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Topic Series
Dean Zimmerman
Saleem Ali on Natural Laws and Human Life
Coming Soon: What is Philosophy of Scientific Breakthroughs?
Coming Soon: What are Scientific Breakthroughs in Biology?
What Are Scientific Breakthroughs In Physics?
Tim Palmer on Doubt: From Quantum Physics to Climate Change
Manil Suri on How to Build the Universe with Math
- Robert Lawrence Kuhn
- Dean, I've been obsessed with the mind-body problem my whole life. Sounds crazy. And it's more than just a philosophical problem, as it really tells us what we are as human beings. I was so nuts about it that I did a PhD in brain science to try to get at the problem. As a philosopher, how can you begin to lay out the mind-body problem so we can understand the scope of it?
- Dean Zimmerman
- I sort of think of it as having two basic components. You can be asking about mental states of various kinds, you can sort of list them. There's various kinds of thinking, believing, desiring, hoping entertaining thoughts, and so on. There's also phenomenal states, various kinds of feelings, bodily feelings, sensations, different kinds. And these seem to fall into two natural categories. The first are often called intentional – you're thinking about something, something distinct from yourself – you're somehow managing with your mind to reach out and grab onto parts of the world in some way. And you can think about things that don't exist, you know, how do you do that? But that's a part of the mind that seems to have to do with referring and with truth and falsehood. So when you think these things—you know, if I think there is a unicorn, I think something false, if I think that there isn't, I think something true—then the phenomenal side doesn't seem to have to do with truth and falsity and referring to things outside yourself. It's a matter of how things feel to you and seems more primitive in a way, I guess. And I think these probably—this is probably a very natural kind of division of mental states into two kinds. And then you can ask two sorts of questions about mental states. You can ask what is it that has these things, and I take this to be the question of—you can call it substance materialism versus substance dualism. So you're asking what is the substance or the thing that has these intentional states and these phenomenal states, what is it? You know, answer is, it's the brain. I mean that's a very natural answer, because—
- Robert Lawrence Kuhn
- And the mind-body problem, that's the way it was characterized hundreds of years ago, but it's really the mind-brain problem?
- Dean Zimmerman
- That feels right, because you look at the whole body, it seems like the whole body doesn't—isn't essentially involved in thinking. You could whittle it away bit by bit until just the brain is left, and in principle it feels like there could still be thinking. So it does seem to focus on the brain as a very natural candidate for the thing that is the subject of these mental states.
- Robert Lawrence Kuhn
- So would that be the substance materialism part?
- Dean Zimmerman
- Yeah, so that would be substance materialism. Now of course there have been other versions of substance materialism that have said, no, no, no, it's not just the brain. I am a thinking thing, I'm also an organism, you know, from my toes to my head. That's the thing that's thinking; it somehow thinks because there's a brain inside of it, but it's not the brain that's the subject of these mental states, it's the animal, the whole animal. I sort of think if I was going to be a materialist, which in my heart of hearts I'm not, but if I was going to be one, I would say yeah well there's this whole organism here, but my toenails and my hair, they don't have much to do with my thinking. I would go to the brain. I would say, it's got to be that organ that's thinking, if any physical thing is thinking. So that's—the alternative to the view that these mental states are possessed by a material object is that it's something else, you know, it's something that somehow is closely associated with this body, but it's not made out of the same kind of parts, not made out of the same kind of parts, not made out of—not made out of the same kind of substances as chairs and tables and things. But of course this body is just made out of the same kind of –
- Robert Lawrence Kuhn
- Yeah, and when you're dealing with substance materialism, that allows us to think about can there be other substances besides brains and bodies that can, in a materialistic way, produce those same kinds of things; can computers, supercomputers, quantum computers, other things represent that same kind of mental states?
- Dean Zimmerman
- Yeah, or is there something special about organic stuff.
- Robert Lawrence Kuhn
- Sure, sure. I mean, that's a derivative question, but it's still under this concept of substance materialism. What is the substance if you're purely a materialist, materialist being that only matter is real or only matters and forces are things in the physical world—naturalism?
- Dean Zimmerman
- Yeah. Right. And there might be different answers to these two different—with respect to these two different kinds of mental states. So you might say look, intentional phenomena, so believing something, desiring something, thinking about an object – you can do all of these things without having any particular phenomenal experiences. So…this is kind of a stock example. If I'm thinking about Vienna, there doesn't have to be any particular mental imagery that goes along with that or any particular feelings. You know, maybe I have a kind of image of a church that I saw there or the sound of an organ that I heard in that church there, or some kind of image of a map of the ring. But none of those are crucial to the thought. So perhaps phenomenal experiences are not really necessary for that kind of thinking, and on the other hand, you know, phenomenal experiences seem kind of more primitive, and we sort of assume that higher animals have them and lack the capacity for some of these more complicated tensional thoughts. So I guess some people have thought no problem about having a computer that has intentional mental states. So you hook up the computer in the right way, and you know, it's processing information, taking in information about the environment and maybe it's got robotic arms and so on, so it's able to interact with the environment. You can say, well, it believes that there's a cube over there, and it wants to move the cube. But you might think it doesn't have any phenomenal experience, and so I think some people have thought that…well they've been really convinced by their gut feeling that the computer could never have phenomenal experiences and have said must have something to do with organic chemistry. So the phenomenal really is…
- Robert Lawrence Kuhn
- Those are still the materialists?
- Dean Zimmerman
- Right. Right, absolutely.
- Robert Lawrence Kuhn
- So they're fully materialists, naturalists, but they still will differentiate between the different kinds of substances that can engender the phenomenal stance.
- Dean Zimmerman
- Right, right. And then you know, plenty of people have thought no computer could…you know, computers could only simulate thinking of any kind. Now if you're a materialist, I don't quite see where the confidence, where that confidence comes from, because after all, we're just big physical things, kind of navigating in our environment, and I don't see anything crucial.
- Robert Lawrence Kuhn
- So you believe if you're a materialist, the distinction between just being a bodily brain, organic materialist and a silicon or gallium arsenide computer, is really the difficult distinction to make?
- Dean Zimmerman
- Yeah, I think that. I think you might be able to make this case that phenomenal qualities are really different and perhaps silicon chips just can't produce those. But that would just be a sort of contingent fact about the way the world works. It turns out you can generate that kind of brilliant, colorful phenomenology; you can generate that if you use this kind of stuff, but you can't generate it if you use chips.
- Robert Lawrence Kuhn
- What about substance dualism?
- Dean Zimmerman
- Right. So, I mean a lot of people have kind of in principle objections to substance dualism. They'll say, look, what's it supposed to be, some kind of extra something or other that has these mental states of some kind, but it's distinct from the body, so it's non-physical, but if it existed, surely it would—if it was any good at all, it would be pushing things around in my brain, it would be interacting with my brain, like Descartes thought that it did. So if it's pushing physical stuff around, well then surely it's just another piece of physical stuff, and so it's not immaterial or non-physical after all. There's a sort of kind of in principle objection that's supposed to keep dualism from even getting off the ground. But I think when you look at the traditional views that have been thought of as dualistic, you know, from animistic kind of views where you know, there's the soul of the tree and there's the souls of animals, and souls of human beings as well, they've thought that there was a different kind of substance. And the substance was different from ordinary objects, and yet somehow able to interact. And then later, kind of more sophisticated dualisms like Descartes, have attributed various properties to this extra thing. So I regard substance dualism as a kind of spectrum of views. You can have a very extreme kind of substance dualism that says the thing that has mental states like thinking about you or having feelings, that thing is utterly unlike the stuff that physics studies, the stuff that can make up non-sentient things, like chairs and tables. And so the parts of our bodies we see that they're made up out of the same kind of stuff as chairs and tables. So the most extreme dualism says the thinkers, that whatever thinkers there are, are very unlike anything that you could make out of that sort of stuff. Most extreme kind would say thinkers are outside of time, outside of space, they have absolutely no properties in common with anything that could be made out of non-sentient material. Less extreme kinds of dualism, more familiar ones, souls are outside of space, but they're in time. So that seems very natural. I mean it's hard to, you know, what do we mean to say I'm outside of time. I have one thought, then I have another thought, then another thought after that. So I seem to be very much you know, enmeshed with temporal events. So uh, less extreme dualisms say, I'm in time, not in space, have no properties in common with insentient, unthinking matter. And then you have other gradations too. So some people—Hermann Lotze, who's one of my favorite philosophers, favorite forgotten philosophers—he thought that souls were in space, that they're located in the brain. Where exactly? Well of course Descartes thought that you interact with the pineal gland, but Lotze knew a bit more about the brain, and he thought, well there's stuff going on all over the place in the brain, so the soul has to be here sometimes, it has to be here sometimes, and it's wherever it needs to be, basically. And it doesn't have parts located here, parts located here. It is just here, and then it's also here, and also here. But anyway, his souls were in space, but they lacked all sorts of other properties that ordinary matter has. And you could have even more sort of—you know, you could have ectoplasmic divisible souls. That still out to count as a kind of dualism, as long as you're claiming only thinkers are made out of this kind of stuff, and thinkers can't be made out of this kind of stuff.