I’ve been reading over Chalmers’ conceivability/possibility arguments against materialist theories of mind. For those that don’t remember, his argument is:
1. We can conceive of zombies.
2. Conceivability implies logical possibility.
3. Therefore, zombies are logically possible.
4. If zombies are logically possible, then physicalism is false.
5. Therefore, physicalism is false.
In trying to give a more charitable reading of his argument, I’d like to find instances where such arguments have been successful in uncontroversial cases. We expect some in math or logic, but even there it isn’t clear that conceivability arguments aren’t just treated as hunches or invitations to explore something further. In my experience in mathematics, anyway, that’s how it has been, they certainly aren’t taken as conclusion-establishing game-stoppers.
We also have the related issue of thought experiments, which certainly have been useful for clarifying conceptual points. Perhaps some thought experiments are instances of a conceivability argument succeeding? There are many instances of conceivability arguments falling on their face, the Don Quixotes of hindsight (e.g., arguments for aether, vitalism, geocentrism).
Such failures are easy to find. What I’m after is conceivability’s Knight in Shining Armor, a single clear historical precedent that suggests it has done real work in the history of western thought.