Logical Possibility of Zombies

From: Stevan Harnad (harnad@coglit.ecs.soton.ac.uk)
Date: Tue Aug 07 2001 - 12:14:12 BST

> I was reading about philosophical zombies (I think it was in a review by
> John Searle), and apparently it's OK to discuss them becuaseu they are
> logically possible (they are not self-contradictory).

Neither are fairies self-contradictory, or tachyons (particles faster
than light, perhaps violating physics), or creationism.

The logical possibility of zombies is (in my view) of no interest
whatsoever. Remember Descartes and Hume: Only math truths are necessary
truths; scientific truths are just almost-certainly true (but it is
logically possible that they are false). The only other thing that is
dead-certain besides maths is that I feel. That is Descartes' Cogito.

Then Hume reminds us that we can be skeptical about everything else,
because everything else could be false (scientific laws and
regularities, the existence of minds other than my own, the existence
of the outside world). But skeptics don't believe that non-necessary
truths ARE false, just that they COULD BE false. Zombies belong in this
"could be" category, and as such they are of no interest whatsoever (in
my opinion).

The only interesting question is "Why and how are we NOT zombies?" THAT
is the real mind/body problem. And no one has an answer. But that has
nothing whatsoever to do with the silly question of whether there are
could be zombies. (There could be LOTS of things, maybe: so what?)

> They can do
> everything we can do, but are not conscious. How can we know if this is a
> logical possibility?

Can you prove, mathematically/logically, that they are impossible? If
not, they are logically possible. So what? You can't prove that
cows can't fly either...

> It seems to me more likely that it is not - maybe
> consciousness would be an emergent property of scaling those "toy"
> tasks that we get computers to do up to absolutely everything humans can
> do.

Maybe, but unless you can show exactly HOW and WHY that is so, it is
mere hand-waving.

On the face of it, "scaling" up behavioral capacities has nothing
whatosever to do with feeling. Why should we have to FEEL to be able to
DO what we can do?

> Basically, what is the advantage of discussing zombies? It seems that
> people might as well discuss the possibilities of brains in jars or
> ethereal minds with no brains or bodies, as these are probably logically
> possible, too.

Those are all variants of the same problem, the so-called "hard
problem." But I agree that discussing the logical possibilities is of
no interest. Facing up to the fact that we have no functional
explanation of the actualities (i.e. that we are NOT zombies) is (in my
view) preferable to fussing with possibilities...

Cheers, Stevan

Harnad, S. (2000) Minds, Machines, and Turing: The Indistinguishability
of Indistinguishables. Journal of Logic, Language, and Information
9(4): 425-445. (special issue on "Alan Turing and Artificial

Harnad, S. (2000) Correlation VS. Causality: How/Why the Mind/Body
Problem Is Hard. [Invited Commentary of Humphrey, N. "How to Solve the
Mind-Body Problem"] Journal of Consciousness Studies 7(4): 54-61.
Harnad, S. (2001) No Easy Way Out. The Sciences 41(2) 36-42.
Original longer version "Explaining the Mind: Problems, Problems"

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