The Mind-Brain Problem: Qualia and Mary the Color Scientist
I’m in the midst of an online debate with neurologist Dr. Steven Novella about this question: can the mind be explained entirely by the brain, or is there an immaterial aspect of mental states that defies materialist reduction? Dr. Novella and I are both well-acquainted with neuroscience (I’m a neurosurgeon), and we have quite different views on the mind-brain problem. Dr. Novella is a materialist, and he believes that neuroscience has demonstrated beyond question that the mind is entirely caused by material processes in the brain. I believe that there are properties of mental states that don’t admit material explanations, and I favor dualism. Dr Novella asserts:
[Egnor] fails to recognize that this battle has already been fought and lost within the scientific arena…[a]s our knowledge of brain function increases, it is squeezing out any role for a non-material ghost in the machine. A non-material cause of mind is…unnecessary…
Of course, the battle over the mind-brain question hasn’t “already been fought and lost,” and it certainly hasn’t been resolved in favor of materialism. Dualism is, if anything, gaining traction in the philosophical community as necessary for an adequate description of the mind, and there are and have been many prominent neuroscientists who adhere to dualism. Charles Sherrington (Nobel laureate and the father of neurophysiology), Wilder Penfield (the father of epilepsy surgery), Sir John Eccles (Nobel laureate and pioneer in the study of neuronal synapses) were dualists, and many modern neuroscientists such as Jeffery Schwartz and Mario Beauregard reject strict materialist understandings of the mind. Dr. Novella’s dogmatic assertion that the “battle has already been fought and lost within the scientific arena” is mere rhetorical bluster.
In the philosophical arena, strict materialism is faring even worse. Over the past few decades, many philosophers of the mind have pointed out the glaring logical problems with materialism as an adequate solution to the mind-body problem. Central to the evidence against materialism is the concept of qualia. Qualia (singular quale) is a philosophical term that refers to the subjective aspect of sensory experience. Qualia is often described as ‘that which it is like to…’. It is the entirely first-person subjective aspect of sensation — the smell of coffee, the experience of the color red, the hurt of pain, as distinguished from third-person objective facts about sensations, such as the chemical formula for coffee, or the wavelength of red light, or the neurotransmitters that mediate pain. Daniel Dennett has described several properties of qualia that are generally agreed upon:
1) Qualia are private experiences, which are accessible directly only to the person experiencing them.
2) Qualia are incorrigible, in the sense that the experience of qualia is all that needs to be known and can be known about them. Qualia are pure subjective experience.
3) Qualia are ineffable, in the sense that they cannot be apprehended by someone who has never experienced them. (i.e. if someone had never had a sense of smell, one could not describe what it is like to smell coffee).
Philosopher Frank Jackson posed a thought question in 1982 that clarifies the problem that qualia poses for the strict materialist approach to the mind-brain question. It is framed as an epistemological problem. Materialism claims that the physical facts about mental states are all the facts there are. We may not understand all the material facts now (we certainly don’t ), but there are no facts about mental states that are not, in the final analysis, reducible to material facts, such as neurotransmitters, neurons, axonal electrochemical gradients, etc. Can materialism really provide all that can be known about color?
Jackson called his thought question “Mary’s Room” (1), and it has since come to be known more generally as the ‘Knowledge Argument’:
Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from a black and white room via a black and white television monitor. She specializes in the neurophysiology of vision and acquires, let us suppose, all the physical information there is to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like ‘red’, ‘blue’, and so on. She discovers, for example, just which wavelength combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal cords and expulsion of air from the lungs that results in the uttering of the sentence ‘The sky is blue’. (…) What will happen when Mary is released from her black and white room or is given a color television monitor? Will she learn anything or not?
Jackson believed that Mary did learn something new: she learned what it was like to experience color.
It seems just obvious that she will learn something about the world and our visual experience of it. But then is it inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physicalism [materialism] is false.[my brackets]
Many philosophers have ventured materialistic hypotheses to explain qualia in an effort to salvage the materialist paradigm, and Jackson himself later in life came to accommodate materialism (grist for future posts). But in the view of most philosophers of the mind, the Knowledge Argument represents a profound problem for any strict materialist solution to the mind-body problem. When we experience qualia, we know something that is not material knowledge. Therefore, the mind cannot be explained completely by materialism. The fact that we experience qualia is difficult to elide, and there is nothing in materialistic explanations, and nothing in neuroscience, that invokes subjective experience.
Dr. Novella, again:
this battle has already been fought and lost within the scientific arena…A non-material cause of mind is…unnecessary…
Dr. Novella misunderstands the profound problem that first-person subjective mental states pose for strict materialism. In his blithe assurance that science has solved the mind-brain problem, he commits a category error. Science has made great progress in describing some of the material (brain state) correlates of mental states. However, neuroscience by its nature deals with law-like correlations between third-person material processes, and there are fundamental first person subjective aspects of mental states, such as qualia, that do not admit material explanations.
Is the mind entirely caused by material processes in the brain? If Dr. Novella has a materialistic explanation for qualia, he should provide it.
(1) (1982) “Epiphenomenal Qualia,” Philosophical Quarterly 32, 127, pp. 127-136.