If we are to construe philosophy as having the highest degree of generality insofar as it legitimates and accounts for all intellectual practices, we may be justified in our belief of it as a queen of the sciences.
Kant proposed, I argue, that there are foundations to our thought, principles that regulate our thinking insofar as we are rational at all; these assumptions underpin the whole enterprise of exploration and thought itself. These reflective principles of judgment are; systematicity, unity, among others. Let us consider unity for now.
Unity is the ideal of knowledge being in a full continuum. That mathematics may be on the same par as aesthetics; that engineering with medicine; that metaphysics be on par with logic. What are the underlying regulative principles upon which they consist? It is such a construal of the question, if it can ever be answered, that may demonstrate the fundamental unity of knoweldge.
Does philosophy have a common base? This seems a most ridiculous suggestion, at least, prima facie. Given the law of a philosopher always having an equal yet opposite opponent; given that there are many who give strong arguments for theses so vastly distinct, and often, so vastly opposite; from atheism to realism, nominalism to realism.
Philosophers, if they are genuine of heritage from the tradition of Socrates; have the fundamental desire to understand, and express this by their fundamental of explaining. This is very vague, indeed. But to explain, one may, as a legitimate normative principle, must have something explainable. It is here, that we may input the desiderata of the principle of suffiicient reason; that every ‘why’ question has an answer.
We are but the immature child, who asks the parent why; the question of why in this child consists of a continuous enquiry, further and further they go, asking deeper truths of an explanation; why did x? why is this answer adequate? what constitutes an answer? why should I accept it?
Knowledge, and reality, we must conceive of the former insofar as we can understand the limits of the latter. Such is the transcendental project of philosophy.