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Zombies… Not Your Average Sleepwalker January 20, 2009

Posted by exk0730 in Philosophy of mind.

When I hear the word “zombie,” the first thing that comes to mind is a blood-covered, grunting, wobbling, decomposing corpse. Well I guess in magical lands and other universes, you could find one of these things. But there’s another connotation of “zombie.” The philosophical zombie. This type of zombie doesn’t grunt, and doesn’t wander around aimlessly trying to find some human to munch on. The p-zombie is a human, with some exceptions. It is physically indistinguishable from a human, yet it lacks conscious experiences, qualia, or sentience. When a p-zombie is poked in the eye, it will say “ow” and recoil, because it has the same behaviors as a human being, but it does not experience what that pain actually feels like. Zombie arguments tend to lend support for dualism by arguing against physicalist theories.

According to physicalism, all things can be explained by physical facts. If God created the world based on purely physical properties and laws governing the behavior of all things in that world, did God have to do something further to provide for human consciousness? If God did have to do something further, then it seems that physical properties must not explain everything there is about the world, suggesting that consciousness could not exist in a world of solely physical properties: a zombie world. It follows that if a zombie world is possible, physicalism is false.

The real question is: are zombies conceivable?



1. Greg - January 21, 2009

I will repeat what I said in class: it doesn’t make very much sense to say that “Zombie arguments tend to lend support for dualism by arguing against physicalist theories,” because “zombies are possible” is transparently equivalent to “physicalism is false.” This could be still be a useful line of argument if we had strong intuitions about whether zombies ought to be possible or not, but speaking for myself I don’t have any intuition at all about zombies. The implication “if zombies can exist then physicalism is false” is true but seems rather useless for arguing against physicalism.

Dragging God into this argument also seems like a rather mysterious move to me. It follows directly from the fact that zombies are (by definition) physically but not experientially identical to humans that if zombies can exist, then physicalism is false. God doesn’t need to come onstage at all for the argument (such as it is) to go through.

2. exk0730 - January 21, 2009

I’m not really sure what you mean by: “zombies are possible” is transparently equivalent to “physicalism is false.” I feel like you’re saying that if P then Q, P therefore Q, doesn’t really work in a logical argument. And, hypothetically speaking, who else could create a world that has only purely physical facts (a zombie world) than a supreme being?

3. Greg - January 21, 2009

Modus ponens works just fine in a logical argument. My main complaint is the following: physicalism says “physically identical implies experientially identical”; the existence of zombies would say “there exist two things (humans and zombies) which are physically identical but not experientially identical.” Given the logical structure here, it seems rather trivial that if zombies can exist, then physicalism is false [1].

Unless you have a strong intuition about whether zombies exist (I don’t), it’s hard to see what this implication brings to the discussion. It seems a bit like saying “if the sky is red, then the sky is not blue.”

I don’t want to get into cosmology here and start talking about supreme beings. My point is mainly that the implication “if zombies can exist, then physicalism is false” holds no matter how the world came into being. I could also say that “if my uncle Tim can make a perpetual motion device, then the laws of thermodynamics are false,” but the existence of the perpetual motion device is all that matters, and mentioning my uncle Tim just kind of clutters things up.

4. Greg - January 21, 2009

Oops, I forgot my footnote:

[1] All I really proved above was “if zombies exist, then physicalism is false”, not “if zombies *can* exist, then physicalism is false.” I’ll grant that there is a subtle difference. If we were feeling really persnickety we could argue about that word “can”, but it’s easy enough to patch that up by revising the physicalist hypothesis to “*necessarily*, physically identical implies experientially identical.”

5. exk0730 - January 21, 2009

If you really want to know the whole argument, I’d suggest going here: http://plato.stanford.edu/entries/zombies/

“It seems clear that physicalists are committed to the view that the physical world specified by P is all there is, in which case all other true statements are alternative ways of talking about that same world. In this sense physicalists must hold that the mental facts ‘supervene’ on the physical facts, and that zombie worlds are not ‘possible’. To show that zombies are possible would therefore, it seems, be to show that the mental facts do not supervene on the physical facts: that a zombie world is possible and physicalism is false. That is why opponents of physicalism do not have to point to actual cases of zombiehood: it is enough if such things are possible.”

Also, this sums it up rather nicely:

“However, the zombie argument against physicalism in general was most famously developed in detail by David Chalmers in The Conscious Mind (1996). According to Chalmers, one can coherently conceive of an entire zombie world: a world physically indiscernible from our world, but entirely lacking conscious experience. In such a world, the counterpart of every being that is conscious in our world would be a p-zombie. The structure of Chalmers’ version of the zombie argument can be outlined as follows:

1. If physicalism is true, then it is not possible for there to be a world in which all the physical facts are the same as those of the actual world but in which there are additional facts.
2. But there is a possible world in which all the physical facts are the same as those of our world but in which there are additional facts.
3. Therefore, physicalism is false.”


I think that in a sense you’re correct, that having an argument saying zombies exist, therefore physicalism is false, does sound trivial. But the argument is whether or not zombies do exist (or are conceivable). Because if we can say they are conceivable then physicalism would be false. Thus the line “the real question is: are zombies conceivable?”

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