Descartes’ Metaphysics: Ego Cogito, Ideas, and the External World
Descartes’ Metaphysics: A Summary
Metaphysics: Building upon his education, Descartes distinguishes the ego cogito, defining it as a thinking thing that cannot be doubted. This intuition, the ‘I’, consists of thought (a mental content as a function of self). He identifies three types of ideas:
Descartes’ Three Types of Ideas
- Adventitious Ideas: Ideas derived from the external world through direct experience (e.g., a table).
- Dummy Ideas: Mental constructions formed from other ideas (e.g., a unicorn).
- Innate Ideas: Knowledge given from neither external nor internal sources, such as the concept of infinity.
Descartes deduces the existence of God from innate ideas. From God, he infers the existence of the external world. The logic is that if we have ideas, they must originate from a perfect being (God). This evidence leads us to deduce the external world before deducing ourselves.
Substance and Attributes
Everything relies on a substance (something that doesn’t require another thing to exist). Descartes defines three infinite substances (God being one, existing in itself but not alone). Substance is formed by attributes, distinguishing between finite and infinite. Attributes are the essential properties that identify substances. Within finite substances, there are two types:
- Res Cogitans (I): A thinking thing; its attribute is thought.
- Res Extensa: The external and material world.
If we have ideas (fullness), they must come from a perfect being (God). This evidence leads us to deduce the external world before deducing ourselves.
Qualities of the External World
Descartes distinguishes two types of qualities applicable to the external world:
- Extent or Magnitude: Geometrically and objectively measurable properties of a body.
- Subjective Sensations: Qualities existing in the mind of the subject, causing sensations.
Descartes posits that nature is composed of large, interrelated bodies. He adds that the physical world (a set of particles governed by rules and deductions of extension and motion) can always be expressed mathematically. Descartes advocates a mechanistic view: nature is a machine operating on the principle of causality, with physical laws governing the world, predetermining all movements.
Anthropology: Mind-Body Dualism
Addressing mind and body (since they have different ontological features), Descartes asserts that man is the union of body (res extensa) and soul (res cogitans). He resolves the mind-body problem (man is determined by the res extensa and is free for the res cogitans) by affirming the existence of the pineal gland in the brain, which unites body and soul.
Morality: Reason and Social Behavior
Moral Philosophy: Descartes uses reason and applies it to practical affairs, setting out the aims of morality as happiness and establishing a set of rules to regulate social behavior:
- Obey the laws and customs of the country where you live, adhering to religion and guided by moderate views.
- Be firm when deciding to fulfill moral obligations.
- Change personal desires rather than the order of the world.
Finally, he says that we must accept God’s will, giving it a stoic character, a firm review of all human concerns to discover what allows us to be happy. He claims that morality is tentative and individualistic.