Picking One's Brain The Hard Way -- Scientific Developments and Electric Probes

"(There are two 'problems' in the study of consciousness), which the philosopher David Chalmers has dubbed the Easy Problem and the Hard Problem. Calling the first one easy is an in-joke: it is easy in the sense that curing cancer or sending someone to Mars is easy." … "The Easy Problem, then, is to distinguish conscious from unconscious mental computation, identify its correlates in the brain and explain why it evolved.
The Hard Problem, on the other hand, is why it feels like something to have a conscious process going on in one's head--why there is first-person, subjective experience. Not only does a green thing look different from a red thing, remind us of other green things and inspire us to say, 'That's green' (the Easy Problem), but it also actually looks green: it produces an experience of sheer greenness that isn't reducible to anything else. As Louis Armstrong said in response to a request to define jazz, 'When you got to ask what it is, you never get to know.'"

Steven Pinker, a psychology professor at Harvard, discusses the latest scientific inquiries into consciousness in his article in Time Magazine.