Please excuse me, this is a bit of a personal musing, or perhaps navel gazing.
It's been 5 years since I graduated from St. John's college. I arrived there a pretty doctrinaire 18 year old who thought he had all the answers, and I left at 22 being somewhat less sure of myself, or at least less settled in my ideals. Even if I didn't learn humility (it will take more than a college to teach me that, I think) I learned that I couldn't, personally, find the answer to everything.
In between those two points I was surrounded by questions. "Can virtue be taught?" "Does Anselm Prove that there is a God?" were some specific ones. Behind them were more general questions 'What is the right way to live our lives?' 'How do we know what we know' and other such things. With a few exceptions -- does Anselm prove that there's a God? No. -- these questions were not answered. Questions like that are odd because people ask them earnestly, and yet, if you ask the asker, they will be forced to admit that they don't expect to find an answer.
What is the point of a question that has no answer? When I was at college people spoke of 'loving the questions' and some authors (such as Heidegger) seemed to assume that asking them was the only point. But language is a set of tools, and a question is a tool get an answer. If a question cannot be answered, isn't it a defective tool, or a tool being misused?
I find a few responses to this somewhat convincing, and they are rather related to each other.
The first is that philosophical questions can be a sort of Koan, a tool of contemplation. They are unanswerable, but in thinking about them we examine our preconception and come to a more enlightened way of thinking. In such a view philosophy need not answer everything it asks in order to make the philosophical life blessed and enlightened, and make all those questions worthwhile, not matter how many times they are asked. The problem with this is that a Koan is designed to be unanswerable, and is phrased in such a way that the question itself does not obsess the student so much that they lose sight of the larger lesson (generally, a koan is trivial, not momentous, in its phrasing). Philosophical questions, on the other hand, are asked earnestly, and are not designed to expand the mind but to set forth an objective -- the answer, the truth. It is a goal that we can never reach.
Next, one could say that philosophical training is useful as a way of expanding young minds, a way of instilling a generally curious but skeptical spirit in people that will persist even when the student ceases to practice philosophy. In this telling, philosophy is just a stage of life, a way of educating the young, but not a good in and of itself. I find this account more convincing, since it matches what I gained from spending 4 years with my words and thoughts chasing their own tale. Philosophical inquiry does not provide you with a set of tools, per say, rather it shapes your mind and gets you used to looking at things from different angles.
If I did gain a concrete tool from those years of study, it was a negative one. I've never seen a philosophy build something up that was convincing -- our assumptions always leave something out of the system, and so in the end it is but a pale reflection of reality, at best. But I have seen philosophy do a wondering job of tearing things down. And not just anything, but specifically other philosophies, other reasonings. Philosophers have no better idea than the rest of us what is right or wrong, or what knowledge is, but they are uniquely positioned and trained to dismantle bad philosophies and spot specious arguments. At its best, this negative work can free us from sophistry and let ordinary life continue as it once did, untroubled by bad but imperious reasoning.