What qualifies a question to be in the philosophy category?

The only questions that really fit well are those that have no answer.

If the question pertains directly to philosophy, it is philosophical in nature and should be in this category.

Depends on perspective.

Some, like Wittgenstein, value "ordinary" questions; others on this forum rule out philosophy homework questions and questions about life that the asker directs to Philosophy section, but could be asked in Polls and Surveys, Dating, etc.

As some 7s regularly reclassify questions to other sections, the kind of question that remains generally references epistemology, ontology, deontics, etc., and is not obviously a class assignment question. Questions about a specific quote/topic are welcome; however, if a 7 believes it is directly answering a class assignment, then it's off to Homework Help for you :-)