it marks a boundary to what physicalist explanation, by its own lights, can reach. — Wayfarer
But I don't think this is an issue for physicalism; this is an issue for any kind of possible explanation. No theoretical framework can account for
what it is like to feel something. A panpsychist or idealist is not going to be able to explain conscious experience anymore than a physicalist; panpsychism and idealism will also both have gaps in explaining how experiences emerge, such as the combination problem.
That is precisely why this has been called the “blind spot of science” — the systematic neglect of lived experience as a condition of intelligibility rather than a phenomenon to be explained. — Wayfarer
Experience may be fundamental to knowledge and explanation in the sense that they can be seen as the information that cognizing organisms utilize, manipulate, predict; but under pains of circularity or dogmatism, that organism will have no articulable explanation or description of it. All explanations and descriptions are relational and predictive; physical explanations are nothing more than a special case that lays out such relations without being able to elucidate "intrinsic" natures of reality. No other form of explanation can do better.
Knowledge and epistemic behavior may be realized within one's experience, but I believe you are assuming that the only meaningful account of realism is through a God's eye perspective. I disagree, and think that realism through a perspectival lense is at least permissible from a deflationary perspective on truth / realism. There is then no conflict between purported realism about physical explanations and the fact that the intelligibility and realization of explanations and descriptions is effectively entirely through our experiences.
That the experiential cannot be given an explanation then suggests that there is no blindspot - which might be emphasized if at somr point we can give computational / information-processing account of the meta-problem of consciousness (i.e. give an account of information processing limitations that cause intelligent information processing agent to hit a brick wall when it comes to accounting for certain things that it perceives or processes, related to what it would call experiences). The blindspot is then only apparent if you think that explanations can do more than give predictive or relational accounts and should be about God's eye perspective; but they simply can't, and there are strictly no unique preferred descriptions either in any God's eye objective sense. If no explanations tell you about "intrinsic" nature of experience, and you can have realism without God's eye perspectives, then there is no conflict with physicalism, which simply excludes alternative reductive accounts like substance dualism that are mutually exclusive to physical explanation.
What is mind-boggling about the hard problem is present in all perspectives, and in my opinion the only reason people feel they need to shift from a physicalist account is because they view physical explanations as aspiring to be explanations of God's eye "intrinsicness", which in my opinion is simply not what physical explanations do and not what any other explanation can do either. No other account can then do better in principle when viewing realism and explanation in a way that does not aspire to some kind of idealized God's eye perspective about "intrinsic" stuff. Being unable to explain experience is no different from being able to explain any other purported "intrinsic" nature of the world that cannot be given an explanation or captured intelligibly due to things like Munchausen trilemma with regard to information processing.
I think a central issue of the mind-body problem is that we take experience as some kind of special ontological primitive when I can't even articulate what that means. I can't even give a non-circular explanation of what "ontology" or "being" means (something which more deflationary attitudes to truth are less likely to have a problem with, imo from what I can see). I then don't think the fact that I
see things necessarily further entails much else about the intrinsic ontology of reality becausr doing so would be going beyond what I can really say or ascertain about my own experiences. I can't even elaborate on what it means to say that I
see things. I just know that it reflects some causal structure in the world at some scale.
And I think this kind of rejection of prematurely attributing properties to experience is what illusionist are actually advocating for - they are not saying that experience doesn't exist, but that seeing things doesn't entail some extra-elaborate ontological account, let alone a dualistic one. The illusion isn't the experience itself but the ontological account people might be prone toward (e.g. that there is some extra substance out there). And the inability to articulate about experiences is evidence that an ontological account of experience is fruitless, imo. The illusionist will then want to explain our difficulties in explanatory accounts of consciousness as being a consequence of information processing without trying to imply something profound about "intrinsic" reality. But ofcourse, being agnostic or even rejecting the role of "intrinsicness" in explanations preserves the role of physical sciences in our web of knowledge whilst revoking any apparent need for additional and mutually exclusive explanatory accounts (e.g. a theory of substance dualism or Kastruppian idealism) which we have no evidence for.
I might be tempted to make a statement like "what "ontology" or "being" means is to have a Markov-blanket" which would mean ontology is scale-relative and informational. I would want to make that statement because its hard to escape the intuition that to be having experiences suggests there is some very vague sense in which reality does not have a preferred scale. But I am not sure this assertion makes "intrinsic" nature of reality anymore articulable, and I am not even sure about the validity of the intuition motivating it. Because my tempted statement doesn't really address what I think of as the "intrinsicness" issue, its not clear that it is that helpful beyond reasserting a trivial fact about nature that systems are nested inside each other as we zoom out.
But if physicalism is perspectivally realist grounded by something like a deflationary notion of truth, not on explaining "intrinsicness", I am not sure there is any sense of a blindspot that physicalism misses out on that is not missed out by any other perspective. Physicalism just asserts the position of physical theories in
articulable explanations about the universe, our web of knowledge also including many non-physical things also.
** Extensive editing for (possibly more my own) clarity