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Logical fallacies ppt[1]

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Logical fallacies ppt[1]

  1. 1. L i l F ll iLogical Fallacies by Dr Karen Lee M F A Ph Dby Dr. Karen Lee, M.F.A., Ph.D. The Writing Center @ Vanguard University of Southern California “Faith and knowledge resting on the hope of eternal life ” (NIV Titus 1 2) Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8 hope of eternal life . . . (NIV, Titus 1.2).
  2. 2. Grateful Acknowledgments • Exercises are briefly excerpted from Classical• Exercises are briefly excerpted from Classical Rhetoric for the Modern Student by Corbett, Edward P.J. and Robert J. Connors. New York: Oxford University Press 1999 (This textbook is used inUniversity Press, 1999. (This textbook is used in our upper-division English course, ENG 370: Advanced Rhetoric & Composition.) • Short passages by H.L. Mencken and Herman Melville are briefly excerpted from Dora Smith’sy p anthology, American Experience: Nonfiction. New York: MacMillan, 1984. Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  3. 3. Introduction Getting to KnowGetting to Know Logical FallaciesLogical Fallacies Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  4. 4. What’s a logical fallacy and why should you care?why should you care? • It’s poor logic partly consisting of li ti d tiovergeneralizations and assumptions. • The presence of logical fallacies may weaken a iti j t Wh ’ d l iwriting project. When you’re developing an argument, your points should follow in logical order and make proper conclusionsorder and make proper conclusions. • When you’re refuting a counterargument (procatalepsis), it’s useful to point out logical(procatalepsis), it s useful to point out logical fallacies as weak points in your opponent’s argument. Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  5. 5. Logical Fallacies: Several ExamplesSeveral Examples • non sequitor: reasoning doesn’t hold together, "doesn't follow“ • bandwagon: recommends a course of action just because “everyone else” is doing it • equivocation: ambiguity• equivocation: ambiguity • either/or: false binaries • faulty generalization: inadequate evidence &faulty generalization: inadequate evidence & jumps to conclusions Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  6. 6. Logical Fallacies: More ExamplesMore Examples • faulty causal: cause & effect problem • faulty analogy: analogy does not hold; compared parts dissimilarp p • begging the question: circular reasoning & tautological definitionsreasoning & tautological definitions • ad hominem: argument switches to character slandercharacter slander Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  7. 7. Logical Fallacies: Still More ExamplesStill More Examples • ad populum: appeals to irrational fears & j di& prejudices • red herring: dodges main issue (refers t d h i d d th thto red herring dragged across the paths of hounds to throw them off in their pursuit)pursuit) • complex question: two-pronged question "When did you stop stealing?"question When did you stop stealing? (combines two questions, one implied) Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  8. 8. Now You Try It! For the next group of slides, identify the logical fallacy at work in each. You may choose among these terms: non sequitor, equivocation, faulty generalization, bandwagon, faulty causal, faulty analogy, begging the question, ad hominem, ad populem, red herring, and complex question. Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  9. 9. Identify Logical Fallacies • “ ‘Either they voted for the candidate or they voted for the candidate’s opponent’ ” (Corbett and Connors 67). • “Any man who is honest will not steal.Any man who is honest will not steal. My client is honest. Therefore, my client would not steal” (Corbett andclient would not steal (Corbett and Connors 69). Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  10. 10. Answers • “ ‘Either they voted for the candidate or they voted for the candidate’s opponent’ ” (Corbettvoted for the candidate’s opponent’ ” (Corbett and Connors 67). EITHER/OR FALLACYEITHER/OR FALLACY “A h i h t ill t t l M li t• “Any man who is honest will not steal. My client is honest. Therefore, my client would not steal” (Corbett and Connors 69)(Corbett and Connors 69). BEGGING THE QUESTION Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  11. 11. Identify the Logical Fallacy • “ ‘My opponent’s arguments are very impressive, but remember, this is the man who deserted his faithful wife and family after he had won his first political victory’ ” (Corbett and Connors 70). Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  12. 12. Answer • “ ‘My opponent’s arguments are very impressive, but remember, this is the man who deserted his faithful wife and family after he had won his first political victory’ ” (Corbett and Connors 70). AD HOMINEMAD HOMINEM Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  13. 13. Identify Logical Fallacies • “ ‘You accuse me of cheating on my income tax, but doesn’t everybody cheat a little bit’ ” (Corbett and Connors 70)? • “ ‘Why did you steal the diamond ring’ ” (Corbett and Connors 71)?ring (Corbett and Connors 71)? Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  14. 14. Answers • “ ‘You accuse me of cheating on my income tax, but doesn’t everybody cheat a little bit’ ” (Corbett anddoesn t everybody cheat a little bit (Corbett and Connors 70)? RED HERRINGRED HERRING OR FAULTY GENERALIZATION • “ ‘Why did you steal the diamond ring’ “ (Corbett and COMPLEX QUESTIONConnors 71)? COMPLEX QUESTION Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  15. 15. Detecting Logical Fallacies: Examine this ExcerptExamine this Excerpt “But it is not meant that all American it h ld t di l l twriters should studiously cleave to nationality in their writings; only this, no American writer should write like anAmerican writer should write like an Englishman or a Frenchman; let him write like a man for then he will be sure tolike a man, for then he will be sure to write like an American. Let us away with this leaven of literary flunkeyism towardsy y England” (Melville 275). Melville, Herman. “Hawthorne and His Mosses.” American Experience: Nonfiction. Dora Smith, Gen. Ed. Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8 New York: MacMillan, 1984. 269-277.
  16. 16. Detecting Logical Fallacies: Examine this ExcerptExamine this Excerpt “Turn, now, to politics. Consider, for example, a campaign more uproariously idiotic – a deafening, nerve-wracking battle to the death between Tweedledum and Tweedledeebattle to the death between Tweedledum and Tweedledee, Harlequin and Sganarelle, Gobbo and Dr. Cook – the unspeakable, with fearful snorts, gradually swallowing the inconceivable? I defy anyone to match it elsewhere on the earth In other lands at worst there are at least intelligibleearth. In other lands, at worst, there are at least intelligible issues, coherent ideas, salient personalities. Somebody says something, and somebody replies. But what did Harding say in 1920, and what did Cox reply? Who wasg y , p y Harding, anyhow, and who was Cox? Here, having perfected democracy, we lift the whole combat to symbolism, to transcendentalism, to metaphysics. Here we load a pair of palpably tin cannon with blank cartridges charged withof palpably tin cannon with blank cartridges charged with talcum powder, and so let fly” (Mencken 388). Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8 Mencken, H. L. “On Being an American.” Dora Smith, Gen. Ed. American Experience: Nonfiction. New York: MacMillan, 1984. 385-389.
  17. 17. Summary • A logical fallacy is simply poor logic. • The presence of logical fallacies may weaken a writing project. • It’s often useful to point out logical fallacies as weak points in your t’ topponent’s argument. • Logical fallacies are usually forms of i t ti bi j iinaccurate assumptions, bias, jumps in thought, & overgeneralizations. Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8
  18. 18. The Writing Center For more help with logical fallacies, contact the Writing Center.g • Where: Heath 214 • What else: Thanks for your interest in our• What else: Thanks for your interest in our resources! “Faith and knowledge resting on the hope“Faith and knowledge resting on the hope of eternal life . . .” (NIV, Titus 1.2). Version Date: 3.10.06, klee@vanguard.edu, Colossians 2.8

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