Post History

Historically, philosophy is broadly scoped and does not exclude any particular domain of knowledge. Most branches of formal knowledge today started out as discussions between philosophers. I think that a good student of philosophy should be able to produce good answers to a very broad set of questions - this was certainly true in ancient Greece, and it should be true to some extent today.

It's hard to exclude a type of question in principle. But in practice, I can see some specific things worth excluding:

* If it's not clear what's being asked (due to poor grammar, poor phrasing, multiple unrelated questions all lumped together) - in this case, users should explain in comments why it's unclear, and encourage the asker to edit and/or delete and ask better new questions
* If it's not possible to provide a real answer of a reasonable length - users should say in comments why the answer would have to be so long, and suggest ways of narrowing the scope or breaking down the question
* If the question is extremely localized, and the analysis of it cannot be generalized - for example, "what should I have for breakfast" is not a good question because it applies only to that person for that day. But reframing it as "how should I decide what to have for breakfast" would, IMO, cleanly bring it under the scope of proper philosophy (and in fact famous philosophers like Sartre contemplated this very question). When asking about a specific situation (deliberate thought experiment aside), questions should be concerned with *how* the answer can be decided rather than *what* the answer is.
* If the question is a matter of fact - for example, "how do we know the capital of France?" is IMO on topic, but "what is the capital of France?" (expecting an answer of just "Paris") is not.
* If the question falls firmly under some other discipline already. For example, questions about the nature of the atom were once a major interest of philosophy, but now we have physics to cover much of that, so they should be asked there unless the question is about an aspect of particle theory that is not addressed by physics.

I would caution against banning subjective questions or those which appear undecidable in our reality. It can be argued that all knowledge is ultimately subjective. There are areas of philosophy that happily investigate subjective topics (aesthetics) and those that are out of reach for our experience (metaphysics). Further, many topics appear undecidable, but on closer (philosophical) inspection prove to be not so. We can hardly expect askers to be able to predict whether that is the case when asking, since usually people ask because they recognize their own ignorance.

That said, subjective questions that merely poll the userbase should not be allowed. So, "what does philosophy say about what color is prettiest" is IMO on topic, while "what do you guys think is the prettiest color" is not.