[Schopenhauer] argues that the world is my representation, and that the forms of space, time and causality are true only for appearances. He rails against materialism, declares that true philosophy is idealistic, and maintains that the true form of idealism is transcendental idealism.
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Still, this truth is only a half-truth. Transcendental idealism is the true philosophy for the world as representation. It is not, however, the true philosophy for the world as will. It is one of the basic principles of Schopenhauer’s philosophy that we have to treat the world from both perspectives. But these perspectives are complementary and begin from opposing starting points. When we view the world as representation, we begin from the subject and see the entire world as its objectification or appearance. That is the standpoint of transcendental idealism. But when we view the world as will, we begin from the object, which is the will, and we interpret the entire world as its objectification or appearance. From the standpoint of the world as will, we construct the entirety of nature as so many stages in the self-objectification of the will, and we see the subject as the ultimate stage of its objectification, the point where it reaches self-consciousness as will. What is first from the standpoint of transcendental idealism—the subject—then becomes secondary or derivative. The subject’s self-consciousness from the subjective standpoint becomes the will’s self-consciousness from the objective standpoint.