CONCEPT
Philosophical Zombie
A hypothetical being physically and behaviorally identical to a conscious human but lacking any subjective experience—the thought experiment that reveals behavioral evidence alone cannot confirm consciousness.
David Chalmers's thought experiment of an entity that is atom-for-atom identical to a conscious human being, exhibiting all the same behaviors and producing all the same outputs, but with no inner experience whatsoever—no qualia, no felt quality, nothing it is like to be the zombie. The zombie says 'I see red' and discriminates wavelengths perfectly, but there is nothing it is like for the zombie to see red; the discrimination occurs in darkness. The philosophical function of the zombie is to demonstrate that functional and behavioral properties can, in principle, come apart from phenomenal properties—that there is a logical gap between what a system does and whether the system experiences anything in the doing. Whether zombies are metaphysically possible is contested; Nagel's contribution to the zombie debate is the weaker but sufficient claim that behavioral evidence alone cannot determine consciousness, because two systems—one conscious, one zombie—could be observationally identical while differing in the single most important respect: whether anyone is home.
