Basically, try as I might, I can't think of any piece of evidence that would let you distinguish between a being -- other than yourself -- who is consciousness and experiences qualia, and a being who pretends to be conscious with perfect fidelity, but does not in fact experience qualia.
As I discussed here - see also this comment for clarification - we should in theory be able to discover if other beings have qualia if we were to learn about their brains in such microscopic detail that we are performing approximately the same computations in our brains that their brains are running; we then "get their qualia" first-hand.
As for arguing about qualia verbally, I hold qualia to be both entirely indefinable (implying that the concept is irreducible, if it exists) and something that the vast majority of humans apprehend directly and believe very strongly to exist. There is little to be gained by arguing about whether qualia exist, because of this problem - the best that can be achieved through argument is that both of you accept the consensus regarding the existence of this indefinable thing that nonetheless needs to be given a name.
Ok, I read your article as well as your comment, and found them very confusing. More on this in a minute.
As for arguing about qualia verbally, I hold qualia to be both entirely indefinable...
How is that different from saying, "I found qualia to be a meaningless concept" ? I may as well say, "I think that human consciousness can best be explained by asdfgh, where asdfgh is an undefinable concept". That's not much of an explanation. In addition, this makes it impossible to discuss qualia at all (with anyone other than yourself, that i...
I encounter many intelligent people (not usually LWers, though) who say that despite our recent scientific advances, human consciousness remains a mystery and currently intractable to science. This is wrong. Empirically distinguishable theories of consciousness have been around for at least 15 years, and the data are beginning to favor some theories over others. For a recent example, see this August 2011 article from Lau & Rosenthal in Trends in Cognitive Sciences, one of my favorite journals. (Review articles, yay!)
Abstract: