Intro to Philosophy Phil 110 Lecture 11: 2-13 Daniel Kelly I. Mechanics A. Upcoming Readings 1. Today we ll discuss a. Descartes, Meditations on First Philosophy (full.pdf) 2. Next time a. Descartes, Meditations on First Philosophy (full.pdf) b. Locke, An Essay Concerning Human Understanding B. Down the road a bit: 1. First Papers: returned this week in sections 2. Midterm Exam: in class, Thursday 3/1 New Chapter: Epistemology: The Theory and Nature of Knowledge I. Some Preliminaries II. Descartes (1596-1650) A. Some Background B. Descartes Epistemological Project 1. The agenda 2. The Plan 3. The Guiding Principle: Avoid Error! 4. Chains of justification a. How are beliefs usually justified? i. Most of our beliefs are justified by other beliefs ii. Which are in turn justified by still other beliefs iii. Forming chains of justification amongst beliefs b. However, Descartes holds that these chains of justification can not go on forever i. They must ultimately come to end ii. So there must be a first link or belief in every chain c. Descartes thinks of that first belief, or the set of first beliefs, as the foundation of justification d. Needs to serve as the ultimate source of justification for all those beliefs in the chain that rest on it i. A chain of justification: B 1 B 2 B 3 B 4 A. The arrows mean justifies B. B 2 B 3 1. B 2 justifies B 3 2. (or B 3 is justified by B 2 ) C. B 1 B 2 1. B 1 justifies B 2 2. (or B 2 is justified by B 1 ) D. In this chain, B 1 is the foundational belief ii. Epistemological theories of justification that have this structure are called foundationalist
5. The Map: An inverted pyramid of knowledge a. B 7 B 8 B 9 B 10 B 4 B 5 B 6 B 2 B 3 B 1 b. (In the above picture, there is only a single belief in the foundation of knowledge i. But as we ll see, Descartes doesn t think there must be one solitary belief on which all others are based ii. There could be more than one lone belief in the foundation iii. As long as those beliefs satisfy Descartes requirement) 6. Certainty and the Method of Cartesian Doubt a. Descartes high standard: i. To properly anchor the chain of beliefs it justifies A. To be a proper, truly foundational belief B. The 1 st link in any chain ii. Descartes requires the belief be absolutely certain A. Descartes wants the most solid foundation possible B. He wants to admit into it only epistemic gold iii. In other words, foundational beliefs must be certain b. Descartes search for a suitable foundation for all knowledge thus amounts to a quest for certainty c. His method of checking beliefs for certainty is called the method of Cartesian doubt i. If there an any way a belief can be coherently doubted ii. Then we can t be absolutely certain about that belief iii. If we cannot be absolute certainty about a belief, it cannot be in foundation d. Descartes time saving device i. He (and we) can not go through and check every individual belief we have for certainty, because ii. We all have an enormous indeed infinite number of beliefs A. My name isn t Manny, my name isn t Sheila B. 1+1=2, 1+2=3 iii. Descartes adopts a principle as a time saver: A. If a particular type of justification has ever led to a false belief B. Then all those beliefs supported by this type of justification are subject to doubt 1. Since such beliefs are subject to doubt, they are not absolutely certain
2. Therefore, no beliefs supported by that type of justification can be in the foundation of knowledge C. Wiping the Slate Clean: 1. Descartes considers 3 distinct arguments a. Each is designed to show that important types of justification have often lead to false beliefs b. And that large swaths of his beliefs fail to meet the standard of certainty c. Each argument is more devastating than the previous one d. Ultimately, he is ruling out candidates, so that he can find the genuine foundations of real knowledge 2. The Argument from Illusion a. Premise 1: Many of our beliefs are justified by the evidence provided by our senses and perceptions b. Premise 2: The senses and perceptions have sometimes deceived us in the past i. Mirages ii. Perceptual illusions iii. Systematic delusions c. Conclusion: Any belief justified by evidence of the senses is doubtable, and not certain i. Upshot for Descartes epistemological project: ii. No perceptual beliefs or beliefs justified by the evidence of the senses can go in the foundation 3. The Dreaming Argument a. Descartes considers a skeptical objection that might be raised to the argument by illusion i. When the senses have mislead us in the past, it has usually been under unusual circumstances: A. The objects were far away B. We weren t concentrating or paying close attention C. We were tired (maybe we stayed up all night writing a paper the night before) D. We were under enormous stress or guilt (MacBeth hallucinates a dagger after he kills Duncan) E. We were in an altered state (ate mushrooms and thought we saw dancing bears; did shots of Jack Daniels and saw pink elephants) ii. So perhaps the senses can be trusted in normal or standard circumstances A. When we re close to what we re perceiving B. When we are concentrating and paying attention C. When we are well rested, calm and sober b. Descartes Reply:
i. Fair enough, but this does not vindicate the senses, or show that they can not be doubted ii. In dreams, we can be completely and systematically deceived about all the evidence from our sense A. When dreaming, my senses might seem to tell me I m on a secluded tropical beach drinking mojitos w/ Cate Blanchett B. But this is completely wrong C. Actually, I m alone in the dark on my couch in West Lafayette, Indiana iii. Indeed, we can even dream that we are in ideal perceptual circumstances iv. Worse, from the inside, we are unable to be certain when we are dreaming and when we are awake! c. Conclusion: We cannot be certain of even those beliefs based on the clearest and most careful perception i. Upshot for Descartes epistemological project ii. This attempt to defend (some instances) of perceptual beliefs fails, and so the previous conclusion still holds: iii. No perceptual beliefs or beliefs justified by the evidence of the senses can go in the foundation 4. The Evil Deceiving Demon Argument a. Taking Stock i. So far, Descartes has convinced himself that no perceptual beliefs whatsoever can go in the foundation of knowledge ii. No other beliefs that are themselves ultimately justified by perceptual beliefs can be fully trusted, and so do not (yet) count as real knowledge, either iii. Where does this leave us? A. Maybe some other kinds of beliefs can provide the foundation and source of justification for all the rest B. What kinds of beliefs? What s left? b. Descartes considers some candidate types of beliefs: i. Generalities about perception: A. Specific beliefs about particular objects, their colors, shapes, and location might be false (or at least systematically doubtable) B. But more generally, it seems hard to doubt that colors and shapes exist somewhere C. So perhaps very general beliefs about objects cannot be doubted 1. That objects have extension 2. That objects have shape 3. That objects have quantity 4. That objects are colored 5. (See Descartes painter example)
ii. Beliefs about mathematics and logic A. Some examples 1. Triangles have 3 sides 2. 5+7=12 3. For any proposition (p), (p) and (Not p) cannot both be true B. Such beliefs appear beyond doubt C. Since we can be certain of these beliefs, they 1. Can serve in the foundation 2. Other beliefs that are justified by appeal to them count as knowledge c. Descartes Reply: The Possibility of an Evil Demon i. Imagines the following (logically possible) scenario A. A being as powerful as God 1. Only who is not benevolent, but evil 2. Is bent on completely deceiving him B. Such an evil demon, claims Descartes, could trick him, cause him to be wrong about: 1. Particular perceptual beliefs 2. Beliefs about the generalities of perception 3. Beliefs about mathematics and logic ii. No sane person needs to believe they are being systematically deceived by an Evil Demon A. What is important, given the way Descartes has set up his project, is that we cannot definitively rule out the possibility B. In other words, we can t be certain that the Evil Demon doesn t exist iii. Conversely A. Since it s possible to doubt the claim that you aren t being systematically deceived by an Evil Demon B. It is thereby possible to doubt any belief that the demon could deceive you about C. Including: 1. Particular perceptual beliefs 2. Beliefs about the generalities of perception 3. Beliefs about mathematics and logic iv. Conclusion: we cannot be certain even of very general beliefs about perception, or mathematical & logical beliefs A. Upshot for Descartes epistemological project is that: 1. No particular or general perceptual beliefs, nor any mathematical or logical beliefs can go in the foundation
2. Nor can any beliefs that are ultimately justified by appeal to those kinds of beliefs B. Um, so what s left? D. The Cogito 1. Descartes Epistemological Project: Progress Report a. With the 3 arguments given at the end of the 1 st Meditation, Descartes takes himself to have shown it possible to cast doubt on just about every belief he s ever had b. This introduces the possibility that all of his knowledge is without foundation i. It is all but castles in the air ii. Says he feels like he fell into a deep whirlpool c. Thus he begins the 2 nd Meditation with a general philosophical oh shit sort of feeling d. But asks an important question: i. Is there even a single belief left that could serve as a foundation for all the rest? ii. Is there any belief he has that even an all powerful Evil Demon could not make him doubt? 2. The Cogito: Cogito ergo sum - roughly I think, therefore I am a. Descartes claims that the one belief that the Evil Demon could not possibly deceive him about is that he exists i. In order to be deceived, to be a candidate for deception ii. In order to be able to doubt his experiences and beliefs, to engage in the cognitive activity of doubting iii. He himself must exist A. There must be a subject of deception B. There must be an agent, a thinking thing, that does the doubting C. That subject of experiences and thinking thing is him D. (Formulated in the first person 1. The one thing an Evil Demon cannot deceive me about is that I exist 2. There must be a subject to be deceived in the first place 3. There must be an agent or thinking thing that does the doubting 4. And that subject and thinking thing is me) b. Thus, there is as least one belief that is certain, that is absolutely beyond doubt I am, I exist i. In other words, Descartes claiming that it is not possible to coherently doubt your own existence ii. At least for that moment when you are actively thinking, I exist
3. Upshot for Descartes Epistemological project: a. He has found a single, lone belief of which he can be certain, that can go in the foundation b. Is this enough? Can a single belief serve as a stable foundation, a source of justification for all the rest E. Extending the Domain of Certainty