Schopenhauer, Kant, Hume e percepção

Arthur Schopenhauer - Wikipedia, the free encyclopedia: "Schopenhauer's identification of the Kantian noumenon (i.e., the actually existing entity) with what he termed Will deserves some explanation. The noumenon was what Kant called the Ding an Sich, the 'Thing in Itself', the reality that is the foundation of our sensory and mental representations of an external world; in Kantian terms, those sensory and mental representations are mere phenomena. Schopenhauer departed from Kant in his description of the relationship between the phenomenon and the noumenon. According to Kant, things-in-themselves cause phenomenal representations in our minds. Schopenhauer, on the other hand, believed phenomena and noumena to be two different sides of the same coin; noumena do not cause phenomena, but rather they are simply the way by which our minds perceive the noumena, according to the Principle of Sufficient Reason, which is explained more fully in Schopenhauer's doctoral thesis, On the Fourfold Root of the Principle of Sufficient Reason.

Schopenhauer's second major departure from Kant's epistemology concerns the body. Kant's philosophy was formulated as a response to the radical philosophical skepticism of David Hume who claimed that causality could not be observed emprically. Schopenhauer begins by arguing that Kant's demarcation between external objects, knowable only as phenomena, and the Thing in Itself of noumenon, contains a significant omission. There is, in fact, one physical object we know more intimately than we know any object of sense perception. It is our own body.

We know our human bodies have boundaries and occupy space, the same way other objects known only through our named senses do. Though we seldom think of our bodies as physical objects, we know even before reflection that it shares some of their properties. We understand that a watermelon cannot successfully occupy the same space as an oncoming truck. We know that if we tried to repeat the experiment with our own bodies, we would obtain similar results. We know this even if we do not understand the physics involved."