The scientific approach to a fact is to explain it, not to ignore or dismiss it, so if consciousness is a valid subject for science, the question raised is:
“Why does conscious experience exist?” (Chalmers, 1996) (p5)
Those who argue that the universe is a machine so consciousness can’t exist must also agree that they are also machines, so why should we listen to them? A detailed review of theories on consciousness divides them exhaustively into six categories A-F (Chalmers, 2003):
A. Materialism-A. Consciousness doesn’t exist except as an imagined effect of the physical brain (Dennett, 1991). If physical causes explain everything, there is nothing beyond the physical brain that needs explaining, so the hard problem doesn’t exist.
B. Materialism-B. Consciousness exists but is identical to certain physical brain states for all practical purposes (Block & Stalnaker, 1999). If consciousness equates to physical states, the hard problem is solved.
C. Materialism-C. Consciousness exists but is a physical derivative of the brain in theory (Nagel, 1974) (Edelman, 2003). If physical causes explain everything, they will one day explain consciousness so the hard problem will be solved, eventually.
Theories A-C argue that consciousness arises from a physical process because physical realism is correct. Yet it isn’t easy to argue that the observer experience is imaginary (A) or that it equates to matter states (B), so most believers in physical realism are left hoping that a miracle will one-day derive consciousness from matter.
D. Dualism-D. Consciousness exists by itself to affect physical events and matter in turn affects consciousness (Stapp, 1993). If consciousness exists as well as matter, the hard problem is solved.
E. Dualism-E. Consciousness is a brain by-product that helps survival but doesn’t affect physical reality (Zizzi, 2003). If consciousness is an epiphenomenon of physical activity, the hard problem is solved.
F. Neutral Monism-F. If both consciousness and matter derive from a primal cause that is neither, then matter doesn’t need to cause consciousness and the hard problem is solved.
Theories D-F argue that consciousness is a non-physical reality. Dualism-D lets it affect matter from a non-physical realm, Dualism-E lets it exist but have no effect on matter, and neutral monism-F sees both consciousness and matter as derivative, but as Chalmers notes:
“No-one has yet developed any sort of detailed theory in this class, and it is not yet clear whether such a theory can be developed.” (Chalmers, 2003)
Quantum realism is therefore a neutral monism but first, we review physical realism.