Handout for 5th Lecture

The Modal Argument
1 - It is conceivable that someone is in pain but doesn’t have their c-fibres firing.
2 - Whatever is conceivable is metaphysically possible.
3 - So, it is metaphysically possible that someone is in pain but doesn’t have their c-fibres firing(1, 2).
4 - If something is an instance of type A but not an instance of type B, then type A isn’t identical with type B.
5 - So, it is metaphysically possible that being in pain is not identical to having ones c-fibres fire (3,4).
6 - If it is metaphysically possible that x is not y, then x is not y.
7 - So, being in pain is not identical to having ones c-fibres fire (5, 6).

(Or, with tokens:
1 - It is conceivable that this pain exists, but this firing of c-fibres does not.
2 - Whatever is conceivable is metaphysically possible.
3 - So, it is possible that this pain exists but this firing of c-fibres does not (1, 2).
4 - So, it is possible that this firing of c-fibres is not identical to this headache (3).
5 - If it’s possible that x is not y, x is not y.
6 - This headache is not this firing of c-fibres (4, 5).

And we can run these arguments the other way around. For example, in the type case we start with the premise:

1 - It is conceivable that someone has their c-fibres firing but isn’t in pain.

And proceed in the obvious way.
And we can do the exactly analogous thing in the token case.)

Metaphysical possibility - very roughly
It is metaphysically possible that P iff it is a mind and language independent fact that the world could have been such that P.

Premise 2
Conceivability is plausibly evidence for possibility. But why suppose that everything conceivable is possible? Our other faculties are not infallible. In response, it has been argued that if we think we can conceive of an F that isn’t a G, even though F is G, we really conceive of a non-F/G with all the properties most commonly associated with Fs but none most commonly associated with Gs. But the pain case cannot be like this. If an experience has all the properties most commonly associated with being in pain, then it’s a pain.

Has the anti-Physicalist described the only way in which the faculty of conceiving can lead us into error?