If one takes Realism according Michael Devitt who says: “The general doctrine of realism about the external world is committed not only to the existence of this world but also to its ‘mind independence’: it is not made up of ‘ideas’ or ‘sense data’ and does not depend for its existence and nature on the cognitive activities and capacities of our minds. Scientific realism is committed to the unobservable world enjoying this independence.” [‘Scientific Realism’]
Then the challenge for any such Realism (epistemic, ontological etc.) comes not only in the affirmation of a mind-independent reality but also the claim that that reality is knowable in itself; that is that true statements can be made about elements of reality.
This seems to necessitate taking one of two, intertwined positions; neither of which is satisfactory to me.
First: Certain forms of Realism necessitate skepticism. This is because if there is a world of which we are part then this world obviously precedes and exceeds us. It transcends us and hence our access to it and knowledge of it must be partial. The transcendental project in both Kant and Phenomenology is a way out of this skepticism and (late) Husserl is quite clear that his phenomenology is realist: "There can be no stronger realism than this, if by this word nothing more is meant than: "'I am certain of being a human being who lives in this world, etc. and I doubt it not in the least'" [Husserl, Crisis of European Sciences... - quoted by Zahavi who makes a strong case for Husserl as a realist.] But it is a different type of realism to Devitt's.
Second: epistemic and ontological realism require reference in order to have meaning. This seems to require some form of abduction to support the knowable existence of a reality that we might have unmediated access to. This is what Putnam meant when he said: “believing that some correspondence intrinsically just is reference (not as a result of our operational and theoretical constraints, or our intentions, but as an ultimate metaphysical fact) amounts to a magical theory of reference.”
And Putnam’s position (in Reason Truth and History at least) is to argue that this requires the claim that a ‘god’s eye view’ of the world is possible in principle. He rejects such a position as incoherent because we can never grasp the world in its totality. Descartes recognized this; hence his need for a 3rd entity – God – to triangulate between Res Extensa (corporeal substance) and Res Cogitans (consciousness) Without God his system would have been incoherent.
Now; this is relevant to the last post because this is also what Luhmann also claims; namely that to have a world in-itself then this world needs a correlate observer with a view from nowhere. Luhmann then historicizes this saying that whilst we used to use God to perform this function (of position-less observation) this god-function has been replaced in the functionally differentiated social systems of modernity and the possibility of a position-less observation of the totality of everything has, necessarily, evaporated.
Also, and there’s so much more to be said on this than the following few lines, I think this points to the role of aesthetics in gesturing toward this totality. I take this to be what Bateson means when he draws together epistemology and aesthetics in grasping totality and claims that: "the loss of the sense of aesthetic unity was, quite simply, an epistemological mistake."
It’s also how I read Graham Harman’s claims that aesthetics is first philosophy and that aesthetics is a branch of metaphysics. Perhaps, then, only certain forms of magical thinking can help us speculate about the world beyond our prison house of language and reference.