Logical Fallacies Logical fallacies are errors in thinking
- Slides: 28
Logical Fallacies Logical fallacies are errors in thinking and writing that result from faulty logic. Watch for them in the materials that you read; avoid them in the argumentative papers you write.
The SIX Logical Fallacies Hasty Generalization Oversimplification Either/Or False Analogy False Causality Circular Reasoning
# 1 Hasty Generalization A hasty generalization is a conclusion based on too little evidence, suggesting a superficial investigation of an issue. TRANSLATED: Someone has jumped to conclusions by pretending they have done the research but they are giving you skewed information instead.
Example of Hasty Generalization “The last three times I drove to school I was late because an old person in front of me was driving too slow. All old people are slow drivers. ” In an interview, a parent picked from a random school claims the quality of education in this country is declining. The evidence she gives is that both her daughter and her neighbor’s daughter
#2 Oversimplification A Oversimplification ignores the complexities, variations, and exceptions relevant to an issue. TRANSLATED: The information you are given is way too simple…someone avoided a bunch of other important factors. As Einstein said, everything should be made as simple as possible, but no simpler.
Oversimplification Examples Political slogans such as "Taxation is theft" “The question of funding medical research comes down to this: do we want to heal the sick and help the injured to recover -- or not? ” “Since the new president took office, the economy has been improving - obviously he is doing a good job and is an asset to the nation. ”
#3 Either/Or The either/or fallacy suggests that only two choices exist when, in fact, there are more. This type of thinking is not only illogical but also unfair. TRANSLATED: They make you think you only have two options…when, really, there are many options.
Either/Or Examples “You're either with us or against us. ” There are only two kinds of politicians: those interested in their own welfare and those interested in the welfare of others. “Math is a tough subject—you either understand it or you don’t. ”
#4 False Analogy A false analogy is a comparison that is not based on relevant points of similarity. For an analogy to be logical, the subjects must be similar in several important, not superficial, ways. TRANSLATION: Comparing two things that don’t have much in common.
False Analogy Examples The universe is like an intricate watch. A watch must have been designed by a watchmaker. Therefore, the universe must have been designed by some kind of creator. People are like dogs. They respond best to clear discipline. Today’s stock market, just like the stock market in the 1920’s, seems headed for trouble.
#5 False Causality A false causality suggests a cause and effect relationship between two things (actions), even though one action simply preceded the other. TRANSLATION: just because one event follows another, doesn’t mean that first event caused the second (they are not connected)
False Causality Examples Since the artificial sweetener aspartame was introduced in 1981, cancer rates have risen in the United States. Every severe recession follows a Republican Presidency; therefore Republicans are the cause of recessions. " Since hair always precedes the growth of teeth in babies, the growth of hair causes the growth of teeth. "
#6 Circular Reasoning Circular reasoning fallacy is an argument based on the repetition of an assertion as a reason for accepting it. TRANSLATION: Saying something over and over again (perhaps using different words) makes people think it’s right.
Examples of Circular Reasoning “You can’t give me a C. I’m an A student!” “Richardson is the most successful mayor the town has ever had because he's the best mayor of our history. ” This restaurant serves the best food in the town, because it has the best chef. It has attracted the best chef because it has the best reputation. It has the best reputation because the chef cooks the best food. “This test is hard because it is so difficult!”
What Fallacy? GAME A fallacy will be presented. Use your notes to guess which logical fallacy is being used! Write your answers on the back of your Notes.
1. What Fallacy? Learning to swim is easy because it’s not a difficult sport to learn.
2. What Fallacy? “We can either burn the house down and collect the insurance money or we can continue living in an unsafe house. Since we shouldn’t keep living in an unsafe house, we should burn it down. ”
3. What Fallacy? “I have a right to say what I want, therefore you shouldn’t try to silence me”
4. What Fallacy? "My roommate said her philosophy class was hard, and the one I'm in is hard, too. All philosophy classes must be hard!"
5. What Fallacy? "President Jones raised taxes, and then the rate of violent crime went up. Jones is responsible for the rise in crime. "
6. What Fallacy? “We can either go to the river or eat sandwiches. We’re both hungry, so we should eat sandwiches and not go to the river. ”
7. What Fallacy? "Guns are like hammers—they're both tools with metal parts that could be used to kill someone. And yet it would be ridiculous to restrict the purchase of hammers—so restrictions on purchasing guns are equally ridiculous. "
8. What Fallacy? "Active euthanasia is morally acceptable. It is a decent, ethical thing to help another human being escape suffering through death. "
9. What Fallacy? It is claimed by some people that severe illness is caused by depression and anger. After all, people who are severely ill are very often depressed angry. Thus, it follows that the cause of severe illness actually is the depression and anger. So, a good and cheerful attitude is key to staying healthy.
10. What Fallacy? All people who get straight “A”s have high I. Q. s
11. What Fallacy? "Caldwell Hall is in bad shape. Either we tear it down and put up a new building, or we continue to risk students' safety. Obviously we shouldn't risk anyone's safety, so we must tear the building down. "
12. What Fallacy? All Americans are patriotic.
THE ANSWERS 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Circular Reasoning Either/or Circular Reasoning Hasty Generalization False Causality Either/Or False Analogy Circular Reasoning False Causality Hasty Generalization Either/Or Hasty Generalization