Nietzsche and Descartes: Body, Soul, and Substance

Nietzsche’s Critique of Traditional Philosophy

From a genealogical perspective, Nietzsche demonstrates that traditional philosophy—specifically Plato and Christianity—has committed the error of rejecting the body and the senses. For Plato, the soul is the substantial component of human beings; it is immortal and eternal. Instead, the body is the accidental component, guilty of vices and errors. The soul must submit to the body and discipline it.

Christianity and the Ascetic Ideal

Christian values are derived from Platonic philosophy. The extreme example is the mystical and ascetic movement, which goes as far as torturing the body so that the soul may reach God. Having denied Christianity and all Western moral foundations, Nietzsche’s thought dedicates itself to offering a new moral system.

Heraclitus and the Reality of the Senses

Heraclitus was the only one who claimed continuous change because he rejected the notion of the eternal and static. He also thought that the senses were deceptive for being too fleeting, but he was wrong; permanence is not the product of the senses, but of reason. According to Nietzsche, the world we perceive through the senses is the only true reality; reason is merely a "deceptive old woman." Nietzsche rejects essentialism and avoids dualism.

Descartes and the Nature of Substance

Descartes speaks of substances defined as "a thing that exists in a way that it needs nothing but itself to exist." However, this can only be fully explained as a property of God. He makes a distinction between infinite substance (God) and finite substance (extension and thought). Substances have an attribute which is their essence, and they identify with it, while modes are the ways in which they appear.

The Human Compound: Res Extensa and Res Cogitans

The human being is a compound of res extensa and res cogitans. The latter possesses the attribute of thought as its essence, and its modes include everything that is an object of consciousness: thinking, doubting, willing, imagining, and even feeling.

The Cogito and the Classification of Ideas

In addition, Descartes' thought on man is defined by the "cogito, ergo sum" (I think, therefore I am), which leads to the question: "What am I?" To this, the philosopher replies: "I am a res cogitans, a substance that thinks." The objects of thought are ideas, which Descartes carefully distinguishes into two aspects: ideas as mental acts and ideas as objective content.

Three Types of Cartesian Ideas

Descartes distinguishes three types of ideas:

• Adventitious ideas: Ideas taken from things outside of the self, originating from the external world.
• Factitious ideas: Ideas created by the mind through the composition of adventitious ideas.
• Innate ideas: Ideas that our reason possesses and forms for itself. This group includes the idea of God and the concept of perfection.