 The question which foundational theories of meaning try to answer is a common sort of question in philosophy. In the philosophy of  action (see entry)  we ask what the facts are in virtue of which a given piece of behavior is an intentional action; in questions about  personal identity (see entry)  we ask what the facts are in virtue of which x and y are the same person; in ethics we ask what the facts are in virtue of which a given action is morally right or wrong. But, even if they are common enough, it is not obvious what the constraints are on answers to these sorts of questions, or when we should expect questions of this sort to have interesting answers.