Consciousness, Zombies, and Brain Damage (Oh my!)
Why we shouldn't trust our gut when it comes to the mind
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Recently,
and I had a conversation about consciousness (if you're into podcasts/videos and want to hear me talk about consciousness, give it a listen!)The conversation was born out of Connor questioning my views of consciousness—that consciousness is a physical process, and is determined by the functions and processing that the brain is performing (a view called functionalism).
A point I made in the conversation that I want to expand on is how we really shouldn't rely too heavily on our intuitions when thinking about consciousness. Our intuitions are often just wrong.
This is important because the popular arguments trying to establish or discredit specific views of consciousness rely on intuitions.
Zombies and Intuitions
Philosophical zombies are a great example of argument by intuition. The idea of a philosophical zombie is a person who behaves exactly in every way like a normal human, but they don't experience consciousness. There are no "lights on", no experience of what it's like, no "qualia". They are an automaton. Yet they behave exactly like a person who is conscious (even down to talking about their conscious experience and writing articles about consciousness, like all of us totally normal non-zombies spend all our time doing).
The argument goes that, since we can conceive of philosophical zombies, where all the same physical happenings are occurring but there is no consciousness happening, physical stuff can't explain consciousness. The physical and mental are different things.
If you feel like some sleight of hand was just played, you're in good company. The eminent neurophilosopher Patricia Churchland gives this devastating (and in my opinion fatal) response to the conceivability of philosophical zombies:
So what?
— Churchland 2002, pg. 182
Simply put, being able to conceive of something doesn't tell us it's possible. If I'm ignorant enough, I can conceive of the molecules in a substance moving quickly without the substance being hot, or H2O molecules without wetness, or the biochemical reactions that make up life without life.
If we have a hazy understanding of something, it’s easy to see a high-level concept as qualitatively different from, and therefore unexplainable by, lower-level concepts.
Ignorance about mechanism isn't an argument. Instead, philosophical zombies (and Mary the Color Scientist, Inverted Qualia, Searle's Chinese Room etc. etc.) are best seen as an appeal to an intuition: "This mental stuff is really weird and it seems like physical mechanisms can't explain it". That's a fine intuition to have! But it's just an intuition—and we should be careful about concluding too much based on an intuition (for a fuller exploration of the argument from zombies, see
’s recent article).Our intuitions about consciousness are often wrong
It's easy to think of consciousness as a sort of theater—we sit in there, watching the input come in through the eyes and hear the sounds that come in through the ears. The eyes act like cameras, faithfully giving us an image of what's going on outside, and the ears act as microphones. This view is sometimes called the Cartesian Theater.
The trouble is, this view is wrong. For someone who believes consciousness is a physical phenomenon, it obviously must be wrong: if there was a little person in your head receiving all this information, you would have to look inside their head for how their brain processes all this visual and auditory information. Would you find another little person in there, and so on ad infinitum? We haven't explained anything by positing this little person in the head.
If you're not a physicalist but a dualist, you can swap the little person in the head out with a little soul and say "well, souls are different stuff so they can do consciousness". You still haven't explained anything, but it doesn't result in an infinite regress, so you get to look down on physicalists with derision.
But regardless of whether you are a physicalist or dualist, this intuitive view is wrong, not just for conceptual reasons but for empirical reasons. Consciousness is weirder than we realize.
Brain damage
We have lots of empirical findings that wreck our intuitive views of consciousness.
Prosopagnosia, also known as face blindness, is a condition where the ability to process or recognize faces is impaired. A patient with the apperceptive version of it shown two faces side by side could not tell you whether they are the same or different face. In the less radical associative type, individuals can't recognize familiar faces—they can see the face of someone they've known their whole life, and with no other cues, be unable to recognize them. This even goes for their own face.
Akinetopsia, also known as motion blindness, is the inability to perceive motion. A person with akinetopsia isn’t blind, and can report on objects in their environment, but can't see the motion itself. In some forms they have to infer that an object has moved from its change in position.
Hemispatial neglect is a form of attentional neglect where an individual doesn't pay attention to one side of their world. They can see objects on their neglected side, but will ignore everything on that side, for example only eating food on one half of a plate or only shaving one side of their face. If specifically prompted, they will interact with objects on their neglected side, but without those prompts they act as if that side doesn't exist.
Capgras syndrome is a disorder where the patient believes some individuals have been replaced by imposters. It is thought to be because of damage disrupting the emotional response the patient has to visual stimuli of people they know—they have the visual stimuli of the person they know, but not the feeling that usually goes along with it, so it feels like something is wrong with the person they see.
These disorders can be caused by specific damage to the brain. The list can go on—blindsight, split brains, alien hand syndrome, etc. all give us a view into what happens with consciousness when specific mechanisms in the brain are disrupted.
Lessons from brain damage
The point isn't just that there is a tight link between the brain and consciousness. It's that each of these disorders is surprising.
I wouldn't have known based on my conscious experience that it would be possible to recognize objects just fine but have trouble with faces, or be able to see my environment and notice that things have moved but not perceive the movement itself. Attentional disorders are weird—why wouldn't I be able to just remember to pay attention to my left side? It seems like I should be able to just consciously do that. Yet that's not how it works.
Capgras syndrome gives us a taste of how complex our processing of sensory information is—when we navigate our lives, visual pattern matching doesn't happen alone. We don't see our loved ones and just visually recognize them. There is a rich response we aren’t consciously be aware of, but the additional processing makes us connect our visual stimuli with the person we know and love.
Much of what generates our conscious experience is invisible to us unless those mechanisms break, and that should make us aware of the limits of introspection and intuition to give us incontrovertible insights into consciousness.
No doubt there are ways, regardless of your views of consciousness, to make sense of each of these disorders on their own. But one question you have to ask is, what's left?
The little person in a theater in our head isn't receiving a video stream. There are mechanisms in the brain that do additional processing—on things like motion and faces. That visual information is connected with a rich emotional response by another brain mechanism. The direction of our attention? Also a mechanism in the brain—and we don't even realize when it's broken.
We can refine our view of what the little person in the brain is doing to accommodate this. But now the picture we have is a lot less intuitive. We are making the person smaller and smaller, and you have to wonder whether it makes sense to make them disappear altogether.
Exercising some humility
Most non-physicalist views of consciousness make a very bold claim: the laws of physics are missing something fundamental. Any view that claims consciousness is made of different stuff (e.g. souls) or is "strongly emergent", but can cause things to happen, is explicitly claiming there is a force acting on the physical world not captured in current theories of physics. And this force only seems to be present in the tiny amount of matter in the universe contained in biological brains. If true, we would be written into the cosmos at a fundamental level.
This claim is particularly bold in the modern day where, in the words of theoretical physicist Sean Carroll: the laws underlying the physics of everyday life are completely understood.
We have an enormously successful Core Theory in physics with incredibly precise and well-validated predictions of the behavior of matter in the circumstances governing everyday life. Decades of high-powered particle accelerator experiments give us unprecedented confidence in this theory. Modifying this theory to add additional forces isn't some small adjustment:
[I]f there are additional particles and forces, they interact too weakly with the known fields to exert any influence on human behavior; otherwise they would have already been detected in experiments.
Our confidence in [the Core Theory capturing all the physical forces in the conditions we live in] derives from the fact that quantum field theories are the practically unique way to satisfy the general principles of quantum mechanics and relativity; from symmetries ensuring that any unobserved fields must be too weakly interacting with ordinary matter to be relevant for everyday-life dynamics; and the property of effective field theories that the dynamics themselves are fully determined in terms of a very small number of parameters.
Claiming the laws of physics need to be modified to make room for action occurring in the (cosmically tiny) matter in our brains is an enormous claim. If such a modification to the Core Theory could be made and found to be true, there would be so many Nobel Prizes to be awarded we might just need to shut the thing down and tell the discoverers that they did it, they won science, no one else gets a prize.
We have a bad history as humans of trying to put ourselves at the center of the universe in various ways only to be proven wrong. Learning the Earth goes around the sun, the sun is just one star of many in the universe, we evolved like all other animals, and life is governed by biochemistry and not unique physical laws—this trajectory should give us some pause about putting ourselves back at the center of the universe by claiming our consciousness is written into the laws of the cosmos.
All this is to say, we should require pretty incontrovertible evidence before suggesting radical departures from such successful theories of physics.
The philosophical arguments aren't this kind of incontrovertible evidence. They're appeals to intuitions that people disagree on. I don't find them particularly persuasive—I can understand the intuitions, but think they are misguided, and have opposing intuitions (for a more direct addressing of the intuitions and philosophical arguments, see the conversation I had with Connor).
The brain damage examples give us lots of reasons to be skeptical about how much we can tell about consciousness through introspection. We should be careful about concluding too much about consciousness, let alone the physical universe, from our armchairs.
In the face of the uncertainty we have around consciousness and the high level of understanding we have about physics, it's worth exercising some humility. Personally I wouldn’t be comfortable claiming the laws of physics are wrong based on vibes.
In case you want to listen to the full conversation about consciousness with Connor, here it is:
Consciousness Conversation w/ Connor
In this video, I discuss consciousness with Connor Jennings who writes Mind Meandering.
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Enjoyed the read. A stimulating one.
Beyond the issue of appealing to our intuitions, which you noted, I immediately noticed another problem with the "zombie argument".
The assumption that an universe can be physically identical to ours and yet have "zombies" for conscious humans is logically equivalent to the assumption that physicalism is false. This is a problem because it is invoked in the argument. If physicalism is false in a metaphysically possible universe, then that universe can exhibit entities appearing to have consciousness outwardly whilst being zombies, and there can be another universe only physically identical to it but with consciousness (explained by other factors) - conversely, if there is such a "zombie universe" which is physically identical to a "non-zombie universe", then physicalism is false (since consciousness is present in one and absent in another in spite of the physical identity). This effectively renders the argument as "Physicalism is false. Therefore, physicalism is false".
All I want to say is "exactly!"