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Epistemology

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Title: Epistemology


1
Epistemology
  • Introduction to Philosophy
  • Weber State University
  • Spring 2006

2
Epistemology
  • Philosophic study of the nature of knowledge
  • Etymology (Greek) episteme (knowledge), and
    logy (study of)

3
Classes of Knowledge
  • Acquaintance knowing someone or something
    directly
  • Competence knowing how to perform certain tasks
  • Propositional knowing the way that the world is

4
Some Examples
  • Acquaintance I know Larry, Moe, and Curly. In
    other words, Im familiar with the Three Stooges.
  • Competence I know how to build a nuclear
    weapon. If the material were available to me, I
    would be able to build a nuclear bomb.
  • Propositional I know that Salt Lake City is the
    capital of Utah. The object of my propositional
    attitude is either true or false.

5
Prevailing Questions
  • What is knowledge?
  • Is knowledge possible?

6
The Nature of Knowledge 1
  • Can we know what is false?
  • No we can believe what is false, but we cant
    know it.

7
The Nature of Knowledge 2
  • Can we know what we do not believe?
  • No, we can believe what we do not know, but we
    cant know what we do not believe.

8
The Nature of Knowledge 3
  • Can we have true belief without having knowledge?
  • Yes, we can have true belief without having
    knowledge.

9
Brain-in-a-Vat Scenario
  • How do we know there is an external world?
  • If I am a brain-in-a-vat, then its possible that
    I dont know I have hands.
  • Its possible that I am a brain-in-a-vat.
  • Therefore, I dont know I have hands.

10
Platos Theaetetus
  • If knowing x is just to believe that x is true,
    it follows that knowing x requires little
    evidence for its truth
  • E.g., Smith believes it is true that UFOs invaded
    Earth in 1938
  • The account of knowledge would have to say
    Smiths true belief is knowledge

11
Theaetetus Solution
  • Knowledge involves not only true belief but also
    justification
  • Proposed definition of knowledgeKnowledge is
    justified true belief
  • Dominated epistemology for 2000 years, until
    Edmund Gettier (1968) showed otherwise

12
What kind of justification do you need to have
knowledge?
  • Descartes absolute certainty
  • Locke good evidence
  • Skepticism no evidence possible
  • Verificationism
  • Causal Theory of Knowledge
  • Naturalized Epistemology

13
Types of Evidence
  • Two types of evidence
  • Defeasible evidence that is consistent with the
    falsity of the proposition it supports
  • Indefeasible evidence that makes the falsity of
    the proposition it supports impossible

14
Descartess Justification Condition
  • Indefeasible evidence is a necessary condition to
    satisfy the justification condition

15
Foundationalism
  • We need to find some class of beliefs, of which
    we have secure knowledge
  • Other beliefs must be supported by the class of
    foundational beliefs

16
Two Main Questions of Foundationalism
  • The nature of the foundations what are the
    foundational beliefs?
  • The nature of justification how do the
    foundational beliefs support the derivative
    beliefs?

17
Consider Skeptical Scenarios
  • I could be dreaming
  • My perception could deceive me and
  • An evil demon could deceive me.

18
Descartess Way Out
  • No matter how powerful the evil demon, it
    couldnt deceive me into believing that I dont
    exist.
  • Descartes believes that it is impossible both to
    be aware of oneself and not to exist.
  • The evidence is indefeasible
  • Cogito ergo sum

19
Descartess Certainty
  • The evidence that we exist entitles us to be
    certain of what we believe.
  • By certain, Descartes means that it is impossible
    to doubt.

20
Certainty to Indefeasibility
  • If its impossible for us to doubt S, then we
    must have evidence that couldnt be true unless S
    is true.
  • Indefeasible evidence is so good that its
    impossible for us to doubt S.
  • So, to know something we must have indefeasible
    evidence for it, the evidence we have is
    indubitable.

21
Descartess View
  • We must believe S
  • S must be true
  • We must have indefeasible evidence for S

22
Necessary Truths
  • Some sentences cannot possibly be false, e.g.
    tautologies or necessary truths
  • Any sentence at all is indefeasible evidence for
    a necessary truth
  • On Descartess view, we know any necessary truths
    we believe

23
Problem with Descartess Account
  • The evidence we have is consistent with our being
    wrong about almost everything except what we
    believe about our own existence and thoughts.
  • Nothing at all about the external world is
    certain.
  • So, apart from necessary truths and our own
    existence, we know nothing at all.
    (solipsism/skepticism)

24
God as a Way Out
  • An omni-benevolent omnipotent God would not
    deceive us
  • Gods guarantee of our senses not deceiving us
    if
  • We know about Gods guarantee and
  • The deductive closure principle obtains

25
New Problems Arise
  • What reason do we have for thinking that we know
    God guarantees the evidence of our senses?
  • Descartess position still leads to skepticism
    about the external world.

26
Descartess Solutions
  • We have to have clear and distinct ideas in
    order to have knowledge.
  • We can only know that we exist, so no conclusion
    can be drawn about the external world

27
The Epistemological Debate
  • Rationalism all knowledge is derived from
    reason alone
  • Empiricism all knowledge is derived from
    experience

28
Who are the Rationalists?
  • Plato, and, by default, Socrates
  • Descartes
  • Spinoza
  • Leibniz

29
Who are the Empiricists?
  • Aristotle
  • Hume
  • Locke
  • Berkeley

30
What is the difference between rationalism and
empiricism?
  • Rationalists believe that when we are born, we
    possess innate ideas, we are born with innate
    dispositions and capacities which will develop
    with proper education.
  • Empiricists believe that the mind is a tabula
    rasa, a blank slate, at birth and everything we
    know must be stamped in through experience.
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