Presentation on theme: "LOGICAL THINKING Recognizing Logical Fallacies"— Presentation transcript:
1 LOGICAL THINKING Recognizing Logical Fallacies English I HonorsMrs. Lutes
2 WHAT ARE FALLACIES? Fallacies are types of faulty reasoning. Usually, they are due to careless thinking; but they may also be used deliberately, as they are in much propaganda and advertising, to mislead.Following are some of the most common fallacies.Be alert to them in your reading and writing.
3 Ad hominem Ad hominem is Latin for “to the man.” It is a form of argument that attacks the person rather than the issues.Example: Our new professor looks like Homer Simpson. How can we take him seriously? [His appearance has nothing to do with his intelligence.]Example: His arguments might impress us more if he didn’t have false teeth. [His false teeth have nothing to do with his arguments.]
4 Appeal to pityAn appeal to pity tries to distract the audience from the legitimate issues by focusing attention on the arguer’s irrelevant miseries.Example: I deserve a raise. My car is in the shop, I’m behind in my mortgage payments, and my wife left me with three children to raise alone. [The listed misfortunes may be reasons for needing a raise, but they are not reasons for deserving a raise.]
5 BandwagonThe bandwagon fallacy—a favorite of advertisers and politicians—is a tactic children often resort to, asserting that something is good or right because “everyone else is doing it.”Example: Four out of five doctors surveyed recommend Brand X painkiller for their patients.Example: Everyone else is cheating, so why shouldn’t I? [The majority is not always right.]
6 Begging the questionBegging the question is circular reasoning. It merely restates in the conclusion (usually in other words) what has been asserted in the premise.Example: Because women are not well suited for fighting, they do not do well in combat duty in the armed forces.Example: He is lazy because he doesn’t like to work. [Being lazy and not liking to work mean essentially the same thing.]
7 False dilemma (aka either/or fallacy) The false dilemma erroneously assumes that only two alternatives are possible when, in fact, others exist.Example: A new car may be expensive, but do you want me to drive around in this junk pile for the rest of my life? [Other options exist besides driving a new car or driving a “junk pile.”]Example: We have only two choices: to build more nuclear power plants or to be completely dependent on foreign oil. [In fact, other possibilities exist.]
8 EquivocationAn assertion that misleads by using a term in two different senses.Example: We should not raise taxes. Life is taxing enough as it is.Example: Your party platform is right about the economy—as far right as you can get. [Right in the first sense implies correct but in the second sense implies a side of the political spectrum.]
9 False analogyA false analogy makes the erroneous assumption that because two objects or ideas seem similar in some ways, they must be similar in other ways.For instance, in the first example below, a political dictator defended the execution of sexual offenders by drawing false analogies between immoral behavior and physical disease and between the population as a whole (or the state) and a diseased body.Example: If your finger suffers from gangrene, what do you do? Let the whole hand and then the body become filled with gangrene, or cut the finger off?Example: Since the books are about the same length and cover the same material, one is probably as good as the other. [The length and coverage of the books cannot predict whether one is as good as the other.]
10 False causeFalse cause (sometimes called post hoc, ergo propter hoc, meaning “after this, therefore because of this”) wrongly assumes that because one event happened after another event, the first somehow caused the second.Example: Our new police uniforms have worked wonders. They were issued on September 2, and in the six months since then, arrests have increased forty percent.Example: The new tax assessor took office last January, and crime in the streets has already increased 25 percent. [The assumption is that having a new tax assessor caused the increase in crime, an assumption unlikely to be true.]
11 False authorityThe assumption that an expert in one field can be a credible expert in another.Example: The defense budget must be cut, as the country’s leading pediatrician has shown. [Pediatric medicine is unrelated to economics or political science.]
12 Guilt by associationAn unfair attempt to make someone responsible for the beliefs or actions of others.Example: Senator Barlow must be dishonest because she belongs to the same club as that judge who was recently disbarred. [People can belong to the same club—or live in the same neighborhood—without committing the same crimes.]
13 Hasty generalizations Hasty generalizations are also called sweeping generalizations.A generalization based on too little evidence or on exceptional or biased evidence.No matter how certain you are of the general applicability of an opinion, use with caution such all-inclusive terms as anyone, everyone, no one, always, and never.Example: Management is never concerned about employees.Example: Computer instructions are always confusing.Example: Anyone can see that taxes should not be raised.Example: Teenagers are reckless drivers. [Many teenagers are careful drivers.]
14 Non sequiturA statement that does not follow logically from what has just been said—a conclusion that does not follow from the premises.Non sequiturs may reflect faulty reasoning, but they often occur when a writer simply neglects to express some logical link in a chain of thought.Example: He enjoyed cooking and was especially fond of cocker spaniels. [The missing link in this alarming sentence is that cooking was one of his interests but he had others, including cocker spaniels.]Example: Billy Joe is honest, therefore, he will get a good job. [Many honest people do not get good jobs.]
15 OversimplificationA statement or agreement that leaves out relevant considerations about an issue.Example: People who pass tests are lucky. [People who pass tests have usually studied and prepared.]
16 Red herringDodging the real issue by drawing attention to an irrelevant issue (sometimes called ignoring the issue).Example: Why worry about a few terrorists when we ought to be doing something about acid rain? [Acid rain has nothing to do with the actions of terrorists.]Example: Before you start worrying about the budget deficit, you’d better take care of those laid-off defense workers.
17 Slippery slopeThe assumption that if one thing is allowed it will only be the first step in a downward spiral.Example: Handgun control will lead to a police state. [Handgun control has not led to a police state in England.]Example: If we continue to allow legal abortions, the next steps will be the elimination of the physically and mentally undesirable and finally the killing of anyone we don’t like for any reason at all.
18 ASSESS YOUR UNDERSTANDING Identify the fallacies in the following statements. For each statement, write one or two sentences in which you explain the flaw in reasoning.
19 Women will vote for him because he is good-looking. A person who cannot spell should not become a journalist.If you walk self-confidently, you probably won’t get mugged.Our jails are full because a lot of people don’t have enough money to buy necessities.
20 He is a man, so he must know how to fix cars. Mike missed class twice last week. He must have been sick.Erika is the most popular girl in the class. You should vote for her for president.These razor blades give the smoothest shave; all the baseball players use them.
21 There are only two kinds of politicians: those interested in their own welfare and those interested in the welfare of people.Why can’t I buy a car? All my friends have cars.
22 Examine several recent magazine advertisements and study the claims the ads make. Look specifically for examples of logical fallacies. Choose one ad that seems especially illogical. Bring a copy of it to class.
23 All text is directly taken from the following sources: Hodges, John C., et al., Harbrace College Handbook. 12th ed. Fort Worth: Harcout Brace College Publishers, 1994.Ebest, Sally Barr, et al, Writing from A to Z: The Easy-to-Use Reference Handbook. 5th ed. New York: McGraw-Hill Companies, Inc., 2005.
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