By Linda Orlando Writings by David Chalmers, a philosopher at the Australian National University, make it clear that one can learn a great deal about the philosophy of consciousness by contemplating the philosophy of zombies. Chalmers, who is Director of the Centre for Consciousness and an ARC Federation Fellow, says that zombies raise very interesting philosophical issues. Although most people doubt that zombies actually exist in the world, many people believe they are at least logically possible. Chalmers has used this logical possibility to draw strong conclusions about consciousness in his book, The Conscious Mind, and elsewhere. The zombies refers to are the ones that are physically and behaviorally identical to human beings, but lack any conscious experience. Chalmers considers that zombies can be used to illustrate the problem of consciousness. In other words, why aren't all people zombies? Why do physical processes express themselves as a conscious experience? If any physical processes would apply just as well to a zombie world as to ours, how can those physical processes cause consciousness to exist in the regular world if they don't exist in the zombie's world? And if zombies do exist, why did the evolutionary process bother to produce conscious humans if zombies would be able to survive and reproduce and populate the planet just as well? The philosophy of zombies can even be used to argue against materialism, according to Chalmers. If a world of zombies is possible, and it is just like this world except for being populated by zombies, then perhaps the existence of consciousness is a non-physical fact about our world. In other words, after creating the physical features of our world and our bodies, God had to continue working to ensure that we weren't all zombies. Hence the development of consciousness. Chalmers says that the logical possibility of zombies is one way of illustrating that there is no logical relationship between physical constructs and consciousness. Of course some philosophers find the logical possibility of zombies to be ludicrous, and some scientists wonder whether anything really important can be drawn from something that is merely conceivable but not known to exist. Chalmers believes that most arguments using zombies "can actually be rephrased in a zombie-free way," to allow people to consider the arguments on their own merits with or without the zombies. Philosophical and psychological literature speaks of two related ideas, the functional zombie and the zombie within. The functional zombie has a non-conscious system that is physically different from a normal human, such as a system with silicon chips instead of neutrons. Some researchers use the logical possibility of such a functional zombie to argue against functionalist theories of consciousness, which postulate that consciousness equals functioning. The other related idea, the zombie within, has recently been studied extensively in psychology and neuroscience. A great deal of human activity like perception, memory, and learning can be accomplished unconsciously. Some have argued that there are major neural pathways devoted to unconscious processing of visual inputs, which leads directly to motor action and physical reaction. These postulations have led some philosophers to suggest that each of us contains a "zombie within" that unconsciously produces many of our motor responses, without us even knowing it. For an entertaining, insightful, and thought-provoking journey through the thoughts of David Chalmers, including a case study of his own zombie twin, visit his website. Not only can you learn more about Chalmers and read many of his postulations on provocative philosophical ideas, you can also read about his book and his ongoing studies. He says that "one of the nice things about being a philosopher is that one is allowed to be interested in all sorts of things." Clearly David Chalmers has found his calling.