In his discussion with Pat Flynn, neurosurgeon Michael Egnor talked about how split-brain surgery – the splitting of the human brain in half as a defense against intractable epilepsy – is an example of things that don’t confirm materialism as one might have expected. The first two excerpts from the interview, with notes, can be found here and here.
Here are some excerpts from the transcript in which Dr. Egnor, professor of neurosurgery and pediatrics at Stony Brook University in New York State, cites examples from the neuroscience literature of split-brain patients who see with their entire mind:
Why do neurosurgeons split brains?
Split-brain surgery, which even Dr. Egnor, who performed it, calls “goosebumps,” is a radical attempt to control epileptic seizures that jump through the corpus callosum – the huge bundle of nerve fibers that connects the two halves of the brain. In the 1940s, surgeons realized that if they simply severed the bundle and severed the connection, the seizure would be confined to one side. This reduced the number of life-destroying seizures. But does that leave the patient living with two brains that mirror each other but cannot communicate?
Neuroscientist Roger Sperry (1913-1994) won a Nobel Prize for his clever experiments with split brains, showing what they could and could not do. But the big story, says Egnor, is rarely emphasized: “You could cut the brain in half and practically nothing would happen.”
That is, the subjects with split brains had to move their heads to associate, for example, the word “apple” with an apple, since the word and recognition are controlled by opposite areas of the brain. On the other hand, he found nothing that resembled a split consciousness or two different personalities. A simple adjustment was all that was needed:
Egnor: The only thing that happens requires Nobel Prize-level research to discover! The analogy I used for this is: imagine you bought this great new computer and you take a chainsaw and you cut the computer in half with a chainsaw and it still works perfectly. It’s all fine. That’s a pretty weird computer. And it would mean that there’s something about that computer that you don’t quite understand yet.
Neuroscientist Justine Sergent (1950-1994) of McGill University recognized this in the 1980s and decided to focus on it:
Egnor: … there are ways of presenting an image, for example, an image for the right hemisphere and an image for the left hemisphere. And if you’re a split-brain patient, those hemispheres can’t talk to each other. They don’t communicate.
For example, she presented an arrow pointing upwards to the right hemisphere and an arrow pointing sideways to the left hemisphere. She asked the person who had undergone split-brain surgery whether the arrows pointed in the same direction or in different directions.
And the split-brain patients were almost always right. They could almost always recognize what the right hemisphere sees and compare it to something the left hemisphere sees.
The problem is that there was no part of her brain that saw both things. And how did they know? How can you compare things when no part of the brain sees both things?
But Sergent was careful not to stop there
She and others wondered whether tiny pathways might allow messages to bypass the corpus callosum, enabling communication between the two hemispheres.
Egnor: We know how long it takes for the nerve impulse to pass through these short-circuit areas. And this time is measurable: hundreds of milliseconds. It doesn’t happen instantly.
She looked at people’s reaction times and this effect never occurred. That means there was no evidence of any cheating going on inside.
And also, certain perceptual functions were definitely split. For example, the right hemisphere is not normally responsible for language. So if you present a word to the right hemisphere, the language comes from the left hemisphere. Split-brain patients know what the word means, but can’t say it. So it still worked.
But there was a part of the human brain that could compare two images that no other part of the brain could see.
The mind connects stories when each side of the split brain sees only one half
After Sergent’s early death, apparently caused by a scientific mob, Dutch neuroscientist Yair Pinto continued his research on the apparently immaterial communication channel.
Egnor: And he’s copied a lot of what Sergent did and gone a little further. He picks a story in pictures and presents part of the story from one hemisphere and part of the story from the other hemisphere. But the story only makes sense if you understand both.
For example, you present the right hemisphere with a picture of a broken window and the left hemisphere with a picture of a baseball and ask the split-brain patient, “What does this story tell me?”
Most split-brain patients will get it right and say the baseball broke the window. But no part of their brain sees both the baseball and the window, so how can they piece the story together?
Pinto said we have misunderstood the split brain phenomenon in the past and thought of it as two different people. But they are not two different people. He said consciousness is unified, although perception may be divided. Despite the brain being split in half, there is still something unified in humans.
Research of this kind is an unacknowledged problem for materialism, notes Egnor: “It may well be that new findings will emerge in the future that offer a way out for materialism. But at the moment there is no way out, because materialism has been refuted by this research alone.”
Dr. Egnor and Denyse O’Leary are the authors of The Immortal Mind: A Neurosurgeon Argues for the Existence of the Soul (Hachette Worthy, June 3, 2025).
Next: The neuroscientific proof of free will
Here are the previous two excerpts from the transcript with notes:
Is materialism slowly losing its stranglehold on science? If so, neuroscientific discoveries will play a key role, neurosurgeon Michael Egnor tells podcaster Pat Flynn in a recent podcast interview. Materialism is a totalitarian claim. If the human mind is not simply the physical processes of the brain without residue, then materialism is refuted.
And
What brain surgery for epilepsy has taught us about the human mind. Michael Egnor continues his discussion with Pat Flynn, noting that neither seizures nor Penfield’s brain stimulation induced abstract thought. To say that one day, with no exact date, we will find a materialistic explanation means that we never expect that we will not.
