I may present, tomorrow night in my Logic class, the argument against physicalism from the conceivability of philosophical zombies. This argument raises many important and interesting things regarding the epistemological problem of how the phenomenal is related to the physical.
It is also significant to me because of the belief that, as Evan Fales states (p. 118), physicalism entails atheism. That is, if physicalism is true, then atheism is true. For Fales the opposite is not the case since he believes physicalism is "stronger" than atheism. One could be an atheist without being a physicalist, but not the other way around. If, therefore, physicalism is false, we then remove one reason that supports atheism. (If I was an atheist I'd be a physicalist, in spite of its internal incoherence.)
The zombie argument against physicalism, as stated by David Chalmers, is this:
1. If zombies are logically possible, then zombies are metaphysically possible.
2. If zombies are metaphysically possible, then physicalism is false.
3. Zombies are conceivable.
4. If zombies are conceivable, then zombies are logically possible.
5. Zombies are logically possible. (from 3 and 4, MP)
6. Zombies are metaphysically possible. (from 1 and 5, MP)
7. Physicalism is false. (from 2 and 6, MP)
2. If zombies are metaphysically possible, then physicalism is false.
3. Zombies are conceivable.
4. If zombies are conceivable, then zombies are logically possible.
5. Zombies are logically possible. (from 3 and 4, MP)
6. Zombies are metaphysically possible. (from 1 and 5, MP)
7. Physicalism is false. (from 2 and 6, MP)
P1 - Chalmers writes: “I confess that the logical possibility of zombies seems equally obvious to me (as that of a mile-high unicycle). A zombie is just something physically identical to me, but which has no conscious experience – all is dark inside.[…] I can discern no contradiction in the description. In some ways an assertion of this logical possibility comes down to a brute intuition, but no more so than with the unicycle.”
The existence of a mile-high unicycle is improbable but metaphysically possible.
P2 - This is because there could be no being that was physically identical to myself in every way yet lack something I have; viz., consciousness/qualia/the experience of what it is like to be myself. In other words, if physicalism is true one could not conceive of physicalism as true and at the same time conceive of a being physically identical to myself yet lacking something that I have; viz., consciousness.
P3 - We can conceive of zombies. Which means: we can think of a being that is indistinguishable from a normal human being except that it lacks conscious experience, qualia, and sentience.
P4 - P5 - Zombies are, unlike square circles, logically possible.
P6 - Therefore zombies could exist, however unlikely this would be.
P7 - Combining P2 & P6 we get, applying modus ponens, the conclusion: "Physicalism is false."
For an excellent presentation of the zombie argument against physicalism see the essay in Stanford Encyclopedia of Philosophy. Also check out David Chalmers's Zombies On the Web.
