The study of Philosophy is not like other subjects. One cannot define philosophy without already doing it. The question "what is philosophy?" demands a philosophical answer. This is not the case for, e.g., history or mathematics - you don't have to be doing history or math in order to define them; you don't give a history of history in order to grasp what historical inquiry is. Instead, "what is history?" and "what is mathematics?" are themselves philosophical questions. The historian or mathematician may ply his trade without defining it, but this very practice of the discipline can only take place according to some implicit supra-historical or supra-mathematical conception of what is being done which can only be articulated in philosophical terms.
This fact in itself may lend some credence to Aristotle's notion that first philosophy is the architectonic science - the knowledge by which all other knowledge is measured and directed. But not every philosopher would accept this characterization of his discipline. There are almost as many conceptions of what philosophy is as there are philosophies! This is surely not the case with other subjects.
When one cannot even grasp what philosophy is without doing it, it seems that one cannot even begin to study it without having already begun. This raises, for me at least, the question of how one is to begin. As has been pointed out many times, in philosophy as in anything else a little mistake at the beginning leads to great errors in the end, so it seems very important to begin philosophizing from the proper place. Anything at all can be made to follow from a falsehood. If two philosophers do not at least broadly agree on what philosophy is, they are likely not to agree on much else in philosophy either. But how are we to adjudicate between them? Shall we conclude that, since philosophers agree neither on their principles nor on their conclusions, therefore knowledge or truth in philosophy is impossible and that there is only opinion or speculation? But this in itself is a highly contested philosophical position, and can only be defended by taking certain definite positions about truth and our relationship to it.
The question "where to begin?" seems equivalent to the question "how do I establish first principles?" Granted that we begin thinking always already holding any number of principles - I presume that there is no really presuppositionless thinking - the trick is to be able to identify those presuppositions which are both certain and fundamental, and to weed out those which are either false or doubtful. We cannot simply begin with our first principles, because the principles we happen to have when we begin need to be tested and approved or rejected. What is "first" in my mind and first in fact may not at all be the same. By what criterion, then, do I examine my own presuppositions?
