The hard problem of consciousness is the problem of explaining how and why we have qualia or phenomenal experiences—how sensations acquire characteristics, such as colors and tastes. The philosopher David Chalmers, who introduced the term "hard problem" of consciousness, contrasts this with the "easy problems" of explaining the ability to discriminate, integrate information, report mental states, focus attention, etc. Easy problems are easy because all that is required for their solution is to specify a mechanism that can perform the function. That is, their proposed solutions, regardless of how complex or poorly understood they may be, can be entirely consistent with the modern materialistic conception of natural phenomena. Chalmers claims that the problem of experience is distinct from this set, and he argues that the problem of experience will "persist even when the performance of all the relevant functions is explained".
The existence of a "hard problem" is controversial and has been disputed by philosophers such as Daniel Dennett and cognitive neuroscientists such as Stanislas Dehaene. Clinical neurologist and skeptic Steven Novella has dismissed it as "the hard non-problem".Frank Jackson
's Mary's room
argument is based around a hypothetical scientist, Mary, who is forced to view the world through a black-and-white television screen in a black and white room. Mary is a brilliant scientist who knows everything about the neurobiology of vision. Even though Mary knows everything about color and its perception (e.g. what combination of wavelengths makes the sky seem blue), she has never seen color. If Mary were released from this room and were to experience color for the first time, would she learn anything new? Jackson initially believed this supported epiphenomenalism
(mental phenomena are the effects, but not the causes, of physical phenomena) but later changed his views to physicalism
, suggesting that Mary is simply discovering a new way for her brain to represent qualities that exist in the world.