Unit 2: Spinoza and Leibniz

Spinoza: Substance

Spinoza, a prominent Rationalist, takes Descartes' definition of substance to its logical conclusion. While Descartes allowed for "created substances," Spinoza argues that if a substance is truly independent, there can only be one.

Pantheism: "Deus Sive Natura"

Spinoza identifies Substance with God and God with Nature. This is summarized in the phrase Deus Sive Natura (God or Nature).

• Infinite: Substance must be infinite because if it were finite, it would be limited by something else, making it dependent.
• Self-Caused (Causa Sui): Substance is its own cause; its essence involves existence.
• Indivisible: Since it is infinite and simple, it cannot be broken into parts.

"By substance, I understand that which is in itself and is conceived through itself." — Spinoza.

Spinoza: Attribute and Mode

To explain how the one infinite substance relates to the diverse world we see, Spinoza introduces Attributes and Modes.

1. Attributes

Attributes are what the intellect perceives as constituting the essence of substance. While God has infinite attributes, the human mind can only perceive two:

• Thought (Extensionless): The realm of minds and ideas.
• Extension (Physical): The realm of matter and bodies.

Crucially, these are not two different things, but two ways of looking at the same substance (Parallelism).

2. Modes (Mensa)

Modes are the modifications or "affections" of substance. They are the individual, finite things we encounter in the world—like a specific chair, a specific thought, or a specific person.

Leibnitz: Monadology

Gottfried Wilhelm Leibniz rejected Spinoza's single substance and Descartes' dualism. Instead, he proposed Pluralism: the universe is made of an infinite number of simple, spiritual substances called Monads.

Characteristics of Monads

• Simple: They have no parts; therefore, they are indivisible and indestructible.
• Windowless: Leibniz famously stated that monads "have no windows". Nothing can enter or leave a monad; they do not interact physically with one another.
• Spiritual/Psychic: They are not material atoms but units of force and perception.
• Unique: No two monads are exactly alike (Identity of Indiscernibles).

"The Monad... is nothing but a simple substance, which enters into compounds; simple, that is to say, without parts." — Leibniz.

Pre-established Harmony

If monads are "windowless" and cannot influence each other, how does the world seem so coordinated? Leibniz explains this through Pre-established Harmony. God, as the supreme monad, created all monads such that their internal changes perfectly correspond to one another, like two clocks set to the exact same time.

Hierarchy of Monads

1. Bare Monads: Have confused perceptions (found in inorganic matter).
2. Soul Monads: Have memory and clearer perception (animals).
3. Spirit Monads: Have self-consciousness or "Apperception" and reason (humans).
4. God: The Monad of Monads; possesses perfectly clear and distinct perception.