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Published bySherman Palmer Modified over 8 years ago
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1 errare humanum est (to err is human)
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FALLACIES
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INDUCTION vs. DEDUCTION PART 1:
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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*
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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.
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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.
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7 INDUCTION *INDUCTIVE FALLACIES: wrong use of data— insufficient sample ( not enough people interviewed ) ignore evidence ( other possibilities )
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8 DEDUCTION (G S) think “decrease” (deduction, decrease) from inductive generalization to conclusion
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9 DEDUCTION 3 Propositions of a Deductive Syllogism 1) MAJOR PREMISE: inductive generalization “All” All humans are mortal. *(“syllogism”: Greek, to calculate using logic)*
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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.
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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.
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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*
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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.
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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.”
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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
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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.”
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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
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END PART 1
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