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Can Materialism Explain Abstract Thought? Part II

Now Dr. Ali argues with Dr. Ali

Psychiatrist Dr. Faizal Ali, who claims not to be a materialist (but plays one on the internet), clings to materialist theories of abstract thought despite the powerful scientific evidence against materialism as a theory of the mind. I replied to him earlier here, noting the difference between abstract and concrete thought. Now let us consider the neuroscience.

I have pointed out the research done by Dr. Roger Sperry on patients who had the two hemispheres of their brains surgically disconnected (for which Sperry won the Nobel Prize). It is clear evidence that higher mental function, such as abstract thought, does not arise from material processes in the brain. The reasoning is straightforward: the patients who had their brains essentially cut in half had completely normal powers of abstract thought after the procedure. They were still one person, and no intellectual function was affected in the slightest.

The changes—changes which were so subtle as to be undetectable in ordinary life or with ordinary medical examination—were subtle but quite interesting perceptual (not abstract) changes. Sperry’s work confirmed the generally accepted neuroanatomical correlates of the left and right cerebral hemispheres: the left hemisphere (in most people) mediates language perception, and elaboration, and the right hemisphere mediates spatial perception. In patients with disconnected hemispheres, abstract thought—mathematics, logic, conceptual thinking about abstractions—were completely unaffected. The inference is obvious: perception (like motor function) is mediated in the cerebral hemispheres and is material in origin. Abstract thought, on the other hand, is an immaterial power not caused by the material brain.

Dr. Ali’s understanding of Sperry’s research is deeply flawed (which I will address in posts to come). But the gaping hole in his argument is evident from another argument he made for the materialist theory of abstract thought.

I pointed out that there are no intellectual seizures—that is, that epileptic seizures never evoke abstract intellectual thought—despite the materialist claim that abstract thought arises entirely from brain function. This inconsistency of materialist theory with scientific evidence was first noted by Dr. Wilder Penfield, who was the pioneer in epilepsy neurosurgery. Penfield noted that during his fifty years of clinical practice and research that stimulation of the brain—either by seizures or by a neurosurgeon during surgery—never evokes abstract thinking. I have noted the same thing in my practice. I know of no report in medical history of an abstract thought evoked by a seizure or by brain stimulation. Which is odd, if the brain causes abstract thought.

Dr. Ali argues that abstract thought arises from delicate complex interactions in the brain:

No knowledgeable person expects a random, massive, disorganized discharge of large parts of the cerebral cortex to result in a precise and specific intellectual idea. That’s just not how this works, and Egnor should know this. If his first argument is the equivalent of expecting to sit at a piano and play Beethoven’s Emperor Concerto by randomly jabbing at two keys at a time with the index fingers, this second argument is the equivalent of expecting to accomplish the task by bashing on all the keys at once with a two-by-four. Neither approach is going to get the job done. What is needed is a trained concert pianist and, in this field… I am simply providing it as an example of the complexity of the research involved in trying to elucidate the brain mechanisms that may be responsible for higher cognitive functions.

Faizal Ali, “Neurosurgeon Argues That Mind Functions Are Immaterial. Badly. (Pt. 2)” at Better Right Than Happy

Dr. Ali contradicts himself. First, he argues that it’s no surprise that cutting the brain in half and separating the cerebral hemispheres, as Sperry did, has no effect on abstract thought. Then he argues, in connection with Penfield’s seizure research, that abstract thought is the wholly material result of delicate complex connections within the brain: (“what is needed [for abstract thought from brain connections] is a [metaphorical] trained concert pianist”).

In short, he argues that it’s no surprise that cutting the brain in half has no effect on abstract thought, and then he argues that delicate complexity and interconnection is essential for abstract thought. Dr. Ali is debating Dr. Ali.

To understand the materialist folly better, consider the three kinds of neuroscientific evidence that can be used to evaluate materialist vs. dualist claims: correlation, evocation, and ablation.

1. Correlation entails studies that measure brain activity as it correlates with abstract thought. For example, Benjamin Libet’s research on “free won’t” shows that there is no brain activity that correlates with a voluntary veto of a decision, which implies that the veto is immaterial.

2. Evocation entails the study of the effect of stimulation of the brain on the production (or lack thereof) of abstract thought. For example, Wilder Penfield was unable to stimulate abstract thought using electrodes during awake brain surgery and he noted that seizures never evoke abstract thought. He reasoned, correctly, that abstract thought did not originate in the brain.

3. Ablation entails the study of the effect on abstract thought of damage to the brain. Ablation experiments include Sperry’s research on split-brain patients, who had entirely normal abstract thought despite essentially disconnecting the cerebral hemispheres (which cuts the brain in half). Other ablation experiments include Owen’s studies of high-level abstract thought in patients with massive brain damage and a large number of studies on near-death experiences. These experiences demonstrate the continuation of mental functions following the complete cessation of brain function.

The standard materialist theory of abstract thought is that it arises from the intricacy and complexity of neural networks in the cerebral cortex. That is Dr. Ali’s argument. But this materialist argument is really just hand-waving amounting to magic (“lots of neurons fire together… and suddenly abstract thought appears!”)

Materialists never explain how the firing of lots of neurons (magically) evokes abstract thought. You just have to trust them on that.

Materialists use this claim of “delicate complexity” theory to attempt to explain why seizures and brain stimulation never evoke abstract thought. The brain mechanisms for abstract thought are said to be too delicate and complex!

But this argument leaves the materialist theory vulnerable to equally compelling ablation research. That is, if abstract thought depends critically on delicate complexity of neural networks, then certainly such networks would be disrupted or destroyed by split-brain surgery or by the massive diffuse brain damage that causes persistent vegetative state.

Yet, contrary to materialist theory, patients after split-brain surgery have completely normal abstract thought (the only changes are subtle changes in non-abstract perceptual thought). Also, patients in a persistent vegetative state often retain high levels of abstract thought despite massive diffuse destruction of much of their brain.

Materialists can’t have it both ways. Either abstract thought depends on delicate complex brain interconnections, or it doesn’t. Not both.

The truth is that the neuroscience research applicable to the question of the materiality or immateriality of abstract thought only makes sense if we acknowledge that abstract thought is not a product of the brain at all. To wit, neuroscience research has shown no correlation between abstract thought and brain activity (Libet’s ‘free won’t’), neuroscience research has shown no evocation of abstract thought by stimulation of the brain or by seizures (Penfield), and neuroscience research has shown no ablation of abstract thought by splitting the brain in half (Sperry) or by massive diffuse brain damage (Owen).

Materialists may attempt to explain one of these findings (with the usual hand-waving), but they cannot explain all of them because materialism would have to contradict itself to explain all these results. If abstract thought is caused by delicate complex brain interconnections, then it should be easily destroyed by cutting those interconnections.

It’s time that materialists set aside their metaphysical bias and follow the obvious scientific evidence. The only explanation that accounts for all of the evidence in neuroscience—correlative, evocative and ablative—is that abstract thought is an immaterial power of the mind.

Also by Michael Egnor on abstract thought:

What is abstract thought?, Part I: A Reply to Dr. Ali Abstract thoughts cannot arise from material things because a cause cannot give what it does not have. Dr. Ali’s deeper fallacy—deeper than his misunderstanding of the research—is his belief that mere complexity of material processes is sufficient to explain immaterial processes.

Four researchers whose work sheds light on the reality of the mind The brain can be cut in half, but the intellect and will cannot. The intellect and will are metaphysically simple


Materialism is an intellectual trap, out of which neuroscience needs to climb. Neurologist Steven Novella refutes himself. He first asserts that everything he knows is an illusion. Then he insists that his illusions slap him in the face with reality.

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Michael Egnor

Senior Fellow, Center for Natural & Artificial Intelligence
Michael R. Egnor, MD, is a Professor of Neurosurgery and Pediatrics at State University of New York, Stony Brook, has served as the Director of Pediatric Neurosurgery, and award-winning brain surgeon. He was named one of New York’s best doctors by the New York Magazine in 2005. He received his medical education at Columbia University College of Physicians and Surgeons and completed his residency at Jackson Memorial Hospital. His research on hydrocephalus has been published in journals including Journal of Neurosurgery, Pediatrics, and Cerebrospinal Fluid Research. He is on the Scientific Advisory Board of the Hydrocephalus Association in the United States and has lectured extensively throughout the United States and Europe.

Can Materialism Explain Abstract Thought? Part II