Seeing red

[A very rough and ready introduction of qualia and stuff for the uninitiated].

To our minds, there appears something unique about appearance. There is a ‘what it is like’ component to seeing red, or hearing a sound, or feeling a surface, that seems apart from its physical basis: even if we can explain in complete detail how our sensory apparatus apprehends these stimuli and processes them, the ‘what it is like’, the ‘redness’ is still missing. ‘Redness’ seems a uniquely private sensation, a secondary quality or (in Phil-o-mind speak) a qualia.

Consider the following (fairly famous) thought experiment. Suppose you wake up one morning and find your colour spectrum inverted: when you look at a red object, you see what you’d have called green, the grass looks red, the sea looks orange, and so on. Plausibly, nothing physical need to have happened to your brain – all the neurons could be functioning the same as before. If so, then how are we getting these qualia: how does a felt experience of a colour (or anything else) arise from our neural goings-on? Continue reading