What kind of a tragedy is Macbeth? Is it a study in ambition, or a study in fear? Does it merely show the case of a 'disobedient' general, or it shows the deep psychological yearnings of every human being?
I suggest Macbeth is all of the above, except I wouldn't necessarily think of this discussion as discussing what kind of a "tragedy" the play is. I'd think of it as discussing what is the central subject or idea in the play. Whatever the central theme is, it is still a tragedy. Whether it is a play about ambition or fear, it is still the same kind of tragedy.
That said, does it have to be just one of the above?
Yes, now that you have said it, I get your point. It is a tragedy after all. What I should think about are the various factors that are shown to bring about whatever happens in the play. Actually I am just a beginner student of English, and I need to develop the sense of looking at things properly. That I why I am looking forward to feedbacks and guidances from every side. The question I have raised here was raised in the classroom by our teacher. Please do carry the discussion further so that we get a more complete idea about it.