1. WEEK 4: EPISTEMOLOGY Introduction to Rationalism

2. Introduction to Rationalism -i In asking “how do we know” epistemology is seeking to identify the source or sources of our ideas In asking “what can we know” epistemology is trying to determine whether or not the source of our ideas is reliable (Does it, and can it provide certain, indubitable knowledge?)

3. Introduction to Rationalism -ii We will study two answers to the first question –Rationalism (Descartes) –Empiricism (Locke) We will study one answer to the second question –Skepticism (Hume)

4. Introduction to Rationalism -iii The basic question here is whether knowledge –Comes through reason alone, prior to sense experience or a priori As the rationalists claim OR –Comes through sense experience (taste, touch, sight, smell, or sound) or a posteriori As the empiricists claim

5. Rationalism -i Descartes’s argument for Rationalism is found in his Meditations on First Philosophy Meditation One proves the unreliability of the Senses Meditation Two presents the Cogito argument for Dualism and the Wax example to argue in support of Rationalism

6. Rationalism -ii To understand Descartes’ Rationalism you must first understand his Dualism Dualism is a metaphysical position regarding the universe Dualists believe that the universe contains two substances –Body / Material Substance –Mind / Immaterial Substance Monists believe it contains one substance –Only Body / Materialism –Only Mind / Idealism

7. Meditation I -i In Meditation One, Descartes argues that there are four possible sources of our ideas –The senses (the Body) –Memory / Dreams –Imagination / Dreams and Phantasms –Abstract / Mathematical Ideas

8. Meditation I -ii Each of the four sources turn out to be unreliable –Senses frequently deceive –Memory is often mistaken –Imagination combines simple (remembered) ideas into new, complex ones –Abstract reasoning is reliable unless some powerful being can mislead us about even this

9. Meditation II - i In Meditation Two, Descartes realizes that even an all-powerful “Evil Deceiver” could not deceive him about everything –He must exist in order to be deceived Therefore, there is at least one thing Descartes knows for certain: He exists –The Cogito: “I am, I exist” is certain whenever I say it or utter it in my mind

10. Meditation II - ii From the Cogito Descartes concludes three things –He has at least one true idea, an idea that cannot be false –His mind must exist separately from his body –As long as his mind is working he is certain that he exists This leads to his Cartesian Dualism –He is both a mind and a body –His mind is the only part of him that must exist for him to exist (a new definition of the human person as a “thinking thing”) and for him to possess knowledge (his Rationalism)

11. Rationalism -iii Descartes’ Argument for Rationalism is (i) I know a priori that I exist (the Cogito), so some knowledge is a priori (ii) Even “experiential” knowledge is a priori. (As he will prove with the melted piece of wax.) (iii) Therefore, all knowledge is a priori.

12. Meditation II - iii We are already familiar with the first premise. The second premise turns on Descartes’ example of the piece of wax –The cool piece of wax has a certain feel, smell, look, taste, and (when knocked against wood, for example) sound. –But when brought close to the fire, the hot wax…

13. Meditation II – iv Has a different feel, smell, look, taste, and sound. Yet, I know it as the same piece of wax as the cool piece. –Since all of its sensible properties have changed, I must know a priori—prior to sense experience—that this is the same piece of wax.

14. Meditation II – v Therefore, the source of my idea of wax cannot be experience –I was able to know it was the same piece of wax after it melted –When it melted every sensible aspect of the wax changed –Therefore, it was not my senses but something else that gave me the ability to know the wax was the same wax

15. Meditation II - vi My idea of the wax must come from somewhere else If the source is not my body (my senses) it must my mind –Descartes is a dualist: he believes that he is made of two substances – body and mind The source of all of my ideas must likewise be my mind