David Chalmers (b. 1966) was born in Sydney, studied mathematics and computer science, and went on to read philosophy at Oxford and Indiana, completing his doctorate under Douglas Hofstadter. The short paper he published in the inaugural issue of the Journal of Consciousness Studies in 1995, and the book that grew out of it — The Conscious Mind (1996) — permanently reframed the consciousness debate.

Chalmers' distinction runs like this. Questions about consciousness fall into two kinds. The 'easy problems' ask the brain to be described: how it attends, how it learns, how it speaks, how it reports sensory information. These problems may be difficult but they are structurally tractable — neuroscience will gradually answer them. The 'hard problem' is different: why is any of the brain's neural processing accompanied by an experience felt from the inside? Why does seeing red, hearing a chord, feeling pain — having these subjective qualities, these qualia — come along at all? Even when every neural correlate is mapped, the question remains untouched: why are the lights on?

Chalmers finds both eliminativism (denying qualia) and classical functionalism (reducing qualia to functions) inadequate, and ends up close to panpsychism — a 'naturalistic dualism' on which consciousness is a fundamental natural property like mass or charge. The conclusion is contested, but the question — the gap between the easy and the hard problems — has become a shared coordinate of the field. Now director of the Center for Mind, Brain and Consciousness at NYU, Chalmers extended the debate into digital territory in 2022 with Reality+, on virtual reality and simulation arguments.