Introduction to Philosophy (Fall '09) - class#9

Introduction to Philosophy (Fall '09) - class#9 -...

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Unformatted text preview: Organizational Information First graded assignment was handed out in First discussion section last Friday (10/2) and will be collected at the beginning of discussion section this Friday (10/9). this Meditations on First Philosophy - Meditation 6 Meditations again again Bartlett 65. Bartlett Reading for next time: Rene Descartes’s Reading Midterm Exam October 22nd at 7pm - 9pm in Midterm There will be no class the during the day on the There day of the midterm. Descartes Review From Last Time In Meditation #3 Descartes argues for the In existence of God. existence Doing so is a crucial part of his anti-skeptical project. His main argument for the existence of God: The His Trademark Argument Trademark The Cartesian Circle The Cosmological Argument In Meditation #4 Descartes confronts the In problem of error: problem How could a perfect God allow him to fall into error How about anything? about He offers three explanations. The third of which is his best attempt. Review From Last Time In Meditation #5 Descartes aims to: (1) llay out what he can know for certain ay about the nature of material things, and… about offer another argument for the existence offer another of God. of (1) Review From Last Time For Descartes, the essence of material For objects are their geometrical / mathematical / quantitative properties. quantitative “[E]ven back in the times when the objects of [E]ven the senses held my attention, I regarded the clearly apprehended propositions of pure mathematics--including arithmetic and geometry--as the most certain of all.” geometry--as Review From Last Time The Ontological Argument for the The Existence of God. Existence It is part of the concept of God that It God exists. God 2. If it is part of the concept of God that If God exists, then God exists. God 3. Therefore, God exists. 1. Review From Last Time Justification for premise 1: The concept of God is the concept of a perfect being. Existence is a perfection. So, as existence is a perfection and God is a perfect So, being, i.e., a being that lacks no perfections, then the concept of God is the concept of a being that exists. concept “[J]ust as it is self-contradictory to think of highlands in [J]ust a world where there are no lowlands, so it is selfworld contradictory to think of God as not existing--that is, to contradictory God --that think of a supremely perfect being as lacking a perfection, namely the perfection of existence.” perfection, So, Descartes holds, it is part of the concept So, of God that God exists. of Review From Last Time Justification for premise 2: If existence is a part of the concept of God, then, I If can’t think of God as non-existent. can’t But if I can’t think of God as non-existent, then it But can’t be that God is non-existent. can’t So, it must be, claims Descartes, that God is not So, non-existent. non-existent. So God exists. “From the fact that I can’t think of God except From as existing, it follows that God and existence God existence are inseparable, which is to say that God really exists.” really Review From Last Time Reason to doubt premise 1: Perfections, if they are anything, they must Perfections, be properties of the thing of which they are attributed. attributed. Properties, however, are ways in which a Properties, thing that exists does exist. thing But, existence itself, is not a way in which a But, thing exists. thing So existence is not a property and thus not So a perfection. perfection. Review From Last Time Reasons to doubt premise 2: To say that a property is part of the concept of a To thing is just to say if a thing satisfying that concept existed, it would have that property. existed, For example: to say that it is For part of the concept of a triangle to have three sides is just to say that if a thing exists and is a triangle, then it has three sides exists So, to say that existence is part of the concept of So, God is just to say that if a thing exists and is God, then it has existence (i.e., it exists). then But it doesn’t follow from that that anything But satisfying the concept God exists. satisfying Meditation 6 In Meditation 6 Descartes sets out to In establish two final and crucially important propositions: important (1) that he can know for certain that material that things do exist, and things that his mind is really and truly distinct that from his body. from (1) Meditation 6 Descartes’s arguments for these two Descartes’s propositions are interweaved in his discussion in Meditation #6. discussion We’ll look at them separately. First, Descartes wants to establish that First, he can be certain that there are material things. things. Meditation 6 In Meditation 2 he argued that he, a thinking thing In exists, but he has left it open whether he is a material thing. thing. So his proof of his own existence hasn’t yet established So whether there are any material things. whether In Meditation 3 (and 5) he argued that God exists, but In that proof left it open whether God is a material thing. that So his proof of God’s existence hasn’t yet established So whether there are any material things. whether In Meditation 5 he took himself to have shown that it In is possible that there be material objects, but that still leaves it open whether there are actually any material things. things. So his proof of the possibility of there being material things So hasn’t yet establish whether there are any material things. hasn’t Meditation 6 “Now I have a passive faculty of sensory perception, Now passive that is, an ability to receive and recognize ideas of receive perceptible objects; but I would have no use for this unless something--myself or something else--had an active faculty for producing those ideas in the first active producing place. But this faculty can’t be in me, since clearly it does not presuppose any thought on my part, and sensory ideas are produced without my cooperation and often against my will. So sensory ideas must be produced by some substance other than me--a substance that actually has (either in a has straightforward way or in a higher form) all the reality that is represented in the ideas that it produces.” represented Meditation 6 “Either (a) this substance is a body, in Either which case it will straightforwardly contain everything that is represented in the ideas; or else (b) it is God, or some creature more noble than a body, in which case it will contain in a higher form what is to be found in the ideas.” form Meditation 6 “I can reject (b) and be confident that God can does not transmit sensory ideas to me either directly from himself or through some creature that does not straightforwardly contain what is represented in the ideas. God has given me no way of recognizing any such ‘higher form’ source for these ideas; on the contrary, he has strongly inclined me to believe that bodies produce them. So if the ideas were transmitted from a source other than corporeal things, God would be a deceiver, and he is not. So bodies exist.” deceiver, Meditation 6 Argument For the Existence of Material Things (1) (2) (3) If my sensory perceptions of material things are If not caused by material things, then God is a deceiver. deceiver. It is not the case that God is a deceiver. Therefore, it is not the case that my sensory Therefore, perceptions of material things are not caused by material things. material 1,2 MT So my sensory perceptions of material So things are caused by material things. things Meditation 6 Justification for Premise 1: My sensory perceptions aren’t caused by me My because they occur to me against my will. because So they must either be caused by material things So themselves or by God. themselves But if God caused them, then because I can have But no way of knowing that they are caused by God and I am naturally inclined to believe that they come from material things, God would be deceiving (or allowing me to be deceived) into thinking that there are material things. thinking God is perfect and deception is an imperfection. Justification for Premise 2: Meditation 6 Though Descartes takes himself to have Though established, by way of this argument, not only that material objects exist, but also that our sensory perceptions of material objects are caused by those objects, he doesn’t concede that our perceptions of them resemble them exactly. exactly. He does grant that they are, in some ways, like He how we perceive them to be. how But he only allows that material things have the But properties that we vividly and clearly understand them to have. Meditation 6 “…. So bodies exist. They may not all So correspond exactly with my sensory intake of them, for much of what comes in through the senses is obscure and confused. But at least bodies have all the properties that I vividly and clearly understand, that is, all that fall within the province of pure mathematics.” within the material things that we seem to perceive do in fact exist and that they have all the mathematical properties that they seem to have. have. So, Descartes claims, we can be certain that So, Meditation If there are material things, then there is a particular If material thing that Descartes can be sure exists because like other material things he perceives it: like His body! Descartes admits that the material thing that he ordinarily Descartes thinks to be his body is intimately related to him in many significant ways. significant But, even so, he argues, he is not identical to his body, But, and, in fact, he is distinct from it. and, He knows he is identical with his mind. (He is certain that He he is a thinking thing, recall.) And he offers an argument for the distinctness of his mind and his body. for Meditation 6 Descartes argues for the distinctness of Descartes his mind and his body. his What does it mean to say that the mind What is distinct from the body? is It means that the mind and the body are It not the same thing. not That is, the mind is a completely distinct That thing from the body. thing Meditation 6 Descartes’s first argument for the Descartes’s distinctness of mind and body has two parts: parts: It is conceivable that my mind exist without my It body. body. If it is conceivable that my mind exist without my If body, then it is possible that my mind exist without my body. my Therefore, it is possible that my mind exist without Therefore, my body. my 1,2 MP Mind/Body Distinctness Argument Part I 1. 2. 3. Meditation 6 Mind/Body Distinctness Argument Part II 1. It is possible that my mind exist It without my body. without 2. If it is possible that my mind exist If without my body, then my mind is distinct from my body. distinct 3. Therefore, my mind is distinct from my Therefore, body. body. 1,2 MP Meditation 6 Back to Part I of the Argument Mind/Body Distinctness Argument Part I 1. It is conceivable that my mind exist without my body. 2. If it is conceivable that my mind exist without my body, then it is If possible that my mind exist without my body. possible 3. Therefore, it is possible that my mind exist without my body. 1,2 MP Justification for premise 1 of Part I: I can conceive of (imagine) what it would be like can if I existed but I didn’t have a body at all if Meditation 6 Justification for premise 2 Justification If it is conceivable that my mind exist without my body, then it is possible that my mind exist without my body. possible of Part I: Whatever I can conceive God could bring about. So, if I can conceive of my mind existing without So, my body, then God could bring it about that my mind exist without my body. mind And if God could make it the case that my mind And exists without my body, then it’s possible that that be the case. be “I know that if I have a vivid and clear thought of know something, god could have created it in a way that exactly corresponds to my thought.” exactly Meditation 6 Now to Part II of the Argument Mind/Body Distinctness Argument Part II 1. It is possible that my mind exist without my body. 2. If it is possible that my mind exist without my body, then my If mind is distinct from my body. mind 3. Therefore, my mind is distinct from my body. 1,2 MP Justification for premise 1 of Part II: Mind/Body Distinctness Argument Part I Meditation 6 Justification for premise 2 Justification If it is possible that my mind exist without my body, then my mind is distinct from my body. from of Part II: Principle of the Indiscernibility of Identicals (PII): If x has ): a property that y does not have, then x ≠ y. (This principle is also sometimes known as Leibniz’s Law.) (This Leibniz’s But if it is possible that my mind exist without my body, then But my mind has the following property: my being able to exist without my body But my body certainly does not have the property: being able to exist without my body So there is a property that my mind has that my body does So not have. not And so if it is possible that my mind exist without my body, And since PII is true, it must be the case that my mind ≠ my PII body. (That is, my mind is distinct from my body.) body. ...
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