Philosophical zombies (as opposed to the ones in the movies, which are slow-witted, bloody and broken people with a crazed and single-minded desire to eat normal people) are hypothetical creatures used in thought experiments to elucidate what we mean by the term "consciousness." They are supposed to act just like humans but lack internal experience. David Chalmers defines them thus: "A zombie is physically identical to a normal human being, but completely lacks conscious experience. Zombies look and behave like the conscious beings that we know and love, but 'all is dark inside.' There is nothing it is like to be a zombie." (http://consc.net/zombies.html)

Derek Allen objects to the concept, saying it makes no sense. (http://philpapers.org/post/6535) In particular he objects to the phrase "There is nothing it is like to be a zombie." I agree that the phrase "what it is like to be " is problematic, but we all know what it is trying to get at. If one has a conscious experience one can talk about it in hopes of getting one's listener to understand how it feels, how it appears or manifests itself, to the one talking about it. What is it like to eat ginger candy? Well it is a bit like eating ginger, but sweeter. It is a bit like eating sugar but far more pungent. And so forth.

The thought experiment about zombies claims that zombies have no conscious experience: nothing appears to them, they have no feeling of anything, no perception or sensation of anything. Hence, of course, they cannot describe or indicate to anyone how the world appears to them because it doesn't.

From my own first-person autobiographical experience I can provide some information that may throw light on that claim, for I have been a zombie.

My memory of having been a zombie is that I was sitting in the dentist's office about to undergo a painful procedure. A nice lady brought me a small pill and a glass of water, and I swallowed the pill and went back to reading my magazine. Then my wife was guiding me out of my car, which was parked in my garage, and into my house, where I clumsily stumbled into bed.

I have no memory whatsoever of the interval between reading the magazine after swallowing the pill and being in my garage. I'm told that I responded to instructions to get up and walk to the dentist's chair, to open my mouth and turn my head just so, and so forth. In response, I'm told, I did in fact walk to the chair, open my mouth and turn my head. After the procedure I was told to get up and sit in a wheelchair and then to get out of the wheelchair and into the car, which I did. I'm told that when I walked I rather lurched and had to be guided. My wife grabbed my belt from behind to prevent me from falling over or bumping into something. But I have no memory of any of that.

I cannot tell you how the world appeared to me when I was a zombie. As far as I know now, nothing appeared to me. But that seems implausible, because I did in fact respond to instructions, so I must have heard them. And I did in fact sit in the chair, so I must have seen it. I suppose to do a true experiment we would have to administer the drug -- Versed, a trade name for Midazolam (http://www.drugs.com/cons/versed.html) -- to a willing and informed subject and then ask them to describe what they see or feel. Would someone like to take that on as a bit of experimental philosophy?

I'm not sure what this means philosophically except to note that memory seems to be an essential component of being conscious. I would appreciate your comments.