1. Ethics Demonstrated in Geometrical Order
Baruch Spinoza
Ethics Demonstrated in Geometrical Order

2. Spinoza’s Life
Spinoza ( ) was a very interesting figure personally, and is notable for the fact that he lived largely by his philosophical views.
Spinoza’s family were wealthy Portuguese Jews who moved to Amsterdam to escape religious persecution.

3. Spinoza’s Life
Unlike other parts of Europe, Jews were free to practice Judaism in Amsterdam provided they did not attempt to convert Christians to Judaism.
This was very different from the marranos Jewish communities of Spain and Portugal, who lived as Catholics in public but illegally practiced Judaism in private.

4. Spinoza’s Life
After both his parents died, Spinoza began to express his philosophical views - and their theological implications - publicly.
His rejection of the immortality of the soul, and his claim that God is both physical and spiritual led to his being excommunicated from the Synagogue in Amsterdam when Spinoza was 24.

5. Spinoza’s Life
His excommunication meant that no Jew could have any contact with Spinoza, including his family.
His works were banned by Catholics, Calvinists, and Jews alike.
And, to protect his intellectual freedom, he refused an offer to be a professor at Heidelberg after Leibniz (who discovered the calculus) recommended Spinoza for a position.

6. Overview of Spinoza’s Ethics
So what did he say that caused his so much trouble?
Spinoza was a monist - he thought that there was only one substance that could be understood in infinitely many ways (including from a physical perspective and from a spiritual perspective).
Since nothing exists except this substance, and everything in the world is an attribute of this substance, Spinoza identified it with God.

7. Overview of Spinoza’s Ethics
Furthermore, since God is the only substance, and everything else is an attribute of Him, everything that exists does so by necessity.
This implies that nothing could be different from how it is.
It also means that free will is an illusion - and that Decartes’ method of doubt (which requires the existence of free will) is impossible.

8. Outline of Spinoza’s Ethics
When reading the Ethics, it’s helpful to keep the following outline in mind - so that you can follow Spinoza’s demonstrations.
The Ethics is divided into five parts.
Part I gives an account of the nature of the universe.

9. Outline of Spinoza’s Ethics
Part II gives an account of the human mind and body as part of the universe as explained in Part I - and of how we can know the universe we are part of.
Parts III - V give an account of the human condition and how we can live the best life given what was shown in Parts I and II.

10. Ethics: Part I
Spinoza’s literary style is heavily influenced by his commitment to Cartesian rationalism.
You may have noticed that he wasn’t kidding when he said he would demonstrate a human ethics “in geometrical order.”

11. Spinoza presents definitions (labeled ‘D’); axioms (labeled ‘A’); propositions (labeled ‘P’); scholia (which are explanatory notes, and are labeled ‘S’); corollaries (which are propositions that follow from ones already proven, and are labeled ‘C’); and notes (labeled ‘N’).
Spinoza’s debt to Euclid’s Geometry should be obvious.

12. Outline of Ethics: Part I
To help you see what Spinoza is doing it helps to keep in mind the organization of his propositions.
Propositions 1-15 prove the essence of God as substance, and His necessary existence.
Propositions prove that God is causally efficatious.
Propositions use the previous proofs to critique Judaism and Christianity.

13. Ethics: Part I
One of Spinoza’s aims in Part I is to reject Descartes’ argument that there must be at least two substances - matter and spirit.
Building on an insight essentially identical to Princess Elizabeth’s objection that two distinct substance cannot causally interact, Spinoza argues that dualism is inherently contradictory and that monism is the only internally consistent account of substance.

14. Proof of God
Spinoza gives a definition of substance that Descartes would agree with (recall Meditation Six): substances can be conceived to exist independently of other things (modes cannot).
But this means that a real substance cannot be caused by anything else (any substance with a different nature), since if it were caused by something else it could only be known through its cause (A4), which means by definition it would not be a substance (D3).

15. Proof of God
Nevertheless, everything must have a cause (again, Descartes would agree with this since it is a restatement of the principle that something cannot come from nothing).
Thus, since substance cannot be caused by anything else, it must be its own cause.
Thus, substance necessarily exists because it is its own cause and by D1 anything that is its own cause necessarily exists (P7).

16. Proof of God
Furthermore, this substance is infinite because if it were finite it would be limited by something like itself (or of the same kind).
But, Spinoza has shown that there cannot be two or more substances of the same kind (P5), because there would be nothing essential to their natures that could distinguish them. If there were, they’d be modes rather than substances.

17. So, nothing could make a substance finite since there is nothing of the same kind to limit it - and so it must be infinite.
Moreover, substance must have infinitely many attributes, because it has infinite reality (it can cause infinitely many things), and the more reality a thing has, the more attributes it must have (P9, P11).
And since two substances cannot have any of the same attributes, there can only be one substance - which necessarily exists.

18. This point is reaffirmed when we consider that a substance must cause itself, since two substances of different kinds cannot cause each other.
Since there cannot be two substances of the same kind; since any substance that exists must have infinite attributes; and since two substances cannot have any attributes in common, exactly one substance exists.
Spinoza identifies this substance as God.

19. Proof of God
This is because God has infinitely many attributes; He necessarily exists; and He is His own cause.
So, pace Descartes’ claim that there is God, matter, and spirit; Spinoza claims that there is exactly one substance - God - and that everything else exists in Him and is conceivable or knowable only through Him.

20. Spinoza’s God-Substance
What Spinoza means when he says that everything exists in God is that everything is a mode of the God-substance.
Extension, for instance, is a mode of this God-substance (in which case God is an extended - i.e., physical - being).

21. Spinoza’s God-Substance
All particular objects - including human minds and bodies - are also modes of the God-substance.
Furthermore, everything that exists necessarily exists (because it is a mode of God and He necessarily exists); and everything that is conceivable exists (because it is only conceivable through God) - and so necessarily exists.

22. Spinoza’s God-Substance
So, Spinoza denies that God exists beyond the created world.
Rather, God and the created world are the same thing.
And God expresses himself and his nature through his infinitely many modes.
This means that for Spinoza, causation is merely the self-expression and self-determination of God.