a. Chalmers David Chalmers coined the name “hard problem” (1995, 1996), but the problem is not wholly new, being a key element of the venerable mind-body problem. Still, Chalmers is among those most responsible for the outpouring of work on this issue. The problem arises because “phenomenal … b. Nagel Thomas Nagel sees the problem as turning on the “subjectivity” of conscious mental states (1974, 1986). He argues that the facts about conscious states are inherently subjective—they can only be fully grasped from limited types of viewpoints. However, scientific explanation demands an o… c. Levine Joseph Levine argues that there is a special “explanatory gap” between consciousness and the physical (1983, 1993, 2001). The challenge of closing this explanatory gap is the hard problem. Levine argues that a good scientific explanation ought to deductively entail what it explains, Consciousness

The hard problem of consciousness is the problem of explaining why and how we have qualia or phenomenal experiences. This is in contrast to the "easy problems" of explaining the physical systems that give us and other animals the ability to discriminate, integrate information, and so forth. These problems are seen as (relatively) easy because all that is required for their solution is to specify a mechanism that can perform the function. Philosopher David Chalmers claims that even once we have solved such problems about the brain and experience, the hard problem will "persist even when the performance