I would say humans are incapable of reflection. If we were, we'd already know how intelligence works and how to make AI capable of reflection.
What we say we "reflect" on, is some minor subset of internal processes, that is being processed like external input, and confuses the hell out of us, making even smart people like Roger Penrose trying to invent up new physics just to explain their subjectivity. Combined with general ability to invent a label for a physical object, and calling one of the physical objects - the one that's always real nearby, etc etc - 'self'.
We also don't really recurse anywhere, we just got a symbol that says 'I am' in the "map", which is distinct from symbol that says 'my brain' (the problem with map analogy, is that two points in the mental map, can correspond to one real world item, as well).
I would say humans are incapable of reflection. If we were, we'd already know how intelligence works and how to make AI capable of reflection.
We are limited when it comes to reflection but we are most certainly not incapable of it. I am reflecting as I write this, analyzing just what my reflective capabilities are!
Are there any essays anywhere that go in depth about scenarios where AIs become somewhat recursive/general in that they can write functioning code to solve diverse problems, but the AI reflection problem remains unsolved and thus limits the depth of recursion attainable by the AIs? Let's provisionally call such general but reflection-limited AIs semi-general AIs, or SGAIs. SGAIs might be of roughly smart-animal-level intelligence, e.g. have rudimentary communication/negotiation abilities and some level of ability to formulate narrowish plans of the sort that don't leave them susceptible to Pascalian self-destruction or wireheading or the like.
At first blush, this scenario strikes me as Bad; AIs could take over all computers connected to the internet, totally messing stuff up as their goals/subgoals mutate and adapt to circumvent wireheading selection pressures, without being able to reach general intelligence. AIs might or might not cooperate with humans in such a scenario. I imagine any detailed existing literature on this subject would focus on computer security and intelligent computer "viruses"; does such literature exist, anywhere?
I have various questions about this scenario, including: