1 errare humanum est (to err is human)

FALLACIES

INDUCTION vs. DEDUCTION PART 1:

4 INDUCTION (S  G)  think “increase” (induction, increase)  from specific/particular instance or instances  to generalization  quantity: (#) sufficient # of items or people asked, sufficient data (stats)  quality: reliable source (authority), accurate & in-depth observation *PROBABILITY, not certainty*

5 INDUCTION BAD EXAMPLE:  You compare the prices of 4 textbooks at store #1 with those at store #2 and notice that the prices are higher at the former than at the latter. You conclude that store #1 is more expensive.

6 INDUCTION GOOD EXAMPLE:  A television documentary focuses on the issue of unwed teenage mothers in a particular city neighborhood. Four girls are interviewed and followed for several days. Then, a noted and respected sociologist who has studied thousands of unwed teenagers is interviewed, and she claims these four girls are representative of the many.

7 INDUCTION *INDUCTIVE FALLACIES:  wrong use of data— insufficient sample ( not enough people interviewed ) ignore evidence ( other possibilities )

8 DEDUCTION (G  S)  think “decrease” (deduction, decrease)  from inductive generalization  to conclusion

9 DEDUCTION 3 Propositions of a Deductive Syllogism  1) MAJOR PREMISE: inductive generalization “All” All humans are mortal. *(“syllogism”: Greek, to calculate using logic)*

10 DEDUCTION 3 Propositions of a Deductive Syllogism  2) MINOR PREMISE: statement about a specific member of that group “This” My English professor is a human.

11 DEDUCTION 3 Propositions of a Deductive Syllogism  3) CONCLUSION: Major Premise + Minor Premise = Conclusion  = 3  S  G, G  S “Therefore” Therefore, my English professor is mortal.

12 DEDUCTION  IF the MAJOR premise = absent or faulty induction  IF the MINOR premise = faulty observation concerning the individual at issue  THEN conclusion = faulty, invalid.  HOWEVER, if the opposite is true, then the conclusion is a valid, strong one — stronger than induction. *CERTAINTY, validity, truth*

13 DEDUCTION *BAD EXAMPLE:  A man is sitting opposite you on a train. He has what appears to be chalk dust on his fingers, and you conclude that he is a teacher.

14 DEDUCTION *BAD EXAMPLE:  Major premise = “All men with chalk on their fingers are school teachers.”  Minor premise = “This man has chalk on his fingers.”  Conclusion = “Therefore, this man is a school teacher.”

15 DEDUCTION *BAD EXAMPLE:  Faulty Conclusion: other occupations:  draftsmen, carpenters, tailors, artists, chalk maker  coach, janitor, field crew, gymnast, father, … other powders:  flour, confectioner’s sugar/powdered doughnut, talcum  pixie dust, cocaine or heroin, anthrax or ricin  sulfate of potash, chlorine, lye, powdered milk  laundry detergent powder, hygiene powder, anhydrous salts

16 DEDUCTION *DEDUCTION & INTRODUCTIONS*  “Funnel Effect,” “Inverted pyramid”  G  S  syllogism, conclusion of syllogism = thesis statement  Major Premise - Generalization = “Reducing awareness of social differences is a desirable goal for the school.”  Minor Premise - Narrowing = “A uniform dress code would help to achieve that goal.”  Conclusion - Thesis = “Therefore, students should be required to dress uniformly.”

17 DEDUCTION *DEDUCTIVE FALLACIES:  failure to follow the logic of a series of statements  an error in one premise or both premises  other possibilities exist that were not taken into consideration  reliance upon support other than facts

END PART 1