My working assumption too, so it’s helpful to have this noted explicitly. (Though I think your use of “intelligibility" there invokes the different “dimension" you referred to, and I’m probably not following you there.)
I think this is a fruitful approach. It suggests there is a certain structure to inquiry, and that this structure is incomplete by nature, but it generates as it goes new pathways, new points of attachment for the structure to grow. If we say the structure allows or enables or encourages this development but not that, we could as well say it’s because such and such development is rational and the other not. Rationality is following the paths that naturally open before you, and not trying to force your way through the thicket. The standards are implicit in the constraints on the growth of the structure.
Since I’ve already mentioned Hume, I’ll note that this doesn’t feel as far as we might want from the way Hume describes how much more easily (readily, frequently) you pass from thought A to thought B than from A to C.
And also I’m developing your description in such a way that it is clearly available to modeling of the usual sort in cognitive psychology. After the last post on problem solving, I had Herbert Simon on my mind, and here he is again. He did an enormous amount of empirical research into problem solving and one of his standard models was search: the challenge of solving a problem is finding a path though the space of possible solutions.
Coming back to your model, I find very attractive the idea that certain movements of mind—inference, say—are “evaluation-apt” rather in the sense that assertions are truth-apt; they have the possibility of being judged and evaluated relative to some standard (of rationality, I suppose) built in:
I’m not sure most people would consider the standards of rationality entirely internal to the practice of inquiry in this way. And your insistence on the individual experience is even less encouraging as an account of a normativity that aspires, I presume, to universality or at least generality. Anyway, some standard we share.
Oddly, there is a solid example of the sort of thing you’re describing, but it’s not rational inquiry, it’s art. The artist proceeds according to a rule only he knows and only he has experience of. (And only he may change.) At each step, he must judge whether he is succeeding or failing, and only he knows what’s relevant to the judgment. (“Why did you throw this one away? It’s beautiful!”)
I might believe you, if you argued that such idiosyncratic thought is largely outside the scope of science, though it may be within reach of biography.
As I said, I agree we ought not expect to find a modus ponens circuit in the brain. But I’m not sure we’ve discussed anything that doesn’t fall squarely within psychology if not neuroscience.
This thread began with a quote from you, invoking the usual distinction:
But we haven’t really talked about that. Am I right in connecting the idea of validity to the standards immanent in rational inquiry?
It would be nice to avoid “What is logic and where does it come from?" but it feels like a big piece of the puzzle is left unplaced if we don’t say something substantive about the validity you consider unavailable for empirical inquiry or explanation.
I know perfectly well what you’re gesturing at. I think I could even say most of the things you’ve said with a clear intellectual conscience. I’m just not sure I actually know what I would mean by saying them.
Added:
This vitiates some of my commentary, and opens a whole new can of worms. (Work must have interfered with my philosophizing.)
And a little more:
“Mind-independent criteria."
I’m genuinely not sure how to take that. If the standards built into inquiry are not external but are mind-independent, I’m not sure what a mind is.