Then, there's a third category of questions where these two approaches fail. In fact, when asked a question of this type, one does not immediately know how to go about proceeding to investigate it, e.g. "What is truth, Is there a God", etc. [...] But apart from its misapplication to scientific matters (such as the shape of the earth), is the moral relativistic approach a useful one, despite its acceptance as an axiom in a lot of universities? Now, that is a long debate.IMHO, the moral relativistic approach as you describe it constitutes an interesting mental exercise, but not a useful one per se.
If there is absolutely no hint or proof that something exists, how can it be useful to debate it (apart from intellectual masturbation) ?
Let's say we live in "the matrix" and that there is _absolutely_ no way to get out of it or anything that could hint its existence. Given that assumption, what is the point of debating whether it exists or not ? Even if there really was a matrix, how could it be useful for us to know this piece of information ? That knowledge wouldn't serve any purpose as the said matrix wouldn't in any way interfere with our universe and even less with our mere human lives. Of course, if there was any way to escape the matrix or if it would even subtly interact with our universe, that would be another question.
In the same vein, I dislike the concept of "agnosticism". If we had to be agnostic about everything that is not possible to prove (or even partially, through subtle hints) then we'd have to be agnostic about an amount of things only limited by our collective imagination. For instance, we'd have to be agnostic about "the matrix", the fact that our universe is an "atom" inside a much larger universe, that we're all imagining this universe through an induced dream, etc.
On a side note, this is one of the reason I find it more interesting to debate with theists that believe they have evidence for God than agnostics or theists that base their belief on faith.
PS: I'm not trying to discard philosophy and I actually admire this discipline. All I'm saying is that it should not attempt to answer the wrong questions.