Epistemology

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Epistemology

• Introduction to Philosophy
• Weber State University
• Spring 2006

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Epistemology

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

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Classes of Knowledge

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

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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.

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Prevailing Questions

• What is knowledge?
• Is knowledge possible?

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The Nature of Knowledge 1

• Can we know what is false?
• No we can believe what is false, but we cant
  know it.

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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.

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The Nature of Knowledge 3

• Can we have true belief without having knowledge?
• Yes, we can have true belief without having
  knowledge.

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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.

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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

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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

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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

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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

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Descartess Justification Condition

• Indefeasible evidence is a necessary condition to
  satisfy the justification condition

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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

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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?

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Consider Skeptical Scenarios

• I could be dreaming
• My perception could deceive me and
• An evil demon could deceive me.

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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

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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.

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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.

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Descartess View

• We must believe S
• S must be true
• We must have indefeasible evidence for S

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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

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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)

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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

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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.

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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

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The Epistemological Debate

• Rationalism all knowledge is derived from
  reason alone
• Empiricism all knowledge is derived from
  experience

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Who are the Rationalists?

• Plato, and, by default, Socrates
• Descartes
• Spinoza
• Leibniz

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Who are the Empiricists?

• Aristotle
• Hume
• Locke
• Berkeley

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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.