It seems like everywhere I turn some scientist is making some claim about solving the problem of consciousness or talking about reality being a simulation. It is hard for me to watch scientists try to be philosophers while pretending philosophy doesn’t exist.  They are always acting like they are saying something new or deep. Dressing up Kant in computer terminology doesn’t make something a new idea.  But that’s the problem: these people have no knowledge of the history of ideas.  If they did, they would see the problems with Kant that later idealists developed (how are our concepts of the brain and evolution supposed to ground our knowledge of the biological prejudice of our concepts?).  But to merely refute neo-Kantianism with some kind of absolute idealism only goes so far.

However much reality is conditioned by the subject, however much there may be no absolute outside or reality absolutely external to consciousness, it does not follow that there is then no kind of realism possible.  The better inference is to realize that reality is “immanent” and being “univocal”.
Kant’s “copernican revolution” may have had the effect of reversing copernicus in some metaphorical sense, at least in the minds of many philosophers all the way down to the many postmodern solipsists of today.  But realism has been coming back, and people are realizing this solipsism has been a roadblock to understanding the nature of the semiotic process. 

But there has always been those less taken in by these threads driven by extreme doubt and the need it creates of fixing reality or meaning on one side of any metaphysical duality.  Peirce critiqued much of idealism as a shallow nominalist reaction to a bad understanding of medieval realism.  Hegel tried to bring idealism out of representation and into immanence, but ultimately fell back on a transcendent view.  Pierce and Heidegger mostly corrected idealism, but since few read Pierce or understood Heidegger (I still think Heidegger is misleadingly if not anthropocentric, than dasein-obsessed), it has taken the more pragmatic anglophone thinkers of the last few decades to really clarify this realism issue, hopefully well enough that we can move on to more interesting things.

The medieval realists and the romantic era scientists were on the right track.  Uexkull read Kant in a productive way, as did many of the Romantic poets dabbling in science.But they had their problems for sure.  Steiner tried to fix romanticism but I think Deleuze and his realist interpreters like Delanda have got the right idea.  I am less into the whole object-orientated craze in philosophy these days.  I like Graham Harman, but he and Delanda both fall back on discrete logic and even Delanda, who stuck to his continuity hypothesis for a while, misses the radicality of Deleuze’s immanence and conception of univocity when he gets pulled into anti-idealism of the new realists.  Harman and Delanda in their book “The Rise of Realism” make some great points, but they still end up discussing whether this or that thing is real or not, which I think misses the point.  Deleuze’s point was to escape this whole dumb debate, to cut through the stupid dialectic of generic abstractions, and form a tradition of immanence. To displace all either/or judgments into an even more destructive and creative critique and transvaluation.  

What “is” a thing? Not that interesting of a question to me and quite a misleading one, unless by it you mean to open up the question to the virtual trajectories of relevant relations.  The boundaries of any system are contingent but still “structured”.  The anglophone tradition of critical realism has been able to model this fairly well, but they still get caught up in reified hierarchies when trying to maintain “structure” without reducing it to any particular instantiation.  Philosophers of science like Feyerabend and Ian Hacking did a good job of grounding representation in specific contexts and interventions but they lack the deeper understanding that is necessary to answer and ground more fundamental questions as Deleuze did. 

Without that grounding in virtual structure as an infinitely differential and heterogeneous continuum as Bergson and Deleuze did, “structure” becomes rather discretely tied to specific circumstances. Rocco Gangle has done a good job giving three of the great philosophers of immanence Deleuze, Pierce and Spinoza the proper modelling in logic I think is necessary to combat the discrete set-theoretic mindset that continually haunts philosophy with these inevitably dogmatic questions about the boundaries of things.

Deleuze’s theory of ideas is a recasting of Plato that diverts the whole history of philosophy away from debates over the preferred representations of this or that philosopher.  He completes Derrida’s project of uncovering the entrenched preferences of a thinker, and makes of those qualities, new powers and points of possibility, opening up every thinker to new interpretations and insights.  But yes it is still “ideas” at the root, but they form a dynamic continuum that is in no way merely subjective or objective.  Being is univocal; trying to make it otherwise or claim one kind of being as fundamental, merely distracts from the play of difference into the power play of identity, which because there is no absolute distinctions, merely hides the poverty of a question that is essentially a tautology.  What is x? It is (a) being of course.  And what is being? It is (a) difference.  And what is difference? Is there some ultimate characterization of being as opposed to beings? Or does this just distract from the real question. Not so much of truth but of relevance. What is the relevant being/difference?

Emphasizing being as awareness might be an important qualification to a materialist age. But there is no ultimate characterization that can resist differences.  Deleuze definitely sides more with Plato here than Aristotle in that Aristotle more forcefully grounded ideas in the arborescent logic of absolute negation. Deleuze makes of Plato’s “forms”, basically what Jane Roberts did in a less formal way in “Adventures in Consciousness”, as a multiplicity always in reciprocal co-creation with its related forms.  
So with a creative difference at the heart of being, as Feyerabend would say, “anything goes”.  But as he would add, different approaches yield different results, and given a certain context, some ideas make more sense than others and some contexts make better ground than others, depending on what you are doing!