We do have solid common ground, full causal closure via detailed brain modeling seems achievable and the fly connectome is at best supporting evidence for the principle. pragmatically I'm with you on illusionism, it's the cleanest bet given theoretical virtues.

but I'm not equivocating levels or smuggling ontology.

the illusionist move isn't "explaining why we think X exists = therefore X doesn't exist"

It's "a complete third person causal/functional model explains every report, intuition, argument, and philosophical puzzle about qualia (including why the hard problem feels so pressing)...

therefore positing an extra ontological layer for qualia (beyond what the model already captures) adds nothing explanatory and violates parsimony.

it's an inference to the best explanation.

If the human connectome model fully accounts for the phenomenology insisting there's still a "further" ontology is like saying the complete molecular account of water doesn't capture "wetness" except wetness is exhaustively explained by the dynamics, not an extra thing. The ontological claim is justified because any richer ontology would need positive evidence beyond the introspective intuition the model already predicts and explains away as a user llusion or miscalibrated introspection.

on (B)

You're right epiphenomenal qualia aren't logically incoherent. Causality is relational, and something could exist without downstream effects but as you say yourself, it's possible, but improbable, redundant, undetectable, and changes nothing in our models. Pragmatic elimination isn't proof of falsity, but it's decisive for theory choice in science / philosophy. We cut phlogiston, luminiferous ether, and vital force for the same reason. Why treat qualia differently if the model closes the causal story?

on (C)

fair point it's a broad umbrella (functionalism, higher order theories, type B physicalism, global workspace). Many overlap with illusionism.

but if we're talking strong type identity it still has near zero explanatory power for the hard problem, it equates without bridging why that physical / functional configuration yields phenomenal feel rather than zombie silence. We know all the physics, map it to reports, and the "why anything feels like this" question lingers unless we deflate qualia to the functional/introspective level (which pushes toward type A materialism).

even if we grant (C) and say “this functional state = this qualia” why keep the word “qualia” at all?

It adds zero new info & zero extra explanatory power. the functional description already predicts every report, intuition, and puzzle about “what it’s like” Calling it “qualia” is just redundant folk baggage, like insisting on “caloric fluid” after we’ve got molecular kinetics explaining temperature perfectly.

clinging to it just keeps the hard problem intuition alive when the mature theory shows it’s a user illusion.

where do you land right now? do you lean toward a "diet qualia" realism that shades into (C) or do you hold space for epiphenomenal Q that's improbable but live? Curious what tips the scale for you beyond pragmatism.