Why is it like anything? Why is it like this?

Trying to explain why physicalism leaves me unsatisfied

Physicalism is the view or class of views that consciousness is a purely physical phenomenon. (I use physicalism and materialism interchangeably, as most philosophers these days seem to. Quibbling about minor definitional differences seems like a waste of time.) Roughly speaking, your mind and your brain are one and the same. Of course, physicalists disagree about the details, and these details lead to different commitments, which become very important when formulating arguments for and against physicalism. Furthermore, physicalists usually at least imply that consciousness came late in the history of the universe and biological evolution. For a physicalist, consciousness is a higher-order phenomenon, restricted only to organisms with sufficiently complex nervous systems. 

“Some physicalist theories hold that consciousness consists merely in some particular type of brain activity or structure – for example, the feeling of love may consist in nothing more than some neural activity involving transmission of serotonin and oxytocin. Others take consciousness to consist in a kind of information processing, or a kind of ‘software’ implemented by the physical ‘hardware’ of the brain.” 

Hedda Hassel Mørch, Non-physicalist Theories of Consciousness (2023) 

The most commonly discussed alternative to physicalism is dualism, on which human beings are composed of two parts: the body and the soul. The brain and the mind interact with each other and can influence each other, but they’re not the same thing – they’re two distinct parts of a human being. Physicalists reject the notion that there’s any immaterial aspect to you. 

P-Zombies

To better understand the physicalist position, let’s briefly discuss a crucial premise of David Chalmers’ well-known conceivability argument. Here’s the argument in a nutshell: (1) Zombies are conceivable, (2) If zombies are conceivable, then they are metaphysically possible, and (3) If zombies are metaphysically possible, then physicalism is false. 

A philosophical zombie, in contrast to a zombie on The Walking Dead, looks and acts just like us, but there’s a total absence of phenomenology. They react to stimuli just like we do, but they have no feelings or experiences, no stream of consciousness – they’re just complex mechanisms. If you built a lifelike robot that acted just like Philip Goff, you might be tempted to attribute an inner life to the Goffbot, but you’d probably suspect that any appearance of sentience would be an illusion (and for the sake of argument, let’s say you’d be right). This robot would merely register information about its surroundings and react to stimuli, all without having an experience of seeing shapes and tasting the spiciness of paprika and so on, just like the sensors on automatic doors register information without having experiences that accompany that information. The zombies that Chalmers wants us to imagine are like that. 

Why would the possibility of zombies be a threat to physicalism? As Mørch (2023) explains, 

“...the argument also presupposes that if two things A and B are identical or A is constituted by B, then it’s metaphysically impossible for B to exist without A (as influentially noted by Kripke (1980) for the case of identity, and the case of constitution is closely related). For example, if the statue David is constituted by a piece of marble in a certain shape, it’s metaphysically impossible (i.e., impossible regardless of what the laws of nature may be) for that piece of marble to exist in that shape without the statue David also existing. In the same way, if consciousness is constituted by a physical state – as physicalism claims – it should be metaphysically impossible for that physical state to exist without consciousness.” 

If the mind is this higher-order phenomenon that’s constituted by a physical state, then it should be impossible for that physical state to exist without consciousness. That’s why the possibility of the physical body without a mind would be devastating to physicalism but not to alternative views. 

If a fact or entity X constitutively grounds Y, then necessarily if X exists, Y exists also. For example, if a brick wall is constituted by nothing more than bricks in a particular arrangement, then if we have a bunch of bricks standing in the right relation to each other, then necessarily, the brick wall exists too. It comes for free, as it were, once the constituents are in place. Likewise, if consciousness is constitutively grounded in the physical, then it shouldn’t be possible for the physical constituents to be in place without the reality of consciousness. There couldn’t be a world that is physically indiscernible from our world but in which there is no consciousness. This is why the possibility of such a world – what philosophers call a “zombie world” – would refute physicalism. 

The third premise of the zombie argument is fairly certain, as far as I’m concerned. (So are the first and second premises, but that’s another post.) For me, the conceivability argument not only refutes physicalism but also goes a long way towards conveying why physicalism is so unsatisfying as an explanation of consciousness. But let me try to explain my discontent another way, inspired by Derek Parfit’s 1998 essay, Why anything? Why this? 

Consider the Houseplant 

Notoriously, phenomenal consciousness – minimally, the qualitative “what it’s like” of experience – is a thorn in the side of physicalism. There are other aspects of the mind that seem problematic for physicalism, including the persistence of personal identity over time, the unity of the mind, the sharpness (i.e. non-vagueness) of conscious experience, intentionality and meaning, and our capacity for reason. In contemporary analytic philosophy of mind, however, accounting for experience is the most discussed problem and often taken to be the main problem for physicalism. 

The apparent gap between the experiential and the physical has been dubbed the “hard problem” of consciousness by Chalmers, who argues that while neuroscience can tell us what’s going on in the brain when we’re having certain experiences, it can’t tell us much more than that. It can reveal which physical states or processes are correlated with a given conscious experience, but not why the correlations hold. For any brain state, no matter how much physical detail is provided, we can always ask the following questions: “Why is it like anything to be in this brain state? And why is it like this instead of like something else?” Non-physicalists argue that study of the austere physical realm alone isn’t going to answer why it’s like something rather than nothing. Just as we can ask “Why anything? Why this?” about the universe itself – Why is there something rather than nothing? Why is there this rather than something else? – we can also ask those questions about the existence of experience. Why is it like anything at all for us to exist? And why is it like this? Neuroscience isn’t going to answer those questions any more than physics is going to answer why there is something rather than nothing. It’s a distinctly non-scientific question that nevertheless does not seem to be meaningless or malformed. It reminds me a bit of the closing paragraphs of Stephen Hawking’s A Brief History of Time: 

“Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe? The usual approach of science of constructing a mathematical model cannot answer the questions of why there should be a universe for the model to describe. Why does the universe go to all the bother of existing? Is the unified theory so compelling that it brings about its own existence?” 

Asking why there is some concrete world for our abstract models to mathematically describe does not seem like a malformed or meaningless question, either. It is, however, as Hawking points out, not really a scientific question. 

Consider the houseplant. Let’s assume, along with most people, that plants are insentient. It’s not like anything to be a plant. If I study a brain and a plant side by side, I can wonder “Why is it like something for this physical object and not that physical object instead?” Replying “Well, the plant doesn’t have a brain” does not answer the question. Why is it like something for this physical object but not that physical object? Neuroscience can tell us what’s going on in the brain when we have certain experiences. It can’t answer the deeper question of why it’s like anything in the first place. 

As an aside, how you answer that question – why is it like something for this brain but not this plant – can say quite a lot about your views. For example, you might’ve thought something along these lines: “Well, if you knew everything about that brain, it would be clear why mental activity goes along with neural activity. In fact, you’d see why it was unavoidable. There wouldn’t be any kind of gap between the physical and the mental.” In that case, you’re a fairly radical type of physicalist. Most physicalists, these days, wouldn’t go as far as you. They don’t want to grant that there's an a priori conceptual entailment from the physical to the phenomenal. 

For any physical property we can identify, we can still ask why it is like something to be that physical thing. Why couldn’t this physical state obtain without any experience going along with it? And as Thomas Nagel famously observed, it seems that no matter how much we know about the brain of another creature, such as a bat who navigates by echolocation, we can’t deduce what it’s like to be that creature. Strictly speaking, we can’t deduce that it’s like anything with certainty. But we also can’t work out what it’s like, even after we grant that it’s like something. Relatedly, if you could see a color I’d never seen, there’s nothing you could say that would make me understand what it’s like to see that color. I would never have knowledge of what it's like to see that color, and neither would a neuroscientist who’d never seen the color. 

For most people, physicalists included, there’s an intuitive basis for an epistemic gap between the physical and the phenomenal. The epistemic gap between our knowledge or concept of the physical and our knowledge or concept of the phenomenal plays a crucial role in non-physicalist arguments like the knowledge argument, explanatory argument, and conceivability argument. These attempt to show that the physical and the phenomenal seem like different things because they are different things. There’s an epistemic gap because there’s an ontic gap. Materialists (since the 1980s and ‘90s) typically try to show that they can grant that there’s an epistemic gap without granting an actual, ontological gap between the physical and phenomenal. Some materialists still try to argue that there’s not even a conceptual gap, but ever since they realized after the Kripke-Putnam revolution that they didn’t have to do that, they mostly kinda stopped doing that. 

What the Zombie is Missing 

What is phenomenal consciousness? Its definition is actually a matter of widespread consensus among neuroscientists and philosophers. As Mørch explains, 

Phenomenally conscious states are characterized by the fact that there is something that it’s like for a creature or entity to be in them, or that they are subjectively experienced or felt. Think of experiences such as seeing red, feeling pain, tasting chocolate, feeling love, or thinking a thought. These experiences may be associated with various functions or abilities, such as perception or reflection, but they also seem to have a subjective quality or feeling to them that goes beyond that. That is their phenomenal aspect. [Footnote: The term “phenomenal” relates to “phenomena” in the sense of what immediately appears to us, as opposed to the reality behind the appearances. Conscious states can be regarded as phenomena in this sense because they are what immediately appear to us, and that through which the rest of reality appears (i.e., via conscious perception).] 

The definition of consciousness in terms of there being something that it’s like is due to Nagel (1974), and has been widely adopted in philosophy. As Nagel notes, to say that consciousness is like something is not to say that it merely resembles something (if so, everything would trivially be conscious, because everything resembles something else in some way or other). The important point, according to Nagel, is rather that there is something that it’s like to be in conscious states for the conscious entity itself. That is, consciousness is subjective in the sense that it’s present only for its subject or from a particular point of view. Physical objects, in contrast, are objective, in the sense that they can be present from multiple points of view or independently of any point of view at all – for example, different people can see, feel, or otherwise perceive the same chair from different points of view, and we usually think that the chair can exist without anyone perceiving or having a point of view on it at all. 

As she goes on to explain, the subjectivity of consciousness is intimately connected with the privacy of consciousness. You can observe my brain states, but my subjective states of consciousness are not publicly observable in the same way. There is something about my mental states that no one else has access to in the same way that I have access to them. 

To say that one’s conscious states are private does not mean that nobody else can know anything about them; it rather means that nobody else can know about them in the same direct way. That is, my own conscious states appear directly to me, whereas the conscious states of other people we infer or perceive indirectly through their behavior, verbal reports, facial expressions, and so on. Because of this direct access, many philosophers also hold that our own consciousness can be known with absolute certainty. René Descartes famously claimed that we have indubitable knowledge of our own consciousness, and thereby our own existence (“cogito ergo sum”). 

Before I got into philosophy of mind, I did not realize anyone even tried to deny the privacy of experience. But privacy poses various problems for physicalism, which is why physicalists often dispute it, or say they just don’t know what privacy means, or something. For me, this is non-negotiable. Not because I’m a non-physicalist partisan – I also believed this was certain when I was a physicalist. I didn’t realize it was in tension with physicalism. But once I did come to see it, I became a lot more confident that physicalism was not true. It’s plain obvious that there is something about my conscious states that nobody else can know about in the same direct way that I know about them. To me, the task is to develop a theory that accounts for this fact. If you can’t adequately explain the privacy of experience, then you at least have to explain why phenomenal consciousness seems private, why it gives us the impression of being private, etc. It won’t suffice to simply deny privacy, burden-shift, or pretend to not understand what’s being discussed. 

It might have slipped by without much notice, but the concept of phenomenal consciousness we’ve been discussing involves more than subjective what-it’s-like-ness. Subjectivity also seems intimately connected to the notion of privacy. I also mentioned ineffability in passing earlier (there’s nothing one could communicate to a neuroscientist to fully convey the knowledge of what it’s like to see a color the scientist has never seen). Further, conscious experience is something we’re directly, immediately acquainted with. We’re honing in on what philosophers of mind sometimes call qualia, which is generally taken as a synonym for phenomenal consciousness. 

That’s what we non-physicalists think is non-physical. That’s what the zombie is missing.