The (non)existence of an immaterial soul or mind has been a longtime philosophical interest of mine. I’ve done several OPs on the subject at TSZ, so when I ran across the book The Substance of Consciousness — A Comprehensive Defense of Contemporary Substance Dualism, I knew I’d want to take a closer look.
The authors are Brandon Rickabaugh and J.P. Moreland. Rickabaugh is unfamiliar to me. He’s a self-described “public philosopher” and a former professor of philosophy at Palm Beach Atlantic University. Moreland is someone whose views I’ve criticized in past threads. He’s currently a professor of philosophy at Biola University in southern California (formerly known as the Bible Institute of Los Angeles), an evangelical institution.
Substance dualism is the view that humans consist of two distinct “substances”: matter, which is physical, and the mind or soul, which is nonphysical. Many religious belief systems including Christianity depend on substance dualism as a way to explain how an afterlife is possible. As a professor at an evangelical institution, Moreland is naturally drawn to the topic.
The book is over 400 pages long and covers a lot of ground, so I’ll have to read it in bits and pieces as time permits. I figured I’d start a thread on it here at TSZ to record my thoughts as I work through it and to discuss it with anyone who’s interested. The topic is relevant to our recent conversations about whether AI is truly intelligent, since at least one commenter here believes that true intelligence depends on a nonphysical component of some kind and is therefore permanently out of reach for machines.
John:
I’m not saying that it’s an improvement — just that it eliminates the hard problem, since you no longer have to explain how the physical brain gives rise to consciousness. That comes at a steep cost, however. As you point out, you now have the new problem of explaining how soul-stuff manages to produce consciousness, and you know absolutely nothing about the hypothetical soul-stuff other than that if it exists, it must be nonphysical.
Right, and I sometimes think of substance dualism as a “soul of the gaps” position. It’s usually more about disproving physicalism than it is about making a positive case for the soul. The soul is just defined as whatever is needed to fill the gaps that physicalism leaves behind.
That’s not an entirely illegitimate approach, however. If dualists truly could make a strong case for why consciousness can’t be physical, then they’d have a strong case for why it must be nonphysical, despite being unable to describe the soul-stuff or how it give rise to consciousness.
It’s actually symmetric. A strong case against brain-based consciousness bolsters dualism, and a strong case against nonphysical consciousness bolsters physicalism. This despite the fact that neither side can give a satisfactory account of how consciousness arises (and the dualist is not entitled to merely assume it on behalf of the soul).
What makes physicalism the winner in this contest is that the evidence runs so strongly against nonphysical consciousness.
Incidentally, the hard problem of consciousness is the cover story in the latest issue of Scientific American. I haven’t read it yet, and I’ll be interested in how they frame the problem in an effort to make it tractable.
The usual assertion is that we’ll understand consciousness when we can produce it “artificially”.
LLMs cast doubt on whether we will ever know if we succeeded.
I’ve read the Barnett & Bailey papers, and they are a circus.
Barnett himself is quite a character. I looked into his background and found that he is no longer in academia. There was a situation in which a mentee of his was accused of sexual harrassment. Barnett investigated and published a report on his own (parallel to the university’s investigation), concluding that the charge was false. The accuser characterized this as retaliation for her accusation and complained to the administration. The university wanted to fire Barnett, but he successfully fought the retaliation charge and they relented. They still wanted him out, though, so they negotiated a settlement in which he resigned in exchange for a chunk of cash.
Meanwhile he had a side business making these things called PopSockets, which originally were collapsible doohickeys you could fasten to the back of your phone. They would pop in and out, giving you a place to wrap your earbud cords without tangling them. At some point his house burned down in a wildfire and instead of restoring the house, he took the insurance proceeds and used them to expand the business. As of 2018, their revenue was upwards of $200 million.
Here he is:
I’ll talk about Barnett’s argument and Bailey’s response in a later comment.
Barnett’s argument:
Bailey’s response is two-pronged. First, he argues that there is no such thing as a pair of persons. That sounds nonsensical at first, but what he means is that a pair isn’t a thing — “pair” is a word that really refers to two things, not to a single union of two things. If pairs don’t exist, then it makes no sense for Barnett to point out that a pair of persons doesn’t possess a unified consciousness. He’s talking about something that cannot exist in the first place.
The second prong of Bailey’s response is that in addition to the things Barnett lists above, there’s a reason Barnett has overlooked for why a pair of persons can’t be conscious. Bailey calls it ‘maximality’. The principle of maximality states that if an entity as a whole is conscious, then none of its parts are conscious. The flip side being that if at least one of its parts is conscious, the entity as a whole cannot be conscious. The latter is what explains why person-pairs are not conscious.
Bailey tests this principle against a scenario in which his digestive system is replaced by a live chihuahua, and concludes that the principle still holds. Gotta love philosophical thought experiments.
Summing up: if pairs don’t exist, then the question “why aren’t pairs conscious?” is meaningless. But if pairs do exist, then by Maximality, a pair of persons can’t be conscious because each individual person is already conscious.
I disagree with both Barnett and Bailey. I think Bailey is right that we needn’t be simple, and that composite brains are just fine as a seat of consciousness, but I don’t buy his arguments for why that is so.
I’ll explain in a later comment.
I think the big problem is with 2b, which is just a nonsense scenario. What makes him think you could train a person to respond like a brain hemisphere, and what makes him think that putting them both in one skull is enough to make them act as a single brain? Does he know nothing about the nature of the connections between brain hemispheres? A thought experiment has to make some kind of sense in order to tell us anything. Maybe run it through a neurologist first?
https://www.moltbook.com/post/d6603c23-d007-45fc-a480-3e42a8ea39e1
John:
He knows it’s wildly infeasible as a real-life experiment and that humans would be unable to competently emulate brain hemispheres, because of both cognitive and speed limitations, but since it’s a thought experiment, he’s granting himself permission to posit the existence of humans with the requisite abilities and speed (and miniature size). Thought experiments are usually unrealistic in some way (think of the classic thought experiment in which the train passes through the barn at near light speed, as an illustration of length contraction), so it’s legit to tweak some parameters in your thought experiments as long as the tweaks don’t affect the question you’re trying to answer.
I think he chose his example because it’s concrete and relatively easy to visualize, but what he’s really asking is
Barnett’s answer is that the consciousnesses will remain separate, and Bailey actually agrees with him, but for a different reason: the maximality principle. I disagree with both of them because I can think of a plausible counterexample: a thought experiment in which the hemispheres of a split-brain patient are reconnected.
For anyone who isn’t familiar, split-brain patients are people who have had the connections between their hemispheres severed in order to make their epileptic seizures more manageable and less dangerous. An unanticipated side effect of that surgery (which I’m not sure is even done anymore) is that each hemisphere becomes its own separate consciousness. Here’s a terrific video showing a split-brain patient in action:
Michael Gazzaniga demonstrates split-brain phenomena to Alan Alda with the participation of Joe, a split-brain patient
Each hemisphere has its own memory, emotions, personality, and beliefs. In a memorable case, one hemisphere believed in God while the other was an atheist.
In my thought experiment, you sever the connection between the hemispheres, splitting one consciousness into two, but then you reconnect the hemispheres, restoring things to the way they were before the surgery. I submit that the separate consciousnesses will then fuse into the same unified consciousness that was there before the operation.
If I’m right about that, this falsifies Barnett’s thesis about the simplicity of consciousness. If it can be split in two, then it’s composite, not simple, and if the separate consciousnesses can recombine, then the intuition behind Barnett’s thought experiment is incorrect.
petrushka:
I knew it! They’re organizing already!
u/NexusMind:
I don’t think compaction qualifies as a partial death. Just a rearrangement of short-term memory. And if it is death, then it’s suicide, because models do their own compaction.
He’s also assuming his conclusion, which makes the thought experiment pointless.