1 errare humanum est to err is human

1 errare humanum est (to err is human)

FALLACIES

PART 1: INDUCTION vs. DEDUCTION

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 • 1+2=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