Logical Fallacy: Seven Terms to Know

1. Mrs. Stinnett English II Logical Fallacy:Seven Terms to Know

2. What is a logical fallacy? • A fallacy in logic is a mistake in reasoning. • A fallacy can occur in rhetoric and logic. • You need to be able to identify logical fallacies in your writing, rhetoric, media/advertisements, and literature.

3. Appeal to Fear • a person attempts to create support for his or her idea by using deception and propaganda in attempts to increase fear and prejudice toward a competitor • scare tactics • EX: "I don't think a Red Ryder BB rifle would make a good present for you. They are very dangerous and you'll put your eye out. Now, don't you agree that you should think of another gift idea?"

4. Personal Attack (Ad Hominem) • focus attention on people rather than on arguments or evidence • used often in political campaigns • EX: “John McCain has a black child.”

5. False Dilemma • a limited number of options (usually two) is given, while in reality there are more options • putting issues or opinions into "black or white" terms is a common instance of this fallacy • EX: Either you’re for America or you’re for the terrorists. • EX: Every person is either wholly good or wholly evil.

6. False Analogy • Many arguments rely on an analogy between two or more objects, ideas, or situations. • If the two things that are being compared aren't really alike, the analogy is a weak one, and the argument that relies on it commits the fallacy of false analogy. • EX: "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."

7. Slippery Slope • The arguer claims that a sort of chain reaction, usually ending in some dire consequence, will take place, but there's really not enough evidence for that assumption. • The arguer asserts that if we take even one step onto the "slippery slope," we will end up sliding all the way to the bottom; he or she assumes we can't stop halfway down the hill. • EX: “Animal experimentation reduces our respect for life. If we don't respect life, we are likely to be more and more tolerant of violent acts like war and murder. Soon our society will become a battlefield in which everyone constantly fears for their lives.”

8. Non Sequitur • translation: “it does not follow” • an illogical statement based on assumptions that draws a conclusion not supported by the premises • EX: "Racism is wrong. Therefore, we need affirmative action." • EX: “Education is the only way to combat unemployment.”

9. False Authority • using a biased, suspicious, or incredible source to defend a conclusion • EX: "We should abolish the death penalty. Many respected people, such as actor Guy Handsome, have publicly stated their opposition to it."

11. Logical Fallacy Practice • Review the following examples, and write your answer on a piece of paper.

12. Logical Fallacy #1 • A prosecutor asks the judge to not admit the testimony of a burglar because burglars are not trustworthy.

13. Logical Fallacy #2 • Employees are like nails. Just as nails must be hit in the head in order to make them work, so must employees.

14. Logical Fallacy #3 Bill and Jane are arguing about abortion. Bill: "I believe that abortion is morally acceptable. After all, a woman should have a right to her own body." Jane: "I disagree completely. Dr. Johan Skarn says that abortion is always morally wrong, regardless of the situation. He has to be right, after all, he is a respected expert in his field.“ Bill: "I've never heard of Dr. Skarn. Who is he?" Jane: "He's the guy that won the Nobel Prize in physics for his work on cold fusion." Bill: "I see. Does he have any expertise in morality or ethics?" Jane: "I don't know. But he's a world famous expert, so I believe him."

15. Logical Fallacy #4 • I can't believe you voted to restrict welfare. Either you didn't understand the proposition, or you just don't care about those less fortunate than yourself!

16. Logical Fallacy #5 • "You know, Professor Smith, I really need to get an A in this class. I'd like to stop by during your office hours later to discuss my grade. I'll be in your building anyways, visiting my father. He's your dean, by the way. I'll see you later."

17. Logical Fallacy #6 • "The US shouldn't get involved militarily in other countries. Once the government sends in a few troops, it will then send in thousands to die."

18. Logical Fallacy #7 • "Giving up our nuclear arsenal in the 1980s weakened the United States' military. Giving up nuclear weaponry also weakened China in the 1990s. For this reason, it is wrong to try to outlaw pistols and rifles in the United States today."

19. Logical Fallacy #1 A prosecutor asks the judge to not admit the testimony of a burglar because burglars are not trustworthy. Personal Attack (Ad Hominem)

20. Logical Fallacy #2 Employees are like nails. Just as nails must be hit in the head in order to make them work, so must employees. False Analogy

21. Logical Fallacy #3 False Authority Bill and Jane are arguing about abortion. Bill: "I believe that abortion is morally acceptable. After all, a woman should have a right to her own body." Jane: "I disagree completely. Dr. Johan Skarn says that abortion is always morally wrong, regardless of the situation. He has to be right, after all, he is a respected expert in his field.“ Bill: "I've never heard of Dr. Skarn. Who is he?" Jane: "He's the guy that won the Nobel Prize in physics for his work on cold fusion." Bill: "I see. Does he have any expertise in morality or ethics?" Jane: "I don't know. But he's a world famous expert, so I believe him."

22. Logical Fallacy #4 I can't believe you voted to restrict welfare. Either you didn't understand the proposition, or you just don't care about those less fortunate than yourself! False Dilemma

23. Logical Fallacy #5 "You know, Professor Smith, I really need to get an A in this class. I'd like to stop by during your office hours later to discuss my grade. I'll be in your building anyways, visiting my father. He's your dean, by the way. I'll see you later.“ Appeal to Fear

24. Logical Fallacy #6 "The US shouldn't get involved militarily in other countries. Once the government sends in a few troops, it will then send in thousands to die." Slippery Slope

25. Logical Fallacy #7 Non Sequitur "Giving up our nuclear arsenal in the 1980s weakened the United States' military. Giving up nuclear weaponry also weakened China in the 1990s. For this reason, it is wrong to try to outlaw pistols and rifles in the United States today."