Saturday, December 18, 2004

Word of the day: Qualia

I was thinking about 'identity' and 'time' (i.e. is a person at time t identical at time t+1?) and ran across this word on Wikipedia:

Qualia (singular: "quale") are most simply defined as the properties of sensory experiences [...] These properties are, by definition, epistemically unknowable in the absence of direct experience of them; as a result, they are also incommunicable.

Daniel Dennett identifies four properties which are commonly ascribed to qualia; that is, qualia are:

  • ineffable; that is, they cannot be communicated, or apprehended by any other means than direct experience.
  • intrinsic; that is, they are non-relational properties, which do not change depending on the experience's relation to other things.
  • private; that is, all interpersonal comparisons of qualia are systematically impossible.
  • 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.

This is interesting given that some scientists look at information and the transfer of information (communication) as fundamental building blocks of the universe. If there are properties of the mind that are incommunicable, then maybe there is a building block missing?

Arguments for qualia:

In Frank Jackson’s “Epiphenomenal Qualia” (Jackson 1982), Jackson offers what he calls the “Knowledge Argument” for qualia. The clearest example of this argument runs as follows:
Mary the color scientist knows all the physical facts about color, including every physical fact about the experience of color in other people, from the behavior a particular color is likely to elicit to the specific sequence of neurological firings that register that a color has been seen. However, she has been confined from birth to a room that is black and white, and is only allowed to observe the outside world through a black and white monitor. When she is allowed to leave the room, it must be admitted that she learns something about the color red the first time she sees it specifically, she learns what it is like to see that color.

Arguments against:

Dennett , a physicalist, also has his own response to the "Mary the color scientist" thought experiment.
He argues that Mary would not, in fact, learn something new if she stepped out of her black and white room to see the color red. Dennett asserts that if she already truly knew "everything about color", that knowledge would include a deep understanding of why and how human neurology causes us to sense the "qualia" of color. Mary would therefore already know exactly what to expect of seeing red, before ever leaving the room. Dennett argues that although we cannot conceive of such a deep knowledge, if a premise of the thought experiment is that Mary knows all there is to know about color, we cannot assume that we can fathom or even describe such knowledge -- or that such knowledge doesn't exist.

This strikes me as a relevant thought experiment, since there has been some debate about "What Color is the Sky on Mars?". Can we ever know without standing on the surface of Mars and looking up?