The Hard Problem of Consciousness

The evidence explained

In a widely influential 1995 paper, David Chalmers distinguished between the 'easy problems' of consciousness, explaining cognitive functions such as attention, memory integration, and behavioral reportability, which in principle admit of functional or mechanistic explanation, and the 'hard problem': explaining why and how physical processes in the brain give rise to subjective, qualitative experience at all, the felt quality of 'what it is like' to see red or feel pain, a phrase drawn from Thomas Nagel's earlier 1974 paper 'What Is It Like to Be a Bat?'

Chalmers and others argue that even a complete functional and neurological account of the brain, explaining every behavioral and cognitive capacity, would seemingly leave open the question of why any of this is accompanied by subjective experience rather than occurring, as philosophers put it, 'in the dark,' an intuition supported by thought experiments such as the philosophical zombie, a hypothetical being physically identical to a conscious person but lacking any inner experience, which many find conceivable even if not physically possible.

Physicalist philosophers respond in several ways. Some, like Daniel Dennett, argue the hard problem is based on a mistaken intuition and that a sufficiently complete functional account of consciousness, once achieved, would dissolve the apparent explanatory gap rather than leave a genuine residue; Dennett's position is sometimes summarized, not entirely fairly, as denying the reality of subjective experience itself, though he denies this characterization and instead argues qualia as typically conceived are a philosophical confusion. Others, like Patricia Churchland, argue neuroscience is progressively closing the gap and that talk of an unbridgeable hard problem is premature.

Non-physicalist responses vary considerably: property dualists such as Chalmers himself propose consciousness involves fundamental, non-reducible features of reality alongside the physical; panpsychists such as Philip Goff and Galen Strawson propose consciousness or proto-consciousness is a basic feature present in some form throughout physical reality; and idealists argue consciousness is in some sense more fundamental than matter. None of these alternative positions commands majority acceptance, and each faces its own significant objections, such as the 'combination problem' for panpsychism concerning how micro-experiences combine into unified macro-experiences.

There is no consensus resolution among philosophers of mind or cognitive scientists. Surveys of professional philosophers, such as the PhilPapers Surveys conducted by David Bourget and Chalmers himself, show physicalism about the mind remains the plurality view among philosophers but is far from a uniform consensus, with substantial minorities favoring various forms of non-reductive physicalism, property dualism, or other positions, reflecting the genuinely unresolved and actively debated status of the hard problem.