1. The argument for the existence of bodies (Meditation 6) 1.Nature provided me with a strong propensity to believe there are bodies. 2.The only way I could have this propensity and be wrong is if God deceives me. 3.God is not a deceiver. Therefore: There are bodies. Cartesian Dualism A person's body is extended substance - it is physical and conforms to physical laws. A person's mind is thinking substance - It’s “the thing that thinks” that I discover in Meditation 2 when I consider the cogito argument. Each person is a mixed substance composed of two substantial parts: a mind (thinking substance) and a body (extended substance). Each mind is essentially thoughtful and unextended (in space). Each body is essentially extended (in space and time) and thoughtless. Mind and body are able to exist independently. Mind and body interact with each other: each can cause changes in the other.

2. A. Argument from certainty 1. I am certain that I exist. (Remember: Cogito ergo sum.) 2. I cannot be certain that my body exists. Therefore: I am something different from my body. B. Argument from conceivability 1. I can clearly conceive of myself as existing without a body. 2. Anything I can clearly conceive is a genuine possibility. (God could make a reality that matches my conception.) Therefore: It is possible for me to exist without a body. (So I can’t be the same thing as my body.) C. Argument from divisibility 1.Bodies are divisible. 2.Minds are not divisible. 3.If a = b then a and b must have exactly the same properties. (Leibniz’s Law) 4.By 1 and 2, minds and bodies do not have the same properties. Therefore: Minds and bodies are distinct things.

3. Mental StuffPhysical Stuff We are aware of it directly, through introspection. Indivisible Unextended Intelligent, aware Free of natural laws Has properties like: Feeling pain Desiring chocolate Expecting nice weather Thinking about Descartes Being afraid of spiders We are aware of it indirectly, through the senses. Divisible Extended in space Without thought, awareness Determined by natural laws. Has properties like: Being wet Having a density of x grams/liter Moving at x meters/second Being on a table Having a temperature of 68 F

4. The Interaction Problem – Correspondence with Princess Elizabeth of Bohemia [May 6, 1643] Elisabeth asks Descartes to explain how the soul can "determine the spirits of the body to produce voluntary actions." She notes that determinations of motion requires an impulsion and, hence requires either contact or extension. She clearly indicates that these can not apply in the case of mental "determination." [May 21, 1643] Descartes distinguishes bodies, souls [minds], and body-souls [body-minds] and claims that each of these "notions" cannot be explained "...except through itself." [June 10, 1643] Elisabeth responds: "...it would be easier for me to concede matter and extension to the soul, than the capacity of moving a body and of being moved, to an immaterial being. For, if the first occurred through `information', the spirits that perform the movement would have to be intelligent, which you accord to nothing corporeal. And although in your metaphysical meditations you show the possibility of the second, it is, however, very difficult to comprehend that a soul, as you have described it, after having had the faculty and habit of reasoning well, can lose all of it on account of some vapors...."