Michael Egnor treats us to a fine explanation of the problems conscious experience poses for a materialist view of the brain. How matter can give rise to the actual sensation of blueness, for example, is a mystery that baffles neuroscientists and which is an embarrassment to those who hold that all of our "mental" experience can be ultimately explained in terms of nothing more than chemical reactions in the brain (i.e. materialism).
Egnor closes his essay with this summary:
The origin of subjective experience is the fundamental question-the hard problem-in understanding the mind. Yet there is nothing in the material world that intrinsically refers to or explains subjective experience. There is nothing in third-person ontogeny from which one would infer first-person ontogeny. No theory in physics or chemistry invokes the emergence of first-person experience. A detailed scientific understanding of the physics and chemistry of the brain-from molecular structure to neurochemistry to electrophysiology to neuroanatomy-would not at any point provide a scientific explanation of why we are subjects and not just objects.
The hard problem of consciousness is the most important problem in understanding the mind, and thus far materialism has provided no insight. It is unclear how it even could provide insight. Nothing about the scientific characterization of matter-and nothing about materialism-explains the emergence of subjective experience. The principal materialist response to this catastrophe for materialist ideology has been to deny the relevance of subjective experience to our understanding of the mind. Yet the retreat to science and the denial of the relevance of philosophy is no refuge. Science is natural philosophy.
You really should read the whole thing, but if you go to the link you should keep in mind that I think he accidentally transposes the words mind and brain in the first sentence. I believe he means to say that materialists hold that the mind is completely caused by the brain.
RLC