Against Dogmatic Physicalism
Why consciousness can't be explained by reductive physicalism
0 A Brief Introduction
Why is there something rather than nothing? This question is quite difficult—perhaps even as difficult as the hard problem of consciousness. However, let’s consider some clearly terrible answers to the question.
There isn’t—something is an illusion.
Something is a weakly emergent property of nothing. When you have nothing for a little while, it combines to form something. Science will soon explain how nothing becomes something. Positing that there’s something that exists and is not reducible to nothing is like vitalism or phlogiston.
But, these answers are quite similar structurally and just as unsuccessful functionally as many “solutions,” to the hard problem of consciousness. In this blog post, I shall spell out why physicalist solutions to the hard problem fail—and why we need to be some type of dualist, idealist, or panpsychist.
Dispositionally, I’m an ardent physicalist. My intuitive, pre-theoretic leanings are strongly physicalist. However, when confronted with a brutal gang of facts, I was forced to abandon my physicalist leanings. This article draws heavily on the arguments of Chalmers in the conscious mind—definitely worth checking out for those who have not yet read it.
Let’s begin by defining physicalism. The SEP writes
Physicalism is, in slogan form, the thesis that everything is physical.
1 Broad Considerations
“Consciousness is a biological phenomena,”
—John Searle, being wrong.
So why do I think that physical stuff cannot even in principle explain consciousness. Well, there are two closely related higher order considerations, and then some more specific arguments.
The first broad consideration which explains why consciousness resists physicalist reduction is that physics explains things in terms of structure and function, as Chalmers notes. Physics gives equations to describe what things do and what they’re composed of. However, this cannot in principle explain what it’s like to eat a strawberry, see the color red, be in love. When we look at an atom, we have no way of verifying whether or not it is conscious, because we only observe its causal impacts.
So this is not analogous to Phlogiston or vitalism or anything else physicalists use as an analogy for consciousness. All of those are broadly explicable in terms of structure and function, and thus they don’t require any extra laws. Consciousness is different—it’s not in principle explainable in terms of structure and function.
A second related broad consideration which has been expressed eloquently by Kastrup is that material stuff can be exhaustively explained quantitatively. Through physics, we get a series of equations. To quote Kastrup
Chalmers basically said that there is nothing about physical parameters – the mass, charge, momentum, position, frequency or amplitude of the particles and fields in our brain – from which we can deduce the qualities of subjective experience. They will never tell us what it feels like to have a bellyache, or to fall in love, or to taste a strawberry. The domain of subjective experience and the world described to us by science are fundamentally distinct, because the one is quantitative and the other is qualitative.
The most obvious way (although not the only way) to investigate the logical supervenience of consciousness is to consider the logical possibility of a zombie: someone or something physically identical to me (or to any other conscious being), but lacking conscious experiences altogether. 1 At the global level, we can consider the logical possibility of a zombie world: a world physically identical to ours, but in which there are no conscious experiences at all. In such a world, everybody is a zombie.
So let us consider my zombie twin. This creature is molecule for molecule identical to me, and identical in all the low-level properties postulated by a completed physics, but he lacks conscious experience entirely. (Some might prefer to call a zombie ''it," but I use the personal pronoun; I have grown quite fond of my zombie twin.) To fix ideas, we can imagine that right now I am gazing out the window, experiencing some nice green sensations from seeing the trees outside, having pleasant taste experiences through munching on a chocolate bar, and feeling a dull aching sensation in my right shoulder.
An adequate model of physics will be able to describe what physically goes on in your brain. However, we can imagine a physical carbon copy of you that lacks consciousness. This shows consciousness is not purely physical, as we can’t imagine a carbon copy of H20 that isn’t water.
One confusion had by many is that the zombie argument presumes some type of epiphenomenalism, the notion that consciousness has no physical effect. This is false. If consciousness has a physical effect, the zombie would have some other law of physics fill in and play the functional role of consciousness. So if consciousness causes me to say things like “I’m conscious,” “I think therefore I am,” “consciousness poses a hard problem,” “Dan Dennett might be a zombie,” “consciousness can’t be explained reductively,” “Okay—Dennett is definitely a zombie,” etc—the zombie world would have some physically identical force fill in the functional role of consciousness and cause me to say all of those things.
Thus, the argument is as follows.
1 A being could be physically identical to me but could not be conscious
2 Two beings that are physically identical must have all physical properties in common
Therefore, consciousness is not a physical property.
There’s much more that can be said on the topic of zombies, however, to me it seems quite obvious that zombies are possible—those who deny their possibility seem conceptually confused to be. No doubt that’s how I seem to them. Yet I haven’t the time in this article to go into all of the accounts of the alleged impossibility of zombies, yet it’s worth noting that zombies are somewhat controversial.
3 Inverted Qualia
Even in making a conceivability argument against logical supervenience, it is not strictly necessary to establish the logical possibility of zombies or a zombie world. It suffices to establish the logical possibility of a world physically identical to ours in which the facts about conscious experience are merely different from the facts in our world, without conscious experience being absent entirely. As long as some positive fact about experience in our world does not hold in a physically identical world, then consciousness does not logically supervene.
It is therefore enough to note that one can coherently imagine a physically identical world in which conscious experiences are inverted, or (at the local level) imagine a being physically identical to me but with inverted conscious experiences. One might imagine, for example, that where I have a red experience, my inverted twin has a blue experience, and vice versa. Of course he will call his blue experiences ''red," but that is irrelevant. What matters is that the experience he has of the things we both call "red"—blood, fire engines, and so on—is of the same kind as the experience I have of the things we both call "blue," such as the sea and the sky.
If consciousness just is a physical phenomena, then it would be impossible to change conscious experiences without making a physical change. However, it seems eminently metaphysically possible that we could change consciousness but not make a physical change. Imagine a world physically identical to ours but in which one tomato that I see appears 1% redder than it does currently. If you think that world is possible, then consciousness is not purely physical.
Note, I’m perfectly willing to grant that based on the world as it currently exists, such a state would be impossible. There are, in my view, psychophysical laws that govern consciousness which make it so that consciousness can’t be different. However, we could make tweaks to those laws without having a physical effect, which shows consciousness is not physical.
4 Epistemic Asymmetry
Argument 3: From Epistemic Asymmetry As we saw earlier, consciousness is a surprising feature of the universe. Our grounds for belief in consciousness derive solely from our own experience of it. Even if we knew every last detail about the physics of the universe —the configuration, causation, and evolution among all the fields and particles in the spatiotemporal manifold —that information would not lead us to postulate the existence of conscious experience. My knowledge of consciousness in the first instance, comes from my own case, not from any external observation. It is my first-person experience of consciousness that forces the problem on me.
From all the low-level facts about physical configurations and causation, we can in principle derive all sorts of high-level facts about macroscopic systems, their organization, and the causation among them. One could determine all the facts about biological function, and about human behavior and the brain mechanisms by which it is caused. But nothing in this vast causal story would lead one who had not experienced it directly to believe that there should be any consciousness. The very idea would be unreasonable; almost mystical, perhaps.
It is true that the physical facts about the world might provide some indirect evidence for the existence of consciousness. For example, from these facts one could ascertain that there were a lot of organisms that claimed to be conscious, and said they had mysterious subjective experiences. Still, this evidence would be quite inconclusive, and it might be most natural to draw an eliminativist conclusion—that there was in fact no experience present in these creatures, just a lot of talk
If consciousness were a reductively explainable physical property, then we’d be able to deduce its existence from knowledge of the lower level facts. However, this is manifestly impossible in the case of consciousness. If you knew everything abut atoms, you’d be able to deduce the existence of fire and explain what it does. However, nothing about consciousness is evident from low level descriptions of physical systems.
Why do you think others are conscious? Well, the reason is because you know you’re conscious and others plausibly have similar features to the ones that make you conscious. However, this is not how we deduce that others can get sick. Rather, we directly observe others getting sick. Even if we were in perfect health, it would be reasonable to infer that others get sick. However, if you were not conscious, it would not be reasonable to infer others were conscious. This is because consciousness is not explainable by low level physical facts.
5 The Knowledge Argument
The Knowledge Argument
The most vivid argument against the logical supervenience of consciousness is suggested by Jackson (1982), following related arguments by Nagel (1974) and others. Imagine that we are living in an age of a completed neuroscience, where we know everything there is to know about the physical processes within our brain responsible for the generation of our behavior. Mary has been brought up in a black-and-white room and has never seen any colors except for black, white, and shades of gray. 7 She is nevertheless one of the world's leading neuroscientists, specializing in the neurophysiology of color vision. She knows everything there is to know about the neural processes involved in visual information processing, about the physics of optical processes, and about the physical makeup of objects in the environment. But she does not know what it is like to see red. No amount of reasoning from the physical facts alone will give her this knowledge.
It follows that the facts about the subjective experience of color vision are not entailed by the physical facts. If they were, Mary could in principle come to know what it is like to see red on the basis of her knowledge of the physical facts. But she cannot. Perhaps Mary could come to know what it is like to see red by some indirect method, such as by manipulating her brain in the appropriate way. The point, however, is that the knowledge does not follow from the physical knowledge alone. Knowledge of all the physical facts will in principle allow Mary to derive all the facts about a system's reactions, abilities, and cognitive capacities; but she will still be entirely in the dark about its experience of red.
If consciousness were a reductively explainable physical property then knowing all of the facts about the brain would make it possible to know what it’s like to see red, despite being color blind. However, this is clearly impossible. No neuroscientific knowledge can communicate what it’s like to see red, for one who has never seen red. If Mary left the room and saw a red tomato, she’d learn something new about what it’s like to see red. Her curiosity would be satisfied by seeing the color red, if she had previously wondered what it was like to see red.
No amount of neurological knowledge could teach a deaf person what it’s like to hear Mozart or a blind person what it’s like to see the grand canyon. However, if consciousness were purely physical, this would be possible. If one knows all of the facts about bricks, they could know all relevant facts about brick walls. This is because a brick wall is an emergent property of bricks. If consciousness were merely physical, then much like full physical knowledge would teach you everything there is to be known about a tumor, supernova, or ocean, the same would be true of consciousness. However, this is manifestly impossible.
6 From The Absence Of Analysis
If proponents of reductive explanation are to have any hope of defeating the arguments above, they will have to give us some idea of how the existence of consciousness might be entailed by physical facts. While it is not fair to expect all the details, one at least needs an account of how such an entailment might possibly go. But any attempt to demonstrate such an entailment is doomed to failure. For consciousness to be entailed by a set of physical facts, one would need some kind of analysis of the notion of consciousness—the kind of analysis whose satisfaction physical facts could imply—and there is no such analysis to be had.
The only analysis of consciousness that seems even remotely tenable for these purposes is a functional analysis. Upon such an analysis, it would be seen that all there is to the notion of something's being conscious is that it should play a certain functional role. For example, one might say that all there is to a state's being conscious is that it be verbally reportable, or that it be the result of certain kinds of perceptual discrimination, or that it make information available to later processes in a certain way, or whatever. But on the face of it, these fail miserably as analyses. They simply miss what it means to be a conscious experience. Although conscious states may play various causal roles, they are not defined by their causal roles. Rather, what makes them conscious is that they have a certain phenomenal feel, and this feel is not something that can be functionally defined away.
—Greg, just kidding, Chalmers obviously.
When we consider facts about a physical system, none of them make it obvious why those things would make it conscious. Consider, for example, the integrated information theory, which says that when one system processes a variety of different types of information, it becomes conscious, with its consciousness proportional to the amount of integrated information. When information is integrated, nothing about that physical state obviously produces consciousness. It seems like there’s a further question—we know a system has integrated information, but that doesn’t settle whether it’s conscious.
Consciousness is not just integrated information. It seems imminently possible to imagine a non conscious system that integrates information. When we identify the neural correlates of consciousness, it’s never obvious why those things would be conscious. We can understand why H20 is water, but no explanation of why the neural correlates of consciousness are consciousness.
7 Disembodied Minds
If consciousness were just a physical phenomena, then disembodied minds would be metaphysically impossible. Because heat just is the rapid movements of particles, disembodied heat is impossible. To have heat, one needs particles to move rapidly.
It would make no sense to talk about a non-physical tortoise, box, or pancreas, because these are physical phenomena. However, disembodied minds—minds without bodies—seem metaphysically possible. We could imagine mental functions going on, even in the absence of a body. This shows that consciousness isn’t a purely physical property—it could exist in the absence of physical things.
8 Some Concluding Thoughts On Why This Isn’t Vitalism
Vitalism is the notion that living organisms have some fundamental life causing non-physical substance—“Élan vital.” Many have given analogies between non-physicalism about consciousness and vitalism, as they both posit a non material thing. However, it’s worth noting that none of the arguments above can apply to vitalism.
Life just is about structure and function and can be described quantitatively—so it’s not susceptible to the first argument. A L zombie, physically identical to an alive thing but that isn’t alive, is obviously impossible. It is possible to use low level phenomena to explain life, unlike for consciousness. There’s no analogy for the inverted qualia argument. Knowing all the physical facts about a physical system would let you know whether it’s alive and all the facts about its life, there is an account of how cells replicate and comprise life, and disembodied life is obviously impossible.
The properties that were appealed to for vitalism were non-physical properties, but ones that we now know don’t exist. There’s nothing it is to be alive over and above the physical facts relating to cell replication, growth, and the other things required for life. Thus, the correct view about vitalism was illusionism—the properties being posited that Elan Vital explained weren’t real. But we know consciousness is real! It’s the most certainly known natural phenomena—we can be more certain that we’re conscious than we can be of anything else.
Abandoning physicalism isn’t abandoning an answer to the problems of consciousness—it merely recognizes the reality of what form the answer must take. Non physicalist theories are testable and make predictions which can be subsequently verified.
Sometimes, the correct answers are surprising and run afoul of our heuristics. Generally people worrying about new technology are wrong, but not when it comes to AI alignment. Usually, Parfit is right, but not when it comes to the repugnant conclusion. Preachy vegans are irritating, but they’re right. Reductionism is enticing—it would be so nice if consciousness were just some physical phenomena, but there are knockdown arguments against such a view. We mustn’t be held captive to reductionist dogma, in the face of overwhelming evidence.