There is a clear difference between P-Zombies (who are biologically identical to humans) and actual humans. Something besides biology seems to be necessary to explain consciousness, mind, thoughts, ideas, and emotions.
I find the intellectual speculation to be both insightful and entertaining. The zombie analogy provides a way to decipher the nature of humanity, at least at a theoretical level. Robert Delfino and Kyle Taylor (“Walking Contradictions”) take the discussion in The Walking Dead and Philosophy a step further. Is the idea of real zombies even coherent, or are we just making a lot of undead ado about nothing?
Their argument builds from two key laws in logic - the Law of Identity and the Law of Non-Contradiction - to argue that a thing cannot exist in such a way that is incompatible with its nature. A thing with mutually exclusive properties cannot exist (like a square circle, or a sane University of Michigan fan). In the same way, a being with mutually exclusive properties cannot exist either. Since the Walkers try to hold two mutually exclusive properties in tension (both physically alive and physically dead), they would seem to be impossible.
But not so fast! Some quasi-living beings (such as viruses and viroids) appear to do just that. One type of fungi can take over carpenter ants and make them act like, well, zombie ants. And if you’ve seen Twilight, you know that zombie actors can even carry commercially successful films.
As (kind of) cool as this sounds, we are comparing fungi apples with zombie oranges. Viruses cannot use dead cells as hosts, and the organs and senses will by no means continue to function. These viruses and their host will also need energy, which requires a working digestive system. This is clearly not the case with zombies (think of the Walkers in The Walking Dead who continue to exist and move even when missing their entire body below the chest).
If zombies actually existed, they would be creatures that burn energy without consuming energy; move because viruses that need live cells are using dead cells; and hear, see, and smell with non-functioning sense organs. Zombies would be physically alive and physically dead simultaneously. They would be incompatible with their own nature, and thus impossible beings. Therefore, they cannot actually exist.
The logic of this conclusion would seem to apply in a much broader fashion as well. If we can show that a philosophy of humanity creates an impossible scenario or an impossible being, we have good reason to reject the theory as well.
Daniel Dennett says that “...mechanistic theories of consciousness...do, in fact, explain everything about consciousness that needs explanation." We may think we are conscious people with subjective experiences of rationality, self-awareness, thoughts, ideas, and emotions, but we aren't. If Dennett is correct, then at some level “machines,” “conscious beings," and "humans" must have at least compatible, if not interchangeable, natures. But do we have compelling reason to believe that our subjective experiences can be reduced to emergent qualities of complex biological and chemical machinery?
After discussing two popular thought experiments about this subject (The Turing Test and John Searles' Chinese Room Argument), the Internet Encyclopedia of Philosophy concluded:
Apparently mechanistic theories of consciousness do not, in fact, explain everything about consciousness that needs explanation. There appears to be more to the human machine than just machinery.‘He [Searles] says that computers or robots are just not made of the right stuff with the right kind of “causal powers” to produce genuine thought or consciousness. After all, even a materialist does not have to allow that any kind of physical stuff can produce consciousness any more than any type of physical substance can, say, conduct electricity. Of course, this raises a whole host of other questions which go to the heart of the metaphysics of consciousness. To what extent must an organism or system be physiologically like us in order to be conscious? Why is having a certain biological or chemical make up necessary for consciousness? Why exactly couldn’t an appropriately built robot be capable of having conscious mental states? How could we even know either way? However one answers these questions, it seems that building a truly conscious Commander Data is, at best, still just science fiction.”