The pain scale: a public number on one side of the desk, an inaccessible experience on the other.
Qualia
The felt quality of an experience - what seeing red or feeling pain is like from the inside, as distinct from anything measurable about it.
- Theme
- Mind, self and consciousness
- Tradition
- Analytic
- Term fixed
- 1929
In plain terms
Look at something red. There is the wavelength, which an instrument can measure, and there is the redness as you see it, which no instrument reads. That second thing - the way the experience seems from where you are sitting - is what philosophers call a quale, and qualia is the plural.
The point of having a word for it is that everything else about you can in principle be described from outside. What your eyes do, what your brain does, what you say afterwards, all of it is observable. The way it seemed is not. You are the only one with access to it, and you cannot hand it over.
That is not a mystical claim. It is a claim about the shape of the problem: there appears to be a fact about your experience that a complete physical description leaves out.
As a philosopher would put it
Qualia are the introspectively accessible, phenomenal properties of mental states - the what it is like of an experience, in Nagel's phrase from his 1974 paper on bats. They are usually characterised by four features: they are intrinsic rather than relational, private, ineffable, and directly apprehensible in consciousness.
Their philosophical work is done through the explanatory gap, named by Joseph Levine in 1983. Even a completed neuroscience would tell us which physical state accompanies the experience of red, and would not tell us why that state feels like anything at all, or why it feels like that. Chalmers calls this the hard problem, in contrast to the tractable problems of explaining discrimination, integration and report.
Two arguments carry most of the weight. Frank Jackson's knowledge argument (1982) asks us to imagine Mary, who knows every physical fact about colour vision but has only ever seen black and white; on release she appears to learn something new, so the physical facts were not all the facts. The inverted spectrum asks whether your red could be my green with no behavioural difference whatever - if that is coherent, qualia are not fixed by function.
Where you meet it
A doctor asks you to rate your pain from one to ten. You say seven.
The seven is public. It goes in the notes, it can be compared with your seven last week, it can be graphed across a ward. What it cannot do is transmit the pain. The doctor does not learn what your seven is like; she learns where you have placed it on a scale whose other end she has to imagine. If your seven and her seven differ, nothing in the procedure could reveal it.
That gap is the whole subject. Everyone involved is behaving rationally, the number is genuinely useful, and the thing the number is about has not been communicated at all. It is why pain research leans so heavily on scales it knows are not measurements, and why a patient saying "you don't understand" is making a philosophical point rather than a complaint.
What is actually disputed
Whether qualia exist at all, as described.
Daniel Dennett's "Quining Qualia" (1988) argues that the four defining features never apply together to anything, and that our confidence in them comes from thought experiments engineered to produce it. On his account there is no residue left over once you have explained all the discriminating, reacting and reporting - the seeming is one of the things being explained, not something outside it.
Representationalists take a middle position: experience does have a felt character, but it is exhausted by what the experience represents about the world, so there is nothing intrinsic to explain. Chalmers holds the strong line that the gap is real and that consciousness will have to be taken as fundamental. None of these is a fringe view, and the dispute is not close to settled.
Commonly confused with
- Consciousness 1641 Consciousness is that there is experience at all; a quale is what a particular experience is like. A theory can grant the first and deny the second.
- Emotion c. 340 BC An emotion has a felt quality, but qualia are not restricted to feelings - the redness of red is one, and nothing about it is emotional.
- Perception c. 330 BC Perception is the process that delivers information about the world; qualia are what that process is like to undergo. A machine can perceive without the question arising.
Defined against
- Objectivity A quale is the part of an experience that survives no shift to a third-person account
Works
- The Conscious Mind Chalmers, 1996 - the book-length case that the gap cannot be closed
- Consciousness Explained Dennett, 1991 - the case that there is no gap to close
Related concepts
Consciousness 1641 · Mind–body problem 1641 · Self 1694 · Perception c. 330 BC · Subjectivity 1846
C. I. Lewis gave the word its modern sense in Mind and the World Order (1929); the Latin plural of quale, a what-sort-of-thing, was already in use for a quality in general.