Monday, February 13, 2006 PHL105Y

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Monday, February 13, 2006PHL105Y

• For Wednesdays class, read Nelson Goodmans The
  New Riddle of Induction (294-297 in the Pojman)
• For Fridays tutorial, answer one of the
  following questions
• Is the statement all emeralds are grue lawlike
  or accidental?
• Goodman doesnt think it will solve the new
  riddle of induction to insist that all predicates
  be purely qualitative. Why not?

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Edmund Gettier

• Is Justified True Belief Knowledge?
• (1963)

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The Analysis of Knowledge

• Can knowledge be analysed into simpler
  components?
• What do we mean we say that someone knows
  something?

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The Analysis of Knowledge

• Consider the sentence
• George Bush knows that Dick Cheney shot someone
  on Saturday.

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The Analysis of Knowledge

• Consider the sentence
• George Bush knows that Dick Cheney shot someone
  on Saturday.
• What can you deduce from this sentence, just
  based on your understanding of the verb knows?

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The Analysis of Knowledge

• Consider the sentence
• George Bush knows that Dick Cheney shot someone
  on Saturday.
• It implies something about the world
• It implies something about George Bush

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The Analysis of Knowledge

• Consider the sentence
• George Bush knows that Dick Cheney shot someone
  on Saturday.
• It implies something about the world
• Dick Cheney shot someone on Saturday.
• It implies something about George Bush
• George Bush believes that Dick Cheney shot
  someone on Saturday.

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Knowledge and truth

• If we say Jones knows that Smith is the killer
  or Wayne knows that he didnt gamble, we are
  implying that Smith is the killer and that Wayne
  didnt gamble.
• If you are speaking literally, and not making a
  joke, then to say that S knows that p is to imply
  that p is true.
• Some fancy ways of saying this Knowledge is
  factive If Kp, then p.

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Knowledge and belief

• Could someone know something without believing it?

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Knowledge and belief

• Could someone know something without believing
  it?
• It doesnt seem so (some philosophers have
  disputed this point, but for our purposes here,
  well just insist that whatever is known is
  believed)

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The two uncontroversial ingredients in knowledge

• TRUTH and BELIEF
• (Why not stop there?)

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Whats wrong with KTB?

• Why cant we just define knowledge as true
  belief?

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Whats wrong with KTB?

• Why cant we just define knowledge as true
  belief?
• If someone has a true belief accidentally (a
  lucky guess, wishful thinking, mistaken handling
  of misleading evidence, etc), then we dont want
  to count this as knowledge knowing is believing
  a truth in the right way

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The attractions of KJTB

• The JTB analysis of knowledge
• S knows that p if and only if
• (i) p is true
• (ii) S believes that p, and
• (iii) S is justified in believing p

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Gettiers Case I JTB but no K

• Suppose that Smith and Jones have applied for a
  certain job. And suppose that Smith has strong
  evidence for the following conjunctive
  proposition
• (d) Jones is the man who will get the job, and
  Jones has ten coins in his pocket.
• Smith's evidence for (d) might be that the
  president of the company assured him that Jones
  would in the end be selected, and that he, Smith,
  had counted the coins in Jones's pocket ten
  minutes ago.

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Gettiers Case I JTB but no K

• (d) Jones is the man who will get the job, and
  Jones has ten coins in his pocket.
• Proposition (d) entails
• (e) The man who will get the job has ten coins in
  his pocket.
• Let us suppose that Smith sees the entailment
  from (d) to (e), and accepts (e) on the grounds
  of (d), for which he has strong evidence. In this
  case, Smith is clearly justified in believing
  that (e) is true.

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Gettiers Case I JTB but no K

• (e) The man who will get the job has ten coins
  in his pocket.
• But imagine, further, that unknown to Smith, he
  himself, not Jones, will get the job. And, also,
  unknown to Smith, he himself has ten coins in his
  pocket. Proposition (e) is then true, though
  proposition (d), from which Smith inferred (e),
  is false. In our example, then, all of the
  following are true (i) (e) is true, (ii) Smith
  believes that (e) is true, and (iii) Smith is
  justified in believing that (e) is true. But it
  is equally clear that Smith does not know that
  (e) is true for (e) is true in virtue of the
  number of coins in Smith's pocket, while Smith
  does not know how many coins are in Smith's
  pocket, and bases his belief in (e) on a count of
  the coins in Jones's pocket, whom he falsely
  believes to be the man who will get the job.

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Did Gettier rely on a sneaky trick?

• Case I is supposed to show that K?JTB (because
  there is justified, true belief but no knowledge)
  but one might wonder whether we really had JTB
  there
• Was Smith really justified in believing that the
  man who will get the job has ten coins in his
  pocket?

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Re-writing the example

• If Gettiers original example of justified true
  belief without knowledge doesnt please you, try
  writing your own example.
• try to think of a scenario where someone has
  ample justification for some belief which happens
  to be true (but somehow the justification and the
  truth of the belief are lined up in a way that
  produces knowledge)

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Havit and Nogot

• Jones, who works with Havit and Nogot, believes
  that one of his co-workers owns a Ford.

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Havit and Nogot

• Jones, who works with Havit and Nogot, believes
  that one of his co-workers owns a Ford.
• Nogot is always talking about having a Ford,
  showing off registration papers, pointing it out
  in the parking lot, offering Jones a ride.
• Havit doesnt talk about cars. Jones has only
  ever seen him on a bike.

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Havit and Nogot

• Jones, who works with Havit and Nogot, believes
  that one of his co-workers owns a Ford.
• Nogot is always talking about having a Ford,
  showing off registration papers, pointing it out
  in the parking lot, offering Jones a ride.
• Havit doesnt talk about cars. Jones has only
  ever seen him on a bike.
• In fact, Nogots car belongs to his mom (the
  papers are fake). Havit, however, does own a
  Ford.

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Lessons?

• Should we insist that in order to know that
  someone has a car, you need to have more
  evidence than Jones had in Havit and Nogot?

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Lessons?

• Should we insist that in order to know that
  someone has a car, you need to have more
  evidence than Jones had in Havit and Nogot?
• This would appear to leave us with the rather
  skeptical result that no one ever knows anything.

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Knowledge and JTB

• Where does the JTB account go wrong?
• What is a justification, anyway?

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Knowledge and JTB

• Where does the JTB account go wrong?
• What is a justification, anyway?
• Why not say that ones justification has to
  amount to knowledge?

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Knowledge and JTB

• Where does the JTB account go wrong?
• What is a justification, anyway?
• Why not say that ones justification has to
  amount to knowledge?
• If KJTB and the J includes K, we have a circular
  definition (which isnt an analysis)