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Logical Fallacies Practice

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Updated on Sep 28, 2011

Review the lesson for Logical Fallacies Help.

Logical Fallacies Practice

  1. Read the following scenario. What other options are available? Either you're a vegetarian or you don't care about the environment.

Read the following arguments carefully. Do the arguers use logic (L) or no in-betweens (NI) to convince you?

  1. Mother to son: "Either you major in engineering or in premed. Nothing else will lead to a good career."
  2. We can go to the movies or to the bowling alley. Unfortunately, because of the holiday, everything else is closed.
  3. Either we raise taxes by 10% or we drown ourselves in a budget deficit.
  4. Either you want to preserve our rainforests or you don't. You can't have it both ways.

Read the following arguments carefully. Are they using logic (L) or slippery slope (SS) to convince you?

  1. If we raise the legal driving age to eighteen, then there will be less car accidents on the roads. People will feel safer on the road, and car insurance rates for everyone will decrease significantly.
  2. If all employers require their employees to take a flu shot, then less people would take sick days. This would result in increased productivity for the nation as a whole.
  3. I wouldn't drop this class if I were you. If you do, you'll be three credits behind and you'll have to take an extra class next semester to graduate on time.

See if you can recognize circular reasoning in the following arguments. If the argument is logical, write an L in the blank. If the argument is circular, write a C in the blank.

  1. I know he's telling the truth because he's not lying.
  2. I know he's telling the truth because I was there with him and I saw what happened.
  3. He should have a break. He deserves it.
  4. Give him a break. He's been working nonstop for eight hours.
  5. It's the right thing to do, because this way, no one will get hurt.
  6. We believe this is the best choice because it's the right thing to do.
  1. Put a check mark next to the arguments below that use the two wrongs make a right fallacy.

a. Go ahead, tell your boss what you saw Edgar do. You know he'd report you in a second if he ever saw you do   something like that.

b. I agree with you, Paula. Since Maria didn't call you on your birthday, I don't think you should call he on her birthday either.

c. John wans the job so badly as I do, so he'll probably start rumors about me to ruin my reputation. I'd better ruin his first.

d. Mitch, you should turn Sam in for skipping school last week. You  know that if you did the same thing someday, he would rush t tell the principal about it.

Answers

  1. There are plenty of other options. You could eat only fish. You could eat meat but take extra measures to recycle and help the environment. You could have been a vegetarian in the past but determined it was not healthy for you. There are many in-between options here.
  2. NI. Indeed, there are other majors that can lead to a good career.
  3. L. If everything else is closed, then these really are the only two options available.
  4. NI. There are definitely other choices. Raising taxes isn't necessarily the only way to fix the budget deficit. Similarly, not raising taxes doesn't necessarily mean drowning in deficit. There are other ways to address the deficit problem.
  5. NI. You can be in between on this issue. For example, you may want to preserve the rainforests, yet feel that we should harvest any plants that have disease-fighting properties.
  6. SS. Raising the driving age to eighteen does not necessarily mean that there would be less car accidents on the roads. First of all, we can't be sure that the majority of car accidents that take place involve drivers under eighteen. Second, even if there were less car accidents as a result of the new driving age, it wouldn't necessarily result in lower insurance rates for everyone.
  7. SS. Again, X doesn't necessarily lead to Y. There's no reason to believe that taking flu shots will increase productivity. Also, people can get sick for other reasons, and flu shots might not help in those cases.
  8. L. This is a good, logical reason not to drop the class.
  9. C. This argument doubles back on itself—"he's not lying" doesn't say any more than what's already been said in the conclusion.
  10. L. The premise here offers a real reason. If the person was there to witness what happened, he or she most likely knows if the other person is telling the truth or not.
  11. C. Notice the premise doesn't give any reason for giving him a break. He "should have" one and "he deserves it" are the same thing.
  12. L. The premise here offers a real reason. If he's been working "eight hours nonstop," he does deserve it.
  13. L. Preventing people from getting hurt is a good supporting premise for the conclusion here.
  14. C. Unlike number 13, the premise and the conclusion here say essentially the same thing.
  15. Arguments a and c use the two wrongs make a right fallacy. Argument b may look like it does, but look again. In this case, the arguer is saying that Paula shouldn't call Maria on her birthday because Maria didn't call Paula on hers. This is truly an eye for an eye, not an eye for a maybe.

 

 

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