PART III - Pearsonwps.prenhall.com/wps/media/objects/5909/6050951/My... · calls for a single vanishing point with which the horizontal lines of the picture are laid out. Relativity,

Some point of view is assumed in all our percep-tions. In looking at a picture the viewer cravessome unambiguous perspective. The coherentrepresentation of things (artists learned long ago)calls for a single vanishing point with which thehorizontal lines of the picture are laid out.Relativity, by M. C. Escher, exhibits the perplex-ing result when that coherence is missing. Thereis no single point of view in this picture; the ceil-ing for one is the floor for another. Which way isup? Three perspectives throw all into confusion.

Knowledge also supposes some steady con-text, some accepted theory or shared perspective

within which explanations can cohere. But thequest for new knowledge brings new perspec-tives that, because they are sometimes inconsis-tent with what had been long supposed, confuseand perplex us. New theories replace the old;what we had thought were facts become suppo-sitions, possibly false. Inductive inquiry is not asdizzy as the world in Escher’s Relativity, but hispicture is a provocative reminder of the uncer-tainty of what we think we know.

M. C. Escher’s Relativity © 2004 The M.C. EscherCompany. Baarn, Holland. All rights reserved.www.mcescher.com

M11_COPI1396_13_SE_C11.QXD 10/24/07 8:21 AM Page 480

P A R T I I IInduction

SECTION A ANALOGY AND CAUSATION

CHAPTER 11 Analogical ReasoningCHAPTER 12 Causal Reasoning

SECTION B SCIENCE AND PROBABILITY

CHAPTER 13 Science and HypothesisCHAPTER 14 Probability

The contrary of every matter of fact is still possible, because itcan never imply a contradiction, and is conceived by the mindwith the same facility and distinctness, as if ever so conforma-ble to reality. That the sun will not rise tomorrow is no lessintelligible a proposition, and implies no more contradictionthan the affirmation, that it will rise. . . . It may, therefore, be asubject worthy of curiosity, to enquire what is the nature of thatevidence which assures us of any real existence and matter offact, beyond the present testimony of our senses, or the recordsof our memory.

David Hume


482

11.1 Induction and Deduction Revisited

Arguments are built on premises that are believed, or assumed, to be true.Some premises we establish by deductive arguments that have preceded, butvery many of the premises on which we must rely cannot be established bydeduction. Our reasoning process usually begins with the accepted truth ofsome “matters of fact,” in David Hume’s phrase. To establish matters of factwe must rely on reasoning that is inductive.

Induction thus provides the starting points—the foundation—for the rea-soning that concerns us most. We reason to establish truths in our everydaylives, to learn facts about our society, to understand the natural world.Deduction is certainly powerful in enabling us to move from known (orassumed) propositions to other propositions that those premises entail, but inthe search for truths with which our reasoning must begin, it is insufficient.

The inductive arguments with which we establish matters of fact differfundamentally from the deductive arguments that were the concern in Part IIof this book. One essential contrast between the two families of argument(noted much earlier in our discussion of basic logical concepts, Section 1.5) liesin the relation of the premises to the conclusion in the arguments of the twogreat families. In deductive arguments, the claim is made that conclusions followwith certainty from their premises. That claim is appropriate because anydeductive argument, if it is good, brings to light in its conclusion what wasalready buried in its premises. The relation between premises and conclusion,in deduction, is one of logical necessity. In every deductive argument, if it isvalid and if its premises are true, its conclusion must be true.

In inductive arguments—the concerns of this chapter and those that follow—the relations between premises and conclusion are not those of logical neces-sity. The claim of certainty is not made. The terms valid and invalid simply donot apply. This does not mean that inductive arguments are always weak;sometimes they are very strong indeed, and fully deserve our confidence.

Analogical Reasoning

11.1 Induction and Deduction Revisited11.2 Argument by Analogy11.3 Appraising Analogical Arguments11.4 Refutation by Logical Analogy

11


Scientists now assert without reservation (for example) that smoking is a causeof cancer. This is true, but it is a truth that cannot be known with the demon-strative certainty of a valid syllogism. If p or q is true, and not p is true, we mayconclude that q must be the case, beyond all doubt. It is a truth we establish asan inescapable consequence of the relations of the concepts involved. Empiricaltruths—about the consequences of smoking, or the causes of cancer, and all oth-ers of that sort—cannot satisfy the standard of deductive certainty. By that stan-dard, as one distinguished medical investigator observes, “no one will ever beable to prove that smoking causes cancer, or that anything causes anything.”1

In the realm of induction, as we seek new knowledge of facts about theworld, nothing is beyond all doubt. We must rely on arguments that supporttheir conclusions only as probable, or probably true. Some such arguments are ofonly moderate worth; others are very powerful, as we shall see. The strengthsand weaknesses of inductive arguments, and the techniques for the evaluationof such arguments, are the focus of Part III of this book.

Arguments grounded on analogies, aiming to establish particular conclu-sions, are examined first, in this chapter. Arguments that go beyond particulars,aiming to establish generally applicable causal laws, are examined in the fol-lowing chapter. The uses of hypotheses and their confirmation in developingscientific theories follows in Chapter 13; and we conclude, in Chapter 14, withan analysis of the concept of probability itself, the conceptual instrument withwhich inductive conclusions are commonly expressed.

11.2 Argument by Analogy

The most common type of inductive argument relies on analogy. If I report thatI got very good service from a computer of a certain make and model, youmay infer that a new computer of the same make and model will serve youwell. That conclusion has some degree of probability, but the argument is farfrom compelling. When a new book is called to my attention and I infer that Iwill enjoy reading it because I have read and enjoyed other books by the sameauthor, I may have my confidence in that author strengthened when I read thebook—or I may be disappointed. Analogy is the common ground of our everyday inferences from past experience to what the future will hold.

Here follow two more carefully formulated analogical arguments. The firstconcludes, on the basis of what we commonly think to be prudent and fair, thatit would be prudent and fair to adopt now a major change in public policy:

Some people look on preemployment testing of teachers as unfair—a kind ofdouble jeopardy. “Teachers are already college graduates,” they say. “Whyshould they be tested?” That’s easy. Lawyers are college graduates and gradu-ates of professional school, too, but they have to take a bar exam. And a number

11.2 Argument by Analogy 483


of other professions ask prospective members to prove that they know their stuffby taking and passing examinations: accountants, actuaries, doctors, architects.There is no reason why teachers shouldn’t be required to do this too.2

The second illustration is an argument—entirely plausible when first pre-sented two centuries ago—whose conclusion is very probably false:

We may observe a very great similitude between this earth which we inhabit, andthe other planets, Saturn, Jupiter, Mars, Venus, and Mercury. They all revolvearound the sun, as the earth does, although at different distances and in differentperiods. They borrow all their light from the sun, as the earth does. Several ofthem are known to revolve around their axis like the earth, and by that means,must have a like succession of day and night. Some of them have moons, thatserve to give them light in the absence of the sun, as our moon does to us. Theyare all, in their motions, subject to the same law of gravitation, as the earth is.From all this similitude, it is not unreasonable to think that those planets may, likeour earth, be the habitation of various orders of living creatures. There is someprobability in this conclusion from analogy.3

Neither these arguments, nor those everyday inferences we draw aboutcomputers and books and the like, are demonstratively valid. Their conclusionsare not claimed to follow from their premises with logical necessity, and theyobviously do not follow with certainty. What is appropriate for judging theemployability of lawyers and doctors may not be appropriate for judging theemployability of teachers. The earth is very likely to be the only inhabited planetin our solar system. Your new computer may prove unsuitable for the work youdo, and I may find my favorite author’s latest book intolerably dull. In all sucharguments it is plainly possible—logically possible—that although the premisesare true, the conclusions are false. Arguments by analogy are not to be classifiedas either valid or invalid; probability is all that is claimed for them.

In addition to their use in arguments, analogies are very often used nonar-gumentatively, for the purpose of lively description. The literary uses of anal-ogy in metaphor and simile are tremendously helpful to the writer who strivesto create a vivid picture in the reader’s mind. In the continuing controversy inthe United States over immigration, for example, one writer expressed hisviews with a forceful analogy:

I’m a third-generation American. I don’t know all the legal details about how mygrandparents got here. But I do know that they worked very hard, paid theirtaxes, and raised a son who served his country. Americans being against immigra-tion is like a house being against its bricks.4

Analogy is also used in explanation, when something that may not be famil-iar to the reader is made somewhat more intelligible by being compared to some-thing else, presumably more familiar, to which it has certain similarities. When

484 CHAPTER 11 Analogical Reasoning


Eric Lander, the director of the Genome Center at the Massachusetts Institute ofTechnology sought to explain the huge eventual impact of the Human GenomeProject, analogy was one of the devices he used to enhance the understanding ofthose unfamiliar with genetic research:

The genome project is wholly analogous to the creation of the periodic table inchemistry. Just as Mendeleev’s arrangement of the chemical elements in the peri-odic table made coherent a previously unrelated mass of data, so the tens ofthousands of genes in present-day organisms will all turn out to be made fromcombinations of a much smaller number of simpler genetic modules or elements,the primordial genes, so to speak.5

The use of analogies in description and explanation is not the same astheir use in argument, though in some cases it may not be easy to decidewhich use is intended. But whether used argumentatively or otherwise, anal-ogy is not difficult to define. To draw an analogy between two or more entitiesis to indicate one or more respects in which they are similar.

This definition explains what an analogy is, but there is still the problemof characterizing an argument by analogy. Let us analyze the structure of a


Analogies—But No Arguments

Nonargumentative analogies are commonly encountered in the writing ofhigh school students—and some of these are quite funny. We pause for achuckle:

1. She grew on him like she was a colony of E. coli and he was room-temperature Canadian beef.

2. McMurphy fell 12 stories, hitting the pavement like a Hefty bag filledwith vegetable soup.

3. Her hair glistened in the rain, like a nose hair after a sneeze.4. Even in his last years, Grandpappy had a mind like a steel trap, only

one that had been left out so long it had rusted shut.5. He was deeply in love. When she spoke he thought he heard bells, like

a garbage truck backing up.6. She had a deep, throaty, genuine laugh, like that sound a dog makes just

before it throws up.7. His thoughts tumbled in his head, making and breaking alliances like

underpants in a dryer without Cling Free.8. The hailstones leaped from the pavement, just like maggots when you

fry them in hot grease.9. The ballerina rose gracefully en pointe and extended one slender leg

behind her, like a dog at a fire hydrant.10. She walked into my office like a centipede with 98 missing legs.

www.qwertyed.com/q_pages.


particular analogical argument, using a very simple example. Consider theargument that a new car whose purchase I am now contemplating will be verysatisfactory because my old car, of the same make and model, has long givenvery satisfactory service. The two entities that are said to be similar are twocars. Three points of analogy are involved, three respects in which the twoentites are said to resemble each other: first, in being cars; second, in being ofthe same make and model; and third, in serving me well.

The three points of analogy do not play identical roles in the argument,however. The first two occur in the premises, whereas the third occurs both inthe premises and in the conclusion. The given argument may be described ashaving premises that assert, first, that two things are similar in two respects,and second, that one of those things has a further characteristic, from which theconclusion is drawn that the other thing also has that further characteristic.

Analogical argument is one of the most fundamental tools of appellatecourts. The inference in the case before the court is shown to be very much likesome other inference drawn previously, and if it was clearly correct in that ear-lier case, it is held to be correct in this one too. In 2004, the U.S. Supreme Courtdecided unanimously a case requiring the interpretation of the SixthAmendment of the U.S. Constitution, which gives to every criminal defendantthe right “to be confronted with the witnesses against him.” Does this forbidthe use, at a defendant’s trial, of testimony from a witness who is not availablefor cross-examination, even if the trial judge believes that testimony to be reli-able? Yes, said Justice Antonin Scalia, delivering the opinion of the Court, itdoes. The right to cross-examine adverse witnesses was firmly established inthe English common law at the time our Constitution was adopted. JusticeScalia’s subsequent analogy epitomizes the argument of the Court:

Admitting statements deemed reliable by a judge is fundamentally at odds withthe right of confrontation. Dispensing with confrontation because testimony isobviously reliable is akin to dispensing with a jury trial because a defendant isobviously guilty. This is not what the Sixth Amendment prescribes.”6

Analogical argument is also common in political controversy. Sometimesthe analogy is effective, sometimes it is far-fetched. The threat of global warm-ing, and the need of our country to respond concretely to that threat, wasargued heatedly before the Congress of the United States, in 2007, by formerpresidential candidate Al Gore, who described the danger as a “planetaryemergency.” Against those who thought him to be exaggerating the dangers,he then argued:

The planet has a fever. If your baby has a fever you go to the doctor. If the doctorsays you need to intervene here, you don’t say “I read a science-fiction novel thatsays it’s not a problem.” You take action.7



Not every analogical argument need concern exactly two things or exactlythree different characteristics, of course. Thus the argument presented earlier,suggesting that other planets in our solar system may well be inhabited,draws analogies among six things (the then-known planets) in some eightrespects. Apart from these numerical differences, however, all analogical argu-ments have the same general structure or pattern. Every analogical argumentproceeds from the similarity of two or more things in one or more respects to the simi-

larity of those things in some further respect. Schematically, where a, b, c, and d areany entities and P, Q, and R are any attributes or “respects,” an analogicalargument may be represented as having the form

a, b, c, d all have the attributes P and Q.a, b, c all have the attribute R.Therefore d probably has the attribute R.

In identifying, and especially in appraising, analogical arguments, it may befound helpful to recast them into this form.

EXERCISES

All of the following passages contain analogies. Distinguish those that con-tain analogical arguments from those that make nonargumentative usesof analogy.

EXAMPLE

1. A Man ought no more to value himself for being wiser than a Woman,if he owes his Advantage to a better Education, than he ought to boastof his Courage for beating a Man when his hands were bound.

—Mary Astell, An Essay in Defence of the Female Sex, 1721

SOLUTION

This is an analogical argument. The analogy drawn here is between beat-ing a man when his hands are bound and being wiser than a woman as aconsequence of a better education, one party having an enormous advan-tage in both cases. In the first case, it is plain that one with such anadvantage ought not to boast of his courage; in the second case (thisargument concludes), it is equally inappropriate for one with such anadvantage to boast of his relative wisdom.

2. “I’m not anti-Semitic, I’m just anti-Zionist” is the equivalent of “I’mnot anti-American, I just think the United States shouldn’t exist.”

—Benjamin Netanyahu, A Place Among the Nations,(New York: Bantam Books, 1993)



3. Instead of investing in the future, we throw money away on absurdluxuries, finance corrupt and hostile oil-rich countries, pollute ouratmosphere and increase our trade deficit. Sort of like driving aHummer to the shopping mall.

—Eric Buckvar, “A Wasteful Society,” The New York Times, 23 March 2007

4. The British are less rigid about punctuation and related matters, such asfootnote and bibliographic form, than Americans are. AnEnglishwoman, lecturing Americans on semicolons is a little like anAmerican lecturing the French on sauces.

—Louis Menand, “Bad Comma,” The New Yorker, 28 June 2004

5. Studies show that girls get better grades in high school and collegethan boys—yet only about 35 percent of National Merit Scholarshipwinners are girls. The Executive Director of FairTest contends that the“inequity is due solely to gender bias in the test used to select eligiblestudents.” But the spokeswoman for the National Merit ScholarshipCorporation, Elaine Detweiler, replies “We don’t really know whygirls do worse on the exams. To blame the test for the differencebetween how boys and girls perform is like blaming a yardstick thatboys are taller than girls.”

—“Merit Test Defended,” The Los Angeles Times, 26 May 1993

6. The famous chemist and biologist Justus von Liebig dismissed the germtheory with a shrug of the shoulders, regarding Pasteur’s view thatmicrobes could cause fermentation as ridiculous and naive as the opinionof a child “who would explain the rapidity of the Rhine current byattributing it to the violent movement of the many millwheels at Maintz.”

—René Dubos, Pasteur and Modern Science(New York: Da Capo Press, 1988)

7. Talking about Christianity without saying anything about sin is likediscussing gardening without saying anything about weeds.

—The Rev. Lord Soper, quoted in The New York Times, 24 December 1998

8. Men and women may have different reproductive strategies, but nei-ther can be considered inferior or superior to the other, any more thana bird’s wings can be considered superior or inferior to a fish’s fins.

—David M. Buss, “Where Is Fancy Bred? In the Genes or in the Head?” The New York Times, 1 June 1999

9. “This is a matter of national spirit,” said Marjorie Wilson, coordinatorof the Kangaroo Protection Cooperative, an Australian wildlife



group. “We believe here that we have enough meat in this country tosatisfy people without them having to eat their national symbol. YouAmericans don’t cook your bald eagles, do you?”

—“Battling over a National Symbol,” The New York Times, 10 July 1995

10. One sure thing is that melting sea ice cannot be implicated in thecoastal flooding that many global warming models have projected.Just as melting ice cubes do not cause a glass of water to overflow,melting sea ice does not increase oceanic volume. Any future rise insea level would result from glaciers melting on land.

—Walter Gibbs, “Research Predicts Summer Doom for Northern Icecap,” The New York Times, 11 July 2000

11. Thomas Henry Huxley, Charles Darwin’s nineteenth-century disci-ple, presented this analogy: “Consciousness would appear to berelated to the mechanism of the body simply as a collateral product ofits working and to be completely without any power of modifyingthat working, as the steam whistle which accompanies the work of alocomotive is without influence upon its machinery.”

12. The Elgin Marbles—17 figures and 56 panels that once decorated theParthenon, on the Acropolis in Athens—were taken from theParthenon in 1801 by Thomas Bruce, the seventh Earl of Elgin, andbrought to the British Museum, in London. The Greeks say that hestole them; the British say that they were properly acquired, by pur-chase. Some Britons urged that the Marbles be returned to Greece intime for the Olympic Games to be held in Athens in 2004. Said one ofthe leaders of the Labor Party: “The Parthenon without the ElginMarbles is like a smile missing a tooth.”

13. The Feminists decided to examine the institution of marriage as it isset up by law in order to find out whether or not it did operate inwomen’s favor. It became increasingly clear to us that the institutionof marriage “protects” women in the same way that the institution ofslavery was said to “protect” blacks—that is, that the word “protec-tion” in this case is simply a euphemism for oppression.

—Sheila Cronan, “Marriage,” in Anne Koedt, Ellen Levine, and Anita Rapone, eds., Radical Feminism (New York: Quadrangle Books, 1976)

14. Wittgenstein used to compare thinking with swimming: just as inswimming our bodies have a natural tendency to float on the sur-face so that it requires great physical exertion to plunge to the bot-tom, so in thinking it requires great mental exertion to force our



minds away from the superficial, down into the depth of a philo-sophical problem.

—George Pitcher, The Philosophy of Wittgenstein(Englewood Cliffs, NJ: 1964)

15. A person without a goal is like a computer without a program. Andthat’s an ugly piece of furniture.

—Steve Danish, “Getting a Life,” The New York Times, March 1998

16. The quest for usable energy from fusion involves the use of inter-locked magnetic fields to contain very hot (180 million degreesFahrenheit) and highly compressed (to a density 20 times that of lead)electrically charged plasma (a kind of gas) within a vacuum chamber.The plasma must never touch the solid walls of its container, for if itdoes it instantly loses its heat and can never be coaxed into undergo-ing fusion. One scientific report put the problem this way:

Everything depends on keeping the plasma’s magnetic bottletightly stoppered . . . [but] confining a dollop of super-hot compressedplasma has proved to be harder than compressing and shaping a blobof jelly using only rubber bands. Each clever idea of the plasma physi-cists for solving this problem has been matched by a new challenge.

—Malcolm W. Browne, “Reviving the Quest to Tame the Energy of the Stars,”The New York Times, 8 June 1999

17. It is important that we make clear at this point what definition is andwhat can be attained by means of it. It seems frequently to be creditedwith a creative power; but all it accomplishes is that something ismarked out in sharp relief and designated by a name. Just as thegeographer does not create a sea when he draws boundary lines andsays: the part of the ocean’s surface bounded by these lines I amgoing to call the Yellow Sea, so too the mathematician cannot reallycreate anything by his defining.

—Gottlob Frege, The Basic Laws of Arithmetic, 1893

18. Children in school are like children at the doctor’s. He can talk him-self blue in the face about how much good his medicine is going to dothem; all they think of is how much it will hurt or how bad it willtaste. Given their own way, they would have none of it.

So the valiant and resolute band of travelers I thought I was lead-ing toward a much hoped-for destination turned out instead to bemore like convicts in a chain gang, forced under threat of punishmentto move along a rough path leading nobody knew where and downwhich they could see hardly more than a few steps ahead. School



feels like this to children: it is a place where they make you go andwhere they tell you to do things and where they try to make your lifeunpleasant if you don’t do them or don’t do them right.

—John Holt, How Children Fail (New York: Delta/Lawrence, 1964)

19. I simply can’t imagine the world will ever be normal again for us. Ido talk about “after the war,” but it’s as if I were talking about a cas-tle in the air, something that can never come true.

I see the eight of us in the Annex as if we were a patch of blue skysurrounded by menacing black clouds. The perfectly round spot onwhich we’re standing is still safe, but the clouds are moving in on us,and the ring between us and the approaching danger is being pulledtighter and tighter. We’re surrounded by darkness and danger, and inour desperate search for a way out we keep bumping into each other.We look at the fighting down below and the peace and beauty upabove. In the meantime, we’ve been cut off by the dark mass ofclouds, so that we can go neither up nor down. It looms before us likean impenetrable wall, trying to crush us, but not yet able to. I canonly cry out and implore, “Oh, ring, ring, open wide and let us out!”

—Anne Frank, from The Diary of a Young Girl, 8 November 1943

20. Unfortunately, the diary [of H. L. Mencken] reveals a man who wasshockingly anti-Semitic and racist, to the point where his stature as agiant of American letters may be in danger. . . . I would draw a com-parison with Richard Wagner, a virulent anti-Semite. One can still lis-ten to Wagner’s operas and appreciate their artistic beauty. The workis separated from the man. Or is it?

—Gwinn Owens, “Mencken—Getting a Bum Rap?”The New York Times, 13 December 1989

11.3 Appraising Analogical Arguments

Some analogical arguments are much more cogent than others. Although noargument by analogy can be deductively valid, some such arguments yieldconclusions that are very probably true, whereas others are very weak indeed.Analogical arguments are evaluated as better or worse depending on thedegree of probability with which, relying on the premises they put forward,their conclusions may be affirmed.

Two commonplace examples will help to exhibit the features of analogicalarguments that make them better or worse. Suppose you choose to purchase agiven pair of shoes because other pairs like it have given you satisfaction inthe past; and suppose you select a dog of a given breed because other dogs of

11.3 Appraising Analogical Arguments 491


that same breed have exhibited the characteristics that you prize. In bothcases, analogical arguments have been relied on. To appraise the strength ofthese sample arguments, and indeed all analogical arguments, six criteria maybe distinguished.

1. Number of entities. If my past experience with shoes of a certain kind islimited to only one pair that I wore and liked, I will be disappointedalthough not surprised by an apparently similar pair that I find flawedin unexpected ways. But if I have repeatedly purchased shoes just likethose, I may reasonably suppose that the next pair will be as good as theones worn earlier. Several experiences of the same kind with an item ofjust that sort will support the conclusion—that the purchase will besatisfying—much more than will a single instance. Each instance may bethought of as an additional entity, and the number of entities is the firstcriterion in evaluating an analogical argument.

In general, the larger the number of entities—that is, cases in our pastexperience—the stronger the argument. But there is no simple ratio betweenthat number and the probability of the conclusion. Six happy experienceswith golden retrievers, intelligent and sweet-tempered dogs, will lead oneto conclude that the next golden retriever will also be intelligent andsweet-tempered. However, the conclusion of an analogical argument thathas six instances in its premises will not be exactly three times as probableas a similar argument that has two such instances in its premises.Increasing the number of entities is important, but so are other factors.

2. Variety of the instances in the premises. If my previous purchases ofthose good shoes had been from both a department store and a specialtystore, and had been made both in New York and in California, by bothmail order and direct sale, I may be confident that it is the shoes them-selves and not their seller that accounts for my satisfaction. If my previ-ous golden retrievers were both males and females, acquired both aspuppies from breeders and as adults from the humane society, I may bemore confident that it is their breed—not their sex or age or source—thataccounts for my earlier satisfaction.

We understand this criterion intuitively: The more dissimilar the

instances mentioned only in the premises of the analogical argument, the

stronger is the argument.

3. Number of similar respects. Among the instances in the premises theremay have been various similarities: perhaps the shoes were of the samestyle, had the same price, were made of the same sort of leather; perhapsthe dogs were of the same breed, came from the same breeder at the sameage, and so on. All the respects in which the instances in the premises are



like one another, and also like the instance in the conclusion, increase theprobability that the instance in the conclusion will have that further attri-bute at which the argument is aimed—giving great satisfaction in the caseof the new shoes, being of a sweet disposition in the case of a new dog.

This criterion also is rooted in common sense: The greater the number

of respects in which the entity in the conclusion is similar to the entities in the

premises, the more probable is that conclusion. Again, of course, there is nosimple numerical ratio between that conclusion and the number of sim-ilar respects identified.

4. Relevance. As important as the number of respects shared is the kind ofrespects in which the instances in the premises are like the instance inthe conclusion. If the new pair of shoes, like the previous pairs, is pur-chased on a Tuesday, that is a likeness that will have no bearing on thesatisfaction they give; but if the new pair, like all the previous pairs, hadthe same manufacturer, that will count heavily. Respects add to the force of

the argument when they are relevant (as style of shoe, and price, and mate-rial surely are)—and a single highly relevant factor contributes more to the

argument than a host of irrelevant similarities.There will sometimes be disagreement about which attributes really

are relevant in establishing the likelihood of our conclusion, but themeaning of relevance itself is not in dispute. One attribute is relevant toanother when it is connected to that other, when there is some kind ofcausal relation between them. That is why identifying causal connectionsof one kind or another is critical in analogical arguments, and whyestablishing such connections is often crucial in determining the admis-sibility of evidence, as relevant or irrelevant, in a court of law.

Analogical arguments can be probable whether they go from causeto effect or from effect to cause. They can even be probable when theattribute in the premise is neither the cause nor the effect of the conclu-sion’s attribute, provided both are the effect of the same cause. A doctor,noting the presence of a certain symptom in her patient, may predictanother symptom accurately not because either symptom is the cause ofthe other, but because they are jointly caused by the same disorder. Thecolor of a manufactured product is most often irrelevant to function, butit may serve as a relevant respect in an argument when that color is veryunusual, and shared by the entities in the premises and the conclusion.The color itself may contribute nothing to the function of the product,but it may serve in argument if it is known to be an attribute of the man-ufacturing process of a unique producer.

The causal connections that are the key to the evaluation of analogi-cal arguments can be discovered only empirically, by observation and



experiment. The general theory of empirical investigation is the centralconcern of inductive logic, and will be discussed at length in the chap-ters that follow.

5. Disanalogies. A disanalogy is a point of difference, a respect in whichthe case we are reasoning about in our conclusion is distinguishablefrom the cases on which the argument is based. Returning to the exam-ple of the shoes, if the pair we plan to buy looks like those we hadowned earlier, but is in fact much cheaper and made by a different com-pany, those disanalogies will give us reason to doubt the satisfactionthey will provide.

What was said earlier about relevance is also important here.Disanalogies undermine analogical arguments when the points of differ-ence identified are relevant—causally connected to the outcome we areseeking. Investors often purchase shares of a stock mutual fund on thebasis of its successful “track record,” reasoning that because earlier pur-chases resulted in capital appreciation, a future purchase will do so aswell. However, if we learn that the person who managed the fund duringthe period of its profitability has just been replaced, we confront a disanal-ogy that substantially reduces the strength of that analogical argument.

Disanalogies weaken analogical arguments. They are therefore com-monly employed in attacking an analogical argument. As critics, we maytry to show that the case in the conclusion is different in important waysfrom the earlier cases, and that what was true of them is not likely to betrue of the present case. In the law, where the uses of analogy are perva-sive, some earlier case or cases are often offered to a court as a precedentfor deciding the case at hand. The argument is analogical. Opposingcounsel will seek to distinguish the case at hand from the earlier cases;that is, counsel will seek to show that because there is some critical dif-ference between the facts in the case at hand and the facts in those earliercases, they do not serve as good precedents in the present matter. If thedifferences are great—if the disanalogy is indeed critical—that maydemolish the analogical argument that had been put forward.

Because disanalogies are the primary weapon against an analogicalargument, whatever can ward off any potential disanalogies willstrengthen the argument. This explains why variety among the instancesin the premises adds force to an argument. The more the instances in thepremises vary from one to another, the less likely it is that a critic will beable to point to some disanalogy between all of them and the conclusionthat will weaken the argument. To illustrate, suppose that Kim Kumarcomes to a university as a first-year student; ten others from her second-ary school have successfully completed studies at the same university.



We may argue analogically that in view of her secondary school prepara-tion, she is likely to succeed as well. If all those other students from herschool were similar to one another in some respect that bears on collegestudy but differ from Kim in that respect, that disanalogy will underminethe argument for Kim’s success. However, if we learn that the ten suc-cessful predecessors varied among themselves in many ways—in eco-nomic background, in family relations, in religious affiliation, and soon—those differences among them ward off such potential disanalogies.The argument for Kim’s success is fortified—as we saw earlier—if theother students from her school serving as premises in the argument donot resemble each other closely, but exhibit substantial variety.

A confusion must be avoided: The principle that disanalogiesweaken analogical arguments is to be contrasted with the principle thatdifferences among the premises strengthen such arguments. In the former,the differences are between the instances in the premises and the instancein the conclusion; in the latter, differences are among the instances in thepremises only. A disanalogy is a difference between the cases with whichwe have experience and the case about which a conclusion is beingdrawn. That conclusion (we may say in presenting the disanalogy asrefutation) is not warranted because circumstances in the critical caseare not similar to circumstances in earlier cases. The analogy is said to be“strained” or “does not hold.” But when we point to dissimilaritiesamong the premises we are strengthening the argument by saying, ineffect, that the analogy has wide force, that it holds in cases like this andin other cases, and that therefore the respects in which the instances inthe premises vary are not relevant to the matter with which the conclu-sion is concerned.

In summary, disanalogies undermine an analogical argument; dis-similarities among the premises reinforce it. And both considerations aretied to the question of relevance: Disanalogies tend to show that thereare relevant respects in which the case in the conclusion differs fromthose in the premises; dissimilarities among the premises tend to showthat other factors, which might have been thought causally relevant tothe attribute of interest, are not really relevant at all.

Note that the very first criterion identified, pertaining to the number

of entities among which the analogy is said to hold, is also linked to rel-evance. The greater the number of instances appealed to, the greater isthe number of dissimilarities likely to obtain among them. Increasingthe number of entities is therefore desirable, but as the number ofentities increases, the impact of each additional case is reduced. The dis-similarity it may provide is more likely to have been provided by earlier



instances, in which case it will add little or nothing to the protection ofthe conclusion from damaging disanalogies.

6. Claim that the conclusion makes. Every argument makes the claim thatits premises give reasons to accept its conclusion. It is easy to see that themore one claims, the greater the burden of sustaining that claim, and that isobviously true for every analogical argument. The modesty of the conclusion

relative to the premises is critical in determining the merit of the inference.If my friend gets 30 miles to the gallon from his new car, I may infer

that, were I to acquire a car of the same make and model, I would get atleast 20 miles to the gallon; that conclusion is modest and therefore veryprobable. Were my conclusion much bolder—say, that I would get atleast 29 miles to the gallon—it would be less well supported by the evi-dence I have. In general, the more modest the claim, the less burden is placed

on the premises and the stronger the argument; the bolder the claim, the

greater is the burden on the premises and the weaker the argument.

An analogical argument is strengthened by reducing the claim madeon the basis of the premises affirmed, or by retaining the claim unchangedwhile supporting it with additional or more powerful premises. Likewise,an analogical argument is weakened if its conclusion is made bolder whileits premises remain unchanged, or if the claim remains unchanged whilethe evidence in its support is found to exhibit greater frailty.

EXERCISES

A. For each of the following arguments by analogy, six additional premises aresuggested. For each of these alternative premises, decide whether its additionwould make the resulting argument more or less probable. Identify the crite-rion of appraisal that justifies this judgment, and explain how that criterionapplies to the given case.

EXAMPLE

1. An investor has purchased one hundred shares of oil stock everyDecember for the past five years. In every case the value of the stockhas appreciated by about 15 percent a year, and it has paid regular div-idends of about 8 percent a year on the price at which she bought it.This December she decides to buy another hundred shares of oil stock,reasoning that she will probably receive modest earnings while watch-ing the value of her new purchase increase over the years.

a. Suppose that she had always purchased stock in eastern oil compa-nies before, and plans to purchase stock in an eastern oil companythis year too.



b. Suppose that she had purchased oil stocks every December for thepast fifteen years, instead of for only five years.

c. Suppose that the oil stocks previously purchased had gone up by30 percent a year, instead of only 15 percent.

d. Suppose that her previous purchases of oil stock had been in for-eign companies as well as in eastern, southern, and western U.S. oilcompanies.

e. Suppose she learns that OPEC has decided to meet every monthinstead of every six months.

f. Suppose she discovers that tobacco stocks have just raised theirdividend payments.

SOLUTION

a. More probable. Number of similar respects. The change provides anadditional respect in which the instance in the conclusion is thesame as those in the premises.

b. More probable. Number of entities. With this change the number ofentities in the premisses is substantially increased.

c. More probable. Claim made by the conclusion. With this change inthe premises, the conclusion, although unchanged, is now, rela-tively speaking, substantially more modest.

d. More probable. Variety among the premises. With this change, thedissimilarity among the instances in the premises is clearly estab-lished.

e. Less probable. Disanalogy. With this change in the premises, a sig-nificant difference between the instance in the conclusion and theinstances in the premises is introduced.

f. Neither. Relevance. It is unlikely that the dividends paid bytobacco companies would have any impact on the profitability ofoil companies or the price of their shares.

2. A faithful alumnus, heartened by State’s winning its last four footballgames, decides to bet his money that State will win its next game, too.

a. Suppose that since the last game, State’s outstanding quarterbackwas injured in practice and hospitalized for the remainder of theseason.

b. Suppose that two of the last four games were played away, and thattwo of them were home games.

c. Suppose that, just before the game, it is announced that a memberof State’s Chemistry Department has been awarded a Nobel Prize.



d. Suppose that State had won its last six games rather than only fourof them.

e. Suppose that it has rained hard during each of the four precedinggames, and that rain is forecast for next Saturday too.

f. Suppose that each of the last four games was won by a margin ofat least four touchdowns.

3. Although she was bored by the last few foreign films she saw, Charleneagrees to go to see another one this evening, fully expecting to bebored again.

a. Suppose that Charlene also was bored by the last few Americanmovies she saw.

b. Suppose that the star of this evening’s film has recently beenaccused of bigamy.

c. Suppose that the last few foreign films that Charlene saw wereItalian, and that tonight’s film is Italian as well.

d. Suppose that Charlene was so bored by the other foreign films thatshe actually fell asleep during the performance.

e. Suppose that the last few foreign films she saw included an Italian,a French, an English, and a Swedish film.

f. Suppose that tonight’s film is a mystery, whereas all of those shesaw before were comedies.

4. Bill has taken three history courses and found them very stimulatingand valuable, so he signs up for another one, confidently expectingthat it too will be worthwhile.

a. Suppose that his previous history courses were in ancient history,modern European history, and U.S. history.

b. Suppose that his previous history courses had all been taught bythe same professor scheduled to teach the present one.

c. Suppose that his previous history courses had all been taughtby Professor Smith, and the present one is taught by ProfessorJones.

d. Suppose that Bill had found his three previous history courses tobe the most exciting intellectual experiences of his life.

e. Suppose that his previous history courses had all met at 9 A.M., andthat the present one is also scheduled to meet at 9 A.M.

f. Suppose that, in addition to the three history courses he took pre-viously, Bill had also taken and enjoyed courses in anthropology,economics, political science, and sociology.



5. Dr. Brown has stayed at the Queen’s Hotel every fall for the past sixyears on her annual visit to New York, and she has been quite satisfiedwith her accommodations there. On her visit to New York this fall, Dr.Brown goes again to the Queen’s Hotel, confidently expecting to enjoyher stay there again.

a. Suppose that when she stayed at the Queen’s Hotel before, she hadoccupied a single room twice, shared a double room twice, andtwice occupied a suite.

b. Suppose that last spring a new manager had been put in charge ofthe Queen’s Hotel.

c. Suppose that she had occupied a suite on all of her previous tripsand is assigned a suite this time as well.

d. Suppose that on her previous trips she had come to New York bytrain, but this time she flew.

e. Suppose that, when she stayed at the Queen’s Hotel before, herquarters had been the most luxurious she had ever known.

f. Suppose that she had stayed at the Queen’s Hotel three times ayear for the past six years.

B. Analyze the structure of the analogical arguments in the following passages,and evaluate them in terms of the six criteria that have been explained.

1. If you cut up a large diamond into little bits, it will entirely losethe value it had as a whole; as an army divided up into small bod-ies of soldiers loses all its strength. So a great intellect sinks to thelevel of an ordinary one, as soon as it is interrupted and disturbed,its attention distracted and drawn off from the matter in hand: forits superiority depends upon its power of concentration—of bring-ing all its strength to bear upon one theme, in the same way as aconcave mirror collects into one point all the rays of light thatstrike upon it.

—Arthur Schopenhauer, “On Noise,” 1851

2. It would be the height of hypocrisy if Pete Rose, one of baseball’s starplayers, were allowed back into baseball and elected to the Hall ofFame after finally admitting that he placed bets on his team and otherteams and lied about it. In coming to a decision about Rose, theBaseball Commissioner should remember that Olympic athletes whohave been caught using performance-enhancing drugs are strippedpermanently of their titles and medals.

—Frank Ulrich, The New York Times, 8 January 2004



3. Look round the world: contemplate the whole and every part of it: youwill find it to be nothing but one great machine, subdivided into an infi-nite number of lesser machines, which again admit of subdivisions, to adegree beyond what human senses and faculties can trace and explain.All these various machines, and even their most minute parts, areadjusted to each other with an accuracy which ravishes into admirationall men who have ever contemplated them. The curious adapting ofmeans to ends, throughout all nature, resembles exactly, though it muchexceeds, the production of human contrivance, of human design,thought, wisdom, and intelligence. Since therefore the effects resembleeach other, we are led to infer, by all the rules of analogy, that the causesalso resemble; and that the Author of Nature is somewhat similar to themind of men; though possessed of much larger faculties, proportionedto the grandeur of the work, which he has executed. By this argument aposteriori, and by this argument alone, do we prove at once the existenceof a Deity, and his similarity to human mind and intelligence.

—David Hume, Dialogues Concerning Natural Religion, 1779

4. The philosopher Metrodorus of Chios, who lived in the fourth centuryB.C., was greatly interested in the heavenly bodies. He wrote: “To con-sider the Earth as the only populated world in infinite space is as absurdas to assert that in an entire field of millet, only one grain will grow.”

5. To the casual observer porpoises and sharks are kinds of fish. Theyare streamlined, good swimmers, and live in the sea. To the zoologistwho examines these animals more closely, the shark has gills, coldblood, and scales; the porpoise has lungs, warm blood, and hair. Theporpoise is fundamentally more like man than like the shark andbelongs, with man, to the mammals—a group that nurses its youngwith milk. Having decided that the porpoise is a mammal, the zoolo-gist can, without further examination, predict that the animal willhave a four-chambered heart, bones of a particular type, and a cer-tain general pattern of nerves and blood vessels. Without using amicroscope the zoologist can say with reasonable confidence that thered blood cells in the blood of the porpoise will lack nuclei. This abil-ity to generalize about animal structure depends upon a system fororganizing the vast amount of knowledge about animals.

—Ralph Buchsbaum, Animals without Backbones(Chicago: University Chicago Press, 1961)

6. The body is the substance of the soul; the soul is the functioning ofthe body. . . . The relationship of the soul to its substance is like that



of sharpness to a knife, while the relationship of the body to its func-tioning is like that of a knife to sharpness. What is called sharpness isnot the same as the knife, and what is called the knife is not the sameas sharpness. Nevertheless, there can be no knife if the sharpness isdiscarded, nor sharpness if the knife is discarded. I have never heardof sharpness surviving if the knife is destroyed, so how can it beadmitted that the soul can remain if the body is annihilated?

—Fan Chen, Essay on the Extinction of the Soul,in Fung Yu-Lan, A History of Chinese Philosophy, 1934

7. If a single cell, under appropriate conditions, becomes a person in thespace of a few years, there can surely be no difficulty in understand-ing how, under appropriate conditions, a cell may, in the course ofuntold millions of years, give origin to the human race.

—Herbert Spencer, Principles of Biology, 1864

8. An electron is no more (and no less) hypothetical than a star. Nowadayswe count electrons one by one in a Geiger counter, as we count the starsone by one on a photographic plate. In what sense can an electron becalled more unobservable than a star? I am not sure whether I ought tosay that I have seen an electron; but I have just the same doubt whetherI have seen a star. If I have seen one, I have seen the other. I have seen asmall disc of light surrounded by diffraction rings which has not theleast resemblance to what a star is supposed to be; but the name “star”is given to the object in the physical world which some hundreds ofyears ago started a chain of causation which has resulted in this particu-lar light-pattern. Similarly in a Wilson expansion chamber I have seen atrail not in the least resembling what an electron is supposed to be; butthe name “electron” is given to the object in the physical world whichhas caused this trail to appear. How can it possibly be maintained that ahypothesis is introduced in one case and not in the other?

—Arthur Eddington, New Pathways in Science, 1939

9. Just as the bottom of a bucket containing water is pressed more heavilyby the weight of the water when it is full than when it is half empty,and the more heavily the deeper the water is, similarly the high placesof the earth, such as the summits of mountains, are less heavily pressedthan the lowlands are by the weight of the mass of the air. This isbecause there is more air above the lowlands than above the mountaintops; for all the air along a mountain side presses upon the lowlandsbut not upon the summit, being above the one but below the other.

—Blaise Pascal, Treatise on the Weight of the Mass of the Air, 1653



10. Suppose that someone tells me that he has had a tooth extractedwithout an anaesthetic, and I express my sympathy, and suppose thatI am then asked, “How do you know that it hurt him?” I might rea-sonably reply, “Well, I know that it would hurt me. I have been to thedentist and know how painful it is to have a tooth stopped [filled]without an anaesthetic, let alone taken out. And he has the same sortof nervous system as I have. I infer, therefore, that in these conditionshe felt considerable pain, just as I should myself.”

—Alfred J. Ayer, “One’s Knowledge of Other Minds,” Theoria, 1953

11. Now if we survey the universe, so far as it falls under our knowledge,it bears a great resemblance to an animal or organized body andseems actuated with a like principle of life and motion. A continualcirculation of matter in it produces no disorder: a continual waste inevery part is incessantly repaired; the closest sympathy is perceivedthroughout the entire system: and each part or member, in perform-ing its proper offices, operates both to its own preservation and tothat of the whole. The world, therefore, I infer, is an animal, and theDeity is the soul of the world, actuating it, and actuated by it.

—David Hume, Dialogues Concerning Natural Religion, 1779

12. One cannot require that everything shall be defined, any more thanone can require that a chemist shall decompose every substance.What is simple cannot be decomposed, and what is logically simplecannot have a proper definition.

—Gottlob Frege, “On Concept and Object,” 1892

13. Most endangered or threatened species in the United States find suit-able habitat on private land, and the destruction of habitat is widelyrecognized as the leading cause of extinctions. For these reasons,protecting wildlife without regulating the use of private land has beencompared by biologists to playing the piano with just the black keys.

—John H. Cushman, Jr., “Environmentalists Gain a Victory,”The New York Times, 30 June 1995

14. Opposing legislation that would restrict handgun ownership in theUnited Kingdom, the husband of Queen Elizabeth II reasoned as follows:

Look, if a cricketer, for instance, suddenly decided to go into a schooland batter a lot of people to death with a cricket bat, which he coulddo very easily, are you going to ban cricket bats?

—Prince Philip, the Duke of Edinburgh, in an interview on the BBC, 19 December 1996



15. . . . The simplest form of the theological argument from design[was] once well known under the name “Paley’s watch.” Paley’sform of it was just this: “If we found by chance a watch or otherpiece of intricate mechanism we should infer that it had been madeby someone. But all around us we do find intricate pieces of naturalmechanism, and the processes of the universe are seen to movetogether in complex relations; we should therefore infer that thesetoo have a Maker.”

—B. A. D. Williams, “Metaphysical Arguments,” in D. F. Pears, ed.,The Nature of Metaphysics (New York: Macmillan, 1957)

11.4 Refutation by Logical Analogy

”You should say what you mean,” [said the March Hare, reproving Alice sharply.]”I do,” Alice hastily replied; “at least—at least I mean what I say—that’s the

same thing, you know.””Not the same thing a bit!” said the Hatter. ”Why, you might just as well say

that ‘I see what I eat’ is the same thing as ‘I eat what I see’!””You might just as well say,” added the March Hare, “that ‘I like what I get’ is

the same thing as ‘I get what I like’!””You might just as well say,” added the Dormouse, which seemed to be talk-

ing in its sleep, “that ‘I breathe when I sleep’ is the same thing as ‘I sleep when Ibreathe’!”

”It is the same thing with you,” said the Hatter, and here the conversationdropped.

—Lewis Carroll, Alice’s Adventures in Wonderland

The Hare, the Hatter, and the Dormouse all seek to refute Alice’s claim—thatmeaning what you say is the same as saying what you mean—by using a logical

analogy. The form of an argument, as distinct from its particular content, is themost important aspect of that argument from a logical point of view. Therefore,we often seek to demonstrate the weakness of a given argument by statinganother argument, known to be erroneous, that has the same logical form.

In the realm of deduction, a refuting analogy for a given argument is anargument that has the same form as the given argument but whose premisesare known to be true and whose conclusion is known to be false. The refutinganalogy is therefore known to be invalid, and the argument under attack,because it has the same form, is thus shown to be invalid as well. This is thesame principle that underlies the testing of categorical syllogisms explained inSection 6.2, and it also underlies the repeated emphasis on the centrality oflogical form, as explained in Section 8.4.

In the realm of inductive argument, our present concern, the technique ofrefutation by logical analogy can also be used to great effect. Scientific, political,

11.4 Refutation by Logical Analogy 503


or economic arguments, not purporting to be deductive, may be countered bypresenting other arguments that have very similar designs, whose conclu-sions are known to be false or are generally believed to be improbable.Inductive arguments differ fundamentally from deductive arguments in thecharacter of the support claimed to be given to the conclusion by the prem-ises. All arguments, however, inductive as well as deductive, may be said tohave some underlying form or pattern. If, when confronted by an inductiveargument we wish to attack, we can present another inductive argument thathas essentially the same form but is clearly flawed and whose conclusion isvery doubtful, we throw similar doubt on the conclusion of the argumentbeing examined.

Consider the following illustration. In two highly controversial casesbefore the U.S. Supreme Court in 2007,8 the central issue was the constitu-tionality of the consideration of race by school boards in the assignment ofstudents to public schools. In an editorial, the New York Times supported therace-conscious systems as fair, and called the objections to it “an assault onlocal school control.“ A prominent critic of the race-based systems wrote a critical response to that editorial, within which appeared the followingpassage:

You argue that the race-based system “is applied to students of all races” and“does not advantage or disadvantage any particular racial group.” But, of course,the same argument might have been made in defense of miscegenation statutes,which forbade blacks from marrying whites as well as whites from marryingblacks.9

The technique of refutation by logical analogy is here very keenly exemplified;the focus is on the form of the two arguments. The argument under attackhas the same form as that of another argument whose unsatisfactoriness isnow universally understood. We surely would not say that miscegenationstatues are acceptable because they apply equally to all races. Some policiesinvolving the use of race by the state are not acceptable (the critic argues) evenwhen it is true that no particular racial group is disadvantaged by that use. Byhighlighting such unacceptability in some well-known settings (regulationsgoverning marriage), he strikes a sharp blow against the argument in this set-ting that relies on the claim that no particular racial group is disadvantaged bythe race-based policy under attack.

The presentation of a refutation by logical analogy is often signaled bythe appearance of some revealing phrase: “You might just as well say,” or someother words having that same sense. In the example just given, the telltalephrase is “the same argument might have been made. . . .” In another context,the argument that because Islamic culture had been brought to the country ofChad from without, it is no more than an Islamic overlay, is attacked with the



refuting analogy of a scholar who introduces the refutation with a slightlydifferent set of words: “One could as sensibly say that France has only aChristian overlay.”10

When the point of the refuting analogy is manifest, no introductoryphrases may be needed. The former governor of Mississippi, Kirk Fordice,argued that “It is a simple fact that the United States is a Christian nation”because “Christianity is the predominant religion in America.” JournalistMichael Kinsley, with whom Fordice was debating on television, respondedwith these telling analogies: “Women are a majority in this country. Does thatmake us a female country? Or does it make us a white country because mostpeople in this country are white?”11

A careless effort to refute an argument with an analogy can backfire whenthe allegedly refuting argument differs importantly from the target argumentin ways that tend to reinforce the one that is under attack. This is illustrated bya recent exchange on the highly controversial topic of global warming.Newspaper columnist John Tierney raised some serious questions about thewisdom of immediate large-scale efforts to combat an apparent but uncertainclimate trend.12 A critic, Ray Sten, responded in this way:

John Tierney suggests that we not worry much about climate change because itsconsequences are uncertain and far in the future, and in the meantime somebodymay discover a technological quick fix. That’s like telling a smoker not to worrybecause it’s not certain whether he’ll develop cancer, and besides, a cure mayhave been found by then. Call me a worry wart, but I’d quit smoking.13

The immediate and large-scale steps whose wisdom Tierney questions arethus likened to quitting smoking. There is, however, an important contrastbetween those two. Quitting has no economic costs (and even some economicbenefits), while industrial changes designed to cut greenhouse gases by reduc-ing the use of fossil fuels will probably be very costly. In presenting an analogyintended to refute Tierney, Mr. Stern (whose position on global warming maywell be correct) undermines his cause by indirectly calling attention to thecosts of the change he seeks to advance.

Here, to conclude, is a letter to the editor from Jeff Weaver, published inThe Ann Arbor (Mich.) News in July 2005:

I find it amusing that anyone would be offended by the name or appearance of ateam mascot. But apparently there are people who are devastated that thereare schools with team names such as the Hurons, Chippewas, Braves, Chiefs,Seminoles, etc.

I sympathize with their plight. I would also suggest that we change the nameof the Pioneers of Ann Arbor Pioneer High School. My forefathers were pioneersand I’m sure they would be devastated that a school adopted their name as ateam mascot. That name and mascot are a direct slap against my people.



While we are at it, we had better change the names of the Cowboys, FightingIrish, Celtics, Hoosiers, Sooners, Boilermakers, Packers, Aggies, Oilers, Mountaineers,Friars, Patriots, Volunteers and Tar Heels, to name a few, because I’m sure thosenames are equally demeaning and degrading to those groups as well. . . .

Refutation by analogy when well designed can be exceedingly effective. If theargument presented as a refuting analogy is plainly rotten, and it does indeedhave the same form as that of the argument under attack, that target argumentmust be seriously wounded.

EXERCISES

Each of the following is intended to be a refutation by logical analogy. Identifythe argument being refuted in each and the refuting analogy, and decidewhether they do indeed have the same argument form.

1. Steve Brill, founder of Court TV, has no doubt that cameras belongin the courtroom, and answers some critics in the following way:“Some lawyers and judges say that TV coverage makes the systemlook bad. They confuse the messenger with the message. If presscoverage of something makes it look bad, that is a reason to have thepress coverage. That criticism is like saying that because journalistswere allowed to be with the troops in Vietnam, the Vietnam War wasruined.”

—Steve Brill, “Trial: A Starting Place for Reform,”Ann Arbor (Mich.) News, 12 June 1995

2. The whole history of bolshevism, both before and after the October revo-lution, is full of instances of maneuvering, temporizing and compromis-ing with other parties, bourgeois parties included! To carry on a war forthe overthrow of the international bourgeoisie, a war which is a hundredtimes more difficult, prolonged and complicated than the most stubbornof ordinary wars between states, and to refuse beforehand to maneuver,to utilize the conflict of interests (even though temporary) among one’senemies, to refuse to temporize and compromise with possible (eventhough transitory, unstable, vacillating and conditional) allies—is thisnot ridiculous in the extreme? Is it not as though, when making a diffi-cult ascent of an unexplored and hitherto inaccessible mountain, wewere to refuse beforehand ever to move in zigzags, ever to retrace oursteps, ever to abandon the course once selected to try others?

—V. I. Lenin, “Left Wing” Communism: An Infantile Disorder, 1920

3. The distinguished naturalist E. O. Wilson argues that humans areno more than a biological species of a certain physical composition,



and that the human mind can have no characteristics attributable tononphysical causes. This claim can no longer be disputed.“Virtually all contemporary scientists and philosophers expert onthe subject agree [he writes] that the mind, which comprises con-sciousness and rational process, is the brain at work. . . . The brainand its satellite glands have now been probed to the point where noparticular site remains that can reasonably be supposed to harbor anonphysical mind.14 Stephen Barr presented the following counter-argument in the form of a logical analogy: “This [Wilson’s argumentquoted above] is on a par with Nikita Krushshev’s announcement[aiming to support atheism] that Yuri Gagarin, the first human visi-tor to space, had failed to locate God. Does Wilson suppose that ifthere were an immaterial component to the mind it would show upin a brain scan?”15

4. The argument against new highways is given forceful statement bythree distinguished urban planners: the authors write: “The only longterm solutions to traffic are public transit and coordinated land use.”New highways, they argue, bring “induced traffic.” So building morehighways will only cause more traffic congestion, not less.16

A highly critical reviewer responds to this argument as follows:“This is nonsense. . . . Long lines at a grocery store would not promptanyone to say, “Well, we can’t build any more grocery stores. Thatwould only bring out more customers.” Building more highwayswouldn’t lure cars. The cars come anyway.”17

5. America’s supply of timber has been increasing for decades, and thenation’s forests have three times more wood today than in 1920.“We’re not running out of wood, so why do we worry so much aboutrecycling paper?” asks Jerry Taylor, the director of natural researchstudies at the Cato Institute. “Paper is an agricultural product, madefrom trees grown specifically for paper production. Acting to con-serve trees by recycling paper is like acting to conserve cornstalks bycutting back on corn consumption.”

—John Tierney, “Recycling Is Garbage,”The New York Times Magazine, 30 June 1996

6. In 1996, heated controversy arose between the states of New Jerseyand New York over formal possession of Ellis Island, located at themouth of the Hudson River near the New Jersey shore, a tiny speckof land on which so many tens of thousands of immigrants to theUnited States first touched American soil. An essay defending NewYork’s claim to the historic island appeared in the New York Times on



23 July 1996. The following letter appeared in the same newspaperfour days later:

Clyde Haberman is right that almost every immigrant who passedthrough Ellis Island was bound for New York, not New Jersey. But thisfact does not determine where the island is. A significant number ofpassengers arriving at Newark International Airport are also on theirway to New York, but it would be hard to argue that New York thus hasa claim on the airport. Cincinnati International Airport is in Covington,Kentucky, and presumably, few travelers are on their way to sparselypopulated northern Kentucky. Would Mr. Haberman suggest that theairport belongs to Ohio?

7. Edward Rothstein suggests that poverty and injustice cannot beconsidered among the root causes of Islamic terrorism becauseOsama bin Laden is a multimillionaire. By that logic, slavery couldnot have caused the Civil War because Abraham Lincoln was not aslave.

—Corey Robin, ”The Root Causes of Terror,”The New York Times, 17 November 2001

8. Each of the multitude of universes may have different laws of nature.Or different values of quantities that determine how they behave,such as the speed of light. Some may be suitable for life, and somemay not. All those suitable for life may have life develop. Sometimeslife will evolve only into dinosaurs rather than something more intel-ligent. We cannot attach any meaning to the fact that a life formwhich could ask anthropic questions [questions about the propertiesthat are essential for intelligent life] did develop in at least one uni-verse. It is very much like a lottery. If you win the lottery, you mayfeel very grateful, but someone had to win, and no one selected whothat was, except randomly. Just because a universe has a unique set oflaws and parameters should not lead one to wonder whether that setwas designed.

—Gordon Kane, “Anthropic Questions,” Phi Kappa Phi Forum, Fall 2002

9. Artificial human minds will never be made (we are told) because“artificial intelligence investigation is based on advanced solidstatephysics, whereas the humble human brain is a viable semiliquid sys-tem!” That is no more reassuring than the suggestion that automobilescould never replace horses because they are made of metal, while thehumble horse is a viable organic system with legs of flesh and bone.

—Michael D. Rohr, The New York Times, 27 March 1998



10. Modern political rhetoric [Ronald Dworkin argues] “is nowextremely repetitive,” and a good bit of it could be dispensed with—by law. “Every European democracy does this,” the world’s mosthighly regarded legal philosopher points out, “and Europeans areamazed that we do not.”

Europeans are also amazed that we bathe as frequently as we do.What the hell kind of argument is that?

—David Tell, “Silencing Free Speech in the Name of Reform,” The Weekly Standard, 25 November 1996

SUMMARY

In this chapter we began the analysis of induction. Section 11.1 reviewedthe fundamental distinction between deductive arguments, which claimcertainty for their conclusions, and inductive arguments, which make nosuch claim. The terms validity and invalidity do not apply to inductive argu-ments, whose conclusions can only have some degree of probability ofbeing true.

In Section 11.2 we explained argument by analogy. An analogy is a like-ness or comparison; we draw an analogy when we indicate one or morerespects in which two or more entities are similar. An argument by analogy isan argument whose premises assert the similarity of two or more entities in

Summary 509

Courtesy of King Features Syndicate.


one or more respects, and whose conclusion is that those entities are similar insome further respect. Its conclusion, like that of every inductive argument, canbe no more than probable.

In Section 11.3 we explained six criteria used in determining whether thepremises of an analogical argument render its conclusion more or less proba-ble. These criteria are

1. The number of entities between which the analogy is said to hold

2. The variety, or degree of dissimilarity, among those entities or instancesmentioned only in the premises

3. The number of respects in which the entities involved are said to be anal-ogous

4. The relevance of the respects mentioned in the premises to the furtherrespect mentioned in the conclusion

5. The number and importance of disanalogies between the instances men-tioned only in the premises and the instance mentioned in the conclu-sion

6. The modesty (or boldness) of the conclusion relative to the premises

In Section 11.4 we explained refutation by logical analogy. To show that agiven argument (whether inductive or deductive) is mistaken, one effectivemethod is to present another argument, which is plainly mistaken, and whoseform is the same as that of the argument under attack.

End Notes1Bert Vogelstein, “So, Smoking Causes Cancer: This Is News?” The New York Times, 27 October 1996.

2Albert Shanker, “Testing Teachers,” The New York Times, 8 January 1995.

3Thomas Reid, Essays on the Intellectual Powers of Man, Essay 1, 1785.

4Andrew Massimino, “Building a Country,” The New York Times, 5 June 2006.

5Eric Lander, quoted in an interview in the The New York Times, 10 September 1996.

6Crawford v. Washington, 541 U.S. 36 (2004).

7F. Barringer and A. Revkin, “A Few Spitballs Greet Professor Gore,” The Ann Arbor (Mich.) News, 22March 2007.

8Parents Involved in Community Schools v. Seattle School District No. 1 (No. 05-908); and Crystal D.

Meredith, Custodial Parent v. Jefferson County (KY) Board of Education (No. 05-915)

9Roger Clegg, “An Issue for the Court: Diversity in Our Schools,” The New York Times, 11 December2006.

10Bassam Abed, in a letter to The New York Times, 26 June 1988.



11“Evangelical Update,” The New York Times, 21 November 1992.

12John Tierney, “Findings,” The New York Times, 13 February 2007.

13Ray Sten, “Debating Climate Change,” The New York Times, 20 February 2007.

14E.O. Wilson, Consilience (New York-Alfred A. Knopf, 1998), p. 99.

15S. N. Barr, “Mindless Science,” The Weekly Standard, 6 April 1998.

16A. Duany, E. Plater-Zyberk, and J. Speck, Suburban Nation: The Rise of Sprawl and the Decline of the

American Dream (New York: North Point, 2000).

17F. Barnes, “Suburban Beauty: Why Sprawl Works,” The Weekly Standard, 22 May 2000.

End Notes 511

M11_COPI1396_13_SE_C11.QXD 11/17/07 12:40 PM Page 511

Documents

PART III - Pearsonwps.prenhall.com/wps/media/objects/5909/6050951/My... · calls for a single vanishing point with which the horizontal lines of the picture are laid out. Relativity,