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P160 hempelhume

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  • 1. PHIL 160 "Induction & Confirmation" PHIL 160
  • 2. LEARNING OBJECTIVES: PHIL 160 Strategy for theorizing & testing Role of deduction Role of induction Problem of induction
  • 3. PHIL 160 meaningful claims are testable Verifiability theory of meaning:
  • 4. SENTENCES IN SCIENTIFIC THEORIES PHIL 160 SENTENCES DESCRIBING EXPERIENCE logical relation that counts as support
  • 5. PHIL 160 True assumptions guarantee true conclusion. DEDUCTIVE LOGIC
    • All men are mortal.
    • Socrates is a man.
    •  Socrates is mortal.
  • 6. PHIL 160 True assumptions support (not guarantee) true conclusion. INDUCTIVE LOGIC
    • Frog 1 died at time t 1 .
    • Frog 2 died at time t 2 .
    • Frog 3 died at time t 3 .
    • n. Frog n died at time t n.
    •  All frogs are mortal.
  • 7. PHIL 160
  • 8. PHIL 160
  • 9. PHIL 160
  • 10. PHIL 160
  • 11. PHIL 160
  • 12. PHIL 160
  • 13. PHIL 160 STRATEGY: • Identify phenomenon to explain (childbed fever). • Find similar settings, one with the phenomenon, the other without.
  • 14. PHIL 160 STRATEGY: • Identify phenomenon to explain (childbed fever). • Find similar settings, one with the phenomenon, the other without. • Identify differences between settings. • Test to see which differences are relevant to the phenomenon.
  • 15. PHIL 160 Find the difference between wards that explains higher rate of childbed fever in 1st division ward. Test: changing the difference lowers rate of childbed fever in 1st division ward. STRATEGY:
  • 16. PHIL 160 Deductive Argument
    • If “priest-terror” causes childbed fever, rerouting priest/removing bell will lower childbed fever rate.
    • Rerouting priest/removing bell does not lower childbed fever rate.
    •  “ Priest-terror” does not cause childbed fever.
  • 17. PHIL 160
    • If delivering on back causes childbed fever, switching to lateral deliveries will lower childbed fever rate.
    • Switching to lateral deliveries does not lower childbed fever rate.
    •  Delivering on back does not cause childbed fever.
    Deductive Argument
  • 18. PHIL 160 Inductive Argument
    • Much higher rates of childbed fever in wards attended by physicians and medical students than in wards attended by midwives.
    •  Childbed fever must be caused by something physicians and medical students (but not midwives) are exposed to.
  • 19. PHIL 160 Inductive Argument
    • Childbed fever caused by something physicians and medical students (but not midwives) are exposed to.
    • Physicians and medical students (but not midwives) do autopsies.
    • Kolletschka got childbed fever after an autopsy.
    •  Childbed fever must be caused by something physicians and medical students (but not midwives) are exposed to in autopsies (“cadaveric matter”).
  • 20. PHIL 160 Inductive Argument
    • Physicians and medical students pick up cadaveric matter from autopsies.
    • If hands and instruments are washed with chlorinated lime, removes or destroys cadaveric matter.
    • When physicians and medical students wash with chlorinated lime, childbed fever rate in 1st division ward declines.
    •  Cadaveric matter causes childbed fever.
  • 21. PHIL 160 Big Assumptions • Cadaveric matter exists, transmitted from autopsies. • Chlorinated lime removes or destroys cadaveric matter. No one observed cadaveric matter!
  • 22.
    • Physicians and medical students pick up cadaveric matter from autopsies.
    • If hands and instruments are washed with chlorinated lime, removes or destroys cadaveric matter.
    • When physicians and medical students wash with chlorinated lime, childbed fever rate in 1st division ward declines.
    •  Cadaveric matter causes childbed fever.
    PHIL 160 Inductive Argument = premises support conclusion Change that affects outcome.
  • 23. PHIL 160 Did Semmelweis prove his conclusion?
    • If H is true, then so is I.
    • (As the evidence shows) I is true.
    •  H is true.
    “ fallacy of affirming the consequent” True premises don’t guarantee a true conclusion. (There might be another reason I is true!)
  • 24. PHIL 160
    • If cadaveric matter causes childbed fever, then removing/destroying it by washing with chlorinated lime will reduce rate of childbed fever.
    • (As the evidence shows) washing with chlorinated lime reduces rate of childbed fever.
    •  Cadaveric matter causes childbed fever.
    Did Semmelweis prove his conclusion? “ fallacy of affirming the consequent”
  • 25. PHIL 160 Semmelweis used his observations to find the relevant difference. His theory led to an effective intervention. But, the data didn’t prove his conclusion.
  • 26. PHIL 160 Where’s the deduction?
    • If H is true, then so is I.
    • (As the evidence shows) I is false.
    •  H is false.
    Ruling out potential causes.
  • 27. PHIL 160
    • If “priest-terror” causes childbed fever, rerouting priest/removing bell will lower childbed fever rate.
    • Rerouting priest/removing bell does not lower childbed fever rate.
    •  “ Priest-terror” does not cause childbed fever.
    Where’s the deduction? Ruling out potential causes.
  • 28. PHIL 160 What’s wrong with induction? Supporting potential causes of childbed fever.
    • If H is true, then so is I.
    • (As the evidence shows) I is true.
    •  H is true.
    “ fallacy of affirming the consequent” Where’s the induction?
  • 29. PHIL 160
  • 30. PHIL 160 All knowledge through experience. Empiricism: (Anything I know has backing in empirical data.)
  • 31. PHIL 160
  • 32. PHIL 160
  • 33. PHIL 160
  • 34. PHIL 160
  • 35. PHIL 160 Can’t get empirical data about things you haven’t observed! Problem of induction: Can’t be certain things you haven’t observed will be like things you have observed!