Fooloso4, you’re asking what specific questions and doubts turn on “here is a hand” and concluding that because we can’t readily point to everyday occasions for saying it, it’s not functioning as a hinge. But that’s backwards. The reason we never say “here is a hand” in ordinary life is precisely because it’s a hinge. It never surfaces because it never comes into question. The absence of occasions for saying it isn’t evidence against its being a hinge. It’s the result of being one.
Your criterion treats hinges as though they do localized work, supporting specific doubts and questions the way a premise supports a conclusion. But the deepest hinges don’t work that way. They make the entire practice of questioning possible (This you don’t seem to see). Asking what specific doubts turn on “here is a hand” is like asking what specific weight the foundation holds at a particular point in a building. The foundation holds the entire structure.
You also distinguish between hinges and “things we simply do not doubt,” as if these are separate categories. But what’s the difference supposed to be? If something is universally presupposed, never comes into question, and can’t intelligibly be doubted, on what grounds is it not a hinge? You need to say what would make something a hinge based on that interpretation, because your criterion seems to rule out the propositions Witt himself cites. OC 7 mentions chairs and doors. OC 35 mentions physical objects. If your test excludes these, the problem is with the test.
Don’t be like others who can’t admit when they’re wrong.