David Chalmers claims that the logical possibility of ‘zombie worlds’ — worlds physically indiscernible from the actual world, but that lack consciousness — reveal that consciousness is a distinct fact, or property, in addition to the physical facts or properties.
The ‘existence’ or possibility of Zombie worlds violates the physicalist demand that consciousness logically supervene upon the physical. On the assumption that the logical supervenience of consciousness upon the physical is, indeed, a necessary entailment of physicalism, the existence of zombie worlds implies the falsity of physicalism. How do we determine the logical possibility of zombie worlds? By conceptual analysis of the concepts involved, keeping empirical facts in mind.