We can physically see the behavior of people with mental illnesses and diagnose them on the basis of those physical observations.
..and so?
My point is that it is not necessarily through physical observations, such as measuring blood plasma,
or what have you..
Diagnoses are based on a wide variety of repeatable observations, including patterns of behavior and other medical tests. I think that you understand what I mean by qualifiers such as "verifiable" and "repeatable". Evidence needs to be manifest to others, not just the person making a claim.
Are you implying that mental illness is only about physical abnormalities in the brain?
Everything having to do with mental activity correlates with physical brain activity, as far as anyone can tell. Whether we characterize that activity and its causes as abnormal depends on how one defines "normal". If mental states were not physical, then we would not be able to affect them by introducing physical changes to the brain--through drugs, therapy, or surgery. But the term "mental illness" is a very broad category, and I don't pretend to have any special expertise on such illnesses.
True .. but philosophy seems to be one of those subjects .. much like history.
Granted, you need to "know your stuff", but if you can waffle, it might increase your chances of passing exams.
That's true of any subject, not just philosophy. In any case, philosophy is a very broad field in the humanities. I suspect that you dismiss such subjects so easily because you haven't spent a lot of time studying them. If you had, you would know that waffling doesn't always work as well as you think it does.
Right, OK.
..but theology isn't dependent on miracles, as I'm sure you are aware.
Actually, I'm not aware of that. I don't see how any study of deities can avoid miraculous events such as divine revelation and prophecies. One can, of course, become expert in the study of religious texts and the divinities associated with them, but one can also do that with any works of fiction. If you want to interpret theology as a branch of the literary arts, I suppose I could see that as a way of maintaining that theology is not dependent on miracles.