Descartes' Philosophy: Physics, Dualism, and Ethics

Descartes' Mechanistic Physics

Influenced by Galileo, Descartes believed that in the material world, only two things are relevant: how the universe is composed of indefinite matter, and the movement that has been assigned (three laws, largely established previously by Galileo).

The highlight of his work is his mechanistic physics, which treats the universe as a giant machine. This machine is formed by compact matter that occupies the entirety (what we call emptiness is actually ether) and forms eddies that adhere to each other. In turn, he states that comets are merely bits of matter expelled from a whirlwind due to centrifugal force, which are then absorbed by another. Finally, he argues that bodies are artifacts, distinguishing between: animals [without sensation or freedom] and humans [with sensation and freedom].

Descartes' Dualism and Anthropology

As a supporter of dualism, Descartes separates humanity into two heterogeneous parts: body and soul. To the body, he attributed all the features explained by his mechanistic conception of physics, while to the soul, he assigned two powers:

• Understanding: The capacity for comprehension.
• Will: The moral capacity to choose one thing over another.

The latter (will) is what differentiates humans from other animals, as it implies freedom (the ability to choose) and accountability. He characterizes this as a private and conservative morality, and sets forth four minimum ethical rules to aid in making correct decisions:

1. Obey the laws and customs in force, and follow the more moderate views.
2. Be firm and decisive in action.
3. Do not desire anything that cannot be attained.
4. Strive to cultivate reason.

From this separation between body and soul arises the problem of the communication of substances. Descartes posited three substances (God, body, soul), and human beings possess both body and soul. But how can two parts, considered independent yet united, communicate? Descartes attempts to answer this issue:

• Descartes appeals to ignorance, as he attributed this function to the pineal gland of the body, whose true function was unknown in medicine at the time.