Zombies and the walking dead make for good copy, but do little to advance our understanding of life and death. Unfortunately, neither did the National Geographic with a cover article entitled, “The Science of Death: Coming Back from the Beyond.”

The article issues forth just about every misconception of life that permeates our national discussion. Sam Parnia, a critical care physician and author of the book Erasing Death, is quoted as saying that death “is a process, not a moment.” So far so good. But then he makes a common but critical error in thinking, which gets to the heart of our problem. In discussing a victim of a whole body stroke, Parnia writes that the patient’s organs can continue to function for a period after the heart stops beating. From this he concludes that “for a significant period of time after death, death is in fact fully reversible.”

Well, no, it is not. If a patient can be revived, the patient was never dead in the first place. But how can that be if we see no brain waves and the heart has stopped beating? Surely that is dead, isn’t it? If someone was revived from that state, clearly we must say he came back from the dead, no? That is certainly what is commonly believed, but no, we can’t. The success of reviving the victim means that during that state in which it seemed as if biological functions ceased, the functions essential for life in fact remained viable enough to be resuscitated — and therefore the patient never died. Reports of Mark Twain’s death were exaggerated only because he was not dead. The same is true for “miracles” like toddler Gardell Martin who was “dead” for an hour and a half after falling into an ice-cold stream. We are very happy to have him among the living, but he never left us in the first place.

We find this curious state of suspended animation difficult to accept as anything other than dead because we are asking the wrong question about life and death, without ever clearly defining what it means to be alive. Most of us hold deeply and unquestioned the idea that life is all-or-nothing , on or off, live or dead, one or the other, black and white. I mean, something is either alive or dead, end of story. Nothing could be further from the truth.

We are in good company in failing to define life. Dating back to the early Greeks and across millennia to modern times, great minds have recoiled from the notion that life might be a matter of degree, because our intuition so strongly demands that something be alive or not. But our intuition serves us poorly here. The problem seems to be that the more rigorously we attempt to define life, the more we encounter ambiguous cases that test our assumptions, stretch the limits of our definitions, and demonstrate where intuition and common sense falter. With even casual observation, the essence of what makes something alive quickly becomes non-intuitive when we are presented by forms that defy easy categorization such as bacterial spores or crystallized virus capsules that can rest inert for centuries before being reanimated. Those viruses would appear to be no more alive than a pile of salt, but we know that only one can be re-introduced into the kingdom of the living.