The Fatal Flaw in Chalmers’ Zombies

The philosophical zombie is a being physically and functionally identical to a conscious person, with nothing it is like to be it. It is the central thought experiment in the modern argument that consciousness cannot be explained in physical terms, and its force comes from seeming possible.

This essay does not dispute that it can be conceived. It argues something narrower: that a system built to that specification could not do what an organism does. A creature facing incommensurable demands -- hunger against a child's safety against a social obligation, none of them measurable on a common scale -- sometimes settles them by reflex, where a demand resolves directly into action and nothing has to weigh anything. But it can also hold a demand unmet while weighing ways of meeting it. That is deliberation, and it is where the argument applies. The essay walks the three ways a zombie might deliberate without anything being felt, and argues that each fails.

A fixed priority rule can cope with far more than anyone foresaw, but each demand's significance for action was settled before the conflict it is supposed to settle; the clearest case is a demand of a kind never met. Learned priority weights are the strongest version of that rule: the weights change with experience, but the rule changing them does not, and how much each demand counts was supplied by the learning rather than by the situation. A meta-algorithm computing priorities on the fly has to settle how much each consideration counts for in this situation, which is the original problem one level up. The essay's central move is that these exhaust the space: any mechanism that settles through parameters of its own is either fixed, in which case the weighing happened in advance, or situation-sensitive, in which case live weighing is occurring and needs its own account of how it terminates.