That dimension is still on a thin film around a little ball floating in one of a great number of possible universes within a great number of possible rule systems. Compared to that space, we are quite similar to fish, in terms of the purposes for which our machinery functions.
But the question is not, "is intelligence explosion possible?" The question is, "explode into what?"
> The author is apparently unaware that this tautological response eliminates the distinction between general and specialized intelligence, as one could just as validly (or vacuously) say that a superhuman intelligence is specialized in being what it is and doing what it does.
It's not a tautology. "Generality" and "specificity" are artifacts of the human experience. What is tautological is to say, "it's general to me, therefore it is general."
You think that more and more progress comes by way of more and more optimization. This is not the whole story. Accidentation is the missing ingredient. Humans - as well as all life on earth - have a knack for creating more and more problems. It is this never-ending fountain of new, accidental problems that allows for what appears to us to be a chain of "progress" stretching into the past.
Our "generality" is in fact a hairball collection of specific functions that have accreted into the human animal over millions and millions of years. Some abstract Java class called `Agent` with an `.optimize()` method hanging off of it simply does not have that context.
If you want a really high quality, generally intelligent function in silicon though, it's hard to beat the XOR function ;)