Pain, injury, and first/third-person asymmetry

Philosophers are wont to say that certain concepts, e.g., the concept of pain, exhibit ‘first/third-person asymmetry’, whereas others, e.g., the concept of injury, do not. The question I wish to address here concerns the status of such claims. They are commonly seen as nothing more than summary reports of how the relevant words are ordinarily used: as statements of ‘grammatical fact’. I want to argue against this view of their status.