A Conversatonwit Patrnica Churchiand NeilA. Campbell Nervoussystems distinguish tions about the brain and that I needed to know the iiSf,' .9X#. animals from all other king- nuts and bolts of the brain, what neurons were and jx i i X doms of life. And certain how they talked to each other. The more neuro- propertiesof thehuman brain science I knew, the more it seemed to me that we distinguishour speciesfrom really had the key to understanding the nature of the all other animals. The human mind via neuroscience. This is not to say that we had Downloaded from http://online.ucpress.edu/abt/article-pdf/58/3/154/47484/4450104.pdf by guest on 29 September 2021 brain is, after all, the only a key that you could use independently of psychol- ii *1 11Pknown collection of matter ogy-behavioral descriptions-but that it was a cru- thattries to understanditself. cial element. l!!11 To most biologists,the brain I was always unconvinced by arguments that in and the mindare one and the addition to the brain, there is a nonphysical soul; and same; understandhow the it's the soul that makes decisions, the soul that feels brainis and how it and thinks. If you're unconvinced by that, then the Patricia Churchland organized works,and we'll understand nature of the brain and its organization have to be such mindfulfunctions as abstractthought and feelings. relevant in understanding these fundamental ques- Somephilosophers are less comfortablewith this mechanis- tions that philosophers are interested in. tic view of the mind, finding Descartes'concept of a mind-bodyduality more attractive. Patricia Churchland has Campbell: How did you then begin to learn neuro- takencenter stage in this debateabout the humanmind. science? Dr. Churchlandis a professorof philosophyat the Churchland:Well, I knew some basic biology, basic Universityof California,San Diego, and an adjunctpro- cell physiology and biochemistry, but I realized that I fessorat the SalkInstitute. Boundaries between the human- needed to know brain anatomy. By this time, I was a ities and the sciences dissolve as ProfessorChurchland faculty member at the University of Manitoba. So I attemptsto synthesizea philosophyof the mind basedon phoned the head of the anatomy department at the whatneuroscience is learningabout the brain.Her seminal University of ManitobaMedical School and explained bookin this new synthesisis Neurophilosophy: Toward my interests. He said, "Why don't you just come and a Unified Science of the Mind-Brain(MIT Press, 1986). take the basic neuroscience course with the medical Biologyis a multidisciplinaryadventure that integrates the students and do as much or as little as you want." I naturalsciences and connectsto the humanitiesand social did all the anatomy and the basic physiology, but that sciences.Neurophilosopher Patricia Churchland is helping wasn't enough. Then I got associated with a lab and makethose connections. learned the basic techniques, such as recording from single cells. But once you have a leg up, you start Campbell: What led you, as a philosopher, to neu- learning more on your own. roscience? Churchland:The questions I was interested in as a Campbell: So you started to bridge that neuroscience philosophy graduate student were really questions training to philosophy of the mind? about the human mind, about the nature of learning Churchland:At a certain point, it seemed to me that and perception, about what it is for something to be if the brain is the thing that does the thinking, the conscious, about the difference between the actions feeling, and the decision making, then we really have we call voluntary and actions we call involuntary- to pay attention to basic brain anatomy and physiol- the free-will problem. As time went on, it became ogy in order to answer some of the philosophical increasingly clear to me that these were really ques- questions. And some of the answers are going to be counterintuitive. Those ideas that seem very likely to us via introspection might well turn out to be false, NellA. Campbell is a MslslngScholar in the Departmentof Plant Sciences,at the Universityof California,Rlverside, CA 92521. just as in any other science. One theme in my book, Neurophilosophy,is that if you stick with your basic 154 THEAMERICAN BIOLOGY TEACHER, VOLUME 58, NO. 3, MARCH1996 intuitions about the way things must work in the understand. With the advent of artificialneural nets mind and don't take the route through neuroscience, that we can design on computers, we are beginning you are going to miss all the depth and the richness to get at least a conceptual frameworkfor making that that underlies the reality. This is partly an argument bridge between the individual neurons on the one for materialism-that there is only the brain-and hand and the systems on the other. We have a long partly an attempt to convince psychologists, who are way to go. So far, we can find really interesting also materialists, that it isn't enough to look just at propertiesof artificialneural nets when they're small: behavior. They learn from examples, and they find approxi- mately good answers when there is no precise an- swer to be found. They can do things fast. They can Campbell: Was it uncomfortable for you, coming have a kind of short-term memory. What we don't from a philosophy background, to challenge the understand is how you can get really interesting tradition of mind-body duality? effects out of big nets, or whether the nervous system Churchland:Not for me personally, because I don't takes lots of little nets and treats them as units of a big think that distinction of mind and body, or brain, net. ever seemed terribly plausible. I was always part of Take the case of categorization,for example. Some that traditionthat says that complexity is not predict- Downloaded from http://online.ucpress.edu/abt/article-pdf/58/3/154/47484/4450104.pdf by guest on 29 September 2021 regions of the brain seem to be specialized for han- able from looking at the constituents, but put them dling categories for natural things and others for together in certain ways, and you get these really manmade things. And within the regions specialized extraordinaryproperties. The mental properties for for manmade things, there is further categorization: perception, for knowledge, for learning, for memory, for example, tools that you use with your hands, and all had to come out of the complexity of the organi- other kinds of things like automobiles. We don't zation of matter. My own backgroundwas very much know how brains do this regionalization,so we don't in that line of thinking. The Darwinian perspective know how to make nets that can help us understand always seemed to me to be the key to making things it. Another key question about brains is how they get sensible. I don't find rejecting a nonphysical soul things done in time. How can an eagle intercept its personally wrenching, but I realize that some people prey? How can you catch an outfield fly? How you do. When students first encounter the thought that get the timing right is a majorissue for a lot of neural maybe there is only the brain-which means that network theory now. What we desperately need is when the brain dies, I die-it's something they have more understanding of neuroanatomyat the network to think through, not just in scientific terms but in level. very personal terms. They will sometimes ask me, doesn't it make you feel as if the world is a very bleak place or that there is no meaning to life? My response Campbell: Modeling neural nets on a computer is is that in lots of ways the idea of an afterlifedoes you one thing, but is the brain itself a type of computer? an enormous disservice. It gives you the idea that you Churchland:It's useful to think of the brain as a kind can defer lots of things and make it all come out right of computer because that allows you a frameworkfor later. I think if you take the view that the planet is the thinking about how individual neurons interact to thing to love and to care for and to see the future achieve a certain effect. Suppose you are trying to for-if you see that as a source of meaning and visually tracka given object and your head is turning value-you'll see that the other story doesn't help in as you walk. Viewing the brain as a kind of computer making life decisions and in feeling comfortable. It helps conceptualize the interactionbetween the neu- doesn't help particularlywith tragic situations and rons in the vestibular organ, which detects head death and the things that we all find deeply trou- movement, and the neurons that control eye move- bling. When students think about it in that context, ment. There are, however, many contrasts between they often do say, yeah, maybe you're right about the brain and a desktop computer. For example, in that, I'll just have to live it for awhile and see if I can. the brain the very elements that process perception are also elements that store information about what you perceive. It isn't that the memory is in one place If we view the mind functions as Campbell: major and the processing for perception is in another place. of the brain what emergent properties organization, The brain's style is parallel and analog computation. do we need to understand about neural complexity to explain these mental functions? Churchland:I think the majorarea we're missing is at Campbell: Do you think knowledge of the brain can the level of neural networks.