Conceptual Analysis, Dualism, and the Explanatory Gap

The explanatory gap. Consciousness is a mystery. No one has ever given an account, even a highly speculative, hypothetical, and incomplete account of how a physical thing could have phenomenal states (Nagel 1974, Levine 1983). Suppose that consciousness is identical to a property of the brain-say, activity in the pyramidal cells of layer 5 of the cortex involving reverberatory circuits from cortical layer 6 to the thalamus and back to layers 4 and 6-as Crick and Koch have suggested for visual consciousness (Crick 1994). Still, that identity itself calls out for explanation! Proponents of an explanatory gap disagree about whether the gap is permanent. Some (e.g., Nagel 1974) say that we are like the scientifically naive person who is told that matter = energy, but does not have the concepts required to make sense of the idea. If we can acquire these concepts, the gap is closable. Others say the gap is unclosable because of our cognitive limitations (McGinn 1991). Still others say that the gap is a consequence of the fundamental nature of consciousness.