Hi Eva,

I would like to critique your "recipe" for building a zombie.

You begin simply enough by reminding us that we all know there are deaf and blind people.  But you forget to remind us how we know there are deaf and blind people.  We do not know this by verbal reports, because such reports would be incomprehensible if we had no other means of identifying blindness or deafness.  (Consider the fact that blind and deaf people would not know they were blind or deaf if there were no people with vision and hearing to tell them.)  We know people are blind and deaf because we can observe their behavior.  And, indeed, how would you react if a person said they were blind and deaf, and then proceeded to respond to visual and aural stimuli just as a normal person would?

When we conceive of perceptual limitations, we are conceiving of observable behavior.  If you disagree with this point, then you will have to clarify what you are conceiving of when you say you can conceive of a person who is blind or deaf.

So, yes, we know there are people with all sorts of perceptual limitations, and there are quite possibly people with perceptual limitations we are not yet aware of.  But if we imagine a person with every possible perceptual limitation, so that they perceived nothing, then we are imagining a person who could not interact in any sensical way with his or her environment.  They would not experience anything in the world, and so receive no information from their environment (or their bodies, if we extend the recipe to internal perceptions and so attempt to cover all notions of consciousness), and so would not be able to respond to anything in a rational manner.  Taking away their internal perceptions, we would have to conclude that they wouldn't even have a sense of balance, nor would they experience hunger or thirst.  They would be as helpless as a person in a coma.

Since we cannot separate our conception of such a person with our conception of their behavior, as I maintain, then we cannot imagine such a person acting like a normal person.  We can say that such a person would not have consciousness, but we must also claim that their behavior would be as far from that of a normally functioning human being as we could imagine.

You wish to avoid this conclusion via the example of blindsight, though I do not think that example is robust enough to do any work here.  For one thing, it is not clear that a person with blindsight lacks consciousness.  I would rather think that a person with blindsight does have salient experiential states, but doesn't have fully-functional knowledge of those experiences.  So their phenomenal knowledge would be impaired, if not non-existant, even though they were conscious.  Furthermore, again, a person with blindsight functions in a noticably different manner than a person without it.