This question asks how much plurality belongs at the most basic level of reality. Spinoza admits one self-sufficient substance, God or Nature, with finite things as its modes. Cartesian substance dualism admits thinking and extended substances as two irreducible kinds. Leibniz instead makes the world rest on infinitely many simple, unextended substances, or monads.
Metaphysics
How Many Fundamental Substances?
Does reality consist fundamentally of one substance, two fundamentally different kinds of substance, or many substances?
Positions
- Leibnizian Substance Pluralism
Reality contains infinitely many simple, unextended substances—monads—and bodies are grounded in them rather than being substances of a second material kind.
- Spinozistic Substance Monism
Exactly one substance exists: God or Nature; every finite thing is a mode of that substance.
Held by Spinozism
- Substance Dualism
Mind and body are fundamentally distinct substances, and the mind is not reducible to the physical body.