Subjective experience is most likely physical
Here’s the argument that convinced me subjective experience is physical. I don’t claim to understand subjective experience, I just see good reasons to believe it’s physical rather than non-physical. I’ll point out in particular some flaws of panpsychism and dualism.
I will be making some assumptions so that I can concentrate on the key points. I will not give an exhaustive list of those assumptions, but they include things like evolution by natural selection and the existence of physical reality. I think for most of the audience here the assumptions would seem natural so I don’t feel the need to discuss them in depth. If this is not the case for you, this article may not provide anything of substance.
What is the evidence for subjective experience?
Take this computer program:
print("This program has subjective experience.")Does this program have subjective experience? I think the consensus is “no” so claiming to have subjective experience is not necessarily evidence for it. What evidence do we have about subjective experience? The evidence is… subjective experience. Well, all evidence fundamentally stems from subjective experience (such as reading a book or performing an experiment) but this is not what I mean here. I mean that we have no third-person evidence that any particular system has subjective experience.
Nevertheless, there seems to be something that needs explaining. For one, we need to explain the causal path that makes a person say “I have subjective experience”.
Evolution of subjective experience
The propensity of people to talk about subjective experience indicates that it is not just a fluke of some brains. There seems to be something universal about it, at least for humans. No direct selection for verbalizing “I have subjective experience” exists, but the fact that we reliably do so implies a deeper adaptive structure. There is something more fundamental, which increases inclusive genetic fitness and also causes the human brain to form an ontological concept of subjective experience.
Panpsychism and Dualism
Both Panpsychism and Dualism make claims about subjective experience:
Panpsychism
Subjective experience arises from inherent mind-like properties of matter
Dualism
Subjective experience is non-physical and distinct from the body and the brain
Those two philosophies are attractive because they confirm common intuitions, but this is not enough of a justification. Their commonality is postulating some mysterious “force”, which we haven’t been able to observe experimentally. Whatever it is, it must be so obscure that microscopes, spectrometers, particle colliders or any other physics machinery gives no indication of its existence. At the same time, that mysterious “force” must impact how neurons in the brain fire and lead people to say “I have subjective experience”.
So the brain, which consists of particles we understand and is produced by a process we understand through developmental biology, somehow acquires a capacity to detect a mysterious “force”, which no other known physical system can detect? How did the brain come to be this way?
Neither theory provides mechanistic insight into subjective experience.
How do we know about subjective experience?
When I say “I feel happy”, this is the result of self-awareness. My brain can detect and reference some things about its internal state. This capability is limited. When I say “I have a visual cortex”, this is not a result of the brain detecting its own visual cortex—it cannot do so. It is the result of me having learned about the visual cortex via means external to the brain (e.g. a book). What is going on when I say “I have subjective experience”?
It is tempting to answer that it is the same type of self-awareness as in the case of being happy. This however leaves no place for any mysterious “force”. So is there something more than self-awareness going on?
Suppose there is a mysterious “force” at play. This is an extraordinary claim, because it requires explaining how that “force” is connected to what we say. In other words, how do we know about it? How come the brain has been shaped by natural selection to reliably detect something which has no experimental impact and thus cannot possibly apply any selective pressure? We cannot expect evolution to build a reliable detector, if there is no feedback allowing to distinguish true positives from false positives.
If subjective experience stems from a mysterious “force”, why would our words be an accurate representation of its essence? This would require a “sense of subjective experience”, in a similar way to how we have a sense of sight or smell and unlike happiness which we can learn about from introspection.
What both panpsychism and dualism lack is an explanation of the epistemic link between subjective experience and the mysterious “force” postulated to explain it. Any theory positing an extra-physical substrate must explain how physical organisms came to systematically talk about it, model it, and report it.
What about Mary’s room?
Mary is a scientist who knows everything about the science of color – wavelengths, optics, neurology, etc. – but has lived her whole life in a black-and-white room and has never seen color. When she sees red for the first time, does she learn something new?
This is a famous thought experiment called Mary’s Room. It comes up in discussions about qualia (instances of subjective experience). It is often used to argue that if Mary gains new knowledge from seeing red, then non-physical knowledge exists, and thus subjective experience is not entirely physical.
Does Mary learn something new?
What Mary experiences when seeing red would seem different from everything she has experienced before. One way to make sense of this is to think about the brain as having multiple “parts”. Not all those parts are under our conscious control. You can consciously read a book, produce speech, or walk – but anyone who has struggled with akrasia or addiction knows that some things are hard to control. There are processes the brain governs that are completely beyond our conscious control, such as gland secretion.
Even if one learns everything about the science of color, this would not affect the parts of their brain that deal with perception in the same way that actually seeing color would. Seeing color causes brain activity that one cannot replicate by merely learning about it. But this doesn’t prove that anything non-physical is going on.
Conclusion
It feels as if there is something special about subjective experience. I tend to think this specialness is a cognitive illusion in a similar way to how there are visual and auditory illusions.
While the nature of subjective experience is still not completely understood, physicalism offers the only account grounded in known science and coherent with evolutionary and epistemic constraints.
Interactive dualism allows a mechanism , epiphenomenal dualism doesnt.
Panpsychists can claim all.causation is mental causation, but that doesn’t explain why only some systems report consciousness.
Dual aspect theorists say that physical causation is valid, but not exclusive...the existence of a physical explanation of a report of conscious does not preclude a mental explanantion.
why does that matter?
Physicalists sometimes respond to Mary’s Room by saying that one can not expect Mary actually to actually instantiate Red herself just by looking at a brain scan. It seems obvious to them that a physical description of brain state won’t convey what that state is like, because it doesn’t put you into that state. As an argument for physicalism, the strategy is to accept that qualia exist, but argue that they present no unexpected behaviour, or other difficulties for physicalism.
That is correct as stated but somewhat misleading: the problem is why is it necessary, in the case of experience, and only in the case of experience to instantiate it in order to fully understand it....that is an assumption of “specialness”. Obviously, it is true a that a description of a brain state won’t put you into that brain state. But that doesn’t show that there is nothing unusual about qualia. The problem is that there in no other case does it seem necessary to instantiate a brain state in order to undertstand something.
If another version of Mary were shut up to learn everything about, say, nuclear fusion, the question “would she actually know about nuclear fusion” could only be answered “yes, of course....didn’t you just say she knows everything”? The idea that she would have to instantiate a fusion reaction within her own body in order to understand fusion is quite counterintuitive. Similarly, a description of photosynthesis will make you photosynthesise, and would not be needed for a complete understanding of photosynthesis.
No we experience it all the time. The problem is that it isn’t captured by physics...and there is no reason it should be. Physics is only interested in the objective and quantifiable....but we don’t know that apriori that everything is objective and quantifiable.
The specialness of qualia lies in their being unexplained by physics, as you effectively concede. And that’s quite possible because physics isn’t necessarily true. And it’s not immediately obvious because physics isnt.
An illusory quale is a quale.
Mary’s room was clearly written by a man; adult human women are overwhelmingly likely to see red substances about a dozen times a year. If she was written as a colorblind person who had their colorblindness cured, the thought experiment would be more plausible. It is interesting in the context of discussing subjective experience how the classic thought experiment shows a lack of understanding of the kind of subjective experience its participant would have.
Anyways. I think for the way you’re calling subjective experience physical, language is also physical. Both acoustic and visual forms of language are constrained by our physical capacities, abilities whose initial development appears to pre-date the formalization of language itself. Words sound like they do based in part on the genetic accidents of our capacities to speak and hear. If our hearing worked better for different pitches, or the physical apparatus of speech could produce different sets of easily differentiable phonemes, we would use very different words.
And yet the physical artifact of language somehow manages to nevertheless be emitted by non-embodied systems. Interesting!
Russelian panpsychism doesn’t postulate a new force—physics already accepts casual role of existence: only existing neurons can fire.
And it explains epistemic link—it’s cogito ergo sum—you’re always right, when you think that universe exists.