Aside from some quibbles that aren't really worth getting into, I have no significant disagreement with your comments. There is nothing wrong with looking at people's acts in practice and observing that they behave as if they operated with subjective probability estimates in some range. However, your statement that "one's own probability assignments are not necessarily introspectable" basically restates my main point, which was exactly about the meaninglessness of analyzing one's own common-sense judgments to arrive at a numerical probability estimate, which many people here, in contrast, consider to be the right way to increase the accuracy of one's thinking. (Though I admit that it should probably be worded more precisely to make sure it's interpreted that way.)