Fire: On the Matter of the Mind, Harper Collins Publishers: New York.

Nagel, T. (1974) What is it like to be a bat?, Philosophical Review, 83, 435-450.

Akins, K. (1997) What is it like to be boring and myopic?, In Dahlbom, B. (Ed.) Dennett and His Critics, Blackwell:New York.

Flangan, O. (1991) The Science of the Mind, second edition, MIT Press: Cambridge, MA. Chapter 1.
Anosognosia Scientific American article about the Ramachandrans' work.