skepticism - philosophical.spacephilosophical.space/philosophy/skepticism.pdf · pyrrhonian...

Skepticism

Saturday, September 28, 19

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• Internalism: Knowledge = justified true belief

• Externalism: Knowledge = belief formed by a reliable process

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Knowledge


• 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

Skepticism


• Even more extreme:

• We have no reason to believe anything

Skepticism


• Socrates: “All I know is that I know nothing.”

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Academic skepticism


• Socrates: “All I know is that I know nothing.”

• Self-refuting? If you know nothing, how can you know that?

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Academic skepticism


• 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.

Academic skepticism


• “I know only this.” So what?

• Academic skeptics make recommendations

• Thesis: Knowledge (of a certain kind) is impossible

• Recommendation: So, one ought to _____.

Thesis and Recommendation


–Thesis

–Therefore, Recommendation



• 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



• “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

Pyrrhonian Skepticism


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Arguments for skepticism


• First to attempt project of reconciling Jewish scriptures with Greek philosophy

• Tries to construct skeptical arguments without metaphysical presuppositions in “On Drunkenness”

Philo of Alexandria (20 BC - 40)


• 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.”

Argument from Illusion


The Müller-Lyer Illusion


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• 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

• http://www.youtube.com/watch?v=vBPG_OBgTWg

Inattention


http://viscog.beckman.uiuc.edu/djs_lab/demos.html




http://www.youtube.com/watch?v=vBPG_OBgTWg




• 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

Argument from Comparison


• “In the mode deriving from relativity as we said above, the existing object appears to be such-and-such relative to the subject judging and to the things observed together with it, but we suspend judgment on what it is like in its nature.”

Argument from Comparison


Sextus Empiricus

• We can’t tell what’s in the object and what we contribute

• Knowledge of “external underlying objects” is impossible

• Recommendation: suspend judgment


Zhuangzi (370–287 BC)


Daoism: Zhuangzi (370–287 BC)

• 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.”


• Cosmological Argument, Plato’s definition of knowledge, problem of the criterion, definitions....

• Say R is

• serial: For all x there is a y such that Rxy

• transitive: If Rxy and Ryz, then Rxz

• irreflexive: For any x, not Rxx

• Then R’s domain is infinite: • — • — • — • — • — • ....

Infinite Regress


• Escapes:

• Deny seriality: stop the regress

• Deny irreflexivity: There is an x such that Rxx (self-R, or loops)

• Have seriality take you outside the domain

Infinite Regress


Argument from 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.”



• 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

• 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.”



• 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!”



• 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!”



• 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.”


• ‘A keeper of monkeys’, replied Zi Qi, ‘said with regard to their rations of chestnuts that each monkey was to have three in the morning and four at night. But at this the monkeys were very angry, so the keeper said they might have four in the morning and three at night, with which arrangement they were all well pleased.’


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?


• Now I would ask you this. If a man sleeps in a damp place, he gets lumbago and dies. But how about an eel? And living up in a tree is precarious and trying to the nerves: but how about monkeys? Of the man, the eel, and the monkey, whose habitat is the right one, absolutely?

Variability


Variability

• ...men admire Mao Ch’iang and Liji, at the sight of whom fishes plunge deep down in the water, birds soar high in the air, and deer hurry away. Yet who shall say which is the correct standard of beauty?


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


• “Who shall I employ as arbiter between us? If I employ some one who takes your view, he will side with you. How can such a one arbitrate between us? If I employ some one who takes my view, he will side with me. How can such a one arbitrate between us? And if I employ some one who either differs from, or agrees with, both of us, he will be equally unable to decide between us.”



• “In the mode deriving from infinite regress, we say that what is brought forward as a source of conviction for the matter proposed itself needs another such source, which itself needs another, and so ad infinitum, so that we have no point from which to begin to establish anything, and suspension of judgment follows.”



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


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?


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.”


• https://drive.google.com/file/d/0B6IHmu1Mzt1eREJBNkMycHdCcTg/view

• Notice: Almost all the beliefs Morty has in the game are false!

• What if we’re in such a game?

A Life Well Lived


https://drive.google.com/file/d/0B6IHmu1Mzt1eREJBNkMycHdCcTg/view




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 & Peace of Mind

• 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.”


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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.”


skepticism - philosophical.spacephilosophical.space/philosophy/skepticism.pdf · pyrrhonian...

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