qua·le (kwä'lē) pronunciation
n., pl. -li·a (-lē-ə).
A property, such as whiteness, considered independently from things having the property.
Qualia (from the Latin, meaning "what sort" or "what kind"; Latin and English singular "quale" (IPA: [ˈkwɑːle])) are most simply defined as qualities or feelings, like redness, as considered independently of their effects on behavior.
In more philosophical terms, qualia are properties of sensory experiences by virtue of which there is something it is like to have them.
Whether qualia actually exist is a hotly debated topic in contemporary philosophy of mind. The importance of qualia in contemporary philosophy of mind comes largely from the fact that they are often seen as being an obvious refutation of physicalism. Much of the debate over their existence, however, hinges on the debate over the precise definition of the term, as various philosophers emphasize or deny the existence of certain properties.
Definitions of qualia
There are a number of different definitions for qualia. The definitions in use have changed over time. One of the simpler, broader, definitions is "The 'what it's like' character of mental states. The way it feels to have mental states such as pain, seeing red, smelling a rose, etc'" [1].
C. I. Lewis, in his book Mind and the World Order published in 1929, was the first to use the term "qualia" in its generally agreed modern sense. (His original definition was that qualia are the "recognizable qualitative characters of the given.") Frank Jackson later defined qualia as: "...certain features of the bodily sensations especially, but also of certain perceptual experiences, which no amount of purely physical information includes" (1982 p.273).
Under definitions like these, which are quite broad, there can be little doubt that qualia exist [2]. However, definitions this broad make it difficult to discuss the precise nature of qualia, and their interaction with the mind and the environment. Some philosophers have made attempts at more precise, and possibly narrower, definitions of qualia, describing things whose existence is more controversial.
Daniel Dennett identifies four properties which are commonly ascribed to qualia. According to these, qualia are:
. ineffable; that is, they cannot be communicated, or apprehended by any other means than direct experience.
2. intrinsic; that is, they are non-relational properties, which do not change depending on the experience's relation to other things.
3. private; that is, all interpersonal comparisons of qualia are systematically impossible.
4. directly or immediately apprehensible in consciousness; that is, to experience a quale is to know one experiences a quale, and to know all there is to know about that quale.
If qualia of this sort exist, then a normally-sighted person who sees red would be unable to describe the experience of this perception in such a way that a listener who has never experienced color will be able to know everything there is to know about that experience. Though it is possible to make an analogy, such as "red looks hot", or to provide a description of the conditions under which the experience occurs, such as "it's the color you see when light of 700 nm wavelength is directed at you," supporters of this kind of qualia contend that such a description is incapable of providing a complete description of the experience.
Another way of defining qualia is as "raw feels". A raw feel is a perception in and of itself, considered entirely in isolation from any effect it might have on behavior and behavioral disposition. In contrast, a "cooked feel" is that perception seen as existing in terms of its effects.
One key consequence of the claim that such things as raw feels can be meaningfully discussed — that qualia exist — is that it leads to the logical possibility of two entities exhibiting identical behavior in all ways despite one of them entirely lacking qualia. While very few ever claim that such an entity, called a philosophical zombie, actually exists, the mere possibility is sufficient to refute physicalism. Those who dispute the existence of qualia therefore necessarily dispute the existence of philosophical zombies.
