Richard L Epstein

by Critical Thinking (3rd Edition) (pdf)

  anywhere—there could be no organized violence of one country against another

  ("What if they gave a war and nobody came?"—an anti-war slogan of the 1960s).

  So? The analogy shouldn't convince. The argument has a dubious premise.

  We did not prove that soldiers should be blamed for wars. As always, when

  you show an argument is bad you haven't proved the conclusion false. You've only

  shown that you have no more reason than before for believing the conclusion.

  Perhaps the premises at ( ) could be modified, using that soldiers are drafted

  for wars. But that's beyond Country Joe's argument. If he meant something more,

  then it's his responsibility to flesh it out. Or we could use his comparison as a

  starting place to decide whether there is a general principle, based on the similarities,

  for why we shouldn't blame soldiers for war.

  256 CHAPTER 12 Reasoning by Analogy

  C. Judging Analogies

  Why was the example of firemen and soldiers so hard to analyze? Like many

  analogies, all we had was a sketch of an argument. Just saying that one side of the

  analogy is like the other is too vague to use as a premise. Unless the analogy is

  very clearly stated, we have to survey the similarities and guess the important ones

  in order to find a general principle that applies to both sides. Then we have to survey

  the differences to see if there isn't some reason that the general principle might not

  apply to one side.

  Example 2 Magic Johnson was allowed to play in the National Basketball

  Association and he was HIV-positive. So people who are HIV-positive should be

  allowed to remain in the military.

  Analysis This doesn't seem very convincing. What has the NBA to do with the

  military? We can list similarities (uniforms, teamwork, orders, winning, penalties

  for disobeying orders) and differences (great pay/lousy pay, game/not a game), but

  none of these matter unless we hit on the basis of the argument.

  The only reason for eliminating someone who is HIV-positive from a job

  is the risk of contracting HIV for others who work with that person.

  Magic Johnson was allowed to play basketball when he was HIV-positive.

  So in basketball the risk of contracting HIV from a fellow worker is

  considered insignificant.

  Basketball players have as much chance of physical contact and

  contracting HIV from one another as soldiers do (except in war).

  Therefore, the risk of contracting HIV from a fellow soldier should be

  considered insignificant.

  Therefore, people with HIV should be allowed to remain in the military.

  Here it is not the similarities between basketball players and soldiers that are

  important. Once we spot the general principle (the first premise, which in this case is

  prescriptive), it is the differences that support the conclusion (basketball players

  sweat and bleed all over one another every day, soldiers normally do not, except in

  war). Whether the analogy is good depends on whether these premises are true, but

  it's certainly a lot better than it seemed at first glance.

  Example 3

  Tom: Homosexual marriage threatens the sanctity of marriage. We should outlaw

  it in order to protect children, since every child needs a mother and a father to

  raise it. A constitutional amendment will ensure that the same laws reign

  throughout this country.

  Zoe: The same argument could be made against divorce. So Britney Spears

  should still be married, 'cause that one-day marriage she had was sure a slam

  against the "sanctity" of marriage. And we should have a constitutional

  SECTION D Analogies in the Law 257

  amendment outlawing divorce. Perhaps also an amendment with severe

  penalties for out-of-wedlock births?

  Analysis Zoe is showing that Tom's argument is bad by showing that another

  argument "just like" his has a conclusion that we would consider absurd. Whatever

  general principle that makes his argument work must also apply in the other case. So

  Zoe has refuted Tom—though that doesn't mean his conclusion is false.

  An analogy of one argument to another can be a powerful way to refute. See

  also Zoe's refutation of Dick's argument about killing flies on pp. 149-150.

  Example 4 It's wrong for the government to run a huge deficit—just as it's wrong

  for any family to overspend its budget.

  Analysis We often draw analogies between individuals and groups. But the

  differences between individuals and groups are usually too great for such an analogy

  to be good. In this example, it's claimed that what is good for a person or family is

  also what is good for a country. But without more premises, this is unconvincing

  because of the enormous differences between a family and a country: a family

  doesn't have to repair roads, can't put up tariffs, nor can it print money. The

  fallacy of composition is to argue that what is true of the individual is therefore true of the group, or that what is true of the group is therefore true of the individual.

  Evaluating an analogy

  1. Is this an argument? What is the conclusion?

  2. What is the comparison?

  3. What are the premises? (one or both sides of the comparison)

  4. What are the similarities?

  5. Can we state the similarities as premises and find a general

  principle that covers the two sides?

  6. Does the general principle really apply to both sides?

  Do the differences matter?

  7. Is the argument strong or valid? Is it good?

  D. Analogies in the Law

  Most analogies are not made explicit enough to serve as good arguments. But in the

  law, analogies are presented as detailed, carefully analyzed arguments, with the

  important similarities pointed out and a general principle stated.

  Laws are often vague, or situations come up which no one ever imagined

  might be covered by the law: Do the tax laws for mail-order purchases apply to the

  Internet? Similarities or differences have to be pointed out, general principles

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  CHAPTER 12 Reasoning by Analogy

  enunciated. Then those principles have to be respected by other judges. That's

  the idea of precedent or common law.

  The basic pattern of legal reasoning is reasoning by example. It is reasoning

  from case to case. It is a three-step process described by the doctrine of

  precedent in which .1 proposition descriptive of the first case is made into a

  rule of law and then applied to a next similar situation. The steps are these:

  similarity is seen between cases; next the rule of law inherent in the first case

  is announced; then the rule of law is made applicable to the second case.

  But why should a judge respect how earlier judges ruled? Those decisions

  aren't actually laws.

  Imagine getting thrown in jail for doing something that's always been legal,

  and the law hadn't changed. Imagine running a business and suddenly finding that

  something you did, which before had been ruled safe and legal in the courts, now left

  you open to huge civil suits because a judge decided differently this week. If we are

  to live in a society governed by laws, the law must be applied consistently. It's rare

  that a judge can say that past decisions were wrong.

  Only a few times has the Supreme Court sa
id that all rulings on one issue,

  including rulings the Supreme Court made, are completely wrong. Brown vs. the

  Board of Education said that segregation in schools, which had been ruled legal for

  nearly a hundred years, was now illegal. Roe vs. Wade said that having an abortion,

  which had been ruled illegal for more than a century, was now legal. Such decisions

  are rare. They have to be. They create immense turmoil in the ways we live. We

  have to rethink a lot. And we can't do that regularly.

  So what does a judge do when he's confronted by fifteen cases that were

  decided one way, the case before him falls under the general principle that was stated

  to cover those cases, yet his sense of justice demands that he decide this case the

  other way? He looks for differences between this case and those fifteen others. He

  tweaks the general principle just enough to get another principle that covers all those

  fifteen cases, but doesn't include the one he's deciding. He makes a new decision

  that now must be respected or overthrown.

  Example 5 The Supreme Court has decided that it is a constitutional right for a

  doctor to terminate medical treatment that prolongs the life of a terminally ill or

  brain-dead person, so long as the doctor acts according to the wishes of that person

  (Cruzan vs. Director, Missouri Department of Health, 497 U.S. 261). Therefore,

  the Supreme Court should decide that assisting someone to commit suicide, someone

  who is terminally ill or in great suffering, as Dr. Kevorkian does, is a constitutionally

  protected right (Compassion in Dying vs. State of Washington).

  EXERCISES for Chapter 12 259

  Analysis The question here is whether the two situations are similar. The court

  should decide with respect to the actual incidents in these cases. The court can

  decide narrowly, by saying this new case is not sufficiently like Cruzan, or broadly,

  by enunciating a principle that applies in both cases or else distinguishes between

  them. Or it can bring in more cases for comparison in trying to decide what general

  principle applies. (In the end the court was so divided that it ruled very narrowly,

  sidestepping the whole issue. You can look it up on the Internet.)

  Summary Comparisons suggest arguments. When we draw a conclusion from a

  comparison, we say we are reasoning by analogy: We can use the similarities to

  draw conclusions, so long as the differences don't matter.

  Analogies are usually incomplete arguments. Often they are best treated as

  motive for finding a general principle to govern our actions or beliefs by surveying

  similarities and differences between two cases. When a general principle is made

  explicit, an analogy can be a powerful form of argument. When no general principle

  is made explicit, an analogy can be a good place to begin a discussion.

  Exercises for Chapter 12

  1. Some words and phrases that suggest an analogy is being used are "like," "just as,"

  and "for the same reason." List three more.

  2. What do you need to make a comparison into reasoning by analogy?

  3. Are analogies typically complete arguments? Explain.

  4. What should you do first in evaluating an analogy? Second?

  Tom has caught on to the idea of how to evaluate analogies pretty well. Here are some of

  the exercises he did, with Dr. E's comments.

  You should treat dogs humanely. How would you feel if you were caged up all day

  and experimented on? Or if you were chained to a stake all day? Or someone beat

  you every time you did something wrong?

  Argument? (yes or no) Yes.

  Conclusion (if unstated, add it): You should treat dogs humanely.

  Comparison: I'm not certain, 'cause they stated most of it as questions. But it

  seems they're comparing being a dog and being treated badly with you being

  treated badly, like getting caged up all day, or chained to a stake all day, or

  someone beating you every time you did something wrong.

  Premises: Most of this is unstated. We're just supposed to put down what's

  actually said here, which I guess would be:

  You shouldn't cage up a person all day.

  You shouldn't chain a person to a stake all day.

  260 CHAPTER 12 Reasoning by Analogy

  You shouldn't beat someone every time she does something wrong.

  People are like dogs.

  So you shouldn't do any of that to dogs.

  Similarities: I know we're supposed to pick out ones that'll give us a general

  principle. I've got to figure out how dogs and humans are similar. Well, dogs

  and humans are both mammals.

  Additional premises (make the comparison explicit, add a general principle):

  Dogs and humans are both mammals. You shouldn't mistreat any mammal.

  Classify (with the additional premises): valid strong weak

  Good argument? (look for differences or ways the general principle could be

  false) I don't know. I guess the added premises are O.K. So probably it's

  pretty good.

  Good, you've got the basis of the analogy right, You understand the method, you've

  picked out a general principle. But is it true? Isn't it too broad? After all, hyenas are

  mammals— does that mean we should treat them humanely? There's one clue you

  overlooked. They said, "How would you feel..." I can imagine hoiv it would feel to

  be a dog and be mistreated, just as I can (sort of) imagine how it would feel to beyou

  and be mistreated. How about:

  We can imagine what it would be like to be a dog and be mistreated.

  We should treat humanely any creature that we am imagine what it

  would feel like to be mistreated.

  That's more plausible because it rules out bats. And it might include fish, which some

  people think should be treated humanely. (But really, you did O.K. We're unsure how

  to repair the original argument because it's too sketchy.

  It is easier for a camel to go through the eye of a needle than for a rich man to enter

  into the kingdom of God.

  Argument? (yes or no) This is from the Bible, right? I think it's supposed

  to make us think that being rich is bad. But I'm not sure. I can't figure out a

  conclusion, so I better say it's not an argument.

  Conclusion (if unstated, add it):

  Comparison:

  Premises: Goodwork!

  Similarities:

  Critical thinking is like learning to drive a car. It requires practice—you can't just

  learn it as theory. That's why I give you so many messy arguments to analyze.

  Argument? (yes or no) Yes, but just barely.

  Conclusion (if unstated, add it): You should have lots of messy arguments to

  analyze in doing critical thinking.

  EXERCISES for Chapter 12 261

  Comparison: Critical thinking isn't at all like driving a car. Driving a car is a kind

  of physical skill, like playing basketball. Critical thinking is something you strain

  your brain over. Sure you need practice on hard stuff till it gets routine. But I

  don't see how messy arguments are anything like driving a car.

  Premises:

  Similarities:

  Additional premises (make the comparison explicit, add a general principle):

  Classify (with the additional premises): valid strong weak

  Good argument? (look for differences or ways the general principle could be

  false) I think it's pretty ba
d. I can't figure out what general principle you'd want.

  Good-— you jumped to the. punch line. There may be something in this comparison,

  but it's not clear yet, and you're justified in stopping here.

  Exercises 5-24 are comparisons for you to evaluate. Use the following outline. There may

  be more than one argument in an exercise.

  Argumentl? (yes or no)

  Conclusion (if unstated, add it):

  Comparison:

  Premises:

  Similarities:

  Additional premises (make the comparison explicit, add a general principle):

  Classify (with the additional premises): valid strong weak

  Good argument? (look for differences or ways the general principle could be false)

  5. You wouldn't buy a kitten at a pet store to give to your dog. Why, then, do you consider

  it acceptable to buy white rats for your boa constrictor?

  6. All the world's a stage, and all the men and women merely players.

  7. Zoe: It's outrageous that Wal-Mart won't sell the morning-after abortion pill or RU486.

  They carry the highly popular and profitable drug Viagra.

  8. Zoe: {while driving) Don't throw that banana peel out the window.

  Dick: Don't worry, it's biodegradable.

  Zoe: So is horse manure.

  9. Dick: Zoe, let's get married.

  Zoe: I've told you before, Dick, I won't get married until we sleep together.

  Dick: But that would be wrong. I won't sleep with you before we get married.

  Zoe: Would you buy a car without a test drive?

  Dick: Why buy the cow when the milk's free?

  10. Dick: Congratulations on getting away with the shoplifting.

  Zoe: What are you talking about?

  Dick: Didn't you just install Adobe Photoshop on your computer from Tom's copy?

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  11. If killing is wrong, why do you punish murderers by killing them?

  12. For at least three years in California, about every third teacher hired was brought aboard

  under an emergency permit, a provisional license that enables people who possess

  college degrees, but no teaching credentials, to work.

  "We wouldn't allow a brain surgeon to learn on the job," says Day Higuchi,

  president of the United Teachers Los Angeles, a 41,000-member teachers union. "Why

  is it OK to let someone who doesn't know what they're doing teach our kids?"

  USA Today, August 30, 1999

  13. Suzy: This candy bar is really healthy. Look, on the label it says "All natural