Scientific explanation

It is only after Schopenhauer has explained the basic principles of his transcendental idealism that he turns, first, to the question of empirical knowledge of the world as representation, and secondly to thing-in-itself in the transcendental metaphysics of the world as Will. This order of topics is appropriate to Schopenhauer's exposition, given his thesis that the only correct philosophical methodology is to begin, not with either the object, in the manner of pure materialists, nor with the subject, as in Fichte's purely subjective idealism, but with representations that are theoretically analysable into interpresuppositional ontically inseparable subject and object. Schopenhauer is now prepared to begin a detailed investigation of the empirical world as representation, to be followed by an analysis of thing-in-itself as Will.

The world as representation for Schopenhauer is the realm where the principium individuationis and fourfold root of the principle of sufficient reason apply. It is also where epistemic criteria of empirical knowledge concerning the world of appearance that are falsely assumed by materialists and naive realists to constitute the only truths about the world find their proper place.