Exercise answers chapter 1, 2 & 3

Exercise Answers and Teaching Tips

Chapter 1: Introduction to Critical Thinking

Students enjoy the exercises in Chapter 1. Most are Socratic exercises, designed to ease students into the course and encourage self-reflection in dialogue with others.

Instructors probably won't want to do all the exercises in this chapter: We generally do about half. Exercise 1.1.1 works well as an icebreaker. Students always enjoy Exercises 1.2 and 1.3, and Exercises 1.6.I and 1.6.III work well for instructors who stress writing.

Exercise 1.4.

Discussion questions:

1. What can you consistently believe with regard to Culture A?

Answer: You must believe that it is right for Culture A to be a totally pacifist culture, and hence that it is right for Culture A to permit themselves to be conquered and enslaved by Culture B. (Assuming that this belief is consistent with what you must believe as a member of Culture C.)

2. What can you consistently believe with regard to Culture B?

Answer: You must believe that it is right for Culture B to be a militaristic and slaveholding culture, and hence that it is right for Culture B to conquer and enslave Culture A. (Assuming that this belief is consistent with what you must believe as a member of Culture C.)

3. What can you consistently do with regard to Culture A?

Answer: Since both Culture A and Culture B are doing what they consider to be morally right, you cannot do anything to interfere with the invasion. (Assuming that your noninterference is permitted by the values of Culture C.)

4. What can you consistently do with regard to Culture B?

Answer: You cannot do anything to interfere with Culture B’s conquest of Culture A. (Assuming that your noninterference is permitted by the values of Culture C.)

Main Lesson of Case 1:

Moral relativism may commit us to certain beliefs or practices that, intuitively, seem to us to be terribly wrong. It makes it impossible for us to criticize the values and practices of other cultures that may seem to us to be clearly wrong or misguided.

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Case 2

Discussion questions:

1. Is there any logical difficulty with being a relativist and also belonging to Culture B?

Answer: Yes. As a moral relativist you must believe that it is right for Culture A to practice pacifism (since this is what Culture A believes is right). But as a member of Culture B you must believe that it is wrong for Culture A to practice pacifism (since this is what Culture B believes).

2. What can you consistently believe with regard to Culture A?

Answer: As explained above, you are committed to inconsistent beliefs with regard to Culture A. You must believe that it is right for Culture A to practice pacifism and that it is wrong for Culture A to practice pacifism.

3. What can you consistently believe with regard to Culture B?

Answer: You must believe that it is right for Culture B to subjugate and enslave Culture A. (Instructors might wish to note that, strictly speaking, inconsistent beliefs imply any conclusion.)

4. What can you consistently do with regard to Culture A?

Answer: Since both Culture A and Culture B are doing what they consider to be right, you, as a member of Culture B, must support the invasion—and indeed participate in it if required to do so.

5. What can you consistently do with regard to Culture B?

Answer: You must support and possibly participate in the invasion and subjugation.

Main Lessons of Case 2:

1. Moral relativism may commit us to certain beliefs or practices that, intuitively, seem to us to be terribly wrong.

2. Moral relativism can easily lapse into inconsistency. One way this can happen is when a relativist is a member of a society that holds beliefs that conflict with moral relativism (as Culture B does in this scenario). Another way inconsistency can occur is when a relativist belongs to a culture that holds inconsistent moral beliefs. A third way in which relativism can lead to inconsistency is explored in Case 3.

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Case 3

Discussion questions:

1. Is it possible for an individual to belong to more than one culture at the same time? If so, does this impose any logical difficulty for the moral relativist?

Answer: Arguably, yes. The Amish, for example, plausibly belong to two cultures: the larger American culture and their own distinctive sub-culture. If an individual belongs to different cultures, and the cultures hold mutually inconsistent moral beliefs, then moral relativism implies inconsistent moral duties.

2. Is there any logical difficulty in being a relativist and belonging to Culture B?

Answer: Yes, for the same reason stated in Case 2. You must believe both that Culture A is right not to practice child sacrifice and that Culture A is wrong not to practice child sacrifice.

3. What can you consistently believe with regard to Culture A and Culture B?

Answer: You seem to be committed to holding inconsistent beliefs: that child sacrifice is both right and wrong for Culture B, and that child sacrifice is both right and wrong for Culture A.

4. What can you consistently do with regard to Culture A and Culture B?

Answer: You would have inconsistent duties--for example, both to support and not to support child sacrifice.

5. If someday the Betas become the majority sub-culture in Culture B, and consequently most members of Culture B no longer believe in child sacrifice, can this be described as "moral progress" from the standpoint of moral relativism?

Answer: No. According to moral relativism, what is morally right for a society is whatever that society believes is right at a particular time. Thus, according to relativism, it is not the case, for example, that contemporary Americans' attitudes toward slavery are "truer" or "more enlightened" than those of most 18th century Americans. Both views are equally true for the people at those times.

Exercise 1.6

II.

The following definitions are offered on the Center for Critical Thinking Web site (http://www.criticalthinking.org):

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Intellectual humility: Having a consciousness of the limits of one's knowledge, including a sensitivity to circumstances in which one's native egocentrism is likely to function self-deceptively; sensitivity to bias, prejudice and limitations.

Intellectual courage: Having a consciousness of the need to face and fairly address ideas, beliefs or viewpoints toward which we have strong negative emotions and to which we have not given a serious hearing.

Fair-mindedness: Having a consciousness of the need to treat all viewpoints alike, without reference to one's own feelings or vested interests, or the feelings or vested interests of one's friends, community or nation.

Intellectual perseverance: Having a consciousness of the need to use intellectual insights and truths in spite of difficulties, obstacles, and frustrations; firm adherence to rational principles despite the irrational opposition of others; a sense of the need to struggle with confusion and unsettled questions over an extended period of time to achieve deeper understanding or insight.

The Web site also offers definitions of three additional intellectual traits: intellectual empathy, intellectual integrity, and faith in reason.

Here are two dictionary definitions of open-mindedness: "Having or showing receptiveness to new and different ideas or the opinions of others." (Source: The American Heritage Dictionary of the English Language, 3rd ed.) "Willingness to listen to other people and consider new ideas, suggestions and opinions." (Source: Cambridge International Dictionary of English.)

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Chapter 2: Recognizing Arguments

Exercise 2.1

I.

1. Statement2. Nonstatement (question)3. Statement4. Nonstatement (suggestion)5. Statement6. Nonstatement (suggestion or exhortation)7. Statement (This is a brief and emphatic way of saying, "This is great.")8. Nonstatement (command)9. Nonstatement (order or request)10. Statement (You might be lying.)11. Statement (rhetorical question)12. Nonstatement (exclamation)13. Nonstatement (request)14. Statement (rhetorical question)15. Nonstatement (question)16. Statement (This is an emphatic way of saying, "This is a crock.")17. Nonstatement (This could be an ought imperative in some contexts, but more likely it is a

request, suggestion, or order.)18. Statement19. Nonstatement ("Please" indicates that this is a request)20. Nonstatement (petition)21. Nonstatement (suggestion or proposal)22. Statement (Spanish for "My house is your house.")23. Statement (rhetorical question)24. Statement (rhetorical question)25. Nonstatement (exclamation)

II.

1. Yes2. No (command)3. Yes4. Yes5. No (suggestion)6. No 7. Yes8. Yes

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9. Yes10. Yes11. No12. Yes13. Yes14. No15. Yes

Exercise 2.2

I.

1. Premise: Light takes time to reach our eyes.Conclusion: All that we see really existed in the past.

2. Premise 1: Life changes when you least expect it to. Premise 2: The future is uncertain.Conclusion: Seize this day, seize this moment, and make the most of it.

3. Premise: A good name shall continue with thee, more than a thousand treasures precious and great. Conclusion: Take care of a good name.

4. Premise: Faith means believing a proposition when there is no good reason for believing it.

Conclusion: Faith is a vice.

5. Premise: If you are not very careful about lying, you are nearly sure to get caught.Conclusion: You want to be very careful about lying.

6. Premise: There is no definitive way to prove any one set of religious beliefs to the exclusion of all others.

Conclusion: Religious freedom is a human right.

7. Premise: Science is based on experiment, on a willingness to challenge old dogma, on an openness to see the universe as it really is.

Conclusion: Science sometimes requires courage--at the very least the courage to question the conventional wisdom.

8. Premise 1: You may not be able to hear warning sirens from emergency vehicles.Premise 2: Hearing damage from loud noise is almost undetectable until it's too

late.Conclusion: Do not play your sound system loudly.

9. Premise 1: Without symbols, no intellectual advance is possible.

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Premise 2: With symbols, there is no limit set to intellectual development except inherent stupidity.

Conclusion: The invention or discovery of symbols is doubtless by far the single greatest event in the history of man.

10. Premise: On average, the lowest animal is a lot nicer and kinder than most of the human beings that inhabit the earth.

Conclusion: Animals have souls.

11. Premise: The more stupid a member of Parliament is, the more stupid his constituents were to elect him.

Conclusion: Democracy has at least one merit, namely, that a member of Parliament cannot be stupider than his constituents.

12. Premise: When senility hit you, you won't know it.Conclusion: Don't worry about senility.

13. Premise: Oil isn't helping anyone when it sits in the ground.Conclusion: There's nothing wrong with burning crude [oil] like crazy, so long as

there's a plan for energy alternatives when the cheap oil runs out.

14. Premise: Everyone recalls the famous incident at Sybil Seretsky's when her goldfish sang "I Got Rhythm"--a favorite tune of her deceased nephew.

Conclusion: There is no doubt that certain events recorded at seances are genuine.

15. Premise: We need quality highways to handle the sharp increase in the number of Mercedes automobiles purchased by lawyers enriched by the tobacco settlement.

Conclusion: It's good that so far states are spending more than 90 percent of the tobacco settlement money on programs unrelated to smoking, such as building highways.

16. Premise: If we encourage each other to blame God for injustice, we are giving the evil or dark side a victory by keeping God's precious children–that's all of us–away from His loving arms.

Conclusion: Although it's part of human nature to be angry at God when bad things happen, there' s no point in doing so.

17. Premise 1: In great contests each party claims to act in accordance with the will of God.

Premise 2: God cannot be for and against the same thing at the same time.Conclusion: Both parties in great contests may be, and one must be, wrong.

18. Premise 1: The Alaska bears are a distinct species.

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Premise 2: Relegating grizzlies to Alaska is like relegating happiness to heaven-- one may never get to heaven or Alaska.Conclusion: It is not good enough for me if grizzlies survive only in Canada and

Alaska.

19. Premise 1: More than 99 percent of the creatures that have ever lived have died without progeny.

Premise 2: Not a single one of your ancestors falls into this group.Conclusion: You are very lucky to be alive.

20. Premise: You put a pen in there, you roll over in the middle of the night, you kill yourself.

Conclusion: You don't need a breast pocket on your pajamas.

II.

1. Premise 1: Man knows that he is dying.Premise 2: Of its victory the universe knows nothing.Conclusion: When the universe has crushed him man will still be nobler than that

which kills him.

2. Premise 1: Rights are either God-given or evolve out of the democratic process.Premise 2: Most rights are based on the ability of people to agree on a social

contract, the ability to make and keep agreements.Premise 3: Animals cannot possibly reach such an agreement with other creatures.Premise 4: Animals cannot respect anyone else's rights.Conclusion: Animals cannot be said to have rights.

3. Premise 1: I need a man.Premise 2: My heart is set on you.Conclusion: You’d better shape up.

4. Premise 1: Moral responsibility presupposes free-will.Premise 2: This freedom is not compatible with universal causal determinism.Premise 3: Universal causal determinism appears to be the case.Conclusion: Contrary to what most people believe, human beings are not morally

responsible.

5. Premise 1: Our faith comes in moments.Premise 2: Our vice is habitual.Premise 3: There is a depth in those brief moments which constrains us to ascribe

more reality to them than to all other experiences.Conclusion: The argument which is always forthcoming to silence those who

conceive extraordinary hopes of man, namely the appeal to experience, is forever invalid and vain.

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6. Premise 1: Travel articles appear in publications that sell large, expensive advertisements to tourism-related industries.

Premise 2: These industries do not wish to see articles with headlines like "Uruguay: Don't Bother."

Premise 3: (subconclusion): No matter what kind of leech-infested, plumbing free destination travel writers are writing about, they always stress the positive.

Conclusion: Never trust anything you read in travel articles.

7. Premise 1: If you are not speeding, you don't have to worry about speed traps.Premise 2: Speed traps could save your life if some other speeder is caught.Conclusion: No one in his right mind can criticize the state police for speed traps.

8. Premise 1: Philosophy is dangerous whenever it is taken seriously.Premise 2: So is life.Premise 3: Safety is not an option.Conclusion: Our choices are not between risk and security, but between a life

lived consciously, fully, humanly in the most complete sense and a life that just happens.

9. Premise: Our nation protests, encourages, and even intervenes in the affairs of other nations on the basis of its relations to corporations.

Conclusion: We cannot dissociate ourselves from the plight of people in those countries.

10. Premise: He that loveth not his brother whom he hath seen, cannot love God whom he hath not seen.

Conclusion: If a man say, "I love God" and hateth his brother, he is a liar.

11. Premise 1: Each of us has an intellectual dimension to his existence.Premise 2: We need ideas as much as we need food, air, or water.Premise 3: Ideas nourish the mind as the latter provide for the body.Conclusion: We need good ideas as much as we need good food, good air, and

good water.

12. Premise 1: The only criterion for distinguishing right from wrong is the moral system of the society in which the act occurs.

Premise 2 (subconclusion): The only ethical standard for judging an action is the moral system of the society in which the act occurs.

Conclusion: What is right in one place may be wrong in another.

13. Premise: If you don't accept reality the way it occurs--namely, as highly imperfect and filled with most fallible human beings—you will experience continual anxiety and desperate disappointments.

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Conclusion: Whether you like it or not, you'd better accept reality the way it occurs: as highly imperfect and filled with most fallible human beings.

14. Premise 1: The more vivid our sense of the approach of death, the more we relish the small things in life.

Premise 2 (subconclusion): Death is necessary for our appreciation of life.Premise 3: Death is necessary for the continued march of evolutionary improvement, an ongoing process leading to more valuable states of good, to take place on earth.Conclusion: We should be emotionally reconciled to the fact of death, rather than fearing it.

15. Premise: The hit rock songs of 1974 included "Kung Fu Fighting," "Seasons in the Sun," "Billy Don't Be a Hero," "The Night Chicago Died" and "(You're) Having My Baby."

Conclusion: It is a scientific fact that 1974 was the worst year in world history for rock music.

16. Premise 1: Those who develop the first-thing-in-the-morning routine tend to be more consistent in their training.

Premise 2: Morning runs avoid the heat and peak air pollution.Premise 3: You can enjoy your runs without carrying along all the stress that

builds up during the day.Premise 4: Early-morning runs save time by combining your morning and postrun

shower.Conclusion: Getting in your run early certainly has its advantages.

17. Premise 1: You go to Duke and it has everything you dream about in college basketball.

Premise 2: Guys play hard.Premise 3: They go to class.Premise 4: They do things the right way.Premise 5: They have discipline.Premise 6: They go out and win.Premise 7: The crowd is behind them.Conclusion: There is nothing not to like about Duke University men’s basketball

program.

18. Premise 1: College professors don’t know how to live any better than the rest of us.

Conclusion: The art of how to live can’t be taught in college.

19. Premise 1: You’ll begin to eat food in season, when they are at the peak of their nutritional value and flavor.

Premise 2: You won’t find anything processed or microwavable.Premise 3 (subconclusion): You’ll cook.Premise 4: You’ll be supporting the farmers in your community.

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Premise 5: You’ll be helping defend the countryside from sprawl.Premise 6: You’ll be saving oil by eating food produced nearby.Premise 7: You’ll be teaching your children that a carrot is a root, not a machine-

lathed orange bullet that comes in a plastic bag.Conclusion; Shop at the farmer’s market.

20. Premise 1: When you understand other positions and points of view, you often learn something new and expand your horizons.

Premise 2: When the person you are talking to feels listened to, he or she willappreciate and respect you far more than when you habitually jump in with your own position.

Premise 3: A side benefit is that the person you are speaking to may even listen to your point of view.

Conclusion: The next time you find yourself in an argument, rather than defend your position, see if you can see the other point of view first.

Exercise 2.4

I.

1. Nonargument (explanation)2. Argument3. Nonargument (explanation)4. Nonargument (conditional statement)5. Nonargument (explanation)6. Argument7. Nonargument (report of an argument)8. Nonargument (illustration)9. Nonargument (explanation)10. Nonargument (illustration)11. Argument12. Nonargument (conditional statement)13. Nonargument (report of argument). (The writer is reporting, not endorsing, Gladstone's

argument.)14. Nonargument (explanation)15. Nonargument (unsupported assertion)16. Nonargument (report of an explanation)17. Nonargument (unsupported assertion)18. Argument19. Nonargument (unsupported assertion). (Notice that the word "because" does not function as a

premise indicator in either sentence of this passage.)20. Nonargument (unsupported assertion)21. Nonargument (explanation)22. Nonargument (unsupported assertion)

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23. Nonargument (unsupported assertion)24. Argument25. Nonargument (illustration)26. Argument27. Nonargument (unsupported assertion)28. Nonargument (conditional statement)29. Nonargument (explanation)30. Nonargument (unsupported assertion)

II.

1. Explanation2. Argument3. Explanation4. Argument5. Explanation6. Explanation7. Explanation8. Explanation9. Explanation10. Explanation11. Argument12. Explanation13. Explanation14. Explanation15. Argument16. Explanation17. Argument18. Explanation19. Explanation20. Explanation

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Chapter 3: Basic Logical Concepts

Exercise 3.1

I.

1. Moriarty

2. Adler, with the revolver

3. Windibank, with the rope, on the downs

II.

1. Mike: Grape juiceAmy: PepsiBrian: Diet CokeLisa: Iced teaBill: 7-Up

2. China and Japan are out because Seth does not want to go to Asia. Australia is out because Maria does not want to go to any country south of the equator. Canada is out because Antoine wants to study in Europe or Australia. England is out because JoBeth is willing to go anywhere except England. Therefore, by a process of elimination, the answer is Germany.

3. Buck: SodaJennifer: PretzelsLi: DipUrsula: ChipsTyler: Ice cream

Exercise 3.2

1. Modus tollens2. Affirming the consequent3. Modus ponens4. Chain argument5. Denying the antecedent6. Modus ponens7. Denying the antecedent8. Affirming the consequent9. Chain argument

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10. Affirming the consequent

Exercise 3.3

1. Deductive (Argument based on mathematics; also, the conclusion follows necessarily from the premises.)

2. Inductive (Argument from authority; also, the conclusion follows only probably from the premises; also, "it’s reasonable to believe that” is an induction indicator phrase.)

3. Inductive (Statistical argument; also, the conclusion follows only probably from the premises; also, probably is an induction indicator word.)

4. Deductive (Argument by elimination; also, the conclusion follows necessarily from the premises.)

5. Deductive. (The conclusion follows necessarily from the premises; also, obviously is a deduction indicator word.)

6. Inductive (Causal argument; also, the conclusion does not follow necessarily from the premises.)

7. Inductive (Given that signs can be wrong, the conclusion follows only probably from the premises.)

8. Deductive (Argument by definition; also, the conclusion follows necessarily from the premises.)

9. Deductive (Categorical syllogism; also, the conclusion follows necessarily from the premises.)

10. Inductive (Argument from authority; also, a prediction; also, probably is an induction indicator word; also, the conclusion does not follow necessarily from the premises.)

11. Deductive (Hypothetical syllogism; note, however, that the conclusion does not follow necessarily from the premises.)

12. Deductive (The conclusion follows necessarily from the premises.)

13. Inductive (The principle of charity dictates that the argument be regarded as inductive, because the conclusion follows at best probably from the premises.)

14. Inductive (Causal argument; also, the conclusion does not follow necessarily from the premises.)

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15. Inductive (Inductive generalization; also, probably is an induction indicator word; also, the conclusion does not follow necessarily from the premises.)

16. Inductive (Argument from authority; also, the conclusion does not follow necessarily from the premises.)

17. Deductive (Hypothetical syllogism; note, however, that the conclusion does not follow necessarily from the premises.)

18. Inductive (Argument from analogy; also, the conclusion does not follow necessarily from the premises.)

19. Inductive. (The principle of charity dictates that the argument be regarded as inductive, because the conclusion does not follow necessarily from the premises.)

20. Deductive (Argument by definition; also, the conclusion follows necessarily from the premises; also, “it must be the case that” is a deduction indicator phrase.)

21. Deductive. (The conclusion follows necessarily from the premises.)

22. Deductive (Argument by elimination; also, the conclusion follows necessarily from the premises.)

23. Inductive (Argument from authority; also, the conclusion follows only probably from the premises.)

24. Inductive (Predictive argument; also, the conclusion follows only probably from the premises.)

25. Deductive (Argument based on mathematics; also, conclusion follows necessarily from the premises; also, "it necessarily follows" is a deduction indicator phrase.)

Exercise 3.4

1. Beta.2. Alpha.3. Delta is a beta.4. Delta is not an alpha.5. Delta is not a beta.6. Delta is not an alpha.7. If Delta is an alpha, then Delta is a theta.8. Delta is a beta.9. Either Delta is a theta or Delta is a sigma.10. Some alphas are thetas (or: Some thetas are alphas).

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Exercise 3.5

I.

1. Valid2. Valid3. Invalid (affirming the consequent)4. Invalid (denying the antecedent)5. Invalid6. Invalid (Not all lions have four legs.)7. Valid8. Valid9. Invalid10. Invalid

II.

1. Sound2. Unsound (The first premise is false.)3. Sound4. Unsound (invalid argument: affirming the consequent)5. Sound6. Sound7. Unsound (invalid argument: denying the antecedent)8. Unsound (The argument is invalid.)9. Unsound (The argument is invalid.)10. Unsound (false premise)

III.

1. Cogent2. Uncogent (Although cigarette smoking significantly increases one's risk of dying from lung

cancer, most heavy smokers do not die from lung cancer.)3. Uncogent (false premise)4. Uncogent (The analogy is a bad one, and the second premise is false.)5. Cogent6. Uncogent (The conclusion does not follow probably from the premises.)7. Cogent8. Uncogent (The first premise is false.)9. Cogent.10. Uncogent (The conclusion does not follow probably from the premises.)

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IV.

1. Deductive, valid2. Deductive, valid3. Inductive, strong4. Inductive, weak5. Inductive, strong6. Deductive, invalid (three socks would suffice)7. Inductive, strong8. Deductive, invalid9. Deductive, valid10. Inductive, weak11. Inductive, strong12. Inductive, strong13. Inductive, weak14. Deductive, valid15. Deductive, invalid16. Inductive, weak17. Deductive, invalid18. Inductive, weak19. Inductive, strong20. Deductive, invalid

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