by Dr. Karen Lee, M.F.A., FA Ph.D. PhD

Transcription

1 Logical Fallacies by Dr. Karen Lee, M.F.A., FA Ph.D. PhD The Writing Vanguard University of Southern California Faith and knowledge resting on the hope of eternal life... (NIV, Titus 1.2).

2 Grateful Acknowledgments 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, (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 s anthology, American Experience: Nonfiction. New York: MacMillan, 1984.

3 Introduction Getting to Know Logical Fallacies

4 What s a logical fallacy and why should you care? It s poor logic partly consisting of overgeneralizations and assumptions. The presence of logical fallacies may weaken a writing project. When you re developing an argument, your points should follow in logical order and make proper conclusions. When you re refuting a counterargument (procatalepsis), it s useful to point out logical fallacies as weak points in your opponent s argument.

5 Logical Fallacies: Several 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 either/or: false binaries faulty generalization: inadequate evidence & jumps to conclusions

6 Logical Fallacies: More Examples faulty causal: cause & effect problem faulty analogy: analogy does not hold; compared parts dissimilar begging the question: circular reasoning & tautological definitions ad hominem: argument switches to character slander

7 Logical Fallacies: Still More Examples ad populum: appeals to irrational fears & prejudices red herring: dodges main issue (refers to red herring dragged d across the paths of hounds to throw them off in their pursuit) complex question: two-pronged question "When did you stop stealing?" (combines two questions, one implied)

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.

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. My client is honest. Therefore, my client would not steal (Corbett and Connors 69).

10 Answers Either they voted for the candidate or they voted for the candidate s opponent (Corbett and Connors 67). EITHER/OR FALLACY Any man who is honest will not steal. My client is honest. Therefore, my client would not steal (Corbett and Connors 69). BEGGING THE QUESTION

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).

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 HOMINEM

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)?

14 Answers You accuse me of cheating on my income tax, but doesn t everybody cheat a little bit (Corbett and Connors 70)? RED HERRING OR FAULTY GENERALIZATION Why did you steal the diamond ring (Corbett and Connors 71)? COMPLEX QUESTION

15 Detecting Logical Fallacies: Examine this Excerpt But it is not meant that all American writers should studiously cleave to nationality in their writings; only this, no American writer should write like an Englishman or a Frenchman; let him write like a man, for then he will be sure to write like an American. Let us away with this leaven of literary flunkeyism towards England (Melville 275). Melville, Herman. Hawthorne and His Mosses. American Experience: Nonfiction. Dora Smith, Gen. Ed. New York: MacMillan,

16 Detecting Logical Fallacies: Examine 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 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 intelligible issues, coherent ideas, salient personalities. Somebody says something, and somebody replies. But what did Harding say in 1920, and what did Cox reply? py Who was 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 with talcum powder, and so let fly (Mencken 388). Mencken, H. L. On Being an American. Dora Smith, Gen. Ed. American Experience: Nonfiction. New York: MacMillan,

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 opponent s argument. Logical fallacies are usually forms of inaccurate assumptions, bias, jumps in thought, & overgeneralizations.

18 The Writing Center For more help with logical fallacies, contact the Writing Center. Where: Heath 214 What else: Thanks for your interest in our resources! Faith and knowledge resting on the hope of eternal life... (NIV, Titus 1.2).