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CHAPTER 3

Criticaj Thinkingand Reasoning

Imagine this situation: You're having dinner with a friend you haven't seen in ayear She has changed dramatically. You remember her as the Queen of BurgerKing, but now she is a committed vegetarian. "I don't eat anything with lips,eyelashes, or fins,"she says, "no Bossy, Porky, Claghorn, Bambi, Thumper, orNema-nada!"

"Wby?"you ask, stunned by her vehemence."Okay,"she says, "here are the reasons."First, she points out that meat costs a lot more than protein-rich grains,

so she saves on groceries. Second, she explains that grains, such as protein-rich soybeans grown for animal feed, would be better used to feed the world'shungry people. Third, she points out that eating red meat high in fat and fishhigh in mercury poses a danger to heal tho

These reasons a11make sense to you. Who doesn't want to save money,help feed the starving, and protect themselves against heart attack or toxicpoisoning?

Next, she becomes emotional. She vividly describes animals, such ascalves, being raised in pens to keep their flesh tender. She relates examples offorce feeding, chemical injections, and slaughterhouse procedures.

Will eating meat be in your future' Maybe or maybe not, but your friendhas presented an argument to back up her opinion. While making her point,she has used both reason and emotion. A reasoned argument engages yourintel1ect, whereas an emotional argument tries to bypass your intel1ect. Mosteffective arguments will balance their appeal to the intellect and emotion.

You may not face many arguments designed to convince you to stop eat-ing meat; however, like everyone in our society, you wilJ face plenty of argu-ments. They'll come from friends, family members, fellow students, teachers,and even the media, and they will be designed to convince you to change yourthmkmg and your behavior in any number of ways.

Chapter 3 Critical Thinking and Reasoning

EXAMINE THE LANGUAGE OF AN ARGUMENT

Whether an argument is spoken Orwritten, its tone often reveals an attitude.The tone can be serious, angry, biased, fair, humorous, or ironic, or have a Com-bination of qualities. In the foUowing example, for instance, the tone is one ofcareful, reasoned questioning and apparent fairness in defending euthanasia,the act of causing someone's death in order to end his or her suffering.

I suppose it's fair to call euthanasia "murder," if wemean that it involvesone human being intentionatty taking the life of another human being. Butwhy must we choose the term "murder" at all, except to cast a bad lighton euthanasia itself? Wedon't label killing in war or the execution of criminals"murder," do we?Wouldit not be more fair to call an instance of euthanasia,as some already do, a "mercydeath" to signify the ending of someone'slife,but also the compassionate cessation of the person's pain and suffering?

An argument that uses emotionally charged, biased, Orprejudicial languageprobably ntisrepresents the truth and might unfairly influence your thinking. Tosay, "Harold Kennedy does not deserve yow' vote because he's a shady politicianwhose policies will feather the nest of the rich" is not an argument; it is an unsub-stantiated attack on Kennedy's character. An argument that uses euphemism,which is language that disguises the true nature of something, is equally asevasive. Through euphemism, a war might be called "social turmoil"; a crime,a "legal indiscretion"; a lawsuit, a "financial dispute." As a critical thinker, youshould be aJert to language and to the extent someone manipulates it to in£lu-ence your judgment. (See the discussion on logical fallacies, pp. ll-J5)

EXAMINE PATTERNS OF REASONING

Two elements are aJways at work in any argument. First is the content, thatis, the information used to convince you that the speaker or author is right.Second is the reasoning process that arranges the information. The first stepin evaluating any argument is to examine the information criticaUy, as we dis-cussed in Chapter 2. The second step is to evaluate the actual reasoning pro-cess, that is, the logic of the argument. Generally, logicians-people who studythe reasoning process-divide logical thinking into two categories: inductivereasoning and deductive reasoning.

INDUCTIVE REASONING

Inductive reasoning relies heavily on interpretation. It begins with specificinformation and moves to a general conclusion. The conclusion is usually ageneralization that explains all the information.

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Part I EffectiveThinkin

Induction is natural to the way all of us think. For example, a child bitesinto a hard green apple and discovers that it tastes bitter. When the childtastes a hard green pear, it, too, is bitter. Another time, the child bites into ahard green plum and an unripe apricot. Both are bitter. By induction, thechild comes to a conclusion: Hard green fruit will taste bitter.

Tracing the Inductive Process

An inductive argument always follows the same process. First, there is apresentation of information; then a conclusion is drawn from the informa-tion. For example, imagine you are exanlining the environmental practices ofyour hometown, Glenwood Hills. The process might begin with a question: IsGlenwood Hills being environmentally responsible? You visit the mayor andcity manager of Glenwood Hills. They give you the following facts:

• Glenwood has curbside recycling for glass, newspaper, aluminum, andplastics.

• Glenwood has a system to dispose of household toxic waste, such as sol-vents and paint.

• Glenwood has laws prohibiting release of ozone-depleting chlorofluoro_carbons from air condi tioners,

• Glenwood has a refuse landfill designed to protect groundwater fromtoxic pollution and to generate methane gas.

• Glenwood plans to develop a wetlands bird habitat to be preserved asopen space.

Based on the information they've provided, you might conclude the fOHowing:

GlenwoodHills is an environmentally responsiblecity.

Next, you discuss the issue with a local environmentalist, who reports thefolloWing:

• Glenwood's curbside recycling is in the experimental stage. It has beenimplemented in the northern quarter of the city, and only a few residentsactually recycle.

• Glenwood's household toxic waste disposal is only available once ayear.

• Glenwood's law prohibiting the release of ozone-depleting agents is notenforced.

• Although Glenwood's landfill design is state-of-the-art, a significant amount-; of pollution had seeped through the soil before it was built.

• Glenwood's wetlands bird habitat has yet to be approved by the state.

Chapter 3 Critical Thinking and Reasoning

Based on new information, your original conclusion needs revision:

Although GlenwoodHillshas environmentallyresponsiblepolicies, the cityhas not effectively implemented them.

When you accept a generalization through inductive reasoning, you aremaking an inductive leap because the conclusion is only a probable conclusion,one based on incomplete information and subject to revision when new infor-mation comes to light. Remember the child sampling green fruit and conclud-ing that such fruit is always bitter? Well, the child has made an inductive leap,but would have to revise the conclusion after tasting a ripe avocado.

EValuating Inductive Reasoning

A probable conclusion is only as good as the information that leads to it.The information should not only stand up under critical scrutiny but it shouldalso be ample. In fact, if your conclusion is based on only a fewpieces of infor-mation, you may be making a hasty generalization (see p. 13), a common flawin thinking. When evaluating an inductive argument, consider the followingquestions:

1. What evidence is the conclusion based on?2. Is there enough evidence?3. What is the source of the evidence, and is the source reliable?4. Does the conclusion explain aJJ the information, or is it contradicted bysome of the evidence?

5. Does the information contain any fallacious reasoning?

DEDUCTIVE REASONING

Inductive reasoning moves from particular information to a generalizationthat explains the particulars. The reasoning trail is strewn with evidence,which makes reviewing the process that leads to a conclusion easy. In contrast,deductive reasoning moves from a broad assumption to a specific instance. Inother words, deductive reasoning begins with a generalization, applies the gen-eralization to a particular example, and arrives at a conclusion. In skeletalform, deductive reasoning looks like this:

GENERALIZATION Natural events are beyond influence.

SPECIFIC INSTANCE Earthquakes are natural events.

CONClUSION Therefore, earthquakes are beyond influence.

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24Part I EffectiveThinking

Tracing the Deductive Process

In formal logic, this deductive pattern is called a syllogism and the reason-ing process is called syllogistic reasoning. Each syllogism begins with a generalassumption, called the major premise, and an instance of that assumption,called the minor premise. The deductive process then leads to the conclusion,which is the logical result of the major and minor premises.

The classic example of syllogistic reasoning comes from the Greek philoso-pher Aristotle:

MAJOR PREMISE

MINOR PREMISE

CONClUSION Therefore, Socrates is mortal.

All humans are mortal.

Socrates is human.

Aristotle explained syllogistic reasoning in this skeletal form, but in actualexperience syllogistic reasoning would be embedded in a discussion or text:

I try nat to think about death; the unknown is frightening. When I dotry to contemplate death, I only see lonely emptiness, nat the heavenly blissI hear religious friends talk about.

If I were a gad, I wouldn't have to worry about death. Gads don't die; theylive forever. The life expectancy for a human is only 82 years, nat long enough.

Although my friends say that I won't be alone in death because everyonedies, I still don't feel consoled because I already know each human beingdies ... and stays dead.

Socrates didn't worry about death. He spent his days lounging around thesquare, talking with friends and students about philosophical subjects-what iscourage, what is the right behavior, and so an. He didn't seem to worry aboutanything, let atone death.

Many of his friends actually thought Socrates was a god and listened tohim as if he were a god. They believed he would never die. But then Socratesmade a mistake and angered the government. He had to take his own life,which saddened everyone. "Get over it," I say. "It had to happen. He's onlyhuman."

Syllogisms can be tricky. Deductive arguments can be reduced to syllo-gisms, but that doesn't mean the arguments are valid. The conclusion of a syl-logism IS aiways drawn from the major and minor premises, both of which

Chapter 3 Critical Thinking and Reasoning25

must be accurate for the conclusion to be accurate. If the premises are com-posed of relevant, sufficient, and representative information-the same criteriaused to evaluate sound conclusions in inductive reasoning-the conclusion ofa syllogism wilt probably be accurate. But if the premises are inaccurate, asyllogism will probably be inaccurate. For example,

MAJOR PREMISE

MINOR PREMISE

CONCLUSION

Natural events are beyond influence.

The existence of humankind is a natural event.

Therefore, humankind is beyond influence.

Although it may appear that humankind is beyond influence, when you lookat your immediate family members, there's plenty of information that showsthey can be influenced.

Here are examples of several other ways that syllogistic reasoning can goawry:

1. An inaccurate major premise may make the syllogism illogical. For instance:

MAJOR PREMISE

MINOR PREMISE

CONCLUSION

Professional gamblers carry large quantities of cash anddrive expensive cars.

John Murphy is a professional gambler.

Therefore, John Murphy must carry large quantities of cashand drive an expensive car.

The major premise is inaccurate. Certainly, not all professional gamblers areSuccessful enough to win a lot of money, let alone choose to carry around cashand drive expensive cars. Because this major premise is inaccurate, the con-clusion is also inaccurate.

2. The language of the syllogism is deceptive. Look at this example:

MAJOR PREMISE

MINOR PREMISE

CONCLUSION

Every good American accepts the provisions of the U.S.Constitution.

Martin Luther King, Jr , did not accept the provisions of theu.S. Constitution because he worked to change it.

Therefore, Martin Luther King, Jr., was not a good American.

Consider how the terms good American, accept, and change are used in thisflawed syllogism. Good American is too vague to describe a class of peopleaccurately. And what do accept and change mean in this context? The U.S.Constitution allows for change. In fact, it has been amended many times.

PartI Effective Tbi~

26

So, anyone who accepts the Constitution accepts the possibility of chanlg::I.zIlit. Because language is used deceptively in the premises, the conclusi<>meaningless.

3. A syllogism is illogical when constructed improperly. Examine this pr><:>erly constructed syUogism, step by step:

MAJOR PREMISEAll artists rely on intuition.

~h-In a properly constructed syllogism, the subject of the major premise-in .._example, artists-must appear in the minor premise and be narrowed.MINOR PREMISE John is an artist.

The conclusion then follows necessarily from the major and minor premise:s=CONCLUSION

Therefore, John relies on intUition.

The preceding syllogism is properly constructed as well as valid. 0'examine the following invalid syllogism:

MAJOR PREMISE

MINOR PREMISE

CONCLUSION

All artists rely on intuition.

A1l psychics rely Onintuition.

Therefore, all psychics are artists.

This syUogism is improperly constructed because the minor premise does not:repeat the subject of the major premise. The conclusion, therefore, is invalid.

Like inductive reasoning, deductive reasoning can help organize discus-sion. But remember; deduction is never quite as Simple as the skeletal form ofsyllogisms we use to illustrate it. Apremise might not be expressed completelybased on the assumption that the listener will supply it mentaUy. AristotlecaUed this partial syllogism an enthymeme, and he pointed out that in discus-sion, speakers often omit premises or conclusions, assuming listeners wiIJfillthem in for themselves. Doing so often leads to faulty conclusions. For exam-ple, consider the follOwingenthymeme:

MigratingCanada geese are disappearing from the marshes where theyforageeach Winter;so we must restrict access to the marshes duringmigration.

At first glance, the conclusion makes sense because most of us would fillin the missing minor premise:

People (Tighten Canada geese.

Chapter 3 Critical Thinking and Reasoning27

What we might not do is evaluate the missing minor premise carefuIJy. Ifthe minor premise had been stated, then a discussion might have raised threekey questions:

Countries that may use weapons of mass destruction against the United Statesshould be invaded. Iraq has weapons of mass destruction, so we need toinvade Iraq.

Do many people visit the marshes during winter months?

Are fewer geese migrating south?

Have the geese found better foraging sites?

These questions might reveal that geese are disappearing for other than theassumed reason.

EValuating the Deductive Process

Some scholars have argued that the rustory of the Middle East would bedramaticaIJy different today if President George W. Bush and his advisors hadmore fully questioned the premises that launched the United States' invasionof Iraq in 2003. Stripped to its basics, their argument goes something like this:

• ON YOUR OWN

Study each of the following items and determine the reasoning patternembedded in it. If the reasoning pattern is deductive, rewrite it in syIJogisticform, changjng the wording if necessary. If the reasoning is incomplete-thatis, if it is an enthymeme-state the missing element in your own words.

As was later discovered, Iraq did not have weapons of mass destmction-andwhether it would ever have used them against the United States is not certain.Even the assumption that Iraq's possession of such weapons would requireinvasion by the United States is questionable: Other means, such as diplo-macy or intervention by the United Nations, might also have been used.

When you evaluate a deductive argument, consider the following questions:

1. What are the premises from which the conclusion is drawn? Are theycompletely identified?

2. Are the premises accurate?3. What is the conclusion?4. Does the conclusion folJow logically from the premises?5. Has the conclusion been reached through emotional appeals?

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28Part I EffectiveThin_

Finally, decide whether the reasoning is accurate or inaccurate and exp,h;;ur=your decision.

1. After hundreds of driving tests of American and imported automobile:sincluding subcompact, compact, midsize, and full-size vehicles, a cc:>rr-surner agency claims that full-size vehicles are the safest of all the care-gories and subcompact cars are the least safe.

2. An important skill in becoming a Successful economist is the ability _interpret statistical information from a variety of sources. Somerirmeeesthat information comes from the far reaches of the world-from unde ...-cl-oped countries as well as highly developed Countries. Phyllis Murph_worked for the Economic Study Institute, a nonprofit institution, whileshe was a graduate student. Her job required that she analyze informationin key production areas.

3. You doubt that this city is dangerous. Check out the statistics. They sho",,-that there has been an increase in muggings and other violent crimes inthe public transportation system as well as in parks, schools, and shop-ping malls. Moreover, the statistics show that home break-ins are on theincrease. Toprotect law-abiding citizens, we must put more police on thestreets and in the neighborhoods, for a city that can't protect its citizensis not worth living in. We just can't seem to protect Our citizens, so I'mlooking for property in Seattle.

4. Only a person who hated the victim could have committed such a brutalcrime. Killers always leave clues to their identity, though. Now, I haveexamined all the evidence: The details from the original crime scene.including photographs, the bloody but blurred shoeprint, the uniden-tifiable smudged thumbprint, the pistol, and the angle at which thebullet entered the head. It all points to murder, not suicide. That leavesus only one suspect: Bill Rimes, with whom the victim had a love-haterelationship. I have no doubt we will find that one of his shoes has bloodon the sole.

5. You keep on jumping from lover to lover like that, and you'll end up alonein life.

6. Steve is exceptional with clients. He has an effective communication styleand he listens carefully. I've had over a hundred employees work for me.I've observed that those who listen well are good communicators.

7. Sociologists have historically pointed out the importance of friendship,and those who are very friendly are wellliked by others. Phil, even thoughhe's from England, is very friendly.

8. Congress approved a plan to provide school vouchers to low-income chil-dren so they can attend private schools. There's a major problem with anyschool-voucher program. Vouchers drain money from public schools.Next year, you'll see, money available for public schools will be less thanthis year.

Chapter 3 Critical Thinking and Reasoning 29

9. Ralph violated the inside trader law, thus breaking the law. I don't carewhat you say, but I believe anyone who breaks the law is a criminal,which means Ralph is a criminal.

10. Psychological tests show that ignorant people are easily persuaded tochange their point of view on most subjects. Of everyone tested, freshmanstudents were the most easily persuaded .

• GROUP WORK

Discuss your analysis of the above items in your work group. Compare yourreconstructed arguments. Clear up any differences of opinion regarding theaccuracy of each item.