The Brain Can Be Split, but Not the Mind | EvolutionNews

https://evolutionnews.org/2025/06/new-bo...-the-mind/

The Brain Can Be Split, but Not the Mind
by Michael Egnor and Denyse O'Leary

For centuries, we have believed that the brain is the organ of the mind and that consciousness arises wholly from the brain. With the brain cut in half, how would one hemisphere of the brain know what was going on in the other hemisphere? How could a person really act as a unified individual with the two halves of the brain disconnected?

[...]

Despite his severed brain, he moved his arms and legs normally, his vision was normal, and so was his speech. In fact, the only thing different about Sam — aside from the bandage swathing his head — was that he was no longer having major seizures. And he certainly seemed like a single, unified person … He knew that surgery had permanently split his brain into two separate brains, but the only effect he actually noticed was that his seizures were gone…

https://evolutionnews.org/2025/06/new-bo...-the-mind/

The Brain Can Be Split, but Not the Mind
by Michael Egnor and Denyse O'Leary

Seems that even the most severe form of hemispherectomy - the actual removal of either the left side or the right side of the brain (but not the deeper structures) - leaving just one lone brain hemisphere, allows people to get on with their lives... quite bizarre considering such an insult to the brain.

https://doi.org/10.1016/j.celrep.2019.10.067
https://doi.org/10.1073/pnas.2212936119

One might think it's almost holographic in it's effect. In the sense that cutting a hologram in half loses definition, but not the overall structure

https://www.youtube.com/watch?v=S8OEiTe8_Dc

This remarkable kid had neither hemisphere at birth!

https://www.youtube.com/watch?v=j4bav2qegN0

David

Thanks Valmar for bringing up this book - I am just reading it!

https://www.amazon.co.uk/s?k=the+immorta...EQQ039JQDE

The neurosurgeon Michael Egnor is associated with the Discovery Institute, and his book does contain some Christian ideas, but the bulk of the book is excellent. Like so many DI books, everyone should read this book for its science. I am going to extend this post over the next few days, but it is nearly midnight here!

He has, for example, performed a number of split-brain operations to relieve intractable epilepsy.

Here is what ChatGPT had to say on the subject:
You said:
I would be interested toknow what you think about Michael Egnor's new book, The Immortal Mind (before I contribute my thoughts). Please be fairly expansive.
ChatGPT said:

Thanks, David—happy to give you an expansive take on The Immortal Mind by Michael Egnor. It’s a fascinating book that’s bound to spark deep philosophical, theological, and scientific conversation. Here's a broad analysis, split across a few key dimensions: philosophical underpinnings, scientific claims, strengths, and critiques.
📚 Core Thesis of the Book

Egnor argues that the mind is not a purely material phenomenon—that human consciousness, particularly aspects like free will, rational thought, and intentionality, cannot be reduced to neural activity. He defends dualism, especially of the Thomistic variety, and asserts that the soul is not only real but also immortal.

He builds a case that neuroscience, rather than disproving the soul, actually supports its existence—particularly in how certain cognitive functions persist or emerge in ways that seem to defy materialist explanations. He draws heavily from classical philosophy (Aristotle, Aquinas), contemporary neurology (his field), and philosophical critiques of materialism (especially from people like David Chalmers and Thomas Nagel).
🧠 On Consciousness and Neuroscience

One of the more provocative parts of Egnor’s argument is that brain damage does not destroy the mind, but rather limits the expression of the mind. He frequently draws analogies—most notably the “radio analogy”—in which the brain is likened to a radio receiver: damage to the hardware interferes with the signal, but the signal (mind/soul) still exists independently.

He also cites cases like hydrocephalic individuals with minimal brain tissue who nonetheless function surprisingly well, using this to argue that consciousness is not strictly dependent on brain mass or structure.
🧩 Philosophical Depth

Egnor's use of Thomistic philosophy is central. He leans on Aquinas’ hylomorphic dualism—where the soul is the form of the body, not a separate Cartesian "ghost" in a machine. In this view, the soul animates the body, gives it life, and carries immaterial faculties like intellect and will. It’s not an add-on to the brain—it’s the principle that makes life and rational thought possible.

He distinguishes sharply between the brain as a material organ and the intellect as an immaterial faculty. This distinction is where he builds his strongest critiques against materialist and physicalist explanations of mind.
⚖️ Strengths of the Book

Interdisciplinary Range: Egnor integrates neuroscience, philosophy, and theology with unusual coherence. That’s rare and valuable.

Philosophical Clarity: His treatment of Thomistic thought is clear and accessible for non-specialists, without being dumbed down.

Courage to Push Against Consensus: He’s willing to challenge dominant materialist views, even within his own scientific discipline.

Case Examples: His use of clinical cases adds a concrete grounding to what might otherwise feel abstract or speculative.

🧱 Critiques and Challenges

Cherry-Picking and Anecdotal Evidence: Critics often say he overemphasizes unusual neurological cases while downplaying the massive body of evidence correlating brain function and mental states.

Radio Analogy Problems: The analogy between brain and radio, while evocative, breaks down under scrutiny. In radios, the signal clearly originates externally; with consciousness, we don't yet have a clear "external transmitter" to point to scientifically.

Dismissal of Alternative Philosophies: Though he critiques materialism robustly, he can be too dismissive of middle-ground theories like property dualism, panpsychism, or neutral monism.

Limited Empirical Proof for Immortality: The central claim—that the soul is immortal—is argued philosophically and theologically, but cannot be substantiated empirically. This may limit the book’s appeal to secular audiences.

🔍 Final Thoughts

The Immortal Mind is both bold and controversial. It’s not just a book about the mind—it’s a book about the nature of personhood, free will, and ultimately our metaphysical destiny. Whether one agrees with Egnor or not, the book makes a strong case that the materialist worldview is not the only—or necessarily the most coherent—framework for understanding the mind.

It's particularly valuable for readers open to classical metaphysics, or those dissatisfied with "mind equals brain" reductionism. For critics, it’s a rich text to grapple with. And for those on the fence, it’s a gateway into one of the most enduring philosophical and spiritual questions of all time.

***To be continued ***

David

This remarkable kid had neither hemisphere at birth!

https://www.youtube.com/watch?v=j4bav2qegN0

David

There’s no such thing as a good media exaggeration, it generates clicks, after all. But while the prognosis for those born with hydrocephalus (fluid in the skull that compresses the brain tissue) is often very good, there are other, far less benign conditions, like hydranencephaly, which literally means being born without brain tissue, as opposed to the media-hyped condition. For those poor children born with this condition, there’s no such thing as recovering to a normal state of consciousness, and life expectancy is short.

There’s no such thing as a good media exaggeration, it generates clicks, after all. But while the prognosis for those born with hydrocephalus (fluid in the skull that compresses the brain tissue) is often very good, there are other, far less benign conditions, like hydranencephaly, which literally means being born without brain tissue, as opposed to the media-hyped condition. For those poor children born with this condition, there’s no such thing as recovering to a normal state of consciousness, and life expectancy is short.

Nobody is saying that these birth defects are anything but tragic for those who suffer them. That is not my point, not that of Egnor.

David

Nobody is saying that these birth defects are anything but tragic for those who suffer them. That is not my point, not that of Egnor.

David

I understand this. But “hydrocephalus” is not being born without a brain. It means your brain is heavily compressed due to fluid build up in the skull. It’s highly debately whether those born literaly without any brain tissue but the brain stem are consciousness.

I understand this. But “hydrocephalus” is not being born without a brain. It means your brain is heavily compressed due to fluid build up in the skull. It’s highly debately whether those born literaly without any brain tissue but the brain stem are consciousness.

And yet there are apparently cases of people born with little to no brain tissue who have normal mental functioning, as far as testing can demonstrate?

[quote="sbu" pid='61814' dateline='1750832332']
@Laird I wanted to delete this post, and I thought there was a functionality to do that - has it vanished?



David

There’s no such thing as a good media exaggeration, it generates clicks, after all. But while the prognosis for those born with hydrocephalus (fluid in the skull that compresses the brain tissue) is often very good, there are other, far less benign conditions, like hydranencephaly, which literally means being born without brain tissue, as opposed to the media-hyped condition. For those poor children born with this condition, there’s no such thing as recovering to a normal state of consciousness, and life expectancy is short.

I wonder if there is evidence that tissues compressed in such a way retain any of their functionality.

Here is what Michael Egnor has to say about hydranencephaly his book:

As a pediatric neurosurgeon, I have cared for some of these children. Although they are quite handicapped, they are certainly conscious and interactive, with a full range of emotions—laughter, crying, glee, fear, and such. In fact, today the condition is often not even diagnosed until several months after birth when the child fails to meet development milestones, thus prompting a neurological examination.

Also, again according to Egnor, the term refers to the complete loss of both hemispheres of the brain, but other structures still exist.

He discusses a whole variety of interesting conditions of this sort which all seem to imply that people (and animals) do have a non-material part to their being, which he calls the soul.

Remember that I am not a Christian, but do find that the DI produces a lot of fascinating scientific evidence that is otherwise pushed to one side.

I would encourage you to read his book, because much of it is very interesting and obviously well informed. However, once he plunges into his Christian views he becomes infuriating!

There are many scientific books from members of the DI that barely mention Christianity, it is a pity he does not follow that style.

David