David Chalmers
He named the hard problem: when science has said everything about the brain's mechanisms, it will remain to explain why they are accompanied by any experience at all, and no functional description reaches that question.
Australian
Australian philosopher of mind, who named the "hard problem" of consciousness: explaining the brain's mechanisms leaves untouched the question of why they are accompanied by any experience at all. From it, through the zombie argument, he draws a property dualism.
Justification
Chalmers separates the easy problems of consciousness, which concern mechanisms and which science will solve, from the hard problem: why are those mechanisms accompanied by any experience at all? No functional explanation answers it, for describing what a system does leaves untouched what it is like to be one. He concludes that are not reducible to physical processes but are tied to them by laws of nature, and calls his position a naturalistic dualism: consciousness is a fundamental feature of the world, like mass or charge, not a separate substance. He also explores, without adopting it, another route to the same intuition: lodging experience in the intrinsic nature of the physical, of which physics describes only the structure. That option, close to Russellian monism and to panpsychism, remains for him a serious avenue, not the thesis he defends.
"Facing Up to the Problem of Consciousness" (1995) · The Conscious Mind (1996)
Justification
Chalmers argues that what carries experience is organizational invariance: it is functional organization that counts, not the matter realizing it. His position here follows from no physicalism: it is because consciousness is for him a fundamental datum, tied to organization by a law of nature, that it tracks that organization whatever the substrate.
"Absent Qualia, Fading Qualia, Dancing Qualia" (1995) · The Conscious Mind (1996)
Justification
Chalmers distinguishes two emergences. Weak emergence covers phenomena one would not have guessed from the parts, but which follow from them once one knows where to look, like the patterns of a cellular automaton. Strong emergence is that of a property deducible from no knowledge of the parts, however complete, and he takes consciousness to be its only uncontestable case in nature. Hence his conclusion: psychophysical laws must be added to the inventory of the world, as physics had to add electromagnetism to mechanics.
"Strong and Weak Emergence" (2006)