Spinoza

The line of argument leading to Baruch Spinoza's proposition that "extension is an attribute of God," or in other words "God is extended," can be explained by first beginning with Spinoza's definition of substance. Spinoza's definition of substance leads to a theory of substance entailing that God, equivalent to everything else, is the only substance to exist. The definition of substance prior to the theory's propositions consists of substance being a response to the Aristotelian and Descarestian definition of substance. For Aristotle, substance signified independent and primary existence for which Descartes contributed to by asserting that God, the only entity independent of everything else, created substance as entities outside of himself (Spinoza, 23). Spinoza challenges these definitions by defining God simply as a substance without making the proposition that substance is the primary building component of everything and that it is created by God as an external entity.

By attribute, I mean that which the intellect perceives as constituting the essence of substance. Ð'...By God, I mean a being absolutely infinite -- that is, a substance consisting in infinite attributes, of which each expresses eternal and infinite essentiality. ...By that which is self-caused, I mean that of which the essence involves existence, or that of which the nature is only

conceivable as existent (Spinoza, 35).

In other words, substance is the sum of the universe and an attribute is a collective property of the universe, and the sum of something's attributes, equals it's substance. Because substance is self-caused, meaning a substance's nature involves existence; it cannot be produced by another substance. Building from Spinoza's proposition that there cannot be more then one substance having the same attribute and that existence belongs to the nature of substance it follows that substance would have to exist as infinite or finite. Substance cannot be finite because that would imply that there are substances of varying nature for which they are limited relative to each other. An example would follow, that if substance were finite, there would be finite bodies for which other greater finite bodies could be conceived. If substance were finite there would be a common attribute of existence amongst them and since substance cannot share attributes (proposition 5) substance is infinite. Following from the proof that substance is infinite, that is having infinite attributes, means that there is only one substance in existence that necessarily contains every possible attribute. I would be impossible for two substances of infinite attributes to co-exist because there