Review Logic

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Review Logic Reasoning

• Deductive Validityformal
• A form such that true premises always ? true
  conclusions
• Informal testimagine an argument in that form
• Core vocabulary if..then.., and, or, not, all,
  some, none
• True premises false conclusion
• Sound df valid and all true premises
• Conclusions of sound deductive arguments are
  true
• Sound deduction from definition premises

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Other Logics

• Inductivevalid when good reasons for the
  conclusion
• Not a guarantee
• Analogy, induction on example(s), sampling,
  science
• Inference to the best explanation
• Practical syllogism belief-desire to intention
• Needs an ought in premises

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Inconsistent Triad (deductive)

• If conclusion false then
• Either premise(s) false or invalid
• Formal test for validity
• Then key to Socratic rational doubt
• Doubt one of your premises
• Also key to science hypothetical decuction
• Take current theory as hypotheses
• Measurements, mathematics
• Predict experimental outcome
• Outcome falsifies?some hypothesis wrong

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Socrates and Religion Application

• Socrates no experimental method
• Needs explicit contradictionharder
• Plato cheats a lot
• Limits reveals error not truth
• No method to discover truth
• Problem of Evil even looser
• Needs formal statement unlike the usual
• Believer has many options
• Accept evil
• Best of all possible worlds Free will
• Limited God
• Not creator

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Theodicy

• What is the alternative to no-evil?
• God does not exist?
• Why does it not prove that?
• Theodicy possible solutions to the problem of
  evil
• Limited god (not perfect/omnipotent)
• Free will and necessary evil
• Necessary for greater good
• Human and divine good
• Or accept the conclusion
• Evil is an illusion

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Questions?

• Tutorials sign up
• Start next week
• 2 quizzes

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Back to Socrates Virtue

• Use metaphysics model on ethics
• Fundamental reality of virtue, justice
• Search for definitions using Socratic method
• one (conventions many)
• unchanging (vs. mores)
• knowable (definitions)
• rational (Socratic method) and
• Real (!)
• Why care about those peculiar facts?
• No man knowingly does evil

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Weakness of Socratic Method

• No answersSocrates the skeptic
• Dies ignorant
• Famous lamentand student response
• At least knows he doesnt know
• ?????????????
• Deeper problem
• Many different consistent doctrines
• Contradiction not easy to prove
• Plato the playwright takes control

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Socrates and Plato Story

• Death by legislaturewrong
• Platos hatred of democracy
• Better for policy and choice of leaders
• Not for judgment of guilt
• separate judiciary rule of law
• Socrates as figure in his dialogues
• Development of Socratic method
• Classic example in Thrasymachus dialogue

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Plato's Synthesis

• Parmenides the real world and ethical ideal
  blend
• Real is rational rational is real
• Focus on search for definitions
• Socrates origin and geometry
• The idea or concept of a thing
• Result is the meaning/value being
• Really that being meaning
• Meaning linked to value, purpose
• The concept is the things reality

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Are Definitions Important?

• Not to knowing how to speak
• Vicious circle
• Real life and children learning
• Examples true, cute, way, water
• Why such emphasis?
• Importance to logical method
• Socratic method and validity
• Problem of evil example
• Cant test validity w/o form

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Definitions Concept Reality

• Conform to rationalist presuppositions
• One concrete instances are many
• Unchanging remain things change
• Knowable -- beliefs about objects
• Heraclitus and Parmenides
• Rational -- Socratic method
• Hence real
• Idealism
• Definitions (meaningsideas) real
• Sensible things" are not

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Rules for Definitions

• Implicit in Plato's Socrates
• No lists. What is common to all instances
• No vagueness. Strong?
• No circularity (or mere synonyms)
• Definition so usable in arguments
• No hearsay -- test by expert knowledge
• Real v. Nominal definitions
• Test by reason. Socratic method

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Conclusion The Forms

• Forms correspond to definitions (meanings)
• Meaning objects
• Provide unified answer to philo questions
• Metaphysics what is realobjective meaning
• Real definitions v. Nominal
• Epistemology what is knowable
• Like soul/mind--intellectual
• Logic the thinkable objects
• Not laws of thought but semantics
• Ethics no man knowingly does evil
• Health of the soul
• Definitions of virtues
• Objects of striving -- teleological account of
  change

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Difficulty Famous Analogies

• Cave sensible appearance v reality
• C.f. taking hallucinatory drugs
• Meditation or rational insight
• Analogy shadow/object as object/form
• Equal difficulty in getting you to accept them
• When you "see" them, you will need no more
  convincing
• The character of the object determines your
  knowledge

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Line Analogy

• Links metaphysics and epistemology
• Knowability depends on nature of object
  (Parmenides)
• Rival view true belief plus an account (the
  modern analysis)
• X knows that P df.
• P is true
• X believes that P
• X has justification for believing that P

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The Sun Analogy

• Rule for identification of forms
• Logic there must be a form of forms
• It must be more real than the forms
• The form of the good of all value
• Form of the truth/beauty/good

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Mystical Result

• Absolute one/being
• No reason leading to see it
• It would blind us
• But necessarily there (or nothing exists)

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Key Political Doctrines

• The Republic a political plan
• Justice of political structure like that of
  individual
• Same in everything
• Rule of the correct rulerintellect

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The Philosopher King

• Anti-democratic and manipulative
• Education and classes
• Social ranks intellectual, spirited, body-like

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End of Plato and Greek Rationalism

• Ancient Chinese idealism next!