The Point of Philosophy?

What is the point of doing philosophy? I've been reading Descartes' Rules for the Direction of the Mind, and he seems to suggest that one sits down and figures out the basics of how we go about thinking. Once this is done, and it should be more or less simple (easy and simple matters are what knowledge consists of, not difficult, obscure, and uncertain ones), one goes off and starts the real learning.

On the one hand, it does seem that there is something unfruitful about spending ones time only doing philosophy. One keeps thinking about thinking, about the truth, about the good, etc., without really engaging it in any particular fashion. Sure, the philosophizing is important, so that we don't go gallivanting off in any ol' direction. And we need to think about the core issues of the different fields to keep them on track and from becoming ossified. But sometimes, I at least tire of merely talking about talking. I want some more tangible field of study. I am doing that to an extent with History (at least history of thought), and I am thinking more and more about doing further work in Islamic Studies. Sometimes, when I am really tired of the field and the books, I'll start thinking about doing something drastic like getting a Psychology degree and doing clinical work (I have enough mental problems that I'm already engaged first-hand in the field, right?). But the point is, it seems good for one to have some more empirical field in which the real work gets done, the work that actually embeds one in the world and gives one some meaning (whether that's a career change, a different focus in one's academic path, or merely extracurricular activities). Do philosophy, then contribute to medicine, or law, or social work, or (gasp!) business. If nothing else, sitting around talking Marxism isn't going to change the world's business practices; more philosophers becoming business people has no worse a shot of working.

On the other hand, the picture is more complicated than Descartes thought. First, the more we've been thinking about basic issues of knowledge and cognition, the murkier they appear. It no longer is plausible that we can simply sit down and work out the issues at one point and be reasonably right. So we need to continue to rethink the issues, and this seems to require at least some people who are really sitting down and devoting themselves to the task full time. There don't seem to be any clearly intuited simples for us anymore, and the Cartesian method requires these simple and perspicacious, independent absolutes which one takes apart and puts together like legos, such that one can track one's process of knowing.

Second, there is far greater specialization going on now than in Descartes' time. Even within a field as neatly defined as mathematics, there just aren't any mathematicians who can claim expertise in every subfield of math. A fortiori, there isn't too much place for someone wishing to learn deeply across discipline. Descartes thought that one can learn about all different fields by oneself. Due to this, he argues that theoretical sciences are fundamentally unlike practical arts: in art, one must focus on a specialty to be any good, but in science, one thinks better and more clearly the more one learns across sciences, since the subject matters come together. All of them rely on the same basic processes of thinking. And he seems right; being able to think across disciplines does seem to be helpful for understanding the individual ones. But there's too much to learn in any given discipline now to be competent in any given one while chasing others. And one can throw off the previous scholastic shackles only if one (a) is independently wealthy and not needing to find an employer or tenure, and (b) is willing to give up all of the richness of the past as well as its errors.

So, to pursue a career purely in philosophy feels sterile and confining, cutting one off from much purpose and meaning in life. But one can't solve the issues in philosophy once and for all to go work in the other disciplines, and the issues are hardly trivial. There are important ethical and political reasons for why we keep going back to them, to rethink them. There are also concerns intrinsic to the other disciplines: physics needs to have a good account of how to get good physics in order to actually get good physics consistently. So how does one balance these concerns, given that one has to get a job somewhere to give one the time to work on the issues?