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Unformatted text preview: Skepticism Skepticism Beliefs (in a certain area) are Unjustified (target: internalism) Unreliable (target: externalism) So, (a certain kind of) knowledge is impossible Extreme form: all beliefs are unjustified or unreliable; all knowledge is impossible Academic skepticism Socrates: "All I know is that I know nothing." Self-refuting? If you know nothing, how can you know that? Perhaps this can be solved: "I know only this." But how do you know it? If you infer it, you must know that it follows from something else you know. Thesis and Recommendation "I know only this." So what? Academic skeptics make recommendations Thesis: Knowledge (of a certain kind) is impossible Recommendation: So, one ought to _____. Problem: How can the extreme skeptic get from the thesis to the recommendation? It seems that it requires an inference But the skeptic can't know that it follows Pyrrhonian Skepticism
"I don't know anything--not even whether I know anything." The Pyrrhonian skeptic argues, but denies knowing whether skepticism follows from the premises Makes no recommendations Skepticism v. Relativism
Relativism: There are no universally valid truths about the world Beliefs are true only relative to a society culture historical epoch interpretative community individual person Skepticism v. Relativism Knowledge of truth is impossible, because... Skepticism: our beliefs are unjustified or unreliable Relativism: there is no truth to know Protagoras: "Man is the measure of all things. . . ." Skepticism v. Relativism These might be seen as allies: Skepticism is sometimes used as an argument for relativism: If we can't know truth, why think there's any truth to know? (But note the inference problem) Or as enemies: Skeptics stress the distance between appearance and reality Relativists tend to bring them closer Arguments for skepticism Philo of Alexandria (20 BCE - 40) First to attempt project of reconciling Jewish scriptures with Greek philosophy Tries to construct skeptical arguments without metaphysical presuppositions in "On Drunkenness" Argument from Illusion We often misperceive things There is no way to tell when we're misperceiving things So, on any given occasion, we might be misperceiving things Argument from Illusion Descartes: "To be sure, whatever I have so far admitted as most true I have learned either from the senses or through the senses. But sometimes I have caught them deceiving me, and it is prudent never to trust fully anything that has once deceived us." Illusion Illusion Illusion Illusion Illusion Illusion Illusion Illusion Ambiguity Illusion Misperception Inattention We're capable of missing a great deal if we're paying attention to something else
http://viscog.beckman.uiuc.edu/djs_lab/demos.html Argument from Comparison We know, not things in themselves, but things in relation to other things-- including us We know things only as they relate to us We can't distinguish what's really in the object from what we are contributing Zeno's Paradoxes Arguments against possibility of motion Runner: one must first go halfway. . . . Achilles and the Tortoise: The tortoise gets a head start; Achilles must first get to its starting point, but by then it has moved on Daoism: Zhuangzi (c. -350) Intellectual distinctions correspond to nothing in reality There's no point to doing anything Zhu Xi: "Laozi still wanted to do something, but Zhuangzi didn't want to do anything at all." Possibility of Dreaming Zhuangzi: "Those who dream of the banquet, wake to lamentation and sorrow. Those who dream of lamentation and sorrow wake to join the hunt. While they dream, they do not know that they dream. Some will even interpret the very dream they are dreaming: and only when they awake do they know it was a dream." Possibility of Dreaming Zhuangzi: "Once upon a time, I, Zhuangzi, dreamt I was a butterfly, fluttering hither and thither, to all intents and purposes a butterfly. I was conscious only of following my fancies as a butterfly, and was unconscious of my individuality as a man. Suddenly, I awaked, and there I lay, myself again. Now I do not know whether I was then a man dreaming I was a butterfly, or whether I am now a butterfly, dreaming I am a man." Possibility of Dreaming Descartes: "In my sleep I experience the same things as madmen do when they are awake-- or sometimes even less probable things. How often have I been persuaded, in the quiet of the night, of familiar things-- that I was here in my robe sitting near the fire-- when in fact I was lying disrobed between the sheets!" Possibility of Dreaming Descartes: "It certainly seems to me now that I am looking at this paper with waking eyes; that this head I move is not asleep; that I deliberately and knowingly extend my hand and feel it. What happens in sleep is not so distinct. No doubt! As if I do not remember being tricked while asleep by similar thoughts on other occasions!" Possibility of Dreaming Descartes: "While I think about this more carefully, I see so plainly that there are no certain indications by which we may clearly distinguish being awake from being asleep that I am dumbfounded. And my astonishment almost persuades me that I am asleep." Possibility of an evil deceiver Evil deceiver --> doubt of logic and mathematics Evil deceiver Descartes: "I shall " therefore suppose not that God who is supremely good and the fountain of truth, but some evil genius of the greatest power and cunning, who has employed all his energies to deceive me." Argument from Variability Variability: Things are perceived differently by different beings at different times Undecidability: There is no neutral way to determine which perceptions are trustworthy Skeptical thesis: Therefore, knowledge is impossible Variability
Variation in perception among different species, different people, even same person on different occasions How do we know which portray reality accurately? Sextus Empiricus (c. 200) We can't tell what's in the object and what we contribute Knowledge of "external underlying objects" is impossible Recommendation: suspend judgment Problem of the Criterion Undecidability: There is no neutral way to tell which perceptions ought to be trusted We need a criterion for determining this But where could we get it? Even if we could get one, we couldn't justify it Problem of the Criterion, 2 Is there a criterion of truth? To settle this, we need a criterion But that's what's at issue! Dogmatist must argue in a circle, Or face infinite regress Nagarjuna (c. 1000) Mahayana Buddhist, 14th Indian Zen patriarch Founder of Madhyamika Buddhism Destroy theorizing Leave ordinary life alone: "For we do not speak without accepting, for practical purposes, the work-a-day world" Attack on externalism
I know something because it arises from a reliable source of knowledge But how do I know that source of knowledge is reliable? Need a source of sources, etc.-- infinite regress Nagarjuna's Regress Argument "And if, for you, there is a source [of knowledge] of each and every object of proof, Then tell how, in turn, for you there is proof of those sources. If by other sources [of knowledge] there would be the proof of a source-- that would be an `infinite regress'; in that case neither a beginning, middle, or and end is proved." Source of sources? Sources of knowledge: perception, inference. . . . Knowledge is justified only if we know we're using the appropriate source What could be source of knowledge for that? Recommendations Zhuangzi's Recommendation
"The true sage rejects all distinctions of this and that. He takes his refuge in Dao and places himself in subjective relation with all things." But how can he justify his recommendation? Does it follow from his thesis? Does he know it? Sextus: Suspension & Ataraxia
Suspension of judgment --> peace of mind (ataraxia) But the sceptic can't know this, or even assert it It just happens Peace of Mind "The Skeptic, in fact, had the same experience which is said to have befallen the painter Apelles. Once, they say, when he was painting a horse and wished to represent in the painting the horses foam, he was so unsuccessful that he gave up the attempt and flung at the picture the sponge on which he used to wipe the paints off his brush, and the mar of the sponge produced the effect of a horse's foam. So, too, the Skeptics were in hopes of gaining quietude by means of a decision regarding the disparity of the objects of sense and of thought, and being unable to effect this they suspended judgment; and they found that quietude, as if by chance, followed upon their suspense, even as a shadow follows its substance." Nagarjuna: Quietism If knowledge is impossible, how can we know the truth of skepticism? Isn't skepticism unreliable or unjustified? "If I would make any proposition whatever, then by that I would have a logical error; But I do not make a proposition, therefore I am not in error." Responses to skepticism Nyaya Response We don't need a source for sources Sources of knowledge and objects of knowledge support each other Sutra 16: Just as the 'measuring instrument' (which usually has the status of a source) can be an object of knowledge as well (i.e. when its own accuracy is subject to investigation). Scales Analogy: scales How do we test the reliability of a scale? We compare weights it gives for objects with known weights by other scales We don't need a "scale of scales" Nyaya Coherentism
No foundation, no given One thing may be justifier or justified, depending on circumstances Epistemic role depends on context Luminosity Sutra 19: . . . these (i.e. perception etc.) are apprehended in the same way as the light of a lamp. Light can be both means of seeing and the thing seen Gangesa (c. 1350) Local doubt (e.g., eyes, scale): we doubt when something anomalous happens, and resolve as in the Nyaya-sutra Global doubt: we have no reason to entertain; makes no sense to say everything is anomaly Pragmatic Inconsistency "Thus it has been said (by Udayana): "That is doubted concerning which as doubted there occurs no contradiction with the doubter's action." For it is not possible at once to resort regularly to fire and the like for smoke and the like and to doubt that fire causes it (it would be meaningless behavior). This is how we should understand Udayana's saying. . . . It is the doubter's own behavior that proves the lie to the doubt, i.e., that blocks it." Augustine (354-430) Logical and mathematical truths can be known, even if skeptical arguments succeed "I am certain that either there is only one world or there are more worlds than one. I am likewise certain that if there are more worlds than one, their number is either finite or infinite." Augustine: Perception "In fact, I believe that the senses are not untrustworthy either because deranged persons suffer illusions, or because we see things wrongly when we are asleep. If the senses correctly intimate things to the vigilant and the sane, it is no affair of theirs what the mind of a sleeping or insane person may fancy for itself." Augustine: Appearances "Restrict your assent to the mere fact of your being convinced that it appears thus to you. Then there is no deception, for I do not see how even an Academic [Skeptic] can refute a man who says: `I know that this appears white to me. I know that I am delighted by what I am hearing. I know that this smells pleasant to me. I know that this tastes sweet to me. I know that this feels cold to me.'" Self-knowledge "I am most certain that I am, and that I know and delight in this. In respect of these truths, I am not at all afraid of the arguments of the Academicians, who say, What if you are deceived? For if I am deceived, I am. . . . [C]ertainly I am not deceived in this knowledge that I am. And, consequently, neither am I deceived in knowing that I know. For, as I know that I am, so I know this also, that I know." G. E. Moore Proof of the external world: "I " can prove now, for instance, that two human hands exist. How? By holding up my two hands, and saying, as I make a certain gesture with the right hand, 'Here is one hand', and adding, as I make a certain gesture with the left, 'and here is another'." Ludwig Wittgenstein
Is Moore missing the point? "... [the skeptic] will say that he was not dealing with the practical doubt which is being dismissed, but there is a further doubt behind that one." But: "Doesn't one need grounds for doubt?" Is skepticism intelligible? "If you are not certain of any fact, you cannot be certain of the meaning of your words either." "If you tried to doubt everything you would not get as far as doubting anything. The game of doubting itself presupposes certainty." What could count as evidence? "If someone doubted whether the earth had existed a hundred years ago, I should not understand, for this reason: I would not know what such a person would still allow to be counted as evidence and what not." So, what difference could skeptical doubt make? Skeptical solution to skepticism It's not meaningful to question everything at once "But I did not get my picture of the world by satisfying myself of its correctness; nor do I have it because I am satisfied with its correctness. No: it is the inherited background against which I distinguish between true and false." ...
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- Fall '08