Why aren't we zombies?
Synapse #4: The nature of consciousness
Around 250 AD, the now infamous first bishop of Paris, Saint Dennis, was sent from Italy to spread Catholicism. After finding success in converting the local Parisians, the nearby pagan priests felt threatened by him and sentenced Saint Dennis to death via decapitation.
Most stories of Christian Martyrs end there, but not Saint Dennis. According to the legend, once decapitated, Saint Dennis stood up, picked up his head, and carried it around the city while continuing to preach. He even stopped to rinse his head off along the way before his final resting place on the hill of Montmartre.
I wonder what it must be like to carry your own head—to view your own body not from a continuous, vertical, first-person point of view but from a third-person observer's perspective. Of course, it's impossible to know what it is like to be any other person, let alone Saint Dennis. The only thing I can know for sure is what it is like to be me—and this is the source of one of the most fundamental and perplexing mysteries of our universe: consciousness.
What is Consciousness?
The best definition that we are ever going to get of consciousness is from Thomas Nagel (1947) who stated that "an organism is conscious if there is something that it is like to be that organism." Certainly, it is like something to be me and like something to be you. It is probably like something to be a monkey or a dog. But our intuitions say that it is probably not like something to be a tree or a bookshelf.
Note that I am not talking about what some have called the 'easy problems' of consciousness which pertain to whether a person is awake or how different neural mechanisms in our brain interpret the world around us. Instead, I am talking about what David Chalmers has coined the 'hard problem' of consciousness which is the problem of explaining why certain sentient organisms have phenomenal experiences and others do not. That is, how do physical processes in our brains give rise to mental experiences?
The Zombie Thought Experiment
The hard problem of consciousness is perhaps best illustrated with David Chalmer's zombie thought experiment which goes as follows. Imagine a being that is physically identical to you, behaves exactly as you do, but does not have a conscious experience or sentience. For example, if you were to burn this zombie's hand, s/he would not feel any experience of pain but would still coil away exactly as one would do if they were conscious.
This kind of zombie is not only logically conceivable but is scientifically conceivable as well because it turns out that, despite our intuitions, consciousness is seemingly not required for any human behavior.
Take, for example, the act of sensing and responding to our environment which is what people normally think of when defining consciousness. Consciousness isn't required for these processes as evidenced by the numerous examples we have of plants who do the same. For example, some trees have incredibly intricate underground Mycorrhizal fungal networks that sense the local nutrient environment and respond and communicate to ensure the survival of both the trees and the fungus. There's also the Venus flytrap which is able to sense the presence of insect prey and even 'remember' states of its local environment.
In fact, as Annaka Harris so eloquently summarizes in her book Conscious, our consciousness is really just along for the ride and is almost certainly the last to know when it comes to our senses. This is easy to understand if one just thinks of the physical processes underlying our senses. If I bang my hand on a red table, the light waves travel at a much faster speed than the sound waves from the bang, and my sense of touch is propagated electrically along my sensory neurons at still a different speed. Despite these differences, I perceive all of this happening at the same time. This is the brain's 'binding' process and is the reason we can have a continuous experience. As Dr. Harris puts it:
Your perception of reality is the end result of fancy editing tricks: the brain hides the difference in arrival times. How? What it serves up as reality is actually a delayed version. Your brain collects up all the information from the senses before it decides upon a story of what happens.
Why aren't we zombies?
So if consciousness has no known function, why aren't we all just zombies like Saint Dennis—thoughtless blobs of biological matter responding to our environment and behaving accordingly with no phenomenal experience of it all?
Maybe it's that consciousness is what David Chalmer's has called 'epiphenomenal' or without meaning.
Maybe consciousness exists to give us meaning and value to our life. After all, it is our experience of a thing that drives us to do that thing.
The zombie thought experiment in particular raises the issue of 'dualism' which is the notion that the universe is split between physical processes and mental processes imbued by a God or otherwise undetected spiritual property of the universe.
These are all possibilities but there is a growing sect of consciousness ideas that state that consciousness is a fundamental property of all matter and that our brains have a particular complexity and integrative ability that gives rise to a light inside that is so easily recognizable as phenomenal experience. Consequently, the computer you're reading these words on would have some form of very low-level consciousness with some intermediate consciousness within, say, an earthworm all the way until there is this overt phenomenological experience in humans and complex animals. This theory—known as panpsychism—not only goes against all of our intuitions but can seem insane. Is a rock conscious? However, there is a lot of interesting scientific evidence for this phenomenon and is something I will be taking you through next week.
🧠Recommendation
If you’re subscribed to this newsletter, you’ll probably also enjoy Shamay’s Friday Brainstorm Newsletter. Shamay is a product manager, neuroscience enthusiast, and writer behind Brain Street. I like Shamay’s newsletter because he focuses on cognitive neuroscience and distills research into actionable and applicable advice for everyone. Check it out and subscribe if you like!
🔗 Links, links, links
If you’re looking for an all-encompassing snapshot of the current state of the COVID-19 pandemic as well as a nuanced recounting of the mistakes we’ve made to get here, I point you to this week’s episode of the Making Sense podcast by Sam Harris. He interviews Siddhartha Mukherjee who is a renowned physician, former virologist, and author of The Emperor of All Maladies and The Gene. Of note to me: there seems to be confidence among immunologists that this is not only a vaccine-able disease but that a workable vaccine (achieving at least 50% protection) could arrive by next January.
I really do recommend Dr. Annaka Harris’s book Conscious. It’s a fantastic and accessible introduction to the mystery of consciousness and is a huge inspiration for not only this week’s issue but my entire newsletter.
The neuroscience of viewing your past like a fly on the wall
🖼 Image of the Week
Pictured above are neuronal stem cells differentiating into neurons. Before turning into neurons, stem cells form clumps as you can see above. Image credit: The Salk Institute.
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