A number of times, my questions have had the set-theory tag removed. One such instance is here: Conglomeration for conglomeration's sake . Another is here {On hold is a welcome topic for another place}: https://math.stackexchange.com/questions/713610/having-elements-as-ideals . In the first one, I was correct in believing that set theory would give an answer. Somewhat related is I also thought that any theory of collections should be considered set theory, whereas the set theorists here seem to have the position that set theory is what set theorists do(perhaps a function of their professionalization).
The second one I tagged set theory, because it is not about rings up to isomorphism, and it was obvious that some set theoretical method/thought was needed (perhaps elementary, I'll give it another shot). So my question is, should the tags of a question reflect the topics of the statement, or the tools needed to resolve the question? My idea was that tags are primarily a tool for matching questions with the required knowledge. If tags are about the tools needed, should I defend my tags in the problem (so that a knowledgeable set theorist doesn't untag a question I have thought about for hours, after a glance)?
