The author uses a lot of soft terms to delineate between "manners" and "political correctness", but never makes a convincing argument about how to identify when

The author uses a lot of soft terms to delineate between "manners" and "political correctness", but never makes a convincing argument about how to identify when something falls in either camp. You can be guaranteed that there are people who use the term political correctness, that have a conception of its limits that you do not agree with. Question is, how do we identify who has the right definition?