When I was an undergraduate philosophy major, I entered my department's student writing contest. I took second place to an essay about zombies. I was troubled by this and couldn't understand how a paper about zombies was taken seriously enough to win. The best I could determine was that it was a kind of thought experiment to test our intuitions about the mind/soul and body distinction.
Recently I encountered zombies again. This time I brought them up in a class where I was making the distinction between physical death and spiritual death. Physical death is when the body stops working to such a degree that it completely shuts down. Analogously, spiritual death is when the mind (or soul, spirit, self, I use these interchangeably here) stops working in such a way that it shuts down. I should reverse the analogy, and say that physical death is a sign of spiritual death, the latter being a more immediate concern. Spiritual death is reported by persons when they say that they feel dead inside, or that life is dull and boring, devoid of meaning. It is accompanied by a general confusion about why life is like this.
Giving the distinction between physical and spiritual death, a zombie is someone who is alive physically but dead spiritually. Since zombies cannot self-identify (someone who is a zombie does not know they are a zombie), we need a test to identify zombies. This is particularly true because, unlike the movies, we are not looking for grotesque outward appearance, but instead an inward spiritual state.
Assuming what I've written in an earlier post titled "Context Part 1," I think we can construct a zombie test. If the function of the mind is to understand, and if we understand by building from what is basic to what is more complex, then a mind that is alive will understand basic things. So we can construct this argument:
1. If a person is spiritually alive then that person understands what is basic
2. Person X does not understand what is basic
3. Therefore, person X is not spiritually alive
In this case, person X is a zombie. Again referring to my earlier post titled "Context Part 1" the reader can identify what is basic. Premise 2 above is determined through discussion with person X. Whereas fictional zombies do not hold discussions, real life zombies can make an effort at some discussion. However, it can quickly be determined if person X really knows, or only thinks he knows, what is basic. Skepticism and/or fideism quickly emerge.
Before concluding, it should be noted that spiritual death can come in degrees, just like a person can be dying in stages. However, at the basic level, one is either in spiritual death or not. A person could have understanding of basic things, mixed with misunderstanding and need for further growth. Or, a person could have misunderstandings of basic things, mixed with some understanding. It is this second condition that is indicative of zombie-hood.
I'd like to suggest that the zombie apocalypse movies have one thing correct in that the zombie condition is widespread, if not universal then dangerously close. Indeed, it may be that all persons begin as zombies and then are cured. It does not seem to be the reverse of this (people begin as non-zombies and then become zombies at some stage in development). This can be empirically verified through the test given above.
This raises the pressing question of a cure, which I'll need to leave for another post. I do believe there is a cure, and that I've indicated what it is by identifying the essence of zombie-hood in the failure to understand what is clear at the basic level. However, more needs to be said.