[MUSIC] MARCELO GLEISER: We have seen that Descartes had separated mind and body as two different substances. Body it is made of matter and has extension, while mind being immaterial, is essentially anywhere and everywhere. Nowadays, the vast majority of scientists and philosophers who study the brain agree that there is only matter, and that mind or consciousness is a property of our brains. The challenge for modern science is to figure out how the brain engenders or creates consciousness. While the brain is easy to define as the soft tissue organ that we have in our skulls, made of about 85 billion neurons and their dendrites, their connections to one another, consciousness is one of those things that is much harder to define than to experience. We can say that mind enables us to be aware of the world and of our experiences, something that allows us to think and to feel. And that consciousness, at least human consciousness, is the self awareness of being that allows us to relate to others and to the world around us. There is a lot of debate among scientists and philosophers about the nature of consciousness and whether we can actually figure out what it is. For example, philosopher Tom Nagel from New York University wrote a famous essay titled, What Is It Like To Be A Bat, where he argues that humans are incapable of experiencing how a bat perceives reality through echolocation. As, you know, bats are blind and create a map of their surroundings using sound waves. Nagel argues that we just can't understand what it means to see the world this way. That certain things are beyond our categories of understanding, that we have no tools to study certain aspects of reality. In essence, Nagel believes that we can't understand our own consciousness. And he is not alone. There is a group of philosophers called The Mysterians, that believe that we can't ever figure out what consciousness is and how the brain creates it. It's sort of like asking a fish inside the fish bowl to describe the ocean as a whole. Why is it so hard? Well, these philosophers and some scientists say that there is a very big difference between understanding how neurons create our sensorial awareness, for example, the way we can see or hear what's going on from our subjective experiences. They say that one thing is to see the color red and understand how photons hitting our eye will eventually become the color red. The other is our own subjective experience of seeing the color red. One thing is the physiology of thinking, the choreography of neurons flashing and neurotransmitters flowing in the brain, and another thing is the substance of the thinking process itself - what the thinking is about. It is really not clear at this point how flashing neurons can give you a sense of who you are in a subjective way. On the other hand, there is no obvious reason why we can't ever understand consciousness. Many scientists believe that once we have enough information about the brain and of the processes that take place in it, we will be able to simulate a working brain in a computer. There are many research projects dedicated to creating a very realistic simulation of the brain, even of the human brain. The real believers think that we will eventually have enough information and computer power to simulate a working brain and hence, human consciousness. I think this optimism is healthy for advancing research, but that it is philosophically naive. After all, the complexity of the brain is so enormous, that I find it very hard to believe that we'll have enough information about all the neurons, all their connections, and all the chemicals flowing through them to put in a computer program. Recall that our tools capture only a fraction of what's out there. The brain as an object of scientific study is no exception. We may know a lot about it, but never all of it. Furthermore, it's also not clear how we can think of consciousness without relating to our bodies. After all, the brain connects to every part of the body through our nervous system. And it's very difficult to imagine a brain functioning on its own - what some call a brain in a vat, and how such thing can generate anything close to human consciousness. What seems more realistic is to imagine that such simulations will create some kind of brain and some kind of consciousness, but not anything close to our own minds. To figure out our minds is what philosopher David Chalmers of New York University called the hard problem of consciousness. To crack this problem, if it can be done, will surely call for very new ways of thinking. We will have much more to say about this during the week. [MUSIC]
