Aug 09 2011
Michael Egnor has responded to my prior post in which I outlined his numerous failings in logic and misrepresentations of neuroscience. His response continues to be incoherent, but does offer some further teaching points.
One of the main points of contention is this – what can we infer from the relationship between damage to the brain and resulting neurological signs and symptoms. My position is that, if the mind is entirely caused by the functioning of the brain, then damage to the brain will damage the mind. I maintain that this is true, as far as we can tell from our current technology and understanding of neuroscience.
Egnor maintains that this is not true – that the relationship is “not the least bit predictable.” Further, that this lack of total correlation is evidence for dualism, that the mind is produced, at least in part, by something immaterial. There are both factual and logical problems with his position. To my criticism of his claims, he writes:
Mental deficits – specific defects in reasoning, judgement, planning, memory– are highly variable. One cannot look at a CT scan done after a head injury and predict with any certainty that ‘this person will have an inability to remember numbers’. High level mental function localizes very poorly to specific brain regions. This is odd, if, as Novella claims, the material brain is entirely the cause of all mental function.
He is trying to rescue his position by arguing that only what he calls “middle level” and “lowest level” neurological functions map well to the brain, and that “high level” functions like those he outlines above do not map well to specific brain regions because, he argues, they are not entirely caused by the brain. He further thinks this is evidence for Thomistic dualism (more on that below).
First – there is a massive factual problem with his line of argument. It is true that not all neurological functions map equally well to specific brain regions. But this does not completely correlate with Egnor’s “higher” vs “lower” mental function. Rather, some functions are simply more localized than others, which in turn are more distributed. Some functions seem to correlate to a network of brain areas – there are areas that have semi-specialized functions and that participate in multiple networks for different mental activities. (I’ve written before about brain modules and networks.) Also – some brain regions are redundant while others are not.
So, a lesion in a part of the brain that is dedicated to a specific function will predictably cause a specific deficit (what we call a focal deficit, because it correlates to a focus in the brain). This remains a good line of evidence for the hypothesis that the brain causes mind. If you damage an area of the brain that is redundant or part of distributed function, then there likely will not be any specific or focal deficits.
This does not mean, however, that the mind has not been changed at all. As I already pointed out – the injury is simply more subtle and difficult to detect. But if you study mental function in detail you find that brain damage (even in “silent” or “non-eloquent” parts of the brain) correlates nicely with decreases in overall mental function. This may cause a measurable decrease in IQ, or even a change in personality. This is essentially what happens in dementia. The brain is damaged diffusely, and loss of cognitive function (even, and in fact especially, the “highest” cognitive functions) occurs even before any focal deficits may be apparent. You can even get dementia from the cumulative effects of small “silent” strokes in the non-eloquent white matter of the brain. Patients with multiple sclerosis will sometimes lose cognitive function because of the cumulative effect of small brain lesions that individually did not cause any focal deficits.
It is simply wrong to state that “silent” brain lesions do not cause any deficits, simply because there is no obvious focal deficit.
Egnor’s higher vs lower mental function distinction is also false. Some sophisticated cognitive functions, like language, are very focal. In fact you can cause specific types of problems with processing language by causing very precise lesions in the brain (in fact this is the origin of the term “eloquent” cortex). Is Egnor arguing that language, literal eloquence, is not a “higher” cognitive function.
He specifically brings up the example of remembering numbers – but this is a bad example for him. Mathematical skills actually localize quite well, to the dominant parietal cortex. There are lots of interesting specific cognitive deficits that result from very focal lesions. There is alexia without agraphia – the inability to read without the inability to write. So a patient can write a sentence and then not be able to read what they just wrote. What about neglect – the inability to think about one half of the world, to include the concept of “left” in one’s modeling of the physical universe. There are focal lesions that can make you feel as if you do not own your arm, or make you feel as if you own an extra arm you don’t have.
There doesn’t seem to be any aspect of cognitive function that cannot be made to go away or change in function with damage. Now we also have the ability to increase or decrease the function of different brain regions with transcranial magnetic stimulation, and we can even change a persons moral judgments with these techniques (one of the exact examples Egnor gives – judgment). I wrote previously about this study:
The brain region in question, the right temporo- parietal junction (TPJ) is involved with a function known as the theory of mind – the ability to imagine what some other creature is thinking or feeling. In other words, we understand that other people have their own thoughts and feelings similar to our own , and this enables us to consider their possible motivations.
Researchers were able to alter moral judgments that are based on the theory of mind by impairing the function of the TPJ. Is Egnor arguing that the theory of mind is not what he calls a “higher” cognitive function?
There is also evidence from patients with epilepsy. We might not be able to look at an MRI scan and say where a specific memory or feeling is located, but patients who have seizures that start in a small part of the brain often have stereotyped auras. They have symptoms that are exactly the same each time, and are determined by where in the brain the seizure starts. It could be a sound, a smell, a visual sensation, a feeling, or a motor twitch. Take a look at some of these case reports of frontal lobe seizures, which tend to be more unusual. One patients experiences fear during a seizure, while another feels the urge to rub his hands together, and another to drink water.
If Egnor believes that “non-eloquent” cortex – like most of the frontal lobes – does not have specific deficits in response to localized trauma, then how does he explain the reproducible changes in personality from frontal lobotomies? Or is personality not a higher mental function in Egnor’s thinking?
We also have evidence from the effects of drugs on the brain. Egnor maintains that judgment is a “higher” mental function and cannot be explained by the brain. But anyone who has used alcohol knows this to be nonsense. Alcohol inhibits brain function and at recreational doses has two very reliable effects – it reduces inhibition and impairs judgment.
Egnor’s claim that brain damage or other lesions do not correlate well with specific deficits (outside of eloquent cortex) is simply wrong.
Egnor’s claim that “silent” brain damage causes no deficits is also wrong.
Egnor’s claim that there is a difference in brain-mental correlation between basic neurological functions and “higher” mental functions is also wrong. There is a difference in the degree to which we can localize specific functions, but that has to do with how distributed and how bilaterally redundant those functions are – not by Egnor’s concept of higher vs lower mental function.
Egnor’s logic that the lack of specific localization of neurological functions argues against the conclusion that the brain causes mind is also not valid. It could simply mean that some function are represented by distributed networks in the brain.
Further, Egnor continues to confuse the limits of our current ability to image and map brain function with the limits of brain function itself. This is like using a small telescope to look at Mars and then claiming Mars has no geological features, while ignoring all the images of Mars from high power telescopes and probes we sent to Mars. There is a vast and growing published literature mapping brain function with fMRI, PET scans, EEG, and transcranial magnetic stimulation. We still have a long way to go, but this approach (the materialist paradigm) is working very well. We are already decades ahead of where Egnor apparently thinks we are, and continuing to advance.
So far there is no mental function so sophisticated or abstract (“higher” in Egnor’s thinking) that we cannot mess with it by messing with the brain, or correlate it with some pattern of brain activity. It’s horrifically complex, but we are making progress.
To push this one point further, Egnor writes:
There is no ‘long division’ area or ‘enjoy Beethoven’ area in the brain that can be mapped with anything resembling precision.
Here Egnor is confusing the ability to map an area of the brain in general vs in a specific individual. There are (conservatively) millions of feelings, ideas, memories, and sensations stored in the brain. Of course we cannot map the brain to such detail, and of course there is no “enjoy Beethoven” area of the brain. This is just an absurd premise. Specialized areas and networks in the brain are not so specific. But there is a part of the brain that allows for calculations, and there is another part that allows for the appreciation of music. Further – he is confusing the ability to map the brain in general vs the localizability of an individual’s brain. We know from people with focal seizures, for example, that one tiny part of the brain does reliably map to one specific experience – that’s why their seizure auras are so stereotyped.
The evidence from trauma, seizures, response to drugs, and brain mapping all nicely fit together within the currently accepted working theory that brain activity causes the mind. Egnor, however, would have his readers put blinders on and look at only one slice of the evidence at a time, so he can distort and misrepresent it. Like all deniers, he is not putting forward a consistent and evidence-based theory of his own. His job is just to cause doubt and confusion regarding the prevailing science.
The closest he comes is when he endorses outdated philosopher, which gets us back to his Thomistic dualism. He writes:
There are three general types souls of living things:
Plants have vegetative souls, which mediate nutrition, metabolism reproduction, growth, etc.
Animals have sensitive souls, which in addition to the capabilities of vegetative souls, mediate sensation, locomotion, appetite, etc.
Humans have rational souls, which in addition to the capabilities of vegetative and sensitive souls, mediate reason, judgement, will, etc.
Previously I had argued that dualism was the logical equivalent of vitalism, and Egnor now seems to be validating that point. Vitalism, the notion of a living force, was always a mental placeholder – the vitalistic force was thought to be responsible for whatever aspect of life we could not currently explain. But as biology advanced, the vital force became unnecessary. The “vegetative soul” is the equivalent of the vital force. We now know that no magical mojo is necessary for plants to metabolize and reproduce. Biology sufficiently explains this.
As biology is to vitalism, neuroscience is to dualism. Animals do not need sensitive souls to feel, eat, and move (wait a minute, wasn’t Egnor just arguing that these functions map well to brain anantomy?). Humans do not need souls to think, reason, and judge – the brain suffices.
Now we see, however, why Egnor came up with his fake division of “higher” vs “lower” neurological function. But it does not reflect underlying reality. Real scientists change their ideas to accommodate what the evidence tells us about reality. Ideologues stick to centuries-old philosophy despite the evidence.
I do need to clarify one point. Neuroscientists do talk about higher and lower brain function – but they are talking about the evolutionary and hierarchical organization of the brain. We have a human brain on top of a monkey brain which sits on a mammalian brain all wrapped around a lizard brain. Our most-recently evolved frontal lobes are involved with planning and inhibition while the more primitive parts of the brain are involved with feelings, motivation, and more basic function. This organization, however, does not correspond well to Egnor’s artificial division of mental functions. Memory, for example, is a primitive function. Whereas language, which evolved recently, is relegated to “eloquent” cortex, which Egnor argues is a middle-level function.
There is a lot more nonsense in Egnor’s post, but as you can see it takes more time to correct nonsense than to spread it, so this will have to do for today.
Egnor has written another response. However, he does not address any of the points I make in the above post. He just repeats his same assertions and distortions. He continues to confuse resolution of detail with lack of correlation and simply cannot understand the distinction. On the whole it’s incoherent and there is nothing new to respond to.
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