Wolfgang , David Deutsch, and lots of other smart and philosophically minded thinkers worry about Qualia. Qualia, it seems are what is happening when we see, say, blue. I think qualia are interesting, but I don't see them as a deep puzzle. I seem to remember watching Sesame Street or some similar program when they would flash some blue stuff on the screen while somebody intoned "blue" and a little balloon displayed the word "blue". The words, of course, were merely labels - but what about that sensation that we perceive as blue, or the other sensations we perceive as loud, love, anger, or red? My guess is that they are labels too, only in the primitive language of thought that pre-existed in brains before there was language. Such categories clearly exist in the minds of creatures without language, and it seems highly plausible that our linguistic capability is built upon such more primitive structures of labeling the world. Of course that leaves the questio...