Explanation
The geometrical method
Spinoza builds later claims upon explicit definitions and axioms. The form is intended to replace moral accusation with causal understanding, although interpreting the starting definitions remains essential.
Substance monism
Only God or Nature exists through itself. Individual things remain real as finite modes, but they are not independent substances.
God or Nature
Spinoza’s God is immanent rather than external to the world. Nature does not wait upon divine decisions; its order expresses divine necessity.
Necessity and freedom
Freedom is not absence of cause. Something is freer when it acts from the necessity of its own understood nature rather than being passively driven by external causes.
Against final causes
People know their desires but not their causes, then project purposes onto nature. Spinoza replaces explanations by ends with explanations through causal structure.
Mind-body parallelism
Mental and bodily events do not push each other as separate substances. They are the same order expressed under thought and extension.
Inadequate and adequate ideas
An inadequate idea is partial and confused because its causes are not sufficiently understood. Adequacy grows through grasping common structures and necessary connections.
Conatus
Striving to persist is not an optional desire added to a thing. It is the active expression of what that finite thing is.
Emotions as natural events
Spinoza refuses to mock or condemn emotions as violations of nature. Causal explanation creates the possibility of transforming them.
Activity and passivity
People are active when events follow from their adequate nature and passive when external causes determine them through fragmentary ideas.
Reason and cooperation
Rational self-interest is not isolation. Human powers grow through friendship, shared knowledge and institutions that reduce fear and conflict.
Intellectual love
Knowledge of necessary reality produces an active joy not dependent upon possession of a changing object. This is Spinoza’s highest blessedness.