Aug 05 2011

The Motivated Reasoning of Egnorance

If you want to see many examples of motivated reasoning, pay a visit to Michael Egnor’s blog, Egnorance. He’s the evolution-denying neurosurgeon that I have sparred with over the last few years, mostly about evolution and dualism. Motivated reasoning is what most people do most of the time – start with a desired conclusion and then find reasons to support it (humans are very good at that). However, the whole point of philosophy is to rise above this tendency and follow strict rules of logic, while the point of science is similar but also to follow the evidence. Egnor can’t seem to do either, as he rants against non-believers, misinterprets study after study, and attacks those who do not share his particular faith.

A few weeks ago he wrote a response to a blog post of mine about materialism. This is familiar ground, but he does nicely reveal his tactics in the article so I thought I should eventually respond. He starts by misrepresenting the very topic of the discussion:

He put together six assertions that he claims are proven scientifically and thus prove his theory that the mind is caused entirely by the brain.

The materialist theory of mind is not my theory – it is the overwhelming consensus of neuroscientists and the result of over a century of research. But Egnor would have his readers believe it is my own quirky “bizarre” theory. This is, of course, nonsense. It is Egnor who is out on the fringe of neuroscience with his antiquated dualist beliefs. But far more important are the actual arguments themselves (I make this point mainly to demonstrate how Egnor constantly rewrites reality).

In our previous discussions I outlined six lines of evidence that clearly establish that the mind is what the brain does – the most parsimonious interpretation of all available evidence is that the mind is a manifestation of the brain. Egnor, however, would rather believe that there is something magical to the mind that cannot be explained by the matter of the brain, and so the motivated reasoning ensues.

My first line of evidence (a prediction made by the materialist hypothesis) is that brain states will correlate with mental and behavioral states, to which Egnor responds:

We can’t scan you and tell what you’re thinking, no matter how we image your brain. Period.

His point is that the correlation between brain activity and mental states is “very loose”. I have already addressed this issue – Egnor is failing to account for the limitations in our current technology. I never claimed that we could look at the brain and tell what someone is thinking. We do not yet have a detailed enough model of the brain nor the ability to measure brain activity with sufficient resolution or calibration to come anywhere near such a task. Neither is that necessary for my argument to be valid.

The point is – to the extent that we are able to visualize brain activity, it correlates nicely with mental activity, within the resolution of our instruments. This has held up with better tools, like fMRI. We can correlate activity in different brain regions with different types of mental activity. The materialist hypothesis of the mind further predicts that as our technology and model of the brain improve, this correlation will hold up. It has so far.

In other words, Egnor is confusing the limitations of our resolution to see brain-mind correlation with evidence for a lack of correlation. These are not the same thing.

He continues:

What does Novella mean by “brain maturity”? Mylenation? If so, then there is a vague correlation. Babies are immature, and their brains are incompletely mylenated. What else could he mean by “brain maturity”? Size? Dendritic complexity? Anatomical (gyral) complexity? None of those brain states correlates in any reliable way with mental and emotional maturity. There are mentally/emotionally mature people with brains of all sizes and shapes and structures. There isn’t the least bit of correlation.

Gross disease states can correlate, somewhat. A patient with advanced Alzheimers will have brain changes at autopsy that would lead the pathologist to predict that the patient was “immature” in behavior. But aside from gross obvious brain pathology, there is no consistent correlation.

Contra Novella, you can’t do an MRI of your prospective spouse to determine how mature/immature he/she is.

I honestly have no idea what Novella means by “brain maturity will correlate with mental and emotional maturity.”

It’s just a stupid assertion.

Egnor’s lack of understanding is not an actual argument, even though he confuses it for one.  Here I am not talking about personality, but the development of the brain as we grow and the fact that this brain development correlates with neurological maturity. The most obvious example is the brain of a baby or child. Babies act like babies because they have a baby’s brain – it’s not just the lack of worldly experience. As parts of their brain mature (developmentally speaking) then they gain new abilities. They cannot walk until their cerebellum develops sufficiently.

I was also referring to research into the teen brain. Scientists followed children over years and imaged their brains while doing specific tasks. This is what they found:

Another series of MRI studies is shedding light on how teens may process emotions differently than adults. Using functional MRI (fMRI), a team led by Dr. Deborah Yurgelun-Todd at Harvard’s McLean Hospital scanned subjects’ brain activity while they identified emotions on pictures of faces displayed on a computer screen.5 Young teens, who characteristically perform poorly on the task, activated the amygdala, a brain center that mediates fear and other “gut” reactions, more than the frontal lobe. As teens grow older, their brain activity during this task tends to shift to the frontal lobe, leading to more reasoned perceptions and improved performance. Similarly, the researchers saw a shift in activation from the temporal lobe to the frontal lobe during a language skills task, as teens got older. These functional changes paralleled structural changes in temporal lobe white matter.

In other words, teens act differently than adults partly because their brains function differently. Their emotional immaturity correlates with functional immaturity in the brain – it’s not just lack of life experience.

It gets worse (words in italics he is quoting from me):

Changing the brain’s function (with drugs, electrical or magnetic stimulation, or other methods) will change mental function.

Sometimes yes, most times no. There are all sorts of induced changes in brain function that have no effect whatsoever on mental function. I’ve had MEP stimulation as an experimental subject, and while it made my arm twitch, it had no effect on my mental function. Magnetic fields change brain states, without necessarily changing mental states. Anti-epileptic drugs change brain states, and often do not change mental states (they are often well-tolerated by patients).  Some seizures change brain states on EEG without discernible changes in mental states (so-called occult electrographic seizures).

This is a similar “resolution” confusion to what Egnor made above – and again he entirely misses the point. I could summarize what he is saying as this: if you change the brain a lot, you change the mental state a lot. If you change the brain a little, you change the mental state a little, and it may too subtle to be obvious or even notice. Amazingly Egnor gives the example (now remember, he’s a neurosurgeon) of his own MEP experience. I don’t know the details of this experiment, but he reports that his arm twitched. I wonder (hmmmm) if they were stimulating the motor cortex that correlates with his arm.

He next argues that antiepilepsy drugs do not always change brain states. So why, in his version of reality, does it sometimes change brain states? These drugs alter the neurotransmitter function in the brain, mostly by increasing inhibition. Put anyone on a high enough dose of these drugs, and their mental state will change. They will become drowsy and eventually comatose. That is very predictable. But of course, people metabolize drugs at different rates, and their receptors may be slightly different and respond differently to the drug. So at any given dose there will be variable effects – but the effects become predictable, 100%, if you make the dose high enough. Also some patients only need a low dose to stop their seizures, and this dose may not be high enough to cause noticeable side effects.

In fact the literature is quite clear – therapeutic doses of AEDs “often” cause cognitive and behavioral changes, and potentially changes in mood. “Well-tolerated” does not mean no effect. For those of us who actually treat seizures medically we can tell you that just about every patient on AEDs will notice some effect on their cognition. Further, when studies actually carefully measure cognitive ability in patients taking AEDs they find a consistent dose-related effect on cognition.

Egnor also notes that some seizures do not cause noticeable changes in mental states. Which seizures would those be? Perhaps they are focal seizures that occur only in a small part of the brain, and not a part that would cause obvious signs. If your entire brain is having a seizure – 100% of the time you are unconscious. A generalized seizure of any type is incompatible with consciousness. Focal seizures cause symptoms that predictably correlate with where they occur in the brain. And yes – some focal seizures are subtle – but that does not mean they have no effect at all.

Next he addresses my argument that damaging parts of the brain cause predictable changes in mental function:

I see damaged brains on a daily basis– trauma, tumors, stroke, etc. Sometimes I cause the damage myself (by placing a catheter in the brain to drain fluid). The specific mental deficits are highly variable, not the least predictable and very often there are no deficits at all. I’ve personally inserted at least 3000 catheters into patients’ brains, and I’ve not once seen a change in a mental state from a catheter insertion that passes deep through brain tissue.

Wow – this is just stunning coming from a neurosurgeon. Deficits are “not the least bit predictable” from the location of trauma? By the time a neurology resident gets half way through their first year I expect that they will be able to examine a patient who just had a stroke and then predict with remarkable accuracy precisely where the lesion will be on the MRI scan. The correlation of anatomy (and therefore pathology) to specific functions and deficits is what first alerted neuroscientists to the fact that the brain has specialized regions with specific tasks. We have now mapped the brain quite extensively. There is a vast experience and literature documenting the close correlation between location of brain injury and specific neurological deficits. It’s hard to emphasize how at odds with reality this assertion by Egnor is.

He further gives the example that he has placed many catheters deep into the brain without causing noticeable changes to the patient’s mental function. What he is not telling you is that surgeons will typically place these catheters through the non-dominant (right side in most people) frontal lobe. There is a reason for this – this is the most redundant part of the cortex. You need to cause damage to both sides of the frontal lobes to cause deficits. The location is chosen specifically to minimize the deficits that result from the procedure. Does Egnor stick his catheters willy-nilly through any part of the brain? I bet not – I bet he follows the standard of care and is very specific about where he places the catheter – because brain anatomy does correlate with function.

Further – the fact that there is no obvious effect does not mean there is no effect. Unfortunately, there isn’t much research looking at the cognitive effects of catheter placement, but the one study I could find showed, “The present study revealed persistent cognitive inefficiencies in memory and executive domains in patients post-ETV intervention. ”

Egnor’s assertions here are just astounding, but mostly he once again  is making the mistake of confusing the limits of our resolution (or just not looking closely) with that of correlation between brain and mind. But further he just flat out misrepresents the current state of the evidence.


There will be no documentable mental phenomena in the absence of brain function.

I don’t know, and neither does Novella. There have been tens of millions of people (at least) who have had near-death experiences in which they had mental experiences during cardiac asystole and lack of brain perfusion.

If neither of us know, then there aren’t any clearly documented cases. If there were – we would know. Egnor here is using speculative and controversial claims as a premise – not exactly solid ground. I have written about NDE before and won’t repeat it here. I argue that the evidence does not support the conclusion of mental activity without brain activity. Egnor, however, is intent on repeating his non sequitur and following up with a straw man.

I don’t know if any of these are real. Neither does Novella. But his statement that there are “no documentable mental phenomena in the absence of brain function.” is rank b.s. There are tens of millions of people who’ve had these experiences, and many have been documented and corroborated.

Are they all nuts? Are they all lying? Are they all deluded? Dr. Novella thinks so, but his opinion is based on his bias, not on any evidence.

Again – if we don’t know whether or not they are real, then they are not evidence – not documentable phenomena.  I also never stated and do not believe that all patients who experienced an NDE are “nuts,” “lying,” or “deluded.” I think they had profound experiences during a life-threatening event. I just further think that these experiences can be explained as brain experiences, the effects of hypoxemia and hypercapnea mixed with memories from the period of recovery.


When the brain dies, mental function ends.

Ditto.  If Novella has scientific evidence proving that there is no afterlife,  I’d love to see it.

This is an attempt to shift the burden of evidence. I also further never said that I can prove there is no afterlife. My position is that there is no evidence for an afterlife, nor is there any evidence for mental activity in the absence of brain activity. If  Egnor thinks he has such evidence, I’d love to see it.

Egnor finishes up with a typical rant, partly writing:

As for Novella, his “proofs” are a tangled mess of scientific ideological assertions that actually make the case opposite the one he thinks they do… if they are to be taken seriously at all, which they shouldn’t be.

Several of his claims, coming from a practicing neurologist, are simply lies.

He keeps putting the word “proofs” in quotation marks. That implies that I used the word “proof” when writing about it. I didn’t (at least not in the article he links to)- I used the phrase “clearly establishes” which I stand by. In any case – he follows with pure ad hominem fantasy. I will let the reader decide who is making unsupported ideological assertions, and who is being loose with the facts.


175 responses so far