Defending Philosophical Zombies
Zombies may be dead, but I don't think the argument is.
I started this article as a recap/further thoughts on my (somewhat) recent conversation with Tommy Blanchard, however it ended up being 90% about Philosophical Zombies - so I’ve decided to ditch the rest and just talk about that instead. Sorry, Tommy.
“It’s okay Connor. Also I’m a stupid loser”.
What are P-Zombies?
If you’re unfamiliar with what Philosophical zombies are, I’ll explain. If you are familiar, you can skip to the next section.
P-Zombies are physically identical to humans. They have all the same cells, organs, behaviours, firing neurons, etc. If you gave them a brain scan, you would see the scan light up - however, there’s no consciousness in there. There are no lights on. There’s nothing that it’s like to be a P-Zombie. The fact that this is conceivable is supposed to act as a proof of Dualism - the view that the physical universe exists, but consciousness is immaterial. If all the physical facts remain the same, but the facts of consciousness don’t, that should illustrate that consciousness isn’t physical (or so the argument goes).
A rough sketch would look something like this:
(1) P-Zombies are conceivable.
(2) If something is conceivable, then it is metaphysically possible.
(3) Therefore P-Zombies are metaphysically possible.
(4) If P-Zombies are metaphysically possible, then consciousness must not be physical.
(5) Therefore consciousness is not physical.
Easy! Physicalism defeated. Let’s all go home and hang out with our friends (except for Tommy, he has none).
A Physicalist Objection
You may have noticed that I didn’t really argue much yet for premise 2. This is going to be the hill that we fight and die on in the article. See, most physicalists don’t deny (1), because it seems pretty obvious that it’s true. You don’t really speak to people who deny (1) very often because they’re trapped inside, unable to work the door knobs, and their drool has short circuited all their electronics.
(3) follows from (1) and (2). (4) seems pretty uncontroversial (although I wouldn’t be surprised if there’s someone out there that pushes back on it), and (5) follows from all the other premises. So, (2) is the battlefield. It’s peppered with the bodies of the philosophers of mind of old. Now, it is my time to take up the sword, and defend my Dualist brethren.
To the untrained eye, (2) might seem obvious - and in fact, I previously naively thought it was a given. If you look at older Philosophy of Mind posts of mine, I don’t even spend time arguing for (2) because it struck me as obvious, and I forgot this is philosophy. We’re all about doubting the obvious here! Tommy rejects the link between conceivability and metaphysical possibility with a counter example.
Take Water and H20. It seems conceivable that water (the wet clear liquid we all drink) could have had a different chemical make up than H20 (the molecule of the clear liquid). However, it turns out, that water just is H20, and that’s true necessarily. We can conceive of water having had a different chemical makeup, but it’s still metaphysically impossible, because if it did, it wouldn’t be water! Likewise, Tommy wants to say we can conceive of consciousness not being present in a P-Zombie, but as it turns out, that’s metaphysically impossible because consciousness just is the functions of the brain. So, no good on premise 2, and the argument falls apart. Take that, Connor, you handsome piece of shit.
Two Dimensional Semantics
So, we’re going to have to talk a lot about conceivability and metaphysical possibility aren’t we? In our original call, you can see the beginnings of a counter argument roll around in my head. I can’t be bothered to go back and get the exact quote, but I think aloud about whether or not the words “Water” and “H20” even reference the same thing.
It turns out that David Chalmers (surprise surprise) beat me to the punch. He thinks the Water/H20 example fails due to those words referencing different intentions. This would mean it fails as a counter example.
In 2D semantics, words have primary and secondary intentions. The primary intention is the thing we talk about in our ordinary macro level existence. It’s how we would identify that thing in every possible world. For water, the primary intention is the wet stuff we drink that comes from lakes, seas, rivers, etc. We can conceive of an alternate world in which water appears much the same to us, but it has the chemical composition XYZ. In this world, we still call that stuff “Water” because what we’re referencing with the primary intention of the word has remained the same - it’s still wet stuff we drink.
The secondary intention is whatever the word references in this world. It’s determined after we discovered it’s actual nature in this universe. So, the secondary intention of water is H20, but in the alternate world it references XYZ. Another example would be heat. The primary intention of “heat” is that warm sensation we experience when we’re near hot things. The secondary intention is the molecules moving about. We can conceive of another world where heat is some other thing - maybe molecules moving slowly - and in this scenario we say that the primary intention of “heat” has stayed the same (warm sensation), but the secondary intention has changed (the behaviour of the molecules).
When we talk about possibility in the context of 2D semantics, we use the terms 1-possible and 2-possible. 1-possible refers to possibility relative to the primary intention, and 2-possible refers to the possibility relative to the secondary. So, for example, it’s 1-possible for water to have not been H20, because in that sentence “water” references the primary intention - the wet stuff. It seems possible for the wet stuff to have had a different chemical makeup. However, it’s not 2-possible for water to not be H20, because that would be saying there’s a world where H20 is not H20 - and that’s just nuts! The reason we say that water not being H20 is conceivable but not metaphysically possible is because it’s conceivably 1-possible but not 2-possible. If it’s inconceivable for something to be 2-possible, then it’s metaphysically impossible (I’m just gonna take it that you agree that if something is inconceivable, it’s impossible. E.g. for a triangle to have 4 sides, for something to be totally red and green at the same time, for someone not to like my substack, etc. In this case, it seems metaphysically impossible for H20 to not be H20.)
To get the P Zombie argument across the finish line then, we need to show that consciousness is 2-possible. This would be what differentiates it from water, and would mean the physicalist objections fail as counter examples. The way Chalmers does this is by proposing that the primary and secondary intentions of “consciousness” coincide.
While it’s not the case that anything that looks like water is water, or anything that feels like heat is heat (in the secondary sense of the words), it seems like the same can’t really be said for consciousness. When we imagine a world with wet stuff that’s composed of XYZ, it is water in some sense, but it isn’t in another. It is in the primary sense, but isn’t in the secondary. However, it seems that consciousness doesn’t really work like this.
Imagine a world where instead of consciousness arising from functions in the brain, it arises from rocks. Just rocks sitting still doing nothing. The physicalist is committed to saying that these beings are conscious in some sense, but aren’t in another. The primary intention of the word consciousness (subjective experience) remains the same, while the secondary intention (functions in the brain) differs. However, this seems a bit strange in the consciousness example! It seems really counterintuitive to say that a being that’s having a subjective experience isn’t conscious in some sense. They just are conscious! Chalmers’ explanation of the primary intention and secondary intention of “consciousness” coinciding explains why that seems odd: the word “consciousness” only refers to the subjective experience.
If we accept that the primary and secondary intentions of “consciousness” coincide, that would mean that it if P-Zombies are 1-possible, they are 2-possible. As we can infer 1-possibility from conceivability, that would mean that in the case of consciousness we can infer 2-possibilty from conceivability - which means they’re metaphysically possible, and Physicalism is false (or Russellian Monism is true, but I couldn’t be bothered to write about that part of the argument, maybe I’ll cover it in a follow up). Okay, my brain hurts. I’m going to take a nap.
Hi Connor. I recently started following you and really enjoy your writing, especially the animal rights stuff. Thank you for sharing your perspective. I’ve been watching this dualism debate on Substack and I’d like to participate if you don’t mind.
"Imagine a world where instead of consciousness arising from functions in the brain, it arises from rocks. Just rocks sitting still doing nothing. The physicalist is committed to saying that these beings are conscious in some sense, but aren’t in another"
If I must imagine this world then I would say the physicalist is only committed to describe the physics of the rock and so the rock must have some measurable way for us to know it has consciousness (communication, movement, intention, etc), otherwise no physicalist in any imaginable world is even going to have this discussion.
If we assume then that the rock has a measurable “consciousness” that means one of two things: The rock has form and function different from rocks in our world (e.g. it could have moving parts or or some otherwise complex dynamic structure) OR there are different laws of physics and different equipment capable of measuring those aspects deemed “conscious” (Forces or energies or whatever you would like to conceive). How else would the imagined philosophers of this world consider that the rock was conscious to begin with?
Also, I think the heat example is actually much better than the H2O one. Although heat, the sensation of warmth (primary intention), can be imagined to come from slow moving particles (secondary intention) it cannot actually come from slow moving particles. At least not without completely changing all of physics in drastic ways (I am working on a way to describe this more clearly in the language of thermodynamics). I can “conceive” of heat in this way but it is metaphysically impossible.
I'm happy to say the primary and secondary meanings don't coincide. When I'm naively conceiving things, I'm using a pretty loose conception of consciousness. Unlike with water/H20, the secondary meaning is the thing in dispute. If I think about it, I think the most likely thing is brain functions.
I can naively imagine rocks being conscious and enjoy a cartoon where they are. But if I take a minute to think about it, I realize "Oh right, there's no brain processing going on in there, I don't think this cartoon is showing me something actually possible!" and then my three-year-old has to deal with my ranting about the scientific inaccuracies in Morphle.
So to me the primary and secondary meanings being pulled out here are just the "naive not thinking about it" vs the "actually thinking about what underlies consciousness", and they seem to pretty obviously not coincide for a physicalist--or for anyone agnostic about what consciousness is.