Unit 8: Knowledge

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Unit 8 Knowledge

• Chris Heathwood
• Office Hellems 192
• heathwood_at_colorado.edu

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What Well Cover in Unit 8

• The Nature of Knowledge
• What is a theory of knowledge?
• Plato on Knowledge
• Theaetetus Theory of Knowledge
• Socrates Refutation of Theaetetus
• Platos Theory of Knowledge
• Gettiers Refutation of Plato
• Humes Problem of Induction

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The Three Fundamental Questions of Philosophy

• What is there?
• What should I do?
• How can I know?

(Metaphysics)
(Ethics)
(Epistemology)
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Some Questions in Epistemology

• What is knowledge?
• What is epistemic justification?
• What are the fundamental sources of knowledge?
• What are the limits of human knowledge?
• What is the status of skepticism?

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The Nature of Knowledge
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Our First Question What Is Knowledge?

• Putting the question this way makes the question
  sound really hard. Here are two other ways to
  put it
• What is it to know something?
• Under what conditions is it true that a person
  qualifies as knowing that something is the case?
• An answer to this question will be a theory of
  knowledge.

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What is a theory of knowledge?

• A theory of knowledge is a statement of the
  conditions under which a person knows that
  something is the case.
• It is a statement of this form

S knows that p if and only if ____S____p____ .
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• Theories are knowledge are supposed to reveal the
  nature of knowledge.

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Further Clarification of the Question What is
Knowledge?

• Three Ways the Word Knows Is Used
• Bob knows how to ride a bicycle.
• Bob knows the president of the U.S.
• Bob knows that the earth is round.

? The theories of knowledge were looking at are
about the third kind of knowledge called
knowledge that, or propositional knowledge.
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How Do We Go About Constructing (and Evaluating)
a Theory of Knowledge?

• Analogy Bachelorhood.
• What is bachelorhood?
• What is it to be a bachelor?
• What are the conditions under which a person
  qualifies as a bachelor?
• What a theory of bachelorhood looks like
• x is a bachelor if and only if _____x_____.

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The Socratic Method, or the Method of
Counterexamples

• A generalization is proposed
• We try to come up with a counterexample to it
  i.e., a concrete example that counters, or
  shows false, the generalization just proposed
• If we do, we have refuted the generalization (but
  we might use the counterexample to help us
  improve on the generalization just refuted)
• If we cant, perhaps the generalization is true.

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What Well Cover in Unit 3

• The Nature of Knowledge
• What is a theory of knowledge?
• Plato on Knowledge
• Theaetetus Theory of Knowledge
• Socrates Refutation of Theaetetus
• Platos Theory of Knowledge
• Gettiers Refutation of Plato
• Humes Problem of Induction

?
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Plato on Knowledge
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Plato (428-347 BC)

• The best known ancient Greek philosopher
• Student of Socrates teacher of Aristotle
• Wrote about 23 philosophical dialogues
• Famous doctrine the Theory of the Forms
• Western philosophy consists of a series of
  footnotes to Plato. -
  A. N. Whitehead (1929)

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Socrates But the question you were asked,
Theaetetus, was not, what are the objects of
knowledge, nor yet now many sorts of knowledge
there are. We did not want to count them, but to
find out what the thing itself knowledge is.
Is there nothing to that? Theaetetus No, you
are quite right. Socrates Then tell me, what
definition can we give with the least risk of
contradicting ourselves? Theaetetus The one we
tried before, Socrates. I have nothing else to
suggest. Socrates What was that?
Theaetetus That true belief is knowledge.
Surely there can at least be no mistake in
believing what is true and the consequences are
always satisfactory.
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Theaetetus Theory of Knowledge

• The True Belief Theory
• S knows that p if and only if
• (i) S believes that p and
• (ii) p is true.

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Socrates Argument Againstthe True Belief Theory

• Soc You will find a whole profession to prove
  that true belief is not knowledge. The
  profession of those paragons of intellect known
  as orators and lawyers. There you have men who
  use their skill to produce conviction, not by
  instruction, but by making people believe
  whatever they want them to believe. You can
  hardly imagine teachers so clever as to be able,
  in the short time allowed by the clock, to
  instruct their hearers thoroughly in the true
  facts of a case of robbery or other violence
  which those hearers had not witnessed. when
  a jury is rightly convinced of facts which can be
  known only by an eyewitness, then, judging by
  hearsay and accepting a true belief, they are
  judging without knowledge, although, if they find
  the right verdict, their conviction is correct?
  But if true belief and knowledge were the same
  thing, the best of jurymen could never have a
  correct belief without knowledge. It now appears
  that they must be different things.

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Socrates Argument Against The True Belief Theory

• The Argument
• If the True Belief Theory is true, then the jury
  knows that I committed the crime.
• But they dont know I committed the crime.
• Therefore, the True Belief Theory is not true.

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• Further Counterexamples to the True Belief Theory
  of Knowledge
• My belief that our football team will win their
  next game.
• b. Groundhogs Day example.
• Each case shows that true belief is not
  sufficient for knowledge.

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The Lesson

• a belief that is truejust because of luck does
  not qualify as knowledge.

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Platos Theory of Knowledge

• Socrates So when a man gets a hold of the true
  notion of something without an account, his mind
  does think truly of it, but he does not know it,
  for if one cannot give and receive an account of
  a thing, one has no knowledge of that thing. But
  when he also has got hold of an account, all this
  becomes possible to him and he is fully equipped
  with knowledge. a true notion with the
  addition of an account is knowledge?

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Platos Theory of Knowledge

• The JTB Theory
• S knows that p if and only if
• (i) S believes that p
• (ii) p is true and
• (iii) S is justified in believing that p.

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Comments About the JTB Theory

• How it avoids the counterexamples to the True
  Belief Theory
• Theory of Justification still needed.
• Some possible ways to be justified in believing
  something
• perception iv. testimony
• introspection v. induction
• memory vi. deduction
• Theory accepted for thousands of years.
• Theory no longer accepted today.

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What Well Cover in Unit 3

• The Nature of Knowledge
• What is a theory of knowledge?
• Plato on Knowledge
• Theaetetus Theory of Knowledge
• Socrates Refutation of Theaetetus
• Platos Theory of Knowledge
• Gettiers Refutation of Plato
• The Problem of Induction

?
?
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Gettiers Refutation of Plato
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Edmund Gettier (1927- )

• Not the best known contemporary American
  philosopher, but pretty well know.
• Student of his teachers at Cornell teacher of me
  at UMass.
• Wrote just one 3-page paper.
• Famous doctrine Justified true belief aint
  knowledge.
• A. N. Whitehead (1929) probably didnt say
  anything about Gettier.
• Really good at badminton.

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A Gettier-style Counterexample

• STEP 1. Suppose I see your drivers license, an
  Alaska drivers license.
• This seems to justify me in believing
• (1) You are from Alaska.
• Note this assumes that justification does not
  entail truth.
• (That is, that what justifies me in believing
  something need not absolutely guarantee that that
  thing is true.)

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A Gettier-style Counterexample

• STEP 2. Now suppose that on the basis of my
  belief that
• (1) You are from Alaska
• I come to believe that
• (2) Someone in my class is from Alaska.
• It seems that I am justified in believing (2).
• This is due to the following principle
• If S is justified in believing p, and p
  entails q, and S believes q on the basis of Ss
  belief that p, then S is justified in believing q.

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A Gettier-style Counterexample

• STEP 3. Now suppose that the drivers license I
  saw was in fact a fake ID, and that
• (1) You are from Alaska
• is in fact false.
• (Note I have a false justified belief in
  (1).)
• (Note also the JTB Theory thus far implies,
  correctly, that I do not know (1).)

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A Gettier-style Counterexample

• STEP 4. Finally, suppose that, just by chance,
  someone else in the class really is from Alaska.
• In other words, my belief that
• (2) Someone in my class is from Alaska
• actually turns out to be true.
• It is true just by luck.

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A Gettier-style Counterexample

• STEP 5. Lets ask some questions about this
  proposition
• (2) Someone in my class is from Alaska.
• FIRST QUESTION Would you say that I know (2)?
• ANSWER No.
• SECOND SET OF QUESTIONS

YES
Is (2) true?
YES
Do I believe (2)?
YES
Am I justified in believing (2)?
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A Gettier-style Counterexample

• STEP 6 Thus, bringing it all together
• I have a justified true belief in (2), but I
  dont know (2).
• In the form of a little argument
• A Gettier-style Argument Against JTB
• If the JTB Theory is true, then I know that
  someone in our class is from Alaska.
• But its not true that I know that someone in our
  class is from Alaska.
• Therefore, the JTB Theory is not true.

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Other Gettier-style Examples

• The Hallucination
• Russells Clock
• The Sheep in the Field

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A Way to Save the JTB Theory

• Note that what all the examples have in common
  the subject has highly reliable, but not
  infallible, evidence for the proposition
  believed.
• To say that e is infallible evidence for p is to
  say that e entails p.
• Recall that Gettiers argument assumed that a
  person can be justified in believing something
  without having infallible evidence for it.

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A Way to Save the JTB Theory

• But consider this thesis about justification
• Infallibilism S is justified in believing p
  only if Ss evidence for p entails p.
• If Infallibilism is true, then Gettiers argument
  against JTB fails.
• But is Infallibilism true?