There has been a bit of discussion of zoombies in the blogosphere of late and I want to keep track of them all so that I can respond to them so I am posting links to them.

1.) Intentional Objects‘ David Gawthorne

Richard Brown’s Zoombies and Shombies

2.) Brain Scam‘s Tony Alterman:

Zombie, Scmombie –Richard Brown’s Efforts to Ressurect Materialism

(and his reply to my reply) Return of the Zombie

3.) And then there’s Richard Chappell’s responses.

In our latest exchange he has acknowledged that the primary and secondary intensions of statements in Q may diverge but seems to think that translating those statements into “semantically neutral” language will still let the argument go through. So, just was “the watery stuff isn’t H2O” comes out true at Twin Earth, “the painful stuff isn’t C-Fiber firing” comes out true at the zombie world. But this move won’t work. Here is what Chalmers has to say about this:

Given the discussion above, one might try generating an anti-materialist argument by simply substituting primary possibility for metaphysical possibility in the original argument.

(1) P&~Q is conceivable

(2) If P&~Q is conceivable, P&~Q is 1-possible

(3) If P&~Q is 1-possible, materialism is false.

_______________

(4) Materialism is false.

On this reading, (1) and (2) are both plausible theses, but (3) is not obviously plausible. The reason is that materialism requires not the 1-impossibility of P&~Q but the 2-impossibility of P&~Q. That is, materialism requires that it could not have been the case that P were true without Q being true. This is a subjunctive claim about ordinary metaphysical possibility, and so invokes 2-impossibility rather than 1-impossibility.

A materialist might reasonably question (3) by holding that even if there is a world W verifying P&~Q, W might be a world with quite different ingredients from our own. For example, it might be that W does not instantiate true microphysical properties (those instantiated in our world), such as mass and charge, but instead instantiates quite different properties: say, pseudo-mass and pseudo-charge, which stand to mass and charge roughly as XYZ stands to H₂O. Likewise, it might be that W does not lack true phenomenal properties, but instead lacks quite different properties: say, pseudophenomenal properties. If so, then the possibility of W has no bearing on whether true microphysical properties necessitate true phenomenal properties. And it is the latter that is relevant for materialism.

Still, it may be that the gap between 1-possibility and 2-possibility could be closed. In particular, when a statement S has the same primary intension and secondary intension, then a world will verify S iff it satisfies S, so S will be 1-possible iff it is 2-possible. If P and Q both have primary intensions that coincide with their secondary intensions, then so will P&~Q, and we could run the following argument:

 

(1) P&~Q is conceivable

(2) If P&~Q is conceivable, P&~Q is 1-possible

(3) If P&~Q is 1-possible, P&~Q is 2-possible.

(4) If P&~Q is 2-possible, materialism is false.

_______________

(5) Materialism is false.

Here, the truth of (3) requires that both P and Q have primary and secondary intensions that coincide. (from The 2-D Argument Against Materialism)