Introduction to Philosophy (Fall '09) - class#4 for website

Introduction to Philosophy (Fall '09) - class#4 for website...

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Unformatted text preview: Descartes Review From Last Time René Descartes Father of modern (western) philosophy Meditations on First Philosophy In Meditation #1 Descartes laments In the fact that he has, in the past, believed many false things. believed The animating (or driving) force of the The Meditations is a quest for certainty. Meditations certainty Review From Last Time But why, in particular, is Descartes But obsessed with certainty? obsessed Is it just because he doesn’t ever want to believe Is anything false? anything Perhaps partly. But more importantly, Descartes wants to establish But something “stable and likely to last” in the sciences. something But, he notes, if he is to do that he needs to firm up But, the foundations of what he believes before proceeding on to any investigation of the world. proceeding For if he begins his investigations presupposing something For false, he can’t be guaranteed that whatever conclusions he comes to about the world aren’t false as a consequence of such a false presupposition. such That’s why it is called the Meditations on First Philosophy. That’s First It is a philosophical investigation into what one can presuppose It with certainty before going on to a scientific investigation of the world. world. Review From Last Time In order to go on to build up such a firm In foundation of beliefs from which to launch his investigation of the world, however, he needs first to tear down the edifice of his current, doubtful structure of beliefs. structure Tearing down that structure of beliefs is Tearing the task of Meditation #1 the Review From Last Time In tearing down his current system of beliefs In and building up a new one, Descartes makes sure that no falsity enters into the structure by adopting the most cautious course possible. adopting He will refrain from believing not only those things He that are false, but also those things for which he can find even the slightest grounds for doubt. can This method of doubt or methodological This method skepticism is a hallmark of the Cartesian skepticism philosophical system. philosophical Review From Last Time He can’t examine and reject all of his beliefs He individually--that would take forever. individually--that But, as he can cast (even the slightest bit of) doubt But, on a belief by casting doubt on the beliefs on which it is based, he will aim his skeptical inquiries at the basic principles upon which all of his other beliefs rest. beliefs As most of our beliefs about the world are based As on our senses, Descartes straightaway attacks the principle of the reliability of our senses. principle Review From Last Time Our senses do sometimes deceive us. Perhaps that is enough to cast doubt on all Perhaps that we believe on the basis of the deliverances of our senses. deliverances For how do we know that for each thing we believe For on the basis of our senses they aren’t deceiving us in that instance? in But, then again, you might think that though the But, senses are sometimes unreliable in some cases, in other cases, it seems, they never lie--cases involving perception of things close up and immediate. perception Review From Last Time Descartes then moves on to his famous Descartes Dreaming Argument Dreaming In response to the claim that we can trust our In senses about things immediately around us he writes (sarcastically): he “What a brilliant piece of reasoning! As if I were What not a man who sleeps at night and often has all the same experiences while asleep as madmen do when awake…. Often in my dreams I am convinced of just such familiar events--that I am sitting by the fire in my dressing-gown--when in fact I am lying undressed in bed!” fact Meditation #1 1. The Dreaming Argument I don’t know that I am not dreaming. 2. If I don’t know that I am not dreaming, If then I don’t know that I have hands. then 3. Therefore, I don’t know that I have Therefore, hands. hands. 1,2 MP Meditation #1 What is the justification for premise 1 of What the Dreaming Argument? the Because we are often duped into thinking Because we are awake when we are dreaming, we can’t from our experience determine whether we are dreaming or not. whether “As I think about this more carefully, I As realize that there is never any reliable way of distinguishing being awake from being asleep.” asleep.” Meditation #1 What is the justification for premise 2 of the What Dreaming Argument? Dreaming As what I take myself to perceive when I am As dreaming is in no way connected up with the world, just because I seem to perceive something when I am dreaming gives me no evidence that what I take myself to perceive is true. what So just because I seem to perceive myself as So having hands, if I am dreaming this gives me no evidence that I do have hands. evidence And so, if I am dreaming, I don’t know that I have And hands. hands. Meditation #1 A similar argument could be run for almost similar any other claim I might be said to know: any That I am a man. That I have a body. That the world exists. One of the tasks of the Meditations is to find a One way to reply to this argument. way As we proceed, we’ll see how Descartes tries As to respond to it. to What do you think of it? Meditation #1 Descartes notes that there might be ways of Descartes trying to preserve some of our beliefs even in the face of the Dreaming Argument. face You might think that what we seem to perceive in dreams at You least must be copies of things that really do exist. least So even if I might not have hands, for me to have the So experience of perceiving that I have hands, there must be such things in the world as hands. such Similarly, you might think that I can be sure of my very Similarly, abstract beliefs--like that 2+3=5 or that every square has 4 sides--even if I am dreaming. sides--even Perhaps, then I can trust my general beliefs about the Perhaps, world--that there are such things as objects, colors, space, time--and my abstract beliefs even if, because of the Dreaming Argument, I can’t be sure of any of my particular beliefs about the world. beliefs Meditation #1 In reply, you might think that we don’t have In any reason to believe that what we experience in our dreams must be copies of things that actually exist. things wrong about our perceptual beliefs when we dream, so too might we be wrong about our most abstract beliefs when we dream. most And, you might also think, just as we might be And, Mightn’t it seem to us that 2+3=7 when we dream? Mightn’t we be muddle-headed when we dream? Mightn’t Meditation #1 But even if the Dreaming Argument But doesn’t persuade you that you don’t know any of these things about the world, Descartes has another powerful skeptical argument up his sleeve. skeptical The Evil Demon Argument Meditation #1 “So I shall suppose that some malicious, So powerful, cunning demon has done all he can to deceive me…. I shall think that the sky, the air, the earth, colours, shapes, sounds and all external things are merely dreams that the demon has contrived as traps for my judgment. I shall consider myself as having no hands or eyes, or flesh, or blood or senses, but as having falsely believed that I had all these things.” had Meditation #1 The Evil Demon Argument I don’t know that I am not being deceived in don’t everything I believe by an evil demon. everything 2. If I don’t know that I am not being deceived in If everything I believe by an evil demon, then nothing I believe do I know to be true. nothing 3. Therefore, nothing I believe do I know to be Therefore, true. true. 1,2 MP 1. Meditation #1 What are the justifications for the What premises of the Evil Demon Argument? premises Thoughts on Meditation #1 In what branch of philosophy are the In questions and issues that Descartes has been addressing in Meditation #1 considered? considered? Epistemology - the study of knowledge A skeptic is one who holds that we don’t skeptic know anything about a particular sphere of facts: facts: An external world skeptic maintains that we don’t An external know anything about the world in which we live, or even that there is such a world. even A moral skeptic maintains that we don’t know moral anything about right and wrong. anything Thoughts on Meditation #1 The Problem of Skepticism is the problem of The Problem explaining how and why arguments like the Dreaming Argument and the Evil Demon Argument are not sound. sound. There are many different kinds of skepticism and There many different kinds of skeptical arguments (we’ve seen a couple already). seen As we proceed through the Meditations we’ll see As Meditations Descartes’s solution to the problem of skepticism. Descartes’s You’ll have to ask yourself is his solution adequate? And if not, what do you think the correct solution is? Or is there no solution? Meditation #2 “Yesterday’s meditation raised doubts--ones that are Yesterday’s too serious to be ignored--which I can see no ways of resolving. I feel like someone who is suddenly dropped into a deep whirlpool that tumbles him around so that he can neither stand on the bottom nor swim to the top. However, I shall force my way up, and try once more to carry out the project that I started on yesterday. I will set aside anything that admits of the slightest doubt, treating it as though I had found it to be outright false; and I will carry on like that until I find something certain, or--at worst--until I become certain that there is no certainty. Archimedes said that if he had one firm and immovable point he could lift the world with a long enough lever; so I too can hope for great things if I manage to find just one little thing that is solid and certain.” certain.” Meditation #2 At the end of Meditation #1 Descartes has At torn down the edifice of his belief and he is looking, at the beginning of Meditation #2 to see if anything remains. see Are there any beliefs that he can’t doubt? Or, perhaps, can he be certain only of the fact that Or, nothing is certain (except that very fact)? nothing Or, perhaps nothing, not even the claim that Or, nothing is certain, is certain? nothing What a quandary! Meditation #2 “I will suppose, then, that everything I see is fictitious. I will will believe that my memory tells me nothing but lies. I have no senses. Body, shape, extension, movement and place are illusions. So what remains true? Perhaps just the one fact that nothing is certain! that Still, how do I know that there isn’t something--not on that Still, list--about which there is no room for even the slightest doubt? Isn’t there a God who gives me the thoughts I am now having? now But why do I think this, since I might myself be the author of But these thoughts? these But then doesn’t it follow that I am, at least, something?… But something But there is a supremely powerful and cunning deceive who But deliberately deceives me all the time! deliberately Even then, if he is deceiving me I undoubtedly exist: let him Even deceive me all he can, he will never bring it about that I am nothing while I think I am something. So after thoroughly nothing think So thinking the matter through I conclude that this proposition, I am, I exist, must be true whenever I assert it or think it.” am Meditation #2 Here we’ve arrived at perhaps the most Here famous part of the Meditations. Meditations Descartes establishes certainty in his Descartes own existence from the fact that he thinks. thinks. Meditation #2 What is the most famous line in all of What Descartes’s philosophy? Descartes’s cogito ergo sum I think, therefore I am Interestingly, that phrase does not appear in the Interestingly, original Latin version of the Meditations. Meditations Rather, it appears only in Descartes’s Discourse on the Rather, Method. Method But though that specific phrase does not appear in the But Meditations, that line of reasoning is implicit in Descartes’s Meditations, establishing the certainty of his own existence. establishing Meditation #2 1. 2. Recall the Evil Demon Argument: I don’t know that I am not being deceived in don’t everything I believe by an evil demon. everything If I don’t know that I am not being deceived If in everything I believe by an evil demon, then nothing I believe do I know to be true. then Therefore, nothing I believe do I know to be Therefore, true. true. 1,2 MP 3. Meditation #2 Descartes has just offered us a reply to Descartes this argument. this Descartes would declare this argument Descartes to be unsound. to Premise 1 Why? Which premise would he claim is false? Meditation #2 As Descartes has shown the Evil Demon As Argument to be unsound, are we out of the skeptical woods? skeptical Certainly not! The only indubitable and certain thing that The Descartes has hit upon is that he exists-Descartes nothing more, as of yet. Argument. Argument. We still don’t have an a reply to the Dreaming We Meditation #2 Nor do we have an adequate reply to this Nor revised version of the Evil Demon Argument: Argument: I don’t know that I am not being deceived in don’t everything I believe--except my belief that I exist-everything by an evil demon. If I don’t know that I am not being deceived in If everything I believe--except my belief that I exist-everything by an evil demon, then nothing I believe--other than by my belief that I exist--do I know to be true. my Therefore, nothing I believe--other than my belief Therefore, that I exist--do I know to be true. that 1,2 MP Revised Evil Demon Argument 1. 2. 3. Meditation #2 So we are still rather far away from a solution So to our skeptical worries, BUT we have made some progress. some Remember Descartes’s words from the opening of Remember Meditation #2: “Archimedes said that if he had one firm and immovable Archimedes point and immovable point he could lift the world…; so I too can hope for great things if I manage to find just one little thing that is solid and certain.” little Descartes hopes that certainty about his own Descartes existence can be the “just one little thing that is solid and certain” with which he can lever himself out of the skeptical hole he has dug himself into. himself ...
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