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Abstract.
Abstract.

Did Consciousness “Evolve”?

One neuroscientist doesn’t seem to understand the problems the idea raises

The other day, I discussed an essay by neuroscientist Michael Graziano on the “mystery of the mind.” I have been responding to Dr. Graziano’s essay line-by-line. So far, I’m still on the subtitle!

Here’s Graziano‘s subtitle in full:

Far from being a mystical “ghost in the machine”, consciousness evolved as a practical mental tool and we could engineer it in a robot using these simple guidelines [emphasis mine]

First, what do we mean by “consciousness”? Graziano is imprecise but he seems to mean what we usually mean by consciousness — subjectivity, which is first-person experience (“I”), as opposed to third-person experience (“it”).

So what does it mean to say that consciousness — the first-person experience of “I” — “evolved”? There are at least two reasons why the evolution of consciousness is problematic.

Let’s look at the first problem: How can natural selection act on something that is not physical? Darwinian natural selection, whatever its worth as a scientific theory, can’t explain how non-physical attributes emerge.

The reason it can’t is this: In order to “evolve” by Darwinism mechanisms, which is apparently what Graziano means, first-person experience must provide a selective advantage over third-person existence. That is, consciousness must manifest itself physically. Any aspect of consciousness that didn’t manifest itself physically could not evolve because Darwinian natural selection can only act on physical attributes.

Consciousness can manifest itself physically in only two ways: either consciousness is itself a physical thing, or it is caused by a physical thing.

Is conscious first-person experience a physical thing? Recall the philosophical zombies (p-zombies) from my earlier post. A p-zombie is a meat machine that does everything a human being does, except it does not have first-person experience. A p-zombie has no “I.” It walks, talks, adapts, registers sensations, behaves, retains information (in the way a book retains the words printed in it), and acts on the basis of the retained information.

The issue for understanding consciousness is not whether a p-zombie can exist but whether there is any scientific contradiction inherent in its existence. In my view, and in the view of many philosophers, there isn’t.

If there is no scientific reason why p-zombies can’t exist (that is, no laws of nature are broken by its existence), then conscious first-person experience must be something other than physical. Consciousness must be non-physical.

But now we are back to our initial question. if consciousness is non-physical, how could it evolve? Darwinian natural selection can only act on a physical attribute.

Thomas Henry Huxley at about 55

There is another possibility. Darwinian theory could account for non-physical consciousness if consciousness were caused by the brain — that is, if non-physical consciousness were a property of brain activity and thus inextricably linked to brain activity. In that case, the argument is that the brain evolved and consciousness was dragged along because it is linked to brain activity.

In this view, consciousness is an epiphenomenal property of the brain. Epiphenomenalism was first explicitly proposed by “Darwin’s bulldog” Thomas Henry Huxley (1825–1895). If consciousness were epiphenomenal to physical brain processes — as a sort of by-product, like smoke from a steam engine — what evolves is the brain. Does this satisfactorily explain the evolution of consciousness?

The problem with this epiphenomenal view of consciousness is that it renders the mind powerless. If consciousness is merely a property of the brain, it has no agency — no power to cause anything — in itself. Properties can’t do anything. For example, if you hit a nail with a yellow hammer, you hit it with the hammer, not with the yellow. Epiphenomenalism, which is the only framework by which an immaterial consciousness could evolve, asserts that what actually causes us to do things is brain activity. Consciousness is a useless spin-off.

But this epiphenomenalist view of consciousness is self-refuting. How can one assert a proposition without a mind that is capable of agency?

Let’s sum up the problem with Dr. Graziano’s claim that consciousness is subjective experience and that it evolved:

  1. Only something physical can evolve. Natural selection can only select attributes that have physical manifestations. If consciousness has no physical manifestation, it can’t evolve.
  2. However, conscious first-person experience must be non-physical because p-zombies don’t violate any physical laws, yet we know we are not p-zombies.
  3. The only way consciousness could be non-physical and still “evolve” is if consciousness were caused by a physical process that could itself evolve.
  4. If non-physical consciousness were caused by physical processes in the brain, it would be an epiphenomenal property of brain activity.
  5. Epiphenomenal properties have no causal power in themselves. Properties can’t do anything. So if consciousness is an epiphenomenal property that could evolve, it would have to be ineffective.
  6. Graziano argues that consciousness is non-physical (subjective experience) and that consciousness evolved; therefore he argues that consciousness is epiphenomenal on brain activity.
  7. Therefore Graziano’s opinion is not caused by his mind, but merely by his brain, like a reflex or a chemical reaction.
  8. If Graziano is right, his argument is mindless.

That much seems to be true. And, goodness gracious, we’re still on the subtitle. There’s a lot more to cover.

I’ll discuss the second problem with Graziano’s “evolution of consciousness” shortly.


Here’s the earlier article on Michael Graziano’s approach to consciousness:

Neuroscientist Michael Graziano should meet the p-zombie. A p-zombie (a philosopher’s thought experiment) behaves exactly like a human being but has no first-person (subjective) experience. The meat robot violates no physical principles. Yet we KNOW we are not p-zombies. Think what that means.

And here is a selection of Dr. Egnor’s articles on consciousness:

In one sense, consciousness IS an illusion. We have no knowledge of the processes of our consciousness, only of the objects of its attention, whether they are physical, emotional, or abstract

Does Your Brain Construct Your Conscious Reality? Part I A reply to computational neuroscientist Anil Seth’s recent TED talk

and

Does Your Brain Construct Your Conscious Reality? Part II In a word, no. Your brain doesn’t “think”; YOU think, using your brain


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.

Did Consciousness “Evolve”?