"The larger questions raised by the existence, or non-existence, of zombies speaks to the very essence of our understanding of consciousness. In Haitian voodoo imaginary a zombie is revived without retaining his soul, or his self-consciousness, or indeed, his mind. But, leaving aside the religious-laden issue of whether or not one has a soul, death is the end of life and consciousness. The voodoo zombie is not in fact then a revived dead person, but a living person who has been brain-damaged. What is interesting is the interest that the Haitian model has sparked in another kind of zombie, a theoretical model, known as the philosophical zombie, or p-zombie. A p-zombie is a human body without consciousness that would nevertheless behave like a human body with consciousness. To some this constitutes a contradictory notion and thus an impossible conception. If it behaves like a person and is indistinguishable from a person, then it is a person (6). Others argue that a p-zombie would be distinguishable from a person even though indistinguishable from a conscious person, because it is stipulated that it is not conscious even though it is indistinguishable from a conscious being (7). (
. At the heart of this debate is the question, what is consciousness? Can consciousness be reduced to a set of materialistic functions? Functionalism implies that life is independent of its material substrate. "Life is ascribed to an emergent property of biochemical processes and functional activities. The contrary viewpoint is Vitalism, which contends that functional descriptions fail to consider or explain an "essential unitary one-ness," which they describe variously as "life force," "élan vital," or "life energy." Therefore, consciousness is more than brain processes and neurological functions and no adequate account of consciousness will ever be produced that is "reductionist," i.e., completely materialistic (9).
Important metaphysical and ethical issues hinge on whether or not there can be p-zombies. For instance, can machines be conscious? If we create a machine that is indistinguishable from a human being, would our artificial creation be a "person" with all the rights and duties of natural persons? It is possible to conceive of a machine which "perceives" without being aware of perceiving. In fact, such machines already exist: motion detectors, touch screens, tape recorders, smoke alarms, certain robots. An android which could process visual, auditory, tactile, and olfactory input but which would lack self-consciousness, i.e., would not be aware of perceiving anything, is conceivable. We can even conceive of such machines resembling humans in the flesh. How would we distinguish such automata from persons? The same way we do now: by the imperfect and fallible methods of conversation and observation. Self-consciousness or the lack of it would ultimately distinguish an automaton from a person. "Visual perception" by a motion detector is unlike visual perception by a person just because of the difference in awareness of perception, i.e., self-consciousness. A smoke detector might "smell" certain chemicals, but it does not process odors the way a person does. And, just how exactly can we know if anyone, beside ourselves is truly self-aware, truly conscious? The truth is that we can't know for sure; we must take each other's word for it. If you tell me you are conscious, I have to believe you, even if you have formerly been my toaster.
Personally, I don't believe that there are such things as zombies, or p-zombies, (by their respective definitions) not because the evidence is overwhelming but because in the absence of overwhelming evidence, not believing is the more ethical standpoint. In light of a human history that has ever been quick to jump to exclusion, to believe that something that looks like a person and acts like a person is somehow not a person is a dangerous proposition. It is this very notion that fostered and perpetuated the practice of slavery. So when I think about the ethical questions regarding how we should treat androids which are behaviorally indistinguishable from human beings, or zombies for that matter, I think that if we stipulate that such creatures are persons with rights, then they will be persons; otherwise, they will not be persons. The concept of personhood, is not a matter of discovery, but of stipulation"