Logic

Spinoza’s Argument for Substance Monism and Common Objections Spinoza’s Ethics is widely thought of as Spinoza’s greatest work. One noteworthy claim that he makes in his Ethics is his argument for substance monism, or the existence of only one substance. In Proposition 14, Part I of his Ethics, Spinoza states that “There can be, or be conceived, no other substance but God.” This statement amounts to saying that everything else in this world, whether it is extended or not, is a mere image of God. Spinoza’s proof for this comes in three steps. One, assume that no two substances can share an attribute. Two, assume that there exists a substance that contains infinite attributes. Three, by these two assumptions, another substance cannot exist because it would have to share an attribute with God. Although there are objections claiming these assumptions and, consequently, the proposition are wrong, these objections are based on misinterpretations of Spinoza’s definitions, and I believe Spinoza is correct in arguing for substance monism. In order to prove my point, I will first define some terms and give some axioms that Spinoza uses. Then I will prove the two assumptions he uses in his proof, and argue for substance monism. Afterwards, I will proceed to give the most common objection to Spinoza’s proof, followed by a refutation of this objection. In the beginning of his Ethics, Spinoza gives the definitions and axioms that all of his propositions are based on. Spinoza defines a substance to be that which is in itself and is conceived through itself. A mode is defined as the affections of substance (we will use the term affections in place of modes.) An attribute is that which the intellect perceives of substance as constituting its essence. For example, if we assume a tree to be a substance, an attribute is what we perceive to be the essences of the tree, and pine, maple and willow would be some of the many modes of trees. In reality we would not consider a tree to be

References: Ariew, Roger, and Eric Watkins. "Baruch Spinoza, The Ethics (1677)." Readings in Modern Philosophy: Volume I. N.p.: Hackett, n.d. 158-165. Brown, Curtis. Classical Modern Philosophy. Course home page. Dept. of Philosophy, Trinity University, San Antonio. 23 Apr. 2008 <http://www.trinity.edu/cbrown/modern/spinozaPartI.html>. Nadler, Steven, "Baruch Spinoza", The Stanford Encyclopedia of Philosophy (Fall 2006 Edition), Edward N. Zalta (ed.), URL = <http://plato.stanford.edu/archives/fall2006/entries/spinoza/>.