Jim Fleming: Consciousness may be the biggest mystery left in science. Think about it: The entire material world we live in seems to be explained by the laws of physics and biology, but consciousness is immaterial. A thought doesn't have mass or volume or speed. It's not made of atoms. It has no genetic structure. You can't weigh or measure a thought. You can't see one on an X-Ray or catch one in a test tube. How does something as physical as wet and gushy as the brain produce something as insubstantial as thought. That's a mystery and a subject of great debate among scientists and philosophers. Steve Paulson explains.
Steve Paulson: One of the big questions is whether consciousness can be explained by the brain. As neuroscience marches on and figures out how the billions of neurons talk with each other, how all the neurotransmitters work, will that explain our subjective experience of consciousness? There are lots of scientists, especially neuroscientists, who say "yes." There are other people who say "no, actually that subjective experience of consciousness is fundamentally beyond science" and that's really the crux of the debate here. To take one example: Marvin Minsky is a famous computer scientist at MIT. For years he's been working on artificial intelligence and he says basically that the brain works like a computer. Part of the problem with the debate about consciousness is, it's about language and he says we should get rid of the word consciousness because it tries to explain too much.
Marvin Minsky: I call it a suitcase word for about twenty different kinds of mental processes and so whenever you try to explain part of it, then you find, well, you've left something out and this makes people feel like there's a big mystery. But I think this is the case with a lot of psychological words.
Paulson: So, you're saying that the word consciousness basically doesn't mean anything. It just, it covers so much ground and so many different brain functions that it's just this vague, amorphous concept.
Minsky: I don't think it's good enough for a scientific word and so we have to replace it by reflection and decisions and about a dozen other things. And once you do that the big problem goes away and instead of talking about the mystery of consciousness, let's talk about the 20 or 30 really important mental processes that are involved and then with a couple of years work you can make a big step toward solving each of them and when you're all done somebody says, "Well, what about consciousness." And you say, "Oh that?" (laughs)
Minsky: That's, that, was what people wasted their time on in the 20th Century.
Paulson: So Marvin Minsky says ultimately we'll be able to build better human brains based on computers, but, of course, there are plenty of other scientists who think that's nonsense.
Roger Penrose: It's very different, I mean, subjective experience. There's nothing in science that tells you that such and such a combination of whosits gives you a subjective experience.
Paulson: This is Roger Penrose with...a renowned British mathematician and physicist. Penrose happened to hear an interview with Marvin Minsky on the radio and became furious. He said this is not the way the brain works. The brain is not just like a computer and, in fact, you really can't reduce the brain to the laws of physics, to biology. There's something else going on here and so he came up with an entirely different idea, a different theory about consciousness.
Penrose: We do need a major revolution in our understanding of the physical world in order to accommodate consciousness. The most likely place, if we're not going to go outside physics altogether, is in this big unknown, namely making sense of quantum mechanics.
Penrose: It's the borderline, if you like, between quantum mechanical behavior and classical behavior.
Paulson: So Roger Penrose has come up with this very controversial theory which he, he, developed along with another scientist named Stuart Hameroff. The idea is consciousness has something to do with quantum physics. Now quantum physics is famously difficult and their theory is that consciousness happens through a process of what they would call quantum computation and they've actually isolated little microtubules, tiny protein structures inside of neurons and they think that somehow inside the act of consciousness is happening in there. Highly speculative, but then there are other people who think that is nonsense and one example of that would be Daniel Dennett, famous materialist philosopher.
Daniel Dennett: I don't think consciousness is a mystery.
Paulson: But there are all kinds of things that I just, I can't imagine how science will ever be able to explain. For instance, the precise nature of how we love someone else. I mean, I'm not, I'm not talking about the sex drive here, but I'm talking about the mystery of love or why we have certain kinds of dreams and, and dreams are not rooted at all in the physical world. I mean, if you dissect the brain somehow and look at all the neural connections, you think science will ever be able to explain those things?
Dennett: Sure, in what sense of explain? Would you find it just unimaginable that science might, oh, in the next 15 or 20 years be able to read people's brains while they sleep and then write down what they're actually dreaming? Would you give me that kind of mind reading?
Paulson: I don't think I would.
Dennett: We can't do it yet, but we can do it a little bit.
Paulson: I don't give you that actually.
Dennett: Well, well, then hang on to your hat...
Dennett: ...because that's, that's coming. We can...
Paulson: You're saying, you're saying science will be able to do that without any kind of self-reporting by the dreamer?
Dennett: Oh, no. We'll, we'll use waking reports by the dreamers, of course, to calibrate the instruments and understand how to decode the neural signals. Um...
Paulson: See, that's my point, that's my point.
Dennett: Well, well...
Paulson: If you don't actually ask the person what they're dreaming, will you ever be able to decipher the dreams?
Dennett: Well, let's build up to it then. So, we ask the person what they're dreaming for 100 nights and we build up a nice library and we translate the, the relevant brain states for that person. Then the idea that one might then be able to say a little bit later, "Oh, look, look, Jones is having that dream about the old car and look, he's falling over a cliff now" and we wake him up and that's what he reports. If you think that's just beyond the reach of science, I think you're wrong.
Paulson: But that's just correlation, that's just, you know...
Dennett: That's right.
Paulson: You're just looking at what so-and-so has dreamed and you're just going to match the brain imaging to some future dream. That still doesn't explain how within the brain that particular kind of dream is generated.
Dennett: Yeah, well so, we have to do that too, but I think we're, we're making good progress on that too. We can't do that now. Might we do that in the future? Certainly.
Paulson: Now, I think that a lot of people find what Daniel Dennett is talking about to be profoundly disturbing. This whole idea that we are nothing but our brain chemistry. Think about the age-old ideas that express the essence of what it means to be human: what our soul is, our spirit, and the idea that that is just nothing but brain chemistry? I mean, that, that really rubs people the wrong way. And think about some of the core religious ideas. You can communicate with God. There is some piece of us that lives on after death. Those beliefs are founded on the idea that consciousness is not just bound to an individual brain. So, I actually think that the core debate about science and religion comes down to questions about consciousness. Consider the spiritual writer Deepak Chopra, an M.D. famous for his writings about mind-body healing. He's actually extremely well-versed in science and particularly of quantum physics. Now he comes back and he says that maybe there is something about science that can explain what we would consider the soul and he goes to quantum physics.
Deepak Chopra: Well, all we have to understand is what comes first. Does consciousness come first or matter comes first? The old paradigm was that consciousness is a, a phenomenon of molecules. But now, you know, we know that molecules are atoms, atoms are subatomic particles and that these subatomic particles are fluctuations of energy and information in a huge void. And the void is not emptiness. It's the womb of creation.
Paulson: Now, in contrast to Deepak Chopra, there are plenty of people, especially atheists, who would say this is nonsense.
Richard Dawkins: Consciousness is the biggest puzzle facing biology, facing neurobiology, facing evolutionary biology. It is a very, very big problem.
Paulson: The world's most famous atheist, Richard Dawkins.
Dawkins: I don't know the answer. Nobody knows the answer. I think they probably one day will know the answer, but even if science doesn't know the answer, I return to the question: What on earth makes you think that religion will? We don't have an explanation. Nobody has an explanation for consciousness. That should be a spur to work harder and try to understand it, not to give up and just say, "Oh well, it must be a soul." You said absolutely nothing when you've said that.
Paulson: Now the really interesting thing about listening to atheists on consciousness is they're actually all over the map. Sam Harris, who is a neuroscientist, he has a Ph.D. in neuroscience, he has a very different view. It's entirely possible that there could be life after death. He is not willing to rule that out.
Sam Harris: There are good reasons to be skeptical of the naive conception of a soul and so that the idea that the brain can die and a soul that still speaks English and recognizes Granny is going to float away into the afterlife, that seems to be profoundly implausible. And yet, we do not know what the relationship between subjectivity and objectivity ultimately is and... For instance, we could be living in a universe where consciousness goes all the way down to the bedrock so that there is some interior subjective dimension to an electron, say.
Paulson: That's interesting, though, because most evolutionary biologists, I mean I'm in particular thinking the, the secular ones would say, "Of course, consciousness can not survive the brain. It will not survive death." You are not willing to make that claim.
Harris: Yeah, I just don't know. If we were living in a universe where consciousness survived death in some sense or just transcended the brain so that, you know, that single neurons were conscious. We would not expect to see it by our present techniques of neuroimaging or cellular neuroscience, and we would never expect to see it. There are profound philosophical and epistimoligical problems that, that anyone must confront who's trying to reduce consciousness to the workings of the brain and this discourse is in its infancy, and who knows where it's going to go?
Paulson: So when I listen to all of these different theories, I actually find it kind of exhilarating, because we don't know what consciousness is about. There are lots of different competing ideas out there, and science keeps making inroads. I mean, we keep learning more about how the brain works, but this ultimate question of who we are, that's very much up in the air whether science can explain that. So, I know, some people get frustrated, some people would say, "Oh, that's just an excuse to say, "Oh, it's all mysterious and we'll never understand it." I think the verdict is very much out and who knows what the coming decades in neuroscience will tell us and philosophy.
Fleming: Steve Paulson brought us that report. We also heard from Sam Harris, Richard Dawkins, Deepak Chopra, Daniel Dennett, Roger Penrose, and Marvin Minsky.