Easy Problems and the Hard Problem

David Chalmers's formalization of the structure implicit in Nagel's work: that the problems of consciousness divide into two categorically distinct classes. The 'easy' problems—discrimination, categorization, reportability, integration of information, attention, deliberate control of behavior, the sleep-wake distinction—are questions about function and mechanism. They ask how the brain produces certain capabilities, and they are 'easy' (despite being extraordinarily difficult in practice) because they have a recognizable form: specify the function, find the mechanism, describe how the mechanism realizes the function. Solving these problems is a matter of sufficiently detailed neuroscience and cognitive science. The 'hard' problem is different in kind: it asks not how the brain performs functions but why the performance is accompanied by subjective experience. Why is there something it is like to discriminate wavelengths? Why does information integration feel like anything? The question is not about mechanism but about the relationship between mechanism and phenomenology—and no mechanistic answer can bridge the gap, because any mechanistic explanation presupposes the very thing it needs