What I would call reductive physicalism envisions a unique (but so far only hypothetical) Theory of Everything, usually identified with fundamental physics, that fixes everything in existence. All other theories and explanations, from chemistry to psychology, at best supervene on and approximate this TOE. The TOE thus has a unique status. Its ontology is the only true ontology, and its causality is the only true causality - everything else being illusory and epiphenomenal. With some variations, this is a pretty popular view among physical scientists (especially physicists, natch) and scientifically-minded laymen. — SophistiCat
Yeah, part of what I'd like to argue is that this kind of approach to things simply is
idealism par excellence, and an insidious one at that, insofar as it couches itself in the language of the ‘physical’, despite being a metaphysical (in the pejorative sense) chimera through and through. It always amazes me that those who hew to this kind of view don’t recognise just how shot-through with theology it is. And I don’t mean this as a cheap-shot (like ‘oh science is just the new religion'), but in a properly philosophical key: it shares with theology its
‘emanative’ logic wherein, to botch Plotinus, everything flows from the One and returns to the One - and where the ‘flow’ is just so much detritus and debris. What you call reductive physicalism mirrors, exactly, ancient theological tropes and, from my perspective, is more or less indistinguishable from them.
You seem to be rejecting the primacy of some fundamental physical ontology and instead insisting on a multiplicity of coequal ontologies.
I am sympathetic to this view, but I might be coming to it from a somewhat different direction, one that deemphasizes ontology in favor of epistemology. To my mind, ontology is theory-dependent. Theory comes first, and whatever entities it operates with, that is its ontology.
I perhaps wouldn’t say ‘co-equal ontologies’: my basic intuition is that ontology ought to be dictated by both the things and what we want to know about them, as it were, and that both are subject to change. A dynamic, pluralist ontology, maybe, one attentive to historical currents and issues of scope, scale, and interest, but one still with synthetic ambition. The philosopher Reza Negarestani probably put it best:
"We can generally investigate the space of the universal through particular instances or local contexts. But once we carry out this investigation through the synthetic environment that the interweaving of continuity and contingency create, we can arrive at very interesting results. Looking at the space of the universal, through particular instances or local contexts is in this sense no longer a purely analytical procedure. It is like looking into an expansive space through a lens that does not produce zooming-in and zooming-out effects by simply scaling up and down the same image but instead it produces synthetic and wholly different images across different scales of magnification. It then becomes almost impossible to intuitively guess what kind of conceptual and topological transformations the local context—a window into the universal— undergoes as it expands its scope and becomes more true to the universal”. (Negarestanti,
Where Is the Concept? [pdf])
But these are very general methodological remarks that are perhaps not quite to the point. I aver to it because I’ve long had a suspicion that the distinction between ontology and epistemology is not a particularly fruitful one, and that
both are abstractions from a more general question about how we go about
conceptualizing phenomena, with concepts being reducible to neither side of the epistemology/ontology divide. To bring this back to the OP, one of the reasons I think this, is because this approach is itself dictated (I like to think) by the necessity of avoiding what I see as idealist approaches in which the world is made to ‘pre-fit’ certain
a priori conceptions of it, or else follow from some eternal, God-given rules from which everything else is just epiphenomena, as with what you referred to ‘reductive physicalism’.