David Chalmers advocates the view that the phenomenon of consciousness is fundamentally different from all other phenomena studied in the life sciences, positing a uniquely hard problem that precludes the possibility of a mechanistic explanation. In this paper, I evaluate three demarcation criteria for dividing phenomena into hard and easy problems: functional definability, the puzzle of the accompanying phenomenon, and the first-person data of subjective experience. I argue that none of the proposed criteria can accurately discriminate between the phenomenon of consciousness and mechanistically explainable phenomena.
