Epistemology: Knowledge, Skepticism, and Ignorance - PowerPoint PPT Presentation


Title: Epistemology: Knowledge, Skepticism, and Ignorance


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Epistemology Knowledge, Skepticism, and
Ignorance
Clark Wolf Director of Bioethics Iowa State
University jwcwolf_at_iastate.edu
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Argument for Analysis
  • Everything I believe is consistent with the
    hypothesis that I am being deceived by a powerful
    evil demon. But even a powerful evil demon could
    not convince me that I dont exist when in fact I
    do exist. For when I doubt my existence, I
    immediately realize that there must be something
    (or someone) doing the doubting. When I doubt
    whether the statement I exist is true, I
    immediately realize that it cannot be false, for
    the act of doubting must be done by someone by
    an I who must exist. Even if I am deceived in
    everything else, I cannot be deceived cannot be
    wrong about my own existence. Thus, after
    everything has been most carefully weighed, it
    must finally be established that this
    pronouncement I am, I exist is necessarily true
    every time I utter it or conceive it in my mind.
    (p. 493.1)

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  • Everything I believe is consistent with the
    hypothesis that I am being deceived by a powerful
    evil demon. But even a powerful evil demon could
    not convince me that I dont exist when in fact I
    do exist. For when I doubt my existence, I
    immediately realize that there must be something
    (or someone) doing the doubting. When I doubt
    whether the statement I exist is true, I
    immediately realize that it cannot be false, for
    the act of doubting must be done by someone by
    an I who must exist. Even if I am deceived in
    everything else, I cannot be deceived cannot be
    wrong about my own existence. Thus, after
    everything has been most carefully weighed, it
    must finally be established that this
    pronouncement I am, I exist is necessarily true
    every time I utter it or conceive it in my mind.
    (p. 493.1)
  • 1) When I try to doubt that the statement I
    exist is true, I realize that there must be some
    subject (me) doing the doubting.
  • 2) If there is a subject doing the doubting,
    that subject must exist.
  • 3) Whenever I doubt the statement I exist, it
    is immediately evident that I exist.
  • 4) Conclusion The statement I exist is self
    evidently true.

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Argument for Analysis
  • Im obviously imperfect, full of doubts and false
    beliefs. But I have an idea of perfection, and
    this idea is itself perfect. Nothing imperfect
    could create something perfect, so this perfect
    idea cannot have come from me, it must have come
    to me from another source. But only a perfect
    source could cause a perfect idea. So there must
    be a perfect beingGod who is the cause of my
    perfect idea.

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  • Im obviously imperfect, full of doubts and false
    beliefs. But I have an idea of perfection, and
    this idea is itself perfect. Nothing imperfect
    could create something perfect, so this perfect
    idea cannot have come from me, it must have come
    to me from another source. But only a perfect
    source could cause a perfect idea. So there must
    be a perfect beingGod who is the cause of my
    perfect idea.
  • 1) I have a perfect idea.
  • 2) Nothing perfect could come from something
    imperfect.
  • 3) I am imperfect.
  • 4) This perfect idea could not have come from
    me. (From 1,2,3)
  • 5) Only a perfect being could be the cause of a
    perfect idea. (A new claim, but interestingly
    related to premise 4.)
  • 6) There must be a perfect being. (From 1,5)
  • 7) If there is a perfect being, that being would
    be God.
  • 8) Conclusion God Exists. (From 6,7)

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Argument for Analysis
  • Mind and body are either the same substance, or
    they are different substances. If two things are
    identical, then they will have all the same
    properties. So if my mind and body are the same
    substance, they must have all properties in
    common. But I can doubt my bodys existence my
    body is dubitable. I cant doubt my minds
    existence my mind is indubitable. Therefore
    mind and body are different substances.

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  • Mind and body are either the same substance, or
    they are different substances. If two things are
    identical, then they will have all the same
    properties. So if my mind and body are the same
    substance, they must have all properties in
    common. But I can doubt my bodys existence my
    body is dubitable. I cant doubt my minds
    existence my mind is indubitable. Therefore
    mind and body are different substances.
  • 1) Mind and body are either the same thing, or
    they are different substances.
  • 2) If two things are identical, then they will
    have all the same properties.
  • 3) So if my mind and body are the same
    substance, theyll have all properties in common.
  • 4) But I can doubt my bodys existence my body
    is dubitable.
  • 5) I cant doubt my minds existence my mind
    is indubitable.
  • 6) Mind and body do not have all properties in
    common.
  • 7) Therefore mind and body are different
    substances.

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Argument for Analysis
  • According to Descartes, we cant know something
    unless we are so absolutely certain that it is
    true that we cant doubt it. But if we accepted
    this, we would be forced to conclude that we know
    nothing at all, or almost nothing. Its just
    wrong to say that we dont know something just
    because we can doubt that its true, or just
    because its possible that its false this isnt
    what we mean by the term know. For example,
    when I say I know where I parked my bike,
    because I remember doing it. I dont mean to
    indicate that I cant possibly be wrong about
    where I parked my bike, even if it turns out that
    Im a brain in a vat. So to know something isnt
    to be certain about it. So the Cartesian
    analysis of knowledge doesnt capture what we
    typically mean by knowledge.

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Argument for Analysis
  • 1) According to Descartes, we cant know
    something unless we are so absolutely certain
    that it is true that we cant doubt it.
  • 2) But if we accepted this, we would be forced
    to conclude that we know nothing at all, or
    almost nothing.
  • 3) But we know more than the Cartesian view
    would support.
  • 4) So to know something isnt to be certain
    about it.
  • 5) Descartes was wrong to believe that certainty
    is necessary for knowledge.

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SKEPTICISM Sextus Empiricus
  • Plato distinguished knowledge from opinion,
    urging that we know only things we discover
    through reason.
  • Aristotle and others call into question Platos
    claim that we know the things Plato thinks we
    know through reason.
  • So what do we know?

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SKEPTICISM Sextus Empiricus
  • Question What is knowledge?
  • CLAIM You dont know something unless you have
    good evidence that it is true.
  • Question Do you know that you are in a
    philosophy classroom in Ames Iowa on a cold March
    morning?

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SKEPTICISM Sextus Empiricus
  • Thought Experiment
  • (1) Do you know that the world did not spring
    into existence four seconds ago.
  • (2) Do you know that you are not a brain in a
    vat?

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An Argument for Skepticism
  • 1) You have no evidence that youre not a brain
    in a vat.
  • 2) If you have no evidence for X, then you dont
    know X.
  • 3) Therefore, You dont know youre not a brain
    in a vat.
  • 4) If you dont know that X is false, but your
    belief Y would be unsupported if X were true,
    then you dont know Y.
  • 5) Therefore, you dont know any of the things
    that depend on the fact that youre not a brain
    in a vat.
  • 6) If youre a brain in a vat, then everything
    else you believe is false.
  • 7) Therefore, you dont know any of those things.
  • 8) Therefore you dont know anything at all.

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An Argument for Skepticism
  • 1) You have no evidence that youre not a brain
    in a vat. (Is this true? What evidence might
    you offer?)
  • 2) If you have no evidence for X, then you dont
    know X.
  • 3) Therefore, You dont know youre not a brain
    in a vat.
  • 4) If you dont know that X is false, but your
    belief Y would be unsupported if X were true,
    then you dont know Y. (Is this a questionable
    premise?)
  • 5) Therefore, you dont know any of the things
    that depend on the fact that youre not a brain
    in a vat.
  • 6) If youre a brain in a vat, then everything
    else you believe is false.
  • 7) Therefore, you dont know any of those things.
  • 8) Therefore you dont know anything at all.

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Skepticism
  • Skepticism We do not have knowledge of anything
    at all.

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Epistemology Theory of Knowledge
  • What is knowledge? What is it to know
    something?
  • What does it mean to say that a belief is
    justified?
  • What can we know?
  • We might start by listing the things we believe

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Knowledge and Belief
  • We have a vast collection of beliefs, and some of
    them are falseSome people believe that
    astrology can inform us about our futures. mind
    is constituted by the physical operation of the
    brain.
  • mind is soul, an entity separate from brain
    activity that will survive the death or our
    bodies.
  • the universe is ultimately describable in terms
    of physical laws.
  • a full description of the universe will include
    magic and super-natural entities.
  • aliens from outer space are in contact with
    human beings. human beings are the product of
    natural evolutionary selection.
  • there is a God who created everything and who
    cares about us. human beings will make
    settlements on Mars. human beings are more
    likely, in the next millenium, to deplete the
    earth of its resources and destroy the ecosystems
    on which we depend for our lives.
  • Sifting and sorting We dont agree on all of
    these (at least, its unlikely that we do.)
    Those beliefs about which we're less certain are
    less likely to count as knowledge than those
    we're more certain of. Are there any beliefs of
    which we are absolutely certain?

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Knowledge and Belief
  • We believe many things.
  • Not all of the things we believe are things we
    know.
  • Among the things I believe, which are the things
    I know?
  • Sextus?
  • Descartes?

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Knowledge and Belief
  • Among the things I believe, which are the things
    I know?
  • Hypothesis The things I know are the beliefs
    that are true.
  • Problem What if I have true beliefs by accident
    or for bad reasons?

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Knowledge Platoss Analysis
  • Plato, Euthyphro Knowledge is Justified True
    Belief.
  • A person S knows a proposition P If and only if
    1) S believes P2) S is is justified in
    believing P3) P is true

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Knowledge Platoss Analysis
  • A person S knows a proposition P If and only if
    1) S believes P2) S is is justified in
    believing P3) P is true
  • 1a) What is belief?
  • (Mental attitude associated with accompanying
  • dispositions) 1b) What are the objects of
    belief?
  • (Propositions Statements that can be true or
    false.)
  • 2) When is belief justified?
  • (There are alternative theories of
    justification)3) What is it for a proposition to
    be true?
  • (There are alternative theories of truth)

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Knowledge Platoss Analysis
  • JUSTIFICATION AND BELIEF
  • The 'Why?' game... at a certain point in a
    childs development, she gets the idea that there
    are reasons for things, and start asking why.
  • Justification A theory of the justification of
    beliefs must provide us with a model of how to
    play the why game, or as it is sometimes called,
    the justification game.

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Skeptical Scenareos
  • Sextus Empiricus' Trilemma
  • (Also called Agrippas Trilemma, after Agrippa
    the Skeptic. This is a Modern Rendition)
  • 1) We have knowledge only if our beliefs are
    justified. 2) 'justification' can take three
    possible forms A) We justify our total belief
    set by reference to some
  • foundational belief or set of such beliefs,
    which are not
  • themselves justified by any further beliefs.
    B) Our beliefs mutually justify one another.
    C) There is an endless regress of justifying
    reasons. 3) Not A A foundational belief could
    not justify other beliefs unless it were itself
    justified. 4) Not B Circular justification is
    no justification at all. 5) Not C An endless
    regress of reasons could not provide
    justification for our first-level beliefs. 6)
    Therefore, we don't have knowledge.

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Skeptical Question
  • Do we know anything at all?
  • If I might be dreaming, might be a brain in a
    vat, might be systematically deceived by an evil
    genius
  • then can I know anything?

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  • Many epistemic theories, like that of Descartes,
    are attempts to show that skepticism is false,
    and that we can have justified beliefs in spite
    of the force of skeptical arguments.

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A Coherent Skepticism?
  • Skepticism The view that we dont have any
    knowledge.
  • Nothing can be known, not even this.
  • -Carneades 214-129 BCE
  • The skeptical dictum is like a purgative when
    we take it, the dictum itself is thrown up along
    with all our other dogmatic beliefs.
  • -Miguel de Montaigne

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Sextus Empiricus
  • Skepticism is an ability to place reasons in
    opposition to one another, so as to achieve a
    balance that leaves us free of dogmatic beliefs.
  • Is skepticism self-contradictory? The skeptic
    claims we have no knowledge (?), but isnt making
    that claim a violation of the skeptical
    imperative to avoid making positive claims?

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Sextus, Epicurus, and Epictetus
  • All three urge that philosophy can provide us
    with peace of mind, and protect us from
    unhappiness.
  • Ataraxia- (Epicurus and Sextus) Freedom from
    worry, created by passions or dogmatic
    convictions.
  • Apatheia (Epicurus, Seneca) Freedom from
    passions, and the false beliefs that generate
    passions.
  • Acatalepsia (Sextus) The ability to withhold both
    assent and denial from doctrines that are
    presented to us for belief.

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Sextus
  • Goal of skepticism is freedom and peace of mind.
  • Skepticism is an ability to withhold assent, that
    can be mastered with practice and study.
  • We exercise this ability by considering all the
    evidence against a proposition alongside the
    evidence for it.

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Sextus Empiricus
  • Q Why is skepticism characterized as an
    ability?
  • A It would be inconsistent for a skeptic to
    have a doctrine, since adherence to a doctrine
    involves belief and commitment.
  • (Connect this with the common charge that
    skepticism is inconsistent)

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A Coherent Skepticism?
  • Skepticism The view that we dont have any
    knowledge.
  • Nothing can be known, not even this.
  • -Carneades 214-129 BCE
  • The skeptical dictum is like a purgative when
    we take it, the dictum itself is thrown up along
    with all our other dogmatic beliefs.
  • -Miguel de Montaigne

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Sextus
  • Question In denying that we know anything, is
    the skeptic denying knowledge in the Platonic
    sense, or merely denying that we have certainty
    about things? (Fallibilism)

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Sextus and the Modes
  • The modes are methods we can use to achieve the
    suspension of judgment (aporea or acatalepsia)
    that allows us a kind of freedom we would not
    have if we were to submit to dogmatic beliefs.

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Modes of Skepticism
  • 1) The same objects dont produce the same
    impression in different animals.
  • 2) Differences between individuals lead to
    differences in perception of the way things are.
  • 3) Different senses give us very different
    information about the objects we perceive.
  • 4) Differences in our circumstances cause things
    to appear differently to us. (sleep/wake,
    drunk/sober)

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Modes of Skepticism
  • 5) When we perceive objects from different
    positions, they appear different to us.
  • 6) We perceive objects in groups, and the
    admixture of different objects causes each to
    be perceived differently by us.
  • 7) When substances are in different states, they
    appear differently to us. (snow/water)
  • 8) Our perception of objects is relative to
    ourselves and circumstances. (?)

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Modes of Skepticism
  • 9) Our perception of objects changes depending on
    whether we see them frequently or seldom.
  • 10) Ethical judgments appear to be based on
    custom, and different people with different
    backgrounds make different judgments.

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Sextuss Instruction
  • Whenever you are tempted by dogmatism, line up
    reasons for and against the proposition until
    they balance out.
  • At this point, you will be free from convictions
    (acatalepsia) having lost the propensity to
    dogmatic adherence.
  • In this state, you will be free trouble (in a
    state of ataraxia) since we are only bothered
    when our dogmatic convictions or judgments are
    thwarted by the world.

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Compare Skepticism and Stoicism
  • Skeptics and stoics (and Epicureans too) agree
    that our goal should be to free ourselves from
    troubles arising from false beliefs.
  • While the stoics recommend extirpation of desires
    and aversions, the Skeptics recommend extirpation
    of dogmatic convictions.
  • The stoics agree that disturbances (desires and
    aversions) arise from false beliefs. But they do
    not recommend eliminating our beliefs.

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Skeptical Ataraxia?
  • Abandoning dogmatic convictions will leave us
    free and happy we will be undisturbed by things
    that disturb other people. Their disturbance
    rests on a mistake they have allowed themselves
    to believe where they should instead have
    withheld belief and judgment.

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Knowledge and Belief Descartess Problem
  • Descartes's Problem How can I have knowledge of
    anything, and which are the things I know?
  • Sifting and sorting Those beliefs about which
    we're less certain are less likely to count as
    knowledge than those we're more certain of. Are
    there any beliefs we're absolutely certain of?

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Knowledge and Belief Descartess Problem
  • DF of "undermining" A proposition P undermines
    another proposition Q just in case the truth of P
    would be good evidence either (i) that Q is
    false, or (ii) that our reasons for believing Q
    are not good reasons for believing Q.
  • Proposed Principle for Negative Justification
    Take any propositions P and Q where P undermines
    Q. If you have no evidence that P is false, then
    you are not fully justified in believing Q.
  • But If you have no evidence that the Demon
    hypothesis is false, then you are justified in
    believing none of the things that would be
    undermined by this hypothesis.

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Knowledge and Belief Descartess Problem
  • Descartes, Meditation I The Dream Argument
  • 1) In Meditation 1, Descartes believes that he
    is sitting before a fire.2) But if Descartes is
    in bed dreaming, then he's not before a fire.3)
    Descartes argues that he has no evidence (or
    inadequate evidence) to justify his belief that
    he's not dreaming. 4) So he doesn't know that
    he's not dreaming. 5) So he doesn't know that
    he's sitting before a fire.

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DESCARTES Meditations on First Philosophy
  • Meditation One Introduces Skeptical Problem,
    Method of Doubt, distinguishes among different
    sources of belief.
  • The Project Wholesale reconstruction of a belief
    system Descartes wants to tear it to the ground
    and build it back from solid foundations.

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DESCARTES Meditations on First Philosophy
  • THE SKEPTICAL PROBLEM
  • The starting point recognition that many
    previously held beliefs are either false or
    unfounded. We need, he believes, a firm
    foundation on which to place our knowledge, to
    insure that our beliefs will be true.

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DESCARTES Meditations on First Philosophy
  • Method of Doubt Test beliefs according to their
    "doubtability." If I can doubt one belief, but I
    cannot doubt another, then surely my belief in
    the second is firmer than my belief in the first.
    For the moment, Descartes recommends that I admit
    only those truths (if any) which I can
    immediately perceive clearly and distinctly. Any
    others whose truth I can derive from this basic
    set will also be justified.

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DESCARTES Meditations on First Philosophy
  • First Possible Way Out Foundationalism A person
    is justified in holding a belief only if it is
    either self evident, or is directly or indirectly
    inferred from self evident propositions by
    self-evident principles of inference.
  • A proposition is self evident(df) just in case
    believing that it is true is sufficient for
    knowing that it is true. Some philosophers have
    doubted that there are any self evident
    propositions.

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DESCARTES Meditations on First Philosophy
  • Two Potential Problems for Foundationalism
    These two are inconsistent with one another. Do
    you see why?
  • 1) Perhaps there are no self-evident
    propositions.
  • 2) Perhaps there are some self-evident
    propositions, but they are inadequate since they
    provide us with no conclusive argument against
    the skeptic.

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DESCARTES Meditations
  • CATEGORIES OF BELIEFS Rather than examining each
    belief in turn, (there are just too many)
    Descartes categorizes his beliefs
  • 1) Blfs deriving from the senses. (Undermined by
    Dream argument) (But the images composing my
    dream must have their source somewhere-- there
    must exist some basic source of this material I
    dream about... no? But what that basic source may
    be is quite mysterious. Do I know that it
    mightn't be me?)
  • 2) Blfs about empirical science have the same
    status as other blfs deriving from the senses.
  • 3) Blfs about "simple and universal" things
    (math Logic) Descartes finds that he can even
    doubt these...(Perhaps I get confused whenever I
    add 2 and 2) (139.2)

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DESCARTES Meditations on First Philosophy
  • ON THE EVIL GENIUS HYPOTHESIS
  • Don't misunderstand Descartes doesn't believe
    that there is an evil demon, he rather considers
    whether he has any evidence which would enable
    him to prove that there is not one. The evil
    demon hypothesis is one way to call into question
    the justification of beliefs which derive from
    the senses it is a potential defeater for many
    of the things we think we know.

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DESCARTES Meditations on First Philosophy
  • Meditation One ends as it starts with unresolved
    doubts. It seems, at the end, that the demon
    hypothesis provides a potential reason for
    doubting just about anything. However, Descartes
    (like Hume later) finds that he cannot maintain
    skepticism See p. 63 "But this undertaking is
    arduous and a certain laziness brings me back to
    my customary way of living."

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DESCARTES Meditations on First Philosophy
  • One Kind of Objection We don't have the
    technology to envat people, and there isn't an
    evil genius... In sum, the evil demon hypothesis
    is just not true.
  • Response This objection is a non-starter since
    it begs the question. Descartes never claimed
    that there is an evil genius (nor did I claim
    that we are really envatted brains). The point is
    to sift among our beliefs to find those that are
    more securely justified than others. The evil
    demon hypothesis is not true, but it is
    conceptually possible (That is, thinking about it
    doesn't involve us in any contradictions.)

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DESCARTES Meditations on First Philosophy
  • Descartes and Skepticism if we can find a
    foundation for our belief system which is both
  • 1) self evidently true, and2) sufficiently
    powerful to enable us to deduce that our
    perceptual beliefs are true, THEN we could escape
    the skeptical argument. Is there such a
    foundation?

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DESCARTES Meditations on First Philosophy
  • ON TO MEDITATION TWO!
  • Descartes DISCOVERS a self-evident belief.
  • Descartes ARGUES that some of his beliefs could
    not have originated with him.
  • Descartes PROVES (?) that God exists and that God
    is not a deceiver.

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DESCARTES Meditations on First Philosophy
  • Cogito Consider the proposition 'I exist.'
  • Apply method of doubt If there is any
    conceivable circumstance in which it could SEEM
    TO ME that I exist, and yet I could be wrong,
    then the proposition 'I exist' can be doubted. Is
    there such a circumstance? Demon world is the
    most complete hallucination imaginable. If I
    couldn't be wrong in the demon world, then I
    couldn't be wrong at all. But in the demon world
    I must exist, since there is an 'I' to be
    deceived.Therefore I know that I exist any time
    I stop to consider the question.
  • "Cogito Ergo Sum." (I think therefore I am.)

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DESCARTES Meditations on First Philosophy
  • Descartess Foundational Belief I exist.
  • 1) I know X only if I perceive that clearly and
    distinctly that X is true, such that it is
    impossible for me to doubt X.
  • 2) Query Can I doubt my own existence.
  • 3) For me to doubt my existence, there must be a
    me to do the doubting.
  • 4) Any time I doubt my existence, I can clearly
    and distinctly understand that I must exist.
  • 5) I cant doubt my own existence.
  • 6) I know the proposition I exist.

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DESCARTES Meditations on First Philosophy
  • "Cogito Ergo Sum." (I think therefore I am.)
  • How far will this get us? Descartes has argued
    that the proposition "I exist." is self evident.
    But is it powerful enough that it can support my
    knowledge of the external world? Can this help me
    out of the vat?

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DESCARTES Meditations on First Philosophy
  • Descartes and Skepticism if we can find a
    foundation for our belief system which is both
  • 1) self evidently true, and2) sufficiently
    powerful to enable us to deduce that our
    perceptual beliefs are true, THEN we could escape
    the skeptical argument. Is there such a
    foundation?

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DESCARTES Meditations on First Philosophy
  • "Cogito Ergo Sum." (I think therefore I am.)
  • Question What is this thing (ME) whom we know to
    exist? Am I my body? Not in the demon world,
    where I still exist...
  • I am a thing that thinks. That's all I know for
    sure. I am something that doubts, affirms,
    understands, denies, wills, refuses, imagines and
    senses.
  • In fact, what I know is that I am a thing that
    has ideas.

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Knowledge and BeliefMotivating Skeptical Doubts
  • DF of "undermining" A proposition P undermines
    another proposition Q just in case the truth of P
    would be good evidence either (i) that Q is
    false, or (ii) that our reasons for believing Q
    are not good reasons for believing Q.
  • Proposed Principle for Negative Justification
    Take any propositions P and Q where P undermines
    Q. If you have no evidence that P is false, then
    you are not justified in believing Q.
  • Proposal The demon hypothesis is an underminer
    for all empirical beliefs. So if (1) you accept
    this proposed principle, and (2) you have no
    evidence that the demon hypothesis is false, then
    you must be a skeptic about all empirical
    beliefs.

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Another ProblemKnowledge and Belief Is
Justified True Belief Knowledge?
  • Example I have on my car a sticker that says
    "Oberlin College." People who see this sticker
    usually form the belief that I graduated from
    Oberlin college. This belief is justified,
    since the sticker is good evidence that I went to
    Oberlin. This justified belief is true, since I
    did attend Oberlin. But is it knowledge?
  • Problem The sticker was on the car when I bought
    it (used), and I didn't put it there. If people
    knew this, it would undermine their belief that I
    went to Oberlin college, by showing that their
    reason for believing that I did was not a good
    reason.
  • Question If you don't know that the sticker was
    on my car when I bought it, is your belief that I
    went to Oberlin College justified?

66
Knowledge and Belief The Gettier Problem
  • 1) John regards the Oberlin sticker on Clarks
    car as evidence that Clark went to Oberlin
    college.
  • 2) Johns belief that ltClark went to Oberlin
    Collegegt is based on the fact that he saw an
    Oberlin sticker on Clarks car.
  • 3) This belief is justified (the reason is a
    good one), true.
  • (I did attend Oberlin)
  • 4) But contrary to Johns belief, the sticker
    on Clarks car is not evidence that Clark went to
    Oberlin.
  • 5) Therefore John does not know that Clark
    went to Oberlin.
  • 6) Therefore justified true belief is not
    knowledge.
  • (Reject 3? Find an additional criterion to add
    to JTB?)

67
Gettier Problem
  • One may BELIEVE P, be JUSTIFIED IN BELIEVING P,
    and P may be TRUE, but this is not enough ones
    belief must be connected with the truth in the
    right way.
  • If Im right by accident, then my justified true
    belief is not knowledge.

68
Responses to the Gettier Prob
  1. Look for a theory of justification that ties the
    justification of a belief more strongly to the
    conditions that render it true.
  2. Accept that JTB is not knowledge
  3. Fallibilism accept that knowledge can be
    fallible.
  4. Skepticism We dont have any knowledge.

69
DESCARTES Meditations on First Philosophy
  • The Wax Example My idea of the wax remains the
    same while the wax goes through drastic changes
    it is the same wax although its properties change
    when it is melted or frozen. My senses do not
    give me an understanding of the wax I get
    different sensory information as the wax changes,
    but my idea of the wax itself persists over these
    changes. So "perceiving the wax" is essentially
    an act of the mind, not of the senses.

70
DESCARTES Meditations on First Philosophy
  • The Wax Example My idea of the wax remains the
    same while the wax goes through drastic changes
    it is the same wax although its properties change
    when it is melted or frozen. My senses do not
    give me an understanding of the wax I get
    different sensory information as the wax changes,
    but my idea of the wax itself persists over these
    changes. So "perceiving the wax" is essentially
    an act of the mind, not of the senses.
  • Theory of Representative Ideas Knowledge is a
    two-way relationship between one's ideas and the
    objects in the external world. We have internal
    access to our ideas, but not to the objects of
    which they are ideas.

71
DESCARTES Meditations on First Philosophy
  • A Problem for Cartesian Foundationalism The
    theory of representative ideas leaves us trapped
    in the confines of our own mind! Descartes has
    (perhaps?) found a foundational belief, but is it
    powerful enough to respond to the skeptic? Does
    it enable us to think ourselves out of the vat?
    Unfortunately, even if we have certainty with
    respect to the cogito and also to our first level
    sensory beliefs (beliefs about the way things
    seem to us), we cannot derive from these basic
    beliefs any statements about the existence of
    external objects. We can't make it out of the
    vat.

72
DESCARTES Meditations on First Philosophy
  • To respond to the skeptic, a foundationalist must
    show two things 1) There are self evident
    propositions, and 2) From these propositions we
    can derive knowledge of empirical reality.
  • So Descartes needs some more equipment He needs
    GOD.

73
DESCARTES Meditations on First Philosophy
  • MEDITATION THREE Concerning the Existence of God
  • Method Descartes has established that he exists
    as a thinking thing. In the third meditation he
    undertakes to examine the ideas that he finds in
    his mind, and to consider their origin. "But
    here I must inquire particularly into those ideas
    that I believe to be derived from things existing
    outside of me." If he can deduce that these ideas
    do nor originate in him, then he may conclude
    that there is something external that is the
    origin of these ideas.

74
DESCARTES Meditations on First Philosophy
  • DESCARTES ARGUMENTS CONCERNING THE EXISTENCE OF
    GOD
  • Argument from the Perfect Idea of an Infinite
    Being 1) I have an idea of God which is the
    idea of a substance that is infinite,
    independent, supremely intelligent, and supremely
    powerful. III.45-62) As a finite and imperfect
    being, I cannot be the cause of a perfect idea of
    an infinite substance. III.45-63) Only an
    infinite and perfect being could be the cause of
    such an idea.4) Therefore, there exists an
    infinite and perfect being who is the cause of my
    idea.

75
DESCARTES Meditations on First Philosophy
  • Ontological Argument (Meditation Five) 1) I
    have an idea of God. 2) The idea of God is the
    idea of a being that has all perfections. 3)
    'Existence' is a perfection. That is, what
    exists in reality is more perfect than what
    exists only in the imagination. 4) Therefore a
    being that has all perfections must have
    'existence.' 5) God exists.

76
DESCARTES Meditations on First Philosophy
  • Anselm's Version of the Ontological Argument 1)
    I have an idea of God. 2) The idea of God is the
    idea of the greatest conceivable being. 3) A
    being that exists in reality as well as in the
    mind (in imagination) is greater than a being
    that exists only in the mind. 4) Suppose that
    the Greatest Conceivable Being exists only in the
    mind but not in reality. 5) Then we can conceive
    of a being that is even greater one who exists
    in reality as well as in the mind. 6) Then we
    can conceive of a being greater than the greatest
    conceivable being-- but that would be a
    contradiction! 7) Therefore it is not the case
    that the greatest conceivable being exists only
    in the mind but not in reality. 8) Therefore the
    greatest conceivable being exists in reality as
    well as in the mind. 9) Therefore God exists.

77
DESCARTES Meditations on First Philosophy
  • Some Further Steps 1) If there is a perfect
    being, then the evil demon hypothesis is
    false. 2) Therefore my senses give me true
    information about the world.  3) Therefore
    skepticism is false.

78
DESCARTES Meditations on First Philosophy
  • Physicalism Mind and body are both physical
    substances, and the consequence of interaction of
    physical particles and forces.
  • Dualism Mind and body are different substances
    that interact but which are essentially
    different.

79
DESCARTES Meditations on First Philosophy
  • Mind and Body
  • Descartes is a Dualist he argues that mind and
    body are different, separate substances. Here is
    one Cartesian argument for Dualism
  • 1) If one substance has a property P while
    another substance lacks property P, then the two
    substances are not identical.2) I can doubt the
    existence of my mind my mind has the property of
    'dubitability'.3) I can't doubt the existence of
    my body my body lacks the property of
    dubitability.4) Therefore my mind is a different
    substance from my body.

80
DESCARTES Meditations on First Philosophy
  • Reservation is 'dubitability' a property of
    things or of thinkers? Perhaps premises two and
    three say more about Descartes thought processes
    than about the things Descartes is considering.

81
For Physicalism
  • Physical Evidence of Anasthesia
  • Contemporary Science of Consciousness presumes
    physicalism.
  • Mind-Brain Identity and Split Brain cases.

82
DESCARTES Meditations on First Philosophy
  • Final Issues in Cartesian Epistemology
  • Does Descartes have a satisfactory response to
    the skeptic? Unless one is satisfied with the
    proof of the existence of God, one may conclude
    that Descartes has escaped the skeptical
    conclusion only because he accepted a bad
    argument. Few believe that any of the
    philosophical arguments for God's existence is
    conclusive indeed James assumes that his
    listeners and readers will already have
    recognized that the evidence for the existence of
    God is inconclusive.

83
Descartes Where from here?
  • Does Descartes have a satisfactory response to
    the skeptic? Unless one is satisfied with the
    proof of the existence of God, one may conclude
    that Descart has escaped the skeptical conclusion
    only because he accepted a bad argument. Few
    believe that any of the philosophical arguments
    for God's existence is conclusive indeed James
    assumes that his listeners and readers will
    already have recognized that the evidence for the
    existence of God is inconclusive.
  • If this is right, where does it leave Descartes?
    Are we still in the vat? Some people conclude
    that Descartes simply failed to provide a
    convincing response to the skeptic. The
    meditations get the epistemological project off
    the ground, but don't really take it beyond the
    vat. Where does the argument go wrong? There are
    several possibilities

84
Descartes Where from here?
  • Conclusions from Descartes Discussion
  • 1) The negative principle of justification may
    just be too strong a condition to place on
    knowledge. Perhaps this principle should be
    rejected. Many (most!) contemporary
    epistemologists would reject it.
  • 2) Some attribute Descartes failure to the
    representative theory of ideas Bertrand Russell
    argued that perception gives us immediate contact
    with the world, and denies Descartes claim that
    we are only in immediate contact with our ideas.
  • 3) Some argue that Descartes' failure shows that
    foundationalism is unacceptable. One might opt
    instead for a Coherentist or Pragmatist account
    of the justification of belief. James' opts for
    a pragmatist solution. Other contemporary
    epistemologists hold that beliefs come in systems
    and deny that it is circular for all beliefs to
    be justified by reference to other fallible
    beliefs.

85
Descartes Where from here?
  • Some Non-Cartesian Alternatives
  • Coherentism There are no adequate foundations
    for knowledge, but we can be justified in our
    beliefs provided that they cohere appropriately
    with other of our beliefs. Coherentists must
    then give a clear account of what 'coherence'
    means, and must respond to the objection that
    fiction may be coherent. See Keith Lehrer Theory
    of Knowledge for a clear, contemporary
    coherentist account of justification.
  • Fallibilism To know a proposition, it not
    necessary to have indubitable certainty that it
    is true.
  • Most fallibilists would reject the Negative
    Principle of Justification. Most contemporary
    epistemologists are fallibilists. Those
    epistemologists who are not fallibilists are
    mostly skeptics. I haven't done a survey, these
    are my impressions.
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Title: Epistemology: Knowledge, Skepticism, and Ignorance


1
Epistemology Knowledge, Skepticism, and
Ignorance
Clark Wolf Director of Bioethics Iowa State
University jwcwolf_at_iastate.edu
2
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3
Argument for Analysis
  • Everything I believe is consistent with the
    hypothesis that I am being deceived by a powerful
    evil demon. But even a powerful evil demon could
    not convince me that I dont exist when in fact I
    do exist. For when I doubt my existence, I
    immediately realize that there must be something
    (or someone) doing the doubting. When I doubt
    whether the statement I exist is true, I
    immediately realize that it cannot be false, for
    the act of doubting must be done by someone by
    an I who must exist. Even if I am deceived in
    everything else, I cannot be deceived cannot be
    wrong about my own existence. Thus, after
    everything has been most carefully weighed, it
    must finally be established that this
    pronouncement I am, I exist is necessarily true
    every time I utter it or conceive it in my mind.
    (p. 493.1)

4
  • Everything I believe is consistent with the
    hypothesis that I am being deceived by a powerful
    evil demon. But even a powerful evil demon could
    not convince me that I dont exist when in fact I
    do exist. For when I doubt my existence, I
    immediately realize that there must be something
    (or someone) doing the doubting. When I doubt
    whether the statement I exist is true, I
    immediately realize that it cannot be false, for
    the act of doubting must be done by someone by
    an I who must exist. Even if I am deceived in
    everything else, I cannot be deceived cannot be
    wrong about my own existence. Thus, after
    everything has been most carefully weighed, it
    must finally be established that this
    pronouncement I am, I exist is necessarily true
    every time I utter it or conceive it in my mind.
    (p. 493.1)
  • 1) When I try to doubt that the statement I
    exist is true, I realize that there must be some
    subject (me) doing the doubting.
  • 2) If there is a subject doing the doubting,
    that subject must exist.
  • 3) Whenever I doubt the statement I exist, it
    is immediately evident that I exist.
  • 4) Conclusion The statement I exist is self
    evidently true.

5
Argument for Analysis
  • Im obviously imperfect, full of doubts and false
    beliefs. But I have an idea of perfection, and
    this idea is itself perfect. Nothing imperfect
    could create something perfect, so this perfect
    idea cannot have come from me, it must have come
    to me from another source. But only a perfect
    source could cause a perfect idea. So there must
    be a perfect beingGod who is the cause of my
    perfect idea.

6
  • Im obviously imperfect, full of doubts and false
    beliefs. But I have an idea of perfection, and
    this idea is itself perfect. Nothing imperfect
    could create something perfect, so this perfect
    idea cannot have come from me, it must have come
    to me from another source. But only a perfect
    source could cause a perfect idea. So there must
    be a perfect beingGod who is the cause of my
    perfect idea.
  • 1) I have a perfect idea.
  • 2) Nothing perfect could come from something
    imperfect.
  • 3) I am imperfect.
  • 4) This perfect idea could not have come from
    me. (From 1,2,3)
  • 5) Only a perfect being could be the cause of a
    perfect idea. (A new claim, but interestingly
    related to premise 4.)
  • 6) There must be a perfect being. (From 1,5)
  • 7) If there is a perfect being, that being would
    be God.
  • 8) Conclusion God Exists. (From 6,7)

7
Argument for Analysis
  • Mind and body are either the same substance, or
    they are different substances. If two things are
    identical, then they will have all the same
    properties. So if my mind and body are the same
    substance, they must have all properties in
    common. But I can doubt my bodys existence my
    body is dubitable. I cant doubt my minds
    existence my mind is indubitable. Therefore
    mind and body are different substances.

8
  • Mind and body are either the same substance, or
    they are different substances. If two things are
    identical, then they will have all the same
    properties. So if my mind and body are the same
    substance, they must have all properties in
    common. But I can doubt my bodys existence my
    body is dubitable. I cant doubt my minds
    existence my mind is indubitable. Therefore
    mind and body are different substances.
  • 1) Mind and body are either the same thing, or
    they are different substances.
  • 2) If two things are identical, then they will
    have all the same properties.
  • 3) So if my mind and body are the same
    substance, theyll have all properties in common.
  • 4) But I can doubt my bodys existence my body
    is dubitable.
  • 5) I cant doubt my minds existence my mind
    is indubitable.
  • 6) Mind and body do not have all properties in
    common.
  • 7) Therefore mind and body are different
    substances.

9
Argument for Analysis
  • According to Descartes, we cant know something
    unless we are so absolutely certain that it is
    true that we cant doubt it. But if we accepted
    this, we would be forced to conclude that we know
    nothing at all, or almost nothing. Its just
    wrong to say that we dont know something just
    because we can doubt that its true, or just
    because its possible that its false this isnt
    what we mean by the term know. For example,
    when I say I know where I parked my bike,
    because I remember doing it. I dont mean to
    indicate that I cant possibly be wrong about
    where I parked my bike, even if it turns out that
    Im a brain in a vat. So to know something isnt
    to be certain about it. So the Cartesian
    analysis of knowledge doesnt capture what we
    typically mean by knowledge.

10
Argument for Analysis
  • 1) According to Descartes, we cant know
    something unless we are so absolutely certain
    that it is true that we cant doubt it.
  • 2) But if we accepted this, we would be forced
    to conclude that we know nothing at all, or
    almost nothing.
  • 3) But we know more than the Cartesian view
    would support.
  • 4) So to know something isnt to be certain
    about it.
  • 5) Descartes was wrong to believe that certainty
    is necessary for knowledge.

11
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12
SKEPTICISM Sextus Empiricus
  • Plato distinguished knowledge from opinion,
    urging that we know only things we discover
    through reason.
  • Aristotle and others call into question Platos
    claim that we know the things Plato thinks we
    know through reason.
  • So what do we know?

13
SKEPTICISM Sextus Empiricus
  • Question What is knowledge?
  • CLAIM You dont know something unless you have
    good evidence that it is true.
  • Question Do you know that you are in a
    philosophy classroom in Ames Iowa on a cold March
    morning?

14
SKEPTICISM Sextus Empiricus
  • Thought Experiment
  • (1) Do you know that the world did not spring
    into existence four seconds ago.
  • (2) Do you know that you are not a brain in a
    vat?

15
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16
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17
An Argument for Skepticism
  • 1) You have no evidence that youre not a brain
    in a vat.
  • 2) If you have no evidence for X, then you dont
    know X.
  • 3) Therefore, You dont know youre not a brain
    in a vat.
  • 4) If you dont know that X is false, but your
    belief Y would be unsupported if X were true,
    then you dont know Y.
  • 5) Therefore, you dont know any of the things
    that depend on the fact that youre not a brain
    in a vat.
  • 6) If youre a brain in a vat, then everything
    else you believe is false.
  • 7) Therefore, you dont know any of those things.
  • 8) Therefore you dont know anything at all.

18
An Argument for Skepticism
  • 1) You have no evidence that youre not a brain
    in a vat. (Is this true? What evidence might
    you offer?)
  • 2) If you have no evidence for X, then you dont
    know X.
  • 3) Therefore, You dont know youre not a brain
    in a vat.
  • 4) If you dont know that X is false, but your
    belief Y would be unsupported if X were true,
    then you dont know Y. (Is this a questionable
    premise?)
  • 5) Therefore, you dont know any of the things
    that depend on the fact that youre not a brain
    in a vat.
  • 6) If youre a brain in a vat, then everything
    else you believe is false.
  • 7) Therefore, you dont know any of those things.
  • 8) Therefore you dont know anything at all.

19
Skepticism
  • Skepticism We do not have knowledge of anything
    at all.

20
Epistemology Theory of Knowledge
  • What is knowledge? What is it to know
    something?
  • What does it mean to say that a belief is
    justified?
  • What can we know?
  • We might start by listing the things we believe

21
Knowledge and Belief
  • We have a vast collection of beliefs, and some of
    them are falseSome people believe that
    astrology can inform us about our futures. mind
    is constituted by the physical operation of the
    brain.
  • mind is soul, an entity separate from brain
    activity that will survive the death or our
    bodies.
  • the universe is ultimately describable in terms
    of physical laws.
  • a full description of the universe will include
    magic and super-natural entities.
  • aliens from outer space are in contact with
    human beings. human beings are the product of
    natural evolutionary selection.
  • there is a God who created everything and who
    cares about us. human beings will make
    settlements on Mars. human beings are more
    likely, in the next millenium, to deplete the
    earth of its resources and destroy the ecosystems
    on which we depend for our lives.
  • Sifting and sorting We dont agree on all of
    these (at least, its unlikely that we do.)
    Those beliefs about which we're less certain are
    less likely to count as knowledge than those
    we're more certain of. Are there any beliefs of
    which we are absolutely certain?

22
Knowledge and Belief
  • We believe many things.
  • Not all of the things we believe are things we
    know.
  • Among the things I believe, which are the things
    I know?
  • Sextus?
  • Descartes?

23
Knowledge and Belief
  • Among the things I believe, which are the things
    I know?
  • Hypothesis The things I know are the beliefs
    that are true.
  • Problem What if I have true beliefs by accident
    or for bad reasons?

24
Knowledge Platoss Analysis
  • Plato, Euthyphro Knowledge is Justified True
    Belief.
  • A person S knows a proposition P If and only if
    1) S believes P2) S is is justified in
    believing P3) P is true

25
Knowledge Platoss Analysis
  • A person S knows a proposition P If and only if
    1) S believes P2) S is is justified in
    believing P3) P is true
  • 1a) What is belief?
  • (Mental attitude associated with accompanying
  • dispositions) 1b) What are the objects of
    belief?
  • (Propositions Statements that can be true or
    false.)
  • 2) When is belief justified?
  • (There are alternative theories of
    justification)3) What is it for a proposition to
    be true?
  • (There are alternative theories of truth)

26
Knowledge Platoss Analysis
  • JUSTIFICATION AND BELIEF
  • The 'Why?' game... at a certain point in a
    childs development, she gets the idea that there
    are reasons for things, and start asking why.
  • Justification A theory of the justification of
    beliefs must provide us with a model of how to
    play the why game, or as it is sometimes called,
    the justification game.

27
Skeptical Scenareos
  • Sextus Empiricus' Trilemma
  • (Also called Agrippas Trilemma, after Agrippa
    the Skeptic. This is a Modern Rendition)
  • 1) We have knowledge only if our beliefs are
    justified. 2) 'justification' can take three
    possible forms A) We justify our total belief
    set by reference to some
  • foundational belief or set of such beliefs,
    which are not
  • themselves justified by any further beliefs.
    B) Our beliefs mutually justify one another.
    C) There is an endless regress of justifying
    reasons. 3) Not A A foundational belief could
    not justify other beliefs unless it were itself
    justified. 4) Not B Circular justification is
    no justification at all. 5) Not C An endless
    regress of reasons could not provide
    justification for our first-level beliefs. 6)
    Therefore, we don't have knowledge.

28
Skeptical Question
  • Do we know anything at all?
  • If I might be dreaming, might be a brain in a
    vat, might be systematically deceived by an evil
    genius
  • then can I know anything?

29
  • Many epistemic theories, like that of Descartes,
    are attempts to show that skepticism is false,
    and that we can have justified beliefs in spite
    of the force of skeptical arguments.

30
A Coherent Skepticism?
  • Skepticism The view that we dont have any
    knowledge.
  • Nothing can be known, not even this.
  • -Carneades 214-129 BCE
  • The skeptical dictum is like a purgative when
    we take it, the dictum itself is thrown up along
    with all our other dogmatic beliefs.
  • -Miguel de Montaigne

31
Sextus Empiricus
  • Skepticism is an ability to place reasons in
    opposition to one another, so as to achieve a
    balance that leaves us free of dogmatic beliefs.
  • Is skepticism self-contradictory? The skeptic
    claims we have no knowledge (?), but isnt making
    that claim a violation of the skeptical
    imperative to avoid making positive claims?

32
Sextus, Epicurus, and Epictetus
  • All three urge that philosophy can provide us
    with peace of mind, and protect us from
    unhappiness.
  • Ataraxia- (Epicurus and Sextus) Freedom from
    worry, created by passions or dogmatic
    convictions.
  • Apatheia (Epicurus, Seneca) Freedom from
    passions, and the false beliefs that generate
    passions.
  • Acatalepsia (Sextus) The ability to withhold both
    assent and denial from doctrines that are
    presented to us for belief.

33
Sextus
  • Goal of skepticism is freedom and peace of mind.
  • Skepticism is an ability to withhold assent, that
    can be mastered with practice and study.
  • We exercise this ability by considering all the
    evidence against a proposition alongside the
    evidence for it.

34
Sextus Empiricus
  • Q Why is skepticism characterized as an
    ability?
  • A It would be inconsistent for a skeptic to
    have a doctrine, since adherence to a doctrine
    involves belief and commitment.
  • (Connect this with the common charge that
    skepticism is inconsistent)

35
A Coherent Skepticism?
  • Skepticism The view that we dont have any
    knowledge.
  • Nothing can be known, not even this.
  • -Carneades 214-129 BCE
  • The skeptical dictum is like a purgative when
    we take it, the dictum itself is thrown up along
    with all our other dogmatic beliefs.
  • -Miguel de Montaigne

36
Sextus
  • Question In denying that we know anything, is
    the skeptic denying knowledge in the Platonic
    sense, or merely denying that we have certainty
    about things? (Fallibilism)

37
Sextus and the Modes
  • The modes are methods we can use to achieve the
    suspension of judgment (aporea or acatalepsia)
    that allows us a kind of freedom we would not
    have if we were to submit to dogmatic beliefs.

38
Modes of Skepticism
  • 1) The same objects dont produce the same
    impression in different animals.
  • 2) Differences between individuals lead to
    differences in perception of the way things are.
  • 3) Different senses give us very different
    information about the objects we perceive.
  • 4) Differences in our circumstances cause things
    to appear differently to us. (sleep/wake,
    drunk/sober)

39
Modes of Skepticism
  • 5) When we perceive objects from different
    positions, they appear different to us.
  • 6) We perceive objects in groups, and the
    admixture of different objects causes each to
    be perceived differently by us.
  • 7) When substances are in different states, they
    appear differently to us. (snow/water)
  • 8) Our perception of objects is relative to
    ourselves and circumstances. (?)

40
Modes of Skepticism
  • 9) Our perception of objects changes depending on
    whether we see them frequently or seldom.
  • 10) Ethical judgments appear to be based on
    custom, and different people with different
    backgrounds make different judgments.

41
Sextuss Instruction
  • Whenever you are tempted by dogmatism, line up
    reasons for and against the proposition until
    they balance out.
  • At this point, you will be free from convictions
    (acatalepsia) having lost the propensity to
    dogmatic adherence.
  • In this state, you will be free trouble (in a
    state of ataraxia) since we are only bothered
    when our dogmatic convictions or judgments are
    thwarted by the world.

42
Compare Skepticism and Stoicism
  • Skeptics and stoics (and Epicureans too) agree
    that our goal should be to free ourselves from
    troubles arising from false beliefs.
  • While the stoics recommend extirpation of desires
    and aversions, the Skeptics recommend extirpation
    of dogmatic convictions.
  • The stoics agree that disturbances (desires and
    aversions) arise from false beliefs. But they do
    not recommend eliminating our beliefs.

43
Skeptical Ataraxia?
  • Abandoning dogmatic convictions will leave us
    free and happy we will be undisturbed by things
    that disturb other people. Their disturbance
    rests on a mistake they have allowed themselves
    to believe where they should instead have
    withheld belief and judgment.

44
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45
Knowledge and Belief Descartess Problem
  • Descartes's Problem How can I have knowledge of
    anything, and which are the things I know?
  • Sifting and sorting Those beliefs about which
    we're less certain are less likely to count as
    knowledge than those we're more certain of. Are
    there any beliefs we're absolutely certain of?

46
Knowledge and Belief Descartess Problem
  • DF of "undermining" A proposition P undermines
    another proposition Q just in case the truth of P
    would be good evidence either (i) that Q is
    false, or (ii) that our reasons for believing Q
    are not good reasons for believing Q.
  • Proposed Principle for Negative Justification
    Take any propositions P and Q where P undermines
    Q. If you have no evidence that P is false, then
    you are not fully justified in believing Q.
  • But If you have no evidence that the Demon
    hypothesis is false, then you are justified in
    believing none of the things that would be
    undermined by this hypothesis.

47
Knowledge and Belief Descartess Problem
  • Descartes, Meditation I The Dream Argument
  • 1) In Meditation 1, Descartes believes that he
    is sitting before a fire.2) But if Descartes is
    in bed dreaming, then he's not before a fire.3)
    Descartes argues that he has no evidence (or
    inadequate evidence) to justify his belief that
    he's not dreaming. 4) So he doesn't know that
    he's not dreaming. 5) So he doesn't know that
    he's sitting before a fire.

48
DESCARTES Meditations on First Philosophy
  • Meditation One Introduces Skeptical Problem,
    Method of Doubt, distinguishes among different
    sources of belief.
  • The Project Wholesale reconstruction of a belief
    system Descartes wants to tear it to the ground
    and build it back from solid foundations.

49
DESCARTES Meditations on First Philosophy
  • THE SKEPTICAL PROBLEM
  • The starting point recognition that many
    previously held beliefs are either false or
    unfounded. We need, he believes, a firm
    foundation on which to place our knowledge, to
    insure that our beliefs will be true.

50
DESCARTES Meditations on First Philosophy
  • Method of Doubt Test beliefs according to their
    "doubtability." If I can doubt one belief, but I
    cannot doubt another, then surely my belief in
    the second is firmer than my belief in the first.
    For the moment, Descartes recommends that I admit
    only those truths (if any) which I can
    immediately perceive clearly and distinctly. Any
    others whose truth I can derive from this basic
    set will also be justified.

51
DESCARTES Meditations on First Philosophy
  • First Possible Way Out Foundationalism A person
    is justified in holding a belief only if it is
    either self evident, or is directly or indirectly
    inferred from self evident propositions by
    self-evident principles of inference.
  • A proposition is self evident(df) just in case
    believing that it is true is sufficient for
    knowing that it is true. Some philosophers have
    doubted that there are any self evident
    propositions.

52
DESCARTES Meditations on First Philosophy
  • Two Potential Problems for Foundationalism
    These two are inconsistent with one another. Do
    you see why?
  • 1) Perhaps there are no self-evident
    propositions.
  • 2) Perhaps there are some self-evident
    propositions, but they are inadequate since they
    provide us with no conclusive argument against
    the skeptic.

53
DESCARTES Meditations
  • CATEGORIES OF BELIEFS Rather than examining each
    belief in turn, (there are just too many)
    Descartes categorizes his beliefs
  • 1) Blfs deriving from the senses. (Undermined by
    Dream argument) (But the images composing my
    dream must have their source somewhere-- there
    must exist some basic source of this material I
    dream about... no? But what that basic source may
    be is quite mysterious. Do I know that it
    mightn't be me?)
  • 2) Blfs about empirical science have the same
    status as other blfs deriving from the senses.
  • 3) Blfs about "simple and universal" things
    (math Logic) Descartes finds that he can even
    doubt these...(Perhaps I get confused whenever I
    add 2 and 2) (139.2)

54
DESCARTES Meditations on First Philosophy
  • ON THE EVIL GENIUS HYPOTHESIS
  • Don't misunderstand Descartes doesn't believe
    that there is an evil demon, he rather considers
    whether he has any evidence which would enable
    him to prove that there is not one. The evil
    demon hypothesis is one way to call into question
    the justification of beliefs which derive from
    the senses it is a potential defeater for many
    of the things we think we know.

55
DESCARTES Meditations on First Philosophy
  • Meditation One ends as it starts with unresolved
    doubts. It seems, at the end, that the demon
    hypothesis provides a potential reason for
    doubting just about anything. However, Descartes
    (like Hume later) finds that he cannot maintain
    skepticism See p. 63 "But this undertaking is
    arduous and a certain laziness brings me back to
    my customary way of living."

56
DESCARTES Meditations on First Philosophy
  • One Kind of Objection We don't have the
    technology to envat people, and there isn't an
    evil genius... In sum, the evil demon hypothesis
    is just not true.
  • Response This objection is a non-starter since
    it begs the question. Descartes never claimed
    that there is an evil genius (nor did I claim
    that we are really envatted brains). The point is
    to sift among our beliefs to find those that are
    more securely justified than others. The evil
    demon hypothesis is not true, but it is
    conceptually possible (That is, thinking about it
    doesn't involve us in any contradictions.)

57
DESCARTES Meditations on First Philosophy
  • Descartes and Skepticism if we can find a
    foundation for our belief system which is both
  • 1) self evidently true, and2) sufficiently
    powerful to enable us to deduce that our
    perceptual beliefs are true, THEN we could escape
    the skeptical argument. Is there such a
    foundation?

58
DESCARTES Meditations on First Philosophy
  • ON TO MEDITATION TWO!
  • Descartes DISCOVERS a self-evident belief.
  • Descartes ARGUES that some of his beliefs could
    not have originated with him.
  • Descartes PROVES (?) that God exists and that God
    is not a deceiver.

59
DESCARTES Meditations on First Philosophy
  • Cogito Consider the proposition 'I exist.'
  • Apply method of doubt If there is any
    conceivable circumstance in which it could SEEM
    TO ME that I exist, and yet I could be wrong,
    then the proposition 'I exist' can be doubted. Is
    there such a circumstance? Demon world is the
    most complete hallucination imaginable. If I
    couldn't be wrong in the demon world, then I
    couldn't be wrong at all. But in the demon world
    I must exist, since there is an 'I' to be
    deceived.Therefore I know that I exist any time
    I stop to consider the question.
  • "Cogito Ergo Sum." (I think therefore I am.)

60
DESCARTES Meditations on First Philosophy
  • Descartess Foundational Belief I exist.
  • 1) I know X only if I perceive that clearly and
    distinctly that X is true, such that it is
    impossible for me to doubt X.
  • 2) Query Can I doubt my own existence.
  • 3) For me to doubt my existence, there must be a
    me to do the doubting.
  • 4) Any time I doubt my existence, I can clearly
    and distinctly understand that I must exist.
  • 5) I cant doubt my own existence.
  • 6) I know the proposition I exist.

61
DESCARTES Meditations on First Philosophy
  • "Cogito Ergo Sum." (I think therefore I am.)
  • How far will this get us? Descartes has argued
    that the proposition "I exist." is self evident.
    But is it powerful enough that it can support my
    knowledge of the external world? Can this help me
    out of the vat?

62
DESCARTES Meditations on First Philosophy
  • Descartes and Skepticism if we can find a
    foundation for our belief system which is both
  • 1) self evidently true, and2) sufficiently
    powerful to enable us to deduce that our
    perceptual beliefs are true, THEN we could escape
    the skeptical argument. Is there such a
    foundation?

63
DESCARTES Meditations on First Philosophy
  • "Cogito Ergo Sum." (I think therefore I am.)
  • Question What is this thing (ME) whom we know to
    exist? Am I my body? Not in the demon world,
    where I still exist...
  • I am a thing that thinks. That's all I know for
    sure. I am something that doubts, affirms,
    understands, denies, wills, refuses, imagines and
    senses.
  • In fact, what I know is that I am a thing that
    has ideas.

64
Knowledge and BeliefMotivating Skeptical Doubts
  • DF of "undermining" A proposition P undermines
    another proposition Q just in case the truth of P
    would be good evidence either (i) that Q is
    false, or (ii) that our reasons for believing Q
    are not good reasons for believing Q.
  • Proposed Principle for Negative Justification
    Take any propositions P and Q where P undermines
    Q. If you have no evidence that P is false, then
    you are not justified in believing Q.
  • Proposal The demon hypothesis is an underminer
    for all empirical beliefs. So if (1) you accept
    this proposed principle, and (2) you have no
    evidence that the demon hypothesis is false, then
    you must be a skeptic about all empirical
    beliefs.

65
Another ProblemKnowledge and Belief Is
Justified True Belief Knowledge?
  • Example I have on my car a sticker that says
    "Oberlin College." People who see this sticker
    usually form the belief that I graduated from
    Oberlin college. This belief is justified,
    since the sticker is good evidence that I went to
    Oberlin. This justified belief is true, since I
    did attend Oberlin. But is it knowledge?
  • Problem The sticker was on the car when I bought
    it (used), and I didn't put it there. If people
    knew this, it would undermine their belief that I
    went to Oberlin college, by showing that their
    reason for believing that I did was not a good
    reason.
  • Question If you don't know that the sticker was
    on my car when I bought it, is your belief that I
    went to Oberlin College justified?

66
Knowledge and Belief The Gettier Problem
  • 1) John regards the Oberlin sticker on Clarks
    car as evidence that Clark went to Oberlin
    college.
  • 2) Johns belief that ltClark went to Oberlin
    Collegegt is based on the fact that he saw an
    Oberlin sticker on Clarks car.
  • 3) This belief is justified (the reason is a
    good one), true.
  • (I did attend Oberlin)
  • 4) But contrary to Johns belief, the sticker
    on Clarks car is not evidence that Clark went to
    Oberlin.
  • 5) Therefore John does not know that Clark
    went to Oberlin.
  • 6) Therefore justified true belief is not
    knowledge.
  • (Reject 3? Find an additional criterion to add
    to JTB?)

67
Gettier Problem
  • One may BELIEVE P, be JUSTIFIED IN BELIEVING P,
    and P may be TRUE, but this is not enough ones
    belief must be connected with the truth in the
    right way.
  • If Im right by accident, then my justified true
    belief is not knowledge.

68
Responses to the Gettier Prob
  1. Look for a theory of justification that ties the
    justification of a belief more strongly to the
    conditions that render it true.
  2. Accept that JTB is not knowledge
  3. Fallibilism accept that knowledge can be
    fallible.
  4. Skepticism We dont have any knowledge.

69
DESCARTES Meditations on First Philosophy
  • The Wax Example My idea of the wax remains the
    same while the wax goes through drastic changes
    it is the same wax although its properties change
    when it is melted or frozen. My senses do not
    give me an understanding of the wax I get
    different sensory information as the wax changes,
    but my idea of the wax itself persists over these
    changes. So "perceiving the wax" is essentially
    an act of the mind, not of the senses.

70
DESCARTES Meditations on First Philosophy
  • The Wax Example My idea of the wax remains the
    same while the wax goes through drastic changes
    it is the same wax although its properties change
    when it is melted or frozen. My senses do not
    give me an understanding of the wax I get
    different sensory information as the wax changes,
    but my idea of the wax itself persists over these
    changes. So "perceiving the wax" is essentially
    an act of the mind, not of the senses.
  • Theory of Representative Ideas Knowledge is a
    two-way relationship between one's ideas and the
    objects in the external world. We have internal
    access to our ideas, but not to the objects of
    which they are ideas.

71
DESCARTES Meditations on First Philosophy
  • A Problem for Cartesian Foundationalism The
    theory of representative ideas leaves us trapped
    in the confines of our own mind! Descartes has
    (perhaps?) found a foundational belief, but is it
    powerful enough to respond to the skeptic? Does
    it enable us to think ourselves out of the vat?
    Unfortunately, even if we have certainty with
    respect to the cogito and also to our first level
    sensory beliefs (beliefs about the way things
    seem to us), we cannot derive from these basic
    beliefs any statements about the existence of
    external objects. We can't make it out of the
    vat.

72
DESCARTES Meditations on First Philosophy
  • To respond to the skeptic, a foundationalist must
    show two things 1) There are self evident
    propositions, and 2) From these propositions we
    can derive knowledge of empirical reality.
  • So Descartes needs some more equipment He needs
    GOD.

73
DESCARTES Meditations on First Philosophy
  • MEDITATION THREE Concerning the Existence of God
  • Method Descartes has established that he exists
    as a thinking thing. In the third meditation he
    undertakes to examine the ideas that he finds in
    his mind, and to consider their origin. "But
    here I must inquire particularly into those ideas
    that I believe to be derived from things existing
    outside of me." If he can deduce that these ideas
    do nor originate in him, then he may conclude
    that there is something external that is the
    origin of these ideas.

74
DESCARTES Meditations on First Philosophy
  • DESCARTES ARGUMENTS CONCERNING THE EXISTENCE OF
    GOD
  • Argument from the Perfect Idea of an Infinite
    Being 1) I have an idea of God which is the
    idea of a substance that is infinite,
    independent, supremely intelligent, and supremely
    powerful. III.45-62) As a finite and imperfect
    being, I cannot be the cause of a perfect idea of
    an infinite substance. III.45-63) Only an
    infinite and perfect being could be the cause of
    such an idea.4) Therefore, there exists an
    infinite and perfect being who is the cause of my
    idea.

75
DESCARTES Meditations on First Philosophy
  • Ontological Argument (Meditation Five) 1) I
    have an idea of God. 2) The idea of God is the
    idea of a being that has all perfections. 3)
    'Existence' is a perfection. That is, what
    exists in reality is more perfect than what
    exists only in the imagination. 4) Therefore a
    being that has all perfections must have
    'existence.' 5) God exists.

76
DESCARTES Meditations on First Philosophy
  • Anselm's Version of the Ontological Argument 1)
    I have an idea of God. 2) The idea of God is the
    idea of the greatest conceivable being. 3) A
    being that exists in reality as well as in the
    mind (in imagination) is greater than a being
    that exists only in the mind. 4) Suppose that
    the Greatest Conceivable Being exists only in the
    mind but not in reality. 5) Then we can conceive
    of a being that is even greater one who exists
    in reality as well as in the mind. 6) Then we
    can conceive of a being greater than the greatest
    conceivable being-- but that would be a
    contradiction! 7) Therefore it is not the case
    that the greatest conceivable being exists only
    in the mind but not in reality. 8) Therefore the
    greatest conceivable being exists in reality as
    well as in the mind. 9) Therefore God exists.

77
DESCARTES Meditations on First Philosophy
  • Some Further Steps 1) If there is a perfect
    being, then the evil demon hypothesis is
    false. 2) Therefore my senses give me true
    information about the world.  3) Therefore
    skepticism is false.

78
DESCARTES Meditations on First Philosophy
  • Physicalism Mind and body are both physical
    substances, and the consequence of interaction of
    physical particles and forces.
  • Dualism Mind and body are different substances
    that interact but which are essentially
    different.

79
DESCARTES Meditations on First Philosophy
  • Mind and Body
  • Descartes is a Dualist he argues that mind and
    body are different, separate substances. Here is
    one Cartesian argument for Dualism
  • 1) If one substance has a property P while
    another substance lacks property P, then the two
    substances are not identical.2) I can doubt the
    existence of my mind my mind has the property of
    'dubitability'.3) I can't doubt the existence of
    my body my body lacks the property of
    dubitability.4) Therefore my mind is a different
    substance from my body.

80
DESCARTES Meditations on First Philosophy
  • Reservation is 'dubitability' a property of
    things or of thinkers? Perhaps premises two and
    three say more about Descartes thought processes
    than about the things Descartes is considering.

81
For Physicalism
  • Physical Evidence of Anasthesia
  • Contemporary Science of Consciousness presumes
    physicalism.
  • Mind-Brain Identity and Split Brain cases.

82
DESCARTES Meditations on First Philosophy
  • Final Issues in Cartesian Epistemology
  • Does Descartes have a satisfactory response to
    the skeptic? Unless one is satisfied with the
    proof of the existence of God, one may conclude
    that Descartes has escaped the skeptical
    conclusion only because he accepted a bad
    argument. Few believe that any of the
    philosophical arguments for God's existence is
    conclusive indeed James assumes that his
    listeners and readers will already have
    recognized that the evidence for the existence of
    God is inconclusive.

83
Descartes Where from here?
  • Does Descartes have a satisfactory response to
    the skeptic? Unless one is satisfied with the
    proof of the existence of God, one may conclude
    that Descart has escaped the skeptical conclusion
    only because he accepted a bad argument. Few
    believe that any of the philosophical arguments
    for God's existence is conclusive indeed James
    assumes that his listeners and readers will
    already have recognized that the evidence for the
    existence of God is inconclusive.
  • If this is right, where does it leave Descartes?
    Are we still in the vat? Some people conclude
    that Descartes simply failed to provide a
    convincing response to the skeptic. The
    meditations get the epistemological project off
    the ground, but don't really take it beyond the
    vat. Where does the argument go wrong? There are
    several possibilities

84
Descartes Where from here?
  • Conclusions from Descartes Discussion
  • 1) The negative principle of justification may
    just be too strong a condition to place on
    knowledge. Perhaps this principle should be
    rejected. Many (most!) contemporary
    epistemologists would reject it.
  • 2) Some attribute Descartes failure to the
    representative theory of ideas Bertrand Russell
    argued that perception gives us immediate contact
    with the world, and denies Descartes claim that
    we are only in immediate contact with our ideas.
  • 3) Some argue that Descartes' failure shows that
    foundationalism is unacceptable. One might opt
    instead for a Coherentist or Pragmatist account
    of the justification of belief. James' opts for
    a pragmatist solution. Other contemporary
    epistemologists hold that beliefs come in systems
    and deny that it is circular for all beliefs to
    be justified by reference to other fallible
    beliefs.

85
Descartes Where from here?
  • Some Non-Cartesian Alternatives
  • Coherentism There are no adequate foundations
    for knowledge, but we can be justified in our
    beliefs provided that they cohere appropriately
    with other of our beliefs. Coherentists must
    then give a clear account of what 'coherence'
    means, and must respond to the objection that
    fiction may be coherent. See Keith Lehrer Theory
    of Knowledge for a clear, contemporary
    coherentist account of justification.
  • Fallibilism To know a proposition, it not
    necessary to have indubitable certainty that it
    is true.
  • Most fallibilists would reject the Negative
    Principle of Justification. Most contemporary
    epistemologists are fallibilists. Those
    epistemologists who are not fallibilists are
    mostly skeptics. I haven't done a survey, these
    are my impressions.
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