Chapter 8, Arguments to and from Generalizations Video Solutions, Cengage Advantage Books: Understanding Arguments: An Introduction to Informal Logic

Problem 1

Assuming a standard context, label each of the following arguments as deductive or inductive. Explain what it is about the words or form of argument that indicates whether or not each argument is intended or claimed to be valid. If it is not clear whether the argument is inductive or deductive, say why.
1. The sun is coming out, so the rain will probably stop soon.
2. It's going to rain tomorrow, so it will either rain or be clear tomorrow.
3. No woman has ever been elected president. Therefore, no woman will ever be elected president.
4. Diet cola never keeps me awake at night. I know because I drank it just last night without any problems.
5. The house is a mess, so Jeff must be home from college.
6. If Harold were innocent, he would not go into hiding. Since he is hiding, he must not be innocent.
7. Nobody in Paris seems to understand me, so either my French is rotten or Parisians are unfriendly.
8. Because both of our yards are near rivers in Tennessee, and my yard has lots of mosquitoes, there must also be lots of mosquitoes in your yard.
9. Most likely, her new husband speaks English with an accent, because he comes from Germany, and most Germans speak English with an accent.
10. There is no even number smaller than two, so one is not an even number.

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Problem 2

By asking the preceding questions, specify what, if anything, is wrong with the following statistical generalizations:
1. This philosophy class is about logic, so most philosophy classes are probably about logic.
2. Most college students like to ski, because I asked a lot of students at several colleges in the Rocky Mountains, and most of them like to ski.
3. K-Mart asked all of their customers throughout the country whether they prefer K-Mart to Walmart, and 90 percent said they did, so 90 percent of all shoppers in the country prefer K-Mart.
4. A Swede stole my bicycle, so most Swedes are thieves.
5. I've never tried it before, but I just put a kiwi fruit in a tub of water. It floated. So most kiwi fruits float in water.
6. I have lots of friends. Most of them think that I would make a great president. So most Americans would probably agree.
7. In exit polls after people had just voted, most people told our candidate that they voted for her, so probably most people did vote for her.
8. Mary told me that all of her older children are geniuses, so her baby will probably be a genius, too.
9. When asked whether they would prefer a tax break or a bloated budget, almost everyone said that they wanted a tax break. So a tax break is overwhelmingly popular with the people.
10. When hundreds of convicted murderers in states without the death penalty were asked whether they would have committed the murder if the state had a death penalty, most of them said that they would not have done it. So most murders can be deterred by the death penalty.

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Problem 3

Carry the story of Marvin two steps further, producing two more reversals in the strength of the statistical application with the conclusion that Marvin voted for Romney.

Tyler Moulton

Numerade Educator

Problem 4

For each of the following statistical applications, identify the reference class, and then evaluate the strength of the argument in terms of the percentages or proportions cited and the relevance of the reference class.
1. Less than 1 percent of the people in the world voted for Romney.

Michelle is a person in the world.
2. Very few teams repeat as Super Bowl champions.
New England was the last Super Bowl champion.
$\therefore$ New England will not repeat as Super Bowl champion.
3. A very high percentage of people in the Senate are men. Elizabeth Warren is in the Senate.
$\therefore$ Elizabeth Warren is a man.
4. Three percent of socialists with blue eyes voted for Romney. Maureen is a socialist with blue eyes.
$\therefore$ Maureen did not vote for Romney.
5. Ninety-eight percent of what John says is true. John said that his father is also named John.
6. Ninety-eight percent of what John says is true. John said that the Giants are going to win.
$\therefore$ The Giants are going to win.
7. Half the time he doesn't know what he is doing.
He is eating lunch.
$\therefore$ He does not know that he is eating lunch.
8. Most people do not understand quantum mechanics. My physics professor is a person.
$\therefore$ My physics professor probably does not understand quantum mechanics.
9. Almost all birds can fly. This penguin is a bird.
$\therefore$ This penguin can fly.
10. Most people who claim to be psychic are frauds. Mary claims to be psychic.
$\therefore$ Mary is a fraud.

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