Thursday, 13 August 2009

Some Thoughts on P-Zombies and the Gap Explanatory Argument

Dedicated to Anna Traußnig...for the several hours of intellectual orgasms, as she likes to call it

Parts of this article have been inspired by the writings of Robert Kirk, William Seager and Daniel Dennett

ResearchBlogging.orgA philosophical zombie (or p-zombie as it is often called), is a curious creature that is central to the basic idea of the explanatory gap. It is a hypothetical being that is indistinguishable from you and I, or any normal human being for that matter, except for one fundamental detail. Such a zombie, for example, cries in pain (when you kick it), but it feels no pain. In other words it lacks any conscious experience. But, given their definition, this singular fact will have no bearing on the physical processes that the zombie will undergo in it's own world. Put another way, a zombie's behaviour should be indistinguishable from the behaviour and physical state of a genuine human being. This first case is the well known "zombie duplicate" -There exists a philosophical zombie that is physically indistinguishable from me , assuming of course that I can be granted consciousness. Let's stick with that for the moment. We shall come back to this point later.

Now I could argue that a perfectly physical duplicate of me should live in a perfectly duplicate realm of reality. It could also be argued that the only possible world that could have a perfectly physical duplicate of me is one which is perfectly duplicated , which might be the very same possible world. Are zombies nomologically or even physically possible? To state that they are nomologically possible would be to state that in some world that shares all physical and natural laws of this world, there exists a "human being" who lacks consciousness. But wait, what happens if certain natural and physical laws do not bear any causal relation? If all natural laws are physical laws or at least dictate physical laws and if, consciousness is causally related to physical states (and there is some evidence for that), then there cannot exist any world with the same physical and natural laws as ours and yet have a zombie. It's not possible. On the other hand, if physical laws were dissociated from natural laws, then zombies could exist by breaking natural laws but not the physical ones. Remember, we have access only to physical laws (which we assume, by default to be natural laws, although this may not necessarily be true). Going further, if mental states (such as consciousness) were non physical, it seems reasonable to claim that zombies are not only nomologically possible but even logically (or physically) possible. Of course, the question still remains whether such another distinct reality, separate from ours does exist (this in itself is another huge philosophical debate). Now if this were the case, one would have a tough time proving what consciousness really is (or is not). It raises another question. How are we to assume that a zombie that exists in another physical realm sharing the same physical laws as ours but not the natural laws does not have consciousness? It may possess a different kind of consciousness that is drawn from the natural laws that govern it's world.

In 1999, Robert Kirk, presented an argument which attempted to demonstrate that philosophical zombies are logically impossible. He starts by assuming that a zombie suddenly acquires non-physical qualia. A weak definition of qualia would be the property that distinguishes us from zombies (consciousness if you will). Parts of his argument are as follows:

  1. My zombie twin is unaffected by anything non-physical
  2. So he remains unaffected when he acquires non-physical qualia
  3. In order to become conscious following acquisition of this non-physical qualia, he must be affected by it in some way
  4. But nothing non-physical affects him. So he doesn't become conscious.
  5. To tell the difference between the subjective character of two different perceptual experiences, he must be sensitive to them or detect them in some way
  6. In any case, nothing non-physical affects the zombie, so he cannot distinguish non-physical qualia from having no qualia
  7. Friends of the zombie maintain that a "conscious" being is simply the zombie component with non-physical qualia. This position entails that "conscious" humans cannot tell the difference between tea and coffe, for example.
  8. But we can tell the difference between tea and coffee.
  9. Hence, we are nothing of the sort that friends of zombies maintain we are and hence zombies in their sense are not genuinely possible

Kirk's paper has been criticized but it presents an interesting case.

One final word on physicalism. In short, there are no kinds of things other than physical things (including consciousness). Daniel Dennett argues that even if consciousness were purely physical, our own conviction that we are not zombies, is simply a product on the external physical world. But, we could still be zombies who think we're conscious, who think we have qualia and who think we feel pain, in ways that are we could never discover. If such were the case, it wouldn't be careless to say that "consciousness" could never be defined or understood or even proved. 

I for one remain hopeful that science may one day provide a good theory on how consciousness works, but Anna and I both think that even if one ends up showing how it works, one would never be able to show what it really is.  


Kirk, R. (1999). The Inaugural Address: Why There Couldn't Be Zombies Aristotelian Society Supplementary Volume, 73 (1), 1-16 DOI: 10.1111/1467-8349.00046

Seager, W.E., Are Zombies Logically Possible?-And Why it Matters

1 comment:

Robert said...

Hi! I just stumpled onto this blog, and find it very interesting.

I have a particular interest in conscious, but my background in the philosophical side of the debate is quite limited (I am a cognitive psychologist, and most of what I know on the topic is from that perspective).

Why *must* a p-zombie be unaffected by everything nonphysical? My understanding of p-zombies is that they merely not *have* anything non-physical. I don't see a reason to assume that they can't gain that later. I understand that this is not your argument, and there is probably something behind the first point that I'm not aware of. I've read a few papers referencing this one, but haven't gone back and read the original yet.

If consciousness is causally *related* to physical states, this does not mean that they are entirely due to physical states (although my personal intuition is that they are). Right?