The answer to the question "how did they get started talking about qualia" is: by definition, the hypothetical Z-world is indistinguishable from ours. In our wo

The answer to the question "how did they get started talking about qualia" is: by definition, the hypothetical Z-world is indistinguishable from ours. In our world, people talk about qualia. Therefore, in the Z-world, zombies talk about qualia. Right. Which implies that the reason that we talk about qualia is not that we have them (otherwise zombies wouldn't), but for some completely different reason that just happens to exactly line up with the qualia that we in fact do have. That would be an astounding coincidence and is a major strike against the theory per Occam's Razor.