PHIL 160 "Induction & Confirmation" PHIL 160
LEARNING OBJECTIVES: PHIL 160 Strategy for theorizing & testing Role of deduction Role of induction Problem of induction
PHIL 160 meaningful claims are testable Verifiability theory of meaning:
SENTENCES IN SCIENTIFIC THEORIES  PHIL 160 SENTENCES DESCRIBING EXPERIENCE logical relation that counts as support
PHIL 160 True assumptions guarantee  true conclusion. DEDUCTIVE LOGIC <ul><li>All men are mortal. </li></ul><ul><li>Socrat...
PHIL 160 True assumptions support (not guarantee) true conclusion. INDUCTIVE LOGIC <ul><li>Frog 1 died at time t 1 . </li>...
PHIL 160
PHIL 160
PHIL 160
PHIL 160
PHIL 160
PHIL 160
PHIL 160 STRATEGY: •  Identify phenomenon to explain (childbed fever). •  Find similar settings, one with the phenomenon, ...
PHIL 160 STRATEGY: •  Identify phenomenon to explain (childbed fever). •  Find similar settings, one with the phenomenon, ...
PHIL 160 Find the difference between wards that explains higher rate of childbed fever in 1st division ward. Test: changin...
PHIL 160 Deductive Argument <ul><li>If “priest-terror” causes childbed fever, rerouting priest/removing bell will lower ch...
PHIL 160 <ul><li>If delivering on back causes childbed fever, switching to lateral deliveries will lower childbed fever ra...
PHIL 160 Inductive Argument <ul><li>Much higher rates of childbed fever  in wards attended by physicians and medical stude...
PHIL 160 Inductive Argument <ul><li>Childbed fever caused by something physicians and medical students (but not midwives) ...
PHIL 160 Inductive Argument <ul><li>Physicians and medical students pick up cadaveric matter from autopsies. </li></ul><ul...
PHIL 160 Big Assumptions •  Cadaveric matter exists, transmitted from autopsies. •  Chlorinated lime removes or destroys c...
<ul><li>Physicians and medical students pick up cadaveric matter from autopsies. </li></ul><ul><li>If hands and instrument...
PHIL 160 Did Semmelweis prove his conclusion? <ul><li>If H is true, then so is I. </li></ul><ul><li>(As the evidence shows...
PHIL 160 <ul><li>If cadaveric matter causes childbed fever, then removing/destroying it by washing with chlorinated lime w...
PHIL 160 Semmelweis used his observations to find the relevant difference. His theory led to an effective intervention. Bu...
PHIL 160 Where’s the deduction? <ul><li>If H is true, then so is I. </li></ul><ul><li>(As the evidence shows) I is false. ...
PHIL 160 <ul><li>If “priest-terror” causes childbed fever, rerouting priest/removing bell will lower childbed fever rate. ...
PHIL 160 What’s wrong with induction? Supporting potential causes of childbed fever. <ul><li>If H is true, then so is I. <...
PHIL 160
PHIL 160 All knowledge through experience. Empiricism: (Anything I know has backing in empirical data.)
PHIL 160
PHIL 160
PHIL 160
PHIL 160
PHIL 160 Can’t get empirical data about things you haven’t observed! Problem of induction: Can’t be certain things you hav...
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P160 hempelhume

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