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Knowledge and Mind

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Title: Knowledge and Mind


1
Knowledge and Mind
  • Thursday, April 19th

2
Testimony Two questions
  • 1. What is the nature of testimony?
  • 2. Can testimonial beliefs be justified?

3
1. The Nature of Testimony
  • Elucidate the nature of testimony by asking
    several questions
  • Does testimony imply truth? Can you testify
    something if what you say is false?
  • Does testimony imply that you believe that what
    you testify is true? Can you testify something if
    you believe that what you say is false (even
    though it might in fact be true)?

4
2. The Nature of Testimony
  • Does testimony imply the intention to testify?
  • John is sitting in his room. In the next room,
    his neighbour Jill is talking to herself again.
    She says I really hate my boyfriend. She did
    not have the intention to communicate this
    information to John. Did she testify that she
    hates her boyfriend?
  • Answer no.
  • Reason no intention to communicate information.

5
3. The Nature of Testimony
  • Does testimony imply the intention to testify?
  • John is sitting in his room. In the next room,
    his neighbour Jill is talking to her friend Anne.
    She says I really hate my boyfriend. She did
    have the intention to communicate this
    information to Anne. John happens to overhear the
    conversation. Did Jill testifying that she hates
    her boyfriend to John?
  • Answer no.
  • Reason no intention to communicate information
    to John.

6
Justification of testimonial-based beliefs
  • Two views
  • Reductionism, and
  • non-reductionism.

7
The Nature of Testimony
  • Perhaps difficult to answer because testimony
    is a technical term?

8
Reductionism
  • For a testimony-based belief to be justified,
    there must be additional evidence to support the
    belief. The testimony all by itself is not
    sufficient to give justification to the belief
    based on that testimony.

9
Two versions of reductionism
  • Global reductionism in order for testimony-based
    belief B to be justified, the hearer must have
    reasons to think that testimony in general is
    reliable.

10
Two problems for global reductionism
  • 1. Children would have to wait with accepting
    testimony until they have been able to check for
    a wide-ranging samples of testimony that these
    samples are based on a reliable source.
  • 2. Unclear that there is a fact of the matter
    regarding whether testimony is reliable in
    general. There are many different types of
    testimony.

11
Local reductionism
  • This is the view that in order for a
    testimony-based belief to be justified, the
    subject must only have reasons to think that the
    particular instance of testimony is reliable.

12
Counterexample to local reductionism
  • Fred has excellent reason to believe that Helen
    is a highly reliable source of information.
    Yesterday, Helen told Fred that Pauline is a
    highly trustworthy person when it comes to
    information regarding wild birds. Pauline told
    Fred that albatrosses, not condors, have the
    largest wingspan among birds. Fred believed her
    testimony. In that case, however, Pauline was
    completely wrong. In fact, Pauline is a very
    incompetent and insincere speaker. (from Lackey
    2006)
  • Is Fred justified?
  • Intuitively no
  • According to local reductionism, however, he is!

13
Non-reductionism
  • The view that a testimony-based belief can be
    justified even though there is no additional
    evidence.

14
Counterexample to non-reductionsim
  • Sam is a human being. One day, he walks through
    the forest and sees something drop a book. The
    individuals appearance enables Sam to identify it
    as an alien from another planet. Sam picks up the
    book, notices that it is a diary, and reads the
    tigers have eater some of the inhabitants of
    Earth. This information is correct. (from
    Jennifer Lackey 2006)
  • Does Sams testimony-based belief have
    justification?
  • Yes, according to non-reductionism.
  • No, according to our intuitions. It seems
    irrational for Sam to believe this. It may well
    be that these aliens are always insincere and
    deceptive when trying to testify to others.

15
Next week
  • Perception

16
Tuesday, April 24th 2007
  • Perception and Radical Scepticism

17
Perception
  • One of the most important sources of knowledge.
  • Testimony even presupposes perception.

18
The problem
  • The way things look isnt always the way things
    are.
  • Example a straight stick will look bend when
    placed underwater.
  • Example you look at a red wall. But the wall is
    actually white but illuminated by a red light.
  • So is perception a reliable guide to the nature
    of reality? Should we trust perception?

19
Radical scepticism and perception
  • Suppose you look at your hand. You perceive what
    you think is your hand. And you form the belief
    that you are seeing your hand.
  • But do you know that you have hands on the basis
    of perception?
  • The sceptic will answer no!

20
Radical scepticism
  • It might be the case that you are a
    brain-in-a-vat (BIV) or that you are deceived by
    an evil demon.
  • The deception is such that it provides you with
    exactly the same experiences as you would have
    had were you not deceived.
  • So there is no way to distinguish between being
    deceived into believing that you are perceiving a
    hand, and genuinely believing that you are
    perceiving a hand.

21
Evidence underdetermined
  • So the problem is that the evidence we have for
    perceptual beliefs is underdetermined. The
    evidence of seeing hands can both be explained by
    us having hands and by our being deceived into
    perceiving hands.

22
Sceptical paradox
  • All this is formalized in the sceptical paradox
  • 1. K BIV
  • 2. K BIV ? -K hands
  • 3. K hands

23
Paradox?
  • Because
  • (i) intuitive premises
  • (ii) sound reasoning
  • (iii) counterintuitive conclusion

24
Ways out of the paradox
  • 1. deny premise 1
  • 2. deny premise 2
  • 3. accept the conclusion

25
Deny premise 1
  • Mooreanism.
  • We can know that we are not BIVs because we know
    that we have hands
  • Reverses the sceptical argument, from modus
    ponens to modus tollens

26
  • Khands
  • Khands --gt K-BIV
  • Hence, K-BIV
  • Problem dialectially improper response. Also
    does not explain why we think the first premise
    is intuitive.

27
Deny second premise
  • 2. K BIV ? -K hands
  • Underlying this premise is the closure principle
    for knowledge
  • If you know that p, and if you know that p
    implies q, then you know that q.
  • If you know that you have hands, and if you know
    that having hands implies not being a BIV, then
    you know that you are not a BIV.
  • But you dont know that you are not a BIV.
  • So you dont know that you have hands.

28
Problems
  • Closure highly intuitive.
  • No explanation of why closure is mistakenly taken
    to be so intuitive.

29
Idealism?
  • The view that knowledge of the external world is
    not knowledge independent of our perception of
    it, but rather is constituted by our perception.
  • The external world is a construct out of our
    appearances.

30
Desideratum
  • Must explain why we thought the premise so
    intuitive even though it appears false.

31
Knowledge and MindThursday April 26th 2007
32
Sceptical paradox
  • 1. K BIV
  • 2. K BIV ? -K hands
  • 3. K hands

33
Solutions to scepticism
  • 1. Mooreanism (deny premise 1)
  • 2. Anti-closure (deny premise 2)
  • 3. Contextualism

34
Anti-closure
  • 2. K BIV ? -K hands
  • Underlying this premise is the closure principle
    for knowledge
  • If you know that p, and if you know that p
    implies q, then you know that q.
  • If you know that you have hands, and if you know
    that having hands implies not being a BIV, then
    you know that you are not a BIV.
  • But you dont know that you are not a BIV.
  • So you dont know that you have hands.

35
Problems
  • Closure highly intuitive.
  • No explanation of why closure is mistakenly taken
    to be so intuitive.

36
Contextualism
  • Intuition the word knows means the same thing
    in every context of use.
  • If we deny this intuition, we might have a way
    out of the sceptical paradox.
  • Specifically the word knows means two
    different things either it means knows
    according to high standards, or it means knows
    according to low standards.

37
Example Bank Case A
  • Suppose that you are driving home with your wife
    on a Friday afternoon. You plan to stop at the
    bank on the way home to deposit your paychecks.
    But driving past the bank, you notice that the
    lines inside are very long. Fortunately, in this
    case it is not important that the checks be
    deposited right away, so you suggest to drive
    straight home and deposit the pay checks on
    Saturday morning. Your wife says, Maybe the bank
    wont be open tomorrow. Lots of banks are closed
    on Saturdays. You reply, No, I know itll be
    open. I was just there two weeks ago on Saturday.
    Its open until noon.

38
Example Bank Case B
  • Now suppose that everything is as in the previous
    case, besides this youve just written a very
    large and very important check, which will bounce
    when not deposited into your checking account
    before Monday morning.And, of course, the bank is
    not open on Sunday.Your wife reminds you of these
    facts. She then says, Banks do change their
    hours. Do you know the bank will be open
    tomorrow?
  • Remaining as confident as you were before that
    the bank will be open then,still,you
    reply,Well,no.Id better go in and make sure.

39
Intuitions
  • Bank case A knowledge
  • Bank case B no knowledge
  • Conclusion knows must mean different things in
    different contexts.

40
Contextualism
  • The truth-conditions of knowledge sentences
    fluctuate with changes in the context.
  • So skp might be true in a low-standards
    context, but might be false in a high-standards
    context.

41
Versions of contextualism
  • 1. Standards for knowledge fluctuate.
  • 2. The amount of alternatives you have to
    eliminate fluctuates.

42
Contextualism and scepticism
  • No knowledge in high-standards contexts.
  • Knowledge in low-standard contexts.
  • So long as sceptical scenarios are not
    mentioned, we know propositions about the
    external world.

43
Alternative explanation for bank cases
  • Warranted assertability maneuver 1
  • Bank Case A there is knowledge
  • Bank Case B there is knowledge, but it would be
    unwarranted to assert that there is knowledge in
    this case.
  • We have confused the truth of the knowledge
    sentence with its assertability conditions.

44
  • Warranted Assertability maneuver 2
  • There is no knowledge in Bank Case A, but it is
    warranted to assert that there is
  • There is no knowledge in Bank Case B
  • We have confused the truth value with the
    conditions for warranted assertion.

45
Tuesday, May 1stKnowledge and Mind
  • Contextualism and Scepticism
  • Sceptical Paradox
  • Three solutions to the paradox
  • New solution contextualism
  • Problem with contextualism

46
Practical information
  • Exam answer three questions out of 8.
  • There will be no division in the exam paper
    between mind and knowledge. You can do
  • 3 mind, 0 knowledge
  • 0 mind, 3 knowledge
  • 2 mind, 1 knowledge
  • 1 mind, 2 knowledge

47
Sceptical Paradox
  • 1. K BIV
  • 2. K BIV ? -K hands
  • 3. K hands

48
Solutions to the sceptical paradox
  • 1. Mooreanism (deny premise 1)
  • 2. Anti-closure (deny premise 2)
  • 3. Scepticism (accept)
  • Always explain why the claim you deny or accept
    seemed intuitive but actually is false.

49
Problems with these solutions
  • All are counterintuitive.
  • New solution contextualism. Defended by Keith
    DeRose, Stewart Cohen, David Lewis.

50
Contextualism
  • Intuition the word knows means the same thing
    in every context of use.
  • If we deny this intuition, we might have a way
    out of the sceptical paradox.
  • Specifically the word knows means two
    different things either it means knows
    according to high standards, or it means knows
    according to low standards.

51
Motivating contextualism The Bank Cases.
  • Bank Case A Suppose that you are driving home
    with your wife on a Friday afternoon. You plan to
    stop at the bank on the way home to deposit your
    paychecks. But driving past the bank, you notice
    that the lines inside are very long. Fortunately,
    in this case it is not important that the checks
    be deposited right away, so you suggest to drive
    straight home and deposit the pay checks on
    Saturday morning. Your wife says, Maybe the bank
    wont be open tomorrow. Lots of banks are closed
    on Saturdays. You reply, No, I know itll be
    open. I was just there two weeks ago on Saturday.
    Its open until noon.

52
Motivating contextualism The Bank Cases.
  • Bank Case B Now suppose that everything is as in
    the previous case, besides this youve just
    written a very large and very important check,
    which will bounce when not deposited into your
    checking account before Monday morning. And, of
    course, the bank is not open on Sunday. Your wife
    reminds you of these facts. She then says, Banks
    do change their hours. Do you know the bank will
    be open tomorrow?
  • Remaining as confident as you were before that
    the bank will be open then, still, you reply,
    Well, no. Id better go in and make sure.

53
Intuitions
  • Bank case A knowledge
  • Bank case B no knowledge
  • Conclusion knows must mean different things in
    different contexts.

54
Contextualism
  • The truth-conditions of knowledge sentences
    fluctuate with changes in the context.
  • So skp might be true in a low-standards
    context, but might be false in a high-standards
    context.

55
Contextualism and scepticism
  • No knowledge in high-standards contexts.
  • Knowledge in low-standard contexts.
  • So long as sceptical scenarios are not
    mentioned, we know propositions about the
    external world.

56
Contextualism and Scepticism
  • Both the sceptic and the non-sceptic are correct.
  • 1. K BIV true in a sceptical context, but
    false in a non-sceptical context.
  • 2. K BIV ? -K hands
  • 3. K hands true in a sceptical context, but
    false in a non-sceptical context

57
Problem for contextualism
  • Warranted assertability maneuver 1
  • Bank Case A there is knowledge
  • Bank Case B there is knowledge, but it would be
    unwarranted to assert that there is knowledge in
    this case.
  • We have confused the truth of the knowledge
    sentence with its assertability conditions.

58
Problem for contextualism
  • Warranted Assertability maneuver 2
  • There is no knowledge in Bank Case A, but it is
    warranted to assert that there is
  • There is no knowledge in Bank Case B
  • We have confused the truth value with the
    conditions for warranted assertion.
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