Plato and Kant

   To understand the revolution brought about by Copernicus in astronomy, one must first know something about the system before the Copernican system. The planetary system of Ptolemy. This is the only way to understand that Copernicus flipped the position of the Earth and the Sun from the older system. Therefore to understand Kant's Copernican revolution, one must know the metaphysical system that came before. It is instructive to view Kant's Copernican revolution from the perspective of the classical metaphysics of Plato based on Plato's Timaeus.

    In the metaphysics based on the "Timaeus" there are two realms; being is divided into. The sensible and the intelligible. The realm of the sensible is the realm of matter, of change. And of growth and decay. This is the realm everyday life. The sensible world of everyday life is dependent or a reflection of the intelligible realm. The sensible realm is regarded as a receptacle or a mirror that reflects the intelligible realm. The intelligible realm is timeless, it is not subject to growth and decay; it is the realm of the Forms. It is the realm of truth, not opinion. The only way to gain access to the intelligible realm is through reason, a rational vision. Through the truths of mathematics and dialectic can a human gain a vision of the intelligible realm. The sensible realm is dependent on the intelligible, not the intelligible on the sensible. It is worth repeating that the only way to gain access or a vision of the intelligible is through reason: the truths of mathematics and dialectical reason are the tools to gain access to the intelligible realm. The sensible realm is the realm is a copy or reflection of the Forms of the intelligible realm. The intelligible realm is the realm of truth, while the sensible realm is the realm of opinion. With this briefest of outlines of Plato's classical metaphysics, we shall turn to Immanuel Kant's metaphysical system.

    Kant also divides existence into two realms. Kant gives these two realms the colorful names of the phenomenonal and the noumenal or the thing in itself. The phenomenal realm is a counterpart to the sensible realm in Plato's metaphysics. As for the noumenal or thing in itself, Kant oddly uses the term "intelligible" to describe it. In reading Kant it is important not to be misled by his colorful coinages. When Kant says transcendental it does not refer to spiritual entities. When Kant says that entities are transcendental, he means that they are innate categories in the subject; that the transcendental can cut objects and or qualities out of the continuum of the thing in itself. An example would be when we say a car is red and a bicycle is red. Red then transcends or goes beyond the objects it resides in. When a quality or object can be cut out; it can be compared with other qualities or objects. It can then become a term in relation to other objects or qualities. Nothing more is meant by transcendental; it has no spiritual meaning for Kant. Kant's phenomenal realm is like the sensible realm described in Plato's "Timaeus." It is the realm of empirical science and everyday life. It is the realm of change, growth and decay. Unlike Plato's sensible realm Kant's phenomenal realm is generated by the subject; everyone has innate categories that generate the phenomenal realm. The innate categories is what Kant calls "transcendental." The transcendental is how subjects construct experience; all subjects possess these categories. It is the transcendental categories that construct the experience of the everyday world. The first of these transcendental functions is the transcendental aesthetic. The transcendental aesthetic cuts or filters raw sensation into space-time. Unless a subject can locate an object in space-time, it cannot compare it with other objects. To repeat space-tine is not in the object, but is put in by the subject. As the transcendental dance continues, Kant's categories impart all the relations of empirical science; all put in by the subject and not intrinsic to the object. A point that cannot be stressed strongly enough is that the categories are universal to all subjects. So we all live in the same world. Thus making Kant's idealism objective instead of personal. The mind is like a mirror, but with certain distortions or functions. The mind with the transcendental categories becomes the counterpart to the receptacle in the "Timaeus."  The other realm of the noumenal or the thing in itself is not dependent on the subject for its existence; nor is it subject to growth and decay. The noumenal is not in space-time. The noumenal is a counterpart to the intelligible realm of Plato. The difference is reason gives access to the intelligible realm in Plato; in Kant it is only accessible through moral intuition. For Kant reason can never go beyond the phenomenal realm. If one tries to use reason to discover what is beyond the phenomenal realm, she shall only be led into illusion.

    Now it is possible to understand Kant's Copernican revolution. In the classical metaphysics of Plato, reason leads to the intelligible realm: the highest realm beyond change and opinion. In Kant, reason can never escape the sensible world of everyday life. Only moral intuition can lead to the timeless realm of ultimate truth. As Copernicus flipped the Sun and the Earth so Kant flipped the use of reason and the position of mind.