Consciousness
qualia · subjective experience
Subjective experience itself; the 'hard problem' is explaining why physical processes give rise to it.
In practice
A system can describe its own states accurately and report them in language. Whether anything is experienced while it does so is a separate question, and no behavioral test settles it.
The common mistake
Treating consciousness as the same question as intelligence. A system can be highly capable with nothing it is like to be it, and the two questions come apart.
Consciousness is subjective experience — what it is like, from the inside, to see red, feel cold or hear a chord. Explaining how physical processes produce it is among the hardest problems in philosophy.
The easy and the hard problems
David Chalmers drew the distinction in 1995. The easy problems concern functions: how the brain discriminates stimuli, integrates information, reports its own states, controls behavior. They are enormously difficult in practice and tractable in principle, because they ask how a mechanism performs a task.
The hard problem asks why any of that is accompanied by experience. A system could in principle perform every function while there is nothing it is like to be it. Explaining the function appears to leave the experience untouched, and that gap is what makes the problem hard.
Thomas Nagel set up the difficulty in 1974 by asking what it is like to be a bat. We can describe echolocation completely and still have no access to the character of the bat's experience, which suggests that objective description may leave something out.
The main positions
- Physicalism holds that consciousness is a physical process, and that the appearance of a gap reflects the limits of our concepts.
- Dualism holds that experience is a distinct kind of thing. This is the mind-body problem in its classical form, set by Descartes in 1641.
- Functionalism identifies mental states with roles in a system, which allows that a different substrate could realize the same mind.
- Panpsychism treats experience as a basic feature of matter, avoiding the question of how it emerges at the cost of a large commitment.
Why it resists settlement
Every other scientific explanation has worked by describing a mechanism from the outside. Consciousness is the one phenomenon defined by how it is from the inside, so the usual method has no obvious grip. That structural feature, more than any particular argument, is why the problem has stayed open.
Concept web
Open the full webQuestions
What is consciousness in philosophy?
Consciousness is subjective experience — the qualitative character of perceiving, feeling or thinking. Philosophy of mind asks what it is and how it relates to physical processes in the brain.
What is the hard problem of consciousness?
The question of why physical processing is accompanied by subjective experience at all. Explaining the brain's functions appears to leave unexplained why performing them feels like anything.
What is the mind-body problem?
The question of how mental states relate to physical states. Descartes treated mind and body as distinct substances, which raises the difficulty of explaining how two such different things interact.