I found that Keith Frankish’s paper Quining Diet Qualia (PDF warning) was very helpful for understanding the Illusionist research program. In the paper, he lays out a few conceptions of qualia, and ultimately concludes that we are faced with a choice between just two of them.
He starts with “classic qualia”:
“Classic qualia: Introspectable qualitative properties of experience that are
intrinsic, ineffable, and subjective.”
This type of qualia doesn’t seem explainable from a physicalist viewpoint, and therefore many physicalists deny this type of qualia, and replace it with something else, which Frankish calls “diet qualia”:
“Diet qualia: The phenomenal characters (subjective feels, what-it-is-likenesses,
etc.) of experience.”
Frankish then introduces another notion, of “zero qualia”:
“Zero qualia: The properties of experiences that dispose us to judge that
experiences have introspectable qualitative properties that are intrinsic,
ineffable, and subjective.”
The main thrust of the paper is that “diet qualia” is a vacuous notion, and that any attempt to define it will ultimately collapse down to zero qualia. In this light, Illusionism as a research program is posing a challenge to orthodox physicalists: if you want to make sense of consciousness within a physicalist perspective, you need to get rid of all talk of phenomenal character and phenomenal consciousness. That talk is replaced with talk of how these dispositions arise that cause us to judge that we have such properties.
For Frankish, then, the choice is between classic qualia and zero qualia. Trying to make sense of some impoverished notion of qualia just doesn’t work. Many people (especially panpsychists and dualists) will be happy to stick with classic qualia, and will see physicalism being forced to embrace zero qualia as evidence that physicalism is just wrong. But many physicalists are happily taking up the challenge of explaining how these dispositions could arise.
Frankish’s work is very valuable in forcing a choice: you need to bite the bullet either way, whether it’s embracing classic qualia as real or denying phenomenal consciousness altogether. And physicalism will be shown to be wrong if some sense can’t be made of the latter.
(Updated) A couple of final comments:
- I’ve been one of the people saying that the “illusion” language isn’t really helpful. But I now better understand why Frankish uses it. He’s trying to make it clear to physicalists that in order to be physicalists, they have to get rid of phenomenal consciousness altogether, and one needs vivid language to make that choice clear.
- Further to that point, I don’t think illusionism is so much an alternative to orthodox physicalism as it is a vivid elaboration of what it means to be a physicalist. And while some will embrace the effort to make sense of illusionism, others will conclude that if physicalism requires the abandonment of phenomenal consciousness, then physicalism must be wrong.