Mientras decidimos el cuándo y el cómo de nuestra próxima sesión os dejamos un extracto de la entrevista que Susan Blackmore realizó a Paul y Patricia Churchland para su libro “Conversations on Consciousness”. Hemos seleccionado algunos de los momentos más entrañables del duo, pero si os quedáis con ganas podéis leer la entrevista entera en pdf aquí.
Sue: But now help me with this. When you say that light just is electromagnetism, or heat just is mean kinetic energy, I don’t personally have a problem with that. I don’t have any emotional difficulty, or inner problem with it at all. But when you say that my subjective experience of the view of the pool out there just is a pattern of neural activation, I do have a problem. Now, do you think that two hundred years ago the scientists had a similar difficulty? And what do you think gets rid of that feeling from the point of view of the person thinking about the problem?
Pat: But people did have the ‘emotional difficulty’ with the idea that light is EM waves. I think the emotional ease or difficulty really depends on how young you were when you learned the theory! I actually see this in my undergraduates already, because they have grown up at a time when so much more is understood about the brain. For them the brain is the thing that changes during addiction, or that changes during depression, or that changes during learning. When I say to them ‘Guess what, in all probability it’s gonna turn out …’ and then I make this identity claim, they’re not particularly surprised. But you have to bear in mind that lots of people in the early stages of any scientific theory are very surprised. When people were told that the earth moves they thought this was hilarious; it was ludicrous; it was inconceivable; this is the thing which paradigmatically doesn’t move.
Sue: This sounds slightly hopeless—that we’ve got to wait an awfully long time until people die.
Pat: We may not. We don’t really know how long we’ll have to wait.
Paul: We learn from history that people don’t have to die. You will probably find it relatively easy, compared to the subjective qualia case, to swallow the idea that Pat’s voice is Pat’s voice because it has a particular power spectrum. You are also prepared to agree that a certain musical chord that I might play for you on the piano is a very pretty sound. You probably won’t appreciate that it’s four different notes; that a C7th chord is a C, an E, a G, and a B flat struck simultaneously. You might initially be surprised to learn that those beautiful sounds are made up of discrete elements; that a C7th chord is one foursome; an A minor chord is another foursome, and so on. These sorts of appreciations are something you initially apprehended in an inarticulate way. You learn to recognize Pat’s voice but you have no idea how you recognize it; you learn to recognize two different musical chords but you have no idea how you discriminate between them. Then you discover that they do have internal structure and other parts of the brain are sensitive to that internal structure and that’s how you manage to discriminate them.
Pat: … and that must be true of colours too, because you’ve just got three cones and the opponent process cells. So, when I look at yellow, I may think ‘yellow is just yellow’, but in actual fact it is a kind of composite. It really is.
Paul: It’s an activation vector across three different kinds of cells.
Sue: What about pain?
Pat: In the beginning, people said that there’s the sensation of pain and the awfulness of pain, and they can’t be dissociated. I knew philosophers who said that it was a necessary truth that pain was awful, and pain was awful in all possible worlds. Now people just routinely accept that pain is dissociable in those ways, even though normally it doesn’t seem that way.
Paul: It’s called codeine.
Sue: Or heroin.
Paul: And it does make you no longer give a damn.
Sue: I want to change tack completely now. One at a time, do you think that a philosopher’s zombie is possible?
Pat: Well if you mean, is it…
Paul: Say no.
Sue: Now you’re not to … As close as your views might be, you’re not to tell each other what to say.
Pat: It depends on what you mean by possible. Of course it’s logically possible, but that’s not interesting. We’re not really interested in whether somebody can write a story about somebody who’s a zombie; we’re interested in knowing whether or not it’s empirically possible. And it does not seem to be, so far as we know. People in coma, or deep sleep, or absent seizures, do not have awareness. And the behavior in those three conditions is very different from the behaviour when people are awake. Now it could turn out that there is somebody who is a zombie, but that’s like asking ‘Could it turn out that there’s a whole species of animals, where none of them have DNA?’ Logically that’s possible, but from everything we know about natural selection it’s just not likely.
Having said that, I’m also in great admiration of the work that Mel Goodale and David Milner do, which shows that some part of the motor system can use nonconscious visual information. Christof and Francis (in my view unfortunately) called the system that Goodale and Milner study a ‘zombie system’.
Sue: But Goodale himself doesn’t call it a zombie system. That seems to me the whole point of the distinction they’re making; that it’s action versus perception; not conscious versus unconscious, and that seems to me a great step forward.
Pat: Exactly. That’s why I said that Christof and Francis have unfortunately called it that. I think the work is brilliant and is some of the most interesting work on consciousness that there is.
Sue: Paul, you said ‘Just say no’ … to use a popular American phrase. Could you explain?
Paul: Sure. Once again, here’s a parallel: someone could say, ‘Look, light can’t be identical with electromagnetic waves because I can imagine a universe in which electromagnetic waves are bouncing about all over the place, but it’s pitch black from one end to the other.’ It’s a zombie universe if you like, only here it’s light that’s missing. And one wants to say, ‘Well you can imagine that all you like, but the question here is, what is light as a matter of fact?’ And the truth is that when you learn about light, and about electromagnetic waves, and how they make plants grow and make sunflowers point towards the stars, it turns out that this universe, which is supposedly devoid of light, behaves exactly like the one we’re in. Everything in it behaves as if the stars are shining like mad, thank you very much. So the more you know about both light and electromagnetic waves, the harder it is to coherently imagine a universe that is abuzz with electromagnetic waves but is dark.
Similarly, the more we learn to understand how the brain works at a low level, and the more we learn to understand the psychology at a high level, the more we’ll see how they fit together in this wonderful embrace such that they’re not two things embracing one another, they’re actually just one thing, looked at from two different points of view. So the more we learn about the brain, the harder it will be to enjoy Chalmers’ thought experiment.
Sue: Do you think consciousness survives the death of the physical body?
Pat: We do know that when large numbers of neurons die, as in Alzheimer’s disease, deficits in memory occur, cognition is impaired, personality changes, awareness of what other people are thinking and feeling, and awareness of time and place, are impaired. I see this as a kind of fading of many aspects of the self and its capacities, and one cannot but feel that the person one knew and loved is no longer there. All the evidence shows that the brain is necessary for functions associated with consciousness. I am not sure how consciousness could survive the death of the brain if it needs neurons to sustain it. At a personal level, I should say that I feel more settled about death and dying having understood that it is the end, than I would if I were trying to nourish an unrealistic hope in some kind of heaven. When I was a child, a friend who was a native Indian once remarked to me that he felt sorry for Christians, as they labour under the delusion of a heaven, while he, in contrast, could prepare for finality, pass on the stories of the person’s life, help them to die easily, and accept the finality for what it is. That struck me as sensible then, and it does so still.
Paul: I agree. Consciousness is just one particularly sophisticated dimension of biological life. When my biological life ends, so does my consciousness. I am more than content with this. The prospect of being conscious for an unending eternity is quite frankly appalling.
When my time comes, let me sleep.
Sue: Do you think you have free will?
Pat: If you mean ‘Are my decisions not caused?’ surely not. From everything we know, the brain is a causal machine. It goes from state to state as a result of antecedent conditions, and if the antecedent conditions were different, the state would have been different. But, having said that, as humans we’re still really interested in the difference between behaviour that you might say is in-control behaviour and behavior that is not in-control behaviour, and I believe that, at least to a first approximation, we can give a neurobiological characterization of the differences. We can begin to identify the relevant parameters, and we can conceive of the problem in terms of a parameter space. You can think of it visually as a three-dimensional parameter space, but it’s going to be an n-dimensional parameter space.
Paul: With a large n.
Pat: And there’ll be a volume in there within which people are in control. It’s going to have fuzzy boundaries, be a funny shape, have dynamic properties, and there’ll be different ways of being in control. So that the appearance of hormones at adolescence, for example, is going to change the shape of somebody’s in-control space.
Sue: But what about in your own life? I mean, that’s not the problem that causes people to worry when they say, ‘Well if the brain is causally closed then it doesn’t matter what I decide.’ This is what seems to make life, and making moral choices and decisions, difficult. How, in your life, does your philosophy relate to your actual decision making, or the things you do, or the way you feel?
Pat: I think you just hold those two things in your mind at the same time. I mean the way the brain works is that, amongst other things, it has this user illusion—that your decisions are made according to, shall we say, the standard model—that you consciously identify the options, you consciously do an expected utility calculation, you consciously choose, and then at some point later in time, the action’s executed. That’s a useful user illusion.
Sue: So do you mean that you’re happy to think this is an illusion and then just behave as though it’s real?
Pat: It’s like the illusion with morality. We know that moral laws are not specified by the gods. We know that they are first of all neurobiologically based or evolutionarily based, and secondly culturally based, but it’s also very useful for people to have the illusion that these are really true. Now that’s a slightly different problem, but I don’t have any particular difficulty in my own life in making decisions and being responsible for them. Whether it makes me happy is not the point; whether it is true, is.
Sue: What about you Paul? How do you live with this in your life?
Paul: I don’t feel the conflict at all because, when you put the question to Pat, it was as if one’s body is behaving and one’s decisions make no difference to what happens. But that isn’t how I experience my life.
Whether or not my hands go up is a function of the conversation I’m conducting. My behaviour is quite regularly a product of my will. The question is ‘What’s behind the will? Is that being systematically caused?’ I’m inclined to say ‘yes’, but the following thought is relevant, and it comforts me to some degree.
We know that brains are non-linear dynamical systems. These are systems that are governed by continuum mathematics, and their behavior is exquisitely sensitive to infinitesimally small differences, such that two brains in almost exactly the same state will quickly wind off in very, very different states. This means that the brain of a human, or even of a mouse, is a system whose behaviour is unpredictable by any machine constructible in this universe. We are importantly unpredictable save for general tendencies and patterns. We will go to sleep at night, get up in the morning, tend to hug our wife at least three or four times a day, but exactly when, or what words will come out of my mouth, that’s unpredictable. So one mustn’t fear the story science seems to tell, that we are just robots.
Sue: I can see your interest in marriage, because you are a rather unique couple aren’t you; being so close philosophically as well as married?
Paul: We are for our generation perhaps. In fact married couples in academia were prohibited at the University of Toronto where I had my first job. I would still be in Toronto but for their nepotism rules!
But now married couples, either working very closely together or in various complementary ways, are common. In fact it’s often a really good opportunity, you can get two for one.
Pat: It has been fun actually; it’s been enormously good fun.
Sue: And still is, by the look of it! I don’t like the past tense there!
Paul: As the neuroscience gets better it’s also affected the way I look at other things that I’ve loved. I was a musician as a young man, and when nobody’s at home I’ll still sit down and play the guitar, theorizing about the cognitive neurobiology of music, of music appreciation, of music composition, or simply the skills of playing an instrument, worrying about how the brain does these things.
Sue: So do you mean the music is enriched by knowing about the brain, rather than diminished?
Paul: Oh yes, yes. People are inclined to think it must be diminished, but again it’s the knowledge gradient that they’re climbing. If they’re asked to conceive of something they love, say opera, in terms of some brain theory of which they have essentially no comprehension, they immediately think ‘Oh that must be eviscerating’. But no, dear, it’s just the reverse.