Maria has asked all but three of the thirty-six people in her class whether they've ever
used heroin. Only two said "yes." So she concluded that almost no one in the class has
used heroin.
Generalization (state it; if none, say so): Almost no one in Maria's class has
used heroin.
Sample: The thirty-three people Maria asked.
Sample is representative? Yes.
Sample is big enough? Yes.
Sample is studied well? Yes.
Additional premises needed:
Good generalization? Yes.
Do you really thinkeveryone who's used heroin is going to admit it to a stranger? The
sample isn't studied well—you'd need anonymous responses at least. So the
generalization isn't good.
Evaluate Exercises 12-30 by answering the following.
Generalization (state it; if none, say so):
Sample:
Sample is representative? (yes or no)
Sample is big enough? (yes or no)
Sample is studied well? (yes or no)
Additional premises needed:
Good generalization?
EXERCISES for Chapter 14 295
12. It's incredible how much information they can put on a CD. I just bought one that
contains a whole encyclopedia.
13. Socialized medicine in Canada isn't working. I heard of a man who had colon cancer
and needed surgery. By the time doctors operated six months later, the man was nearly
dead and died two days later.
14. Lee: Every rich person I've met invested heavily in the stock market. So I'll invest in
the stockmarket, too.
15. Don't take a course from Dr. E. I know three people who failed his course last term.
16. Everyone I've met at this school is either on one of the athletic teams or has a boyfriend
or girlfriend on one of the athletic teams. Gosh, I guess just about everyone at this
school is involved in sports.
17. Dick: Hold the steering wheel.
Zoe: What are you doing? Stop! Are you crazy?
Dick: I' m just taking my sweater off.
Zoe: I can't believe you did that. It's so dangerous.
Dick: Don't be silly. I've done it a thousand times before.
18. Manuel to Maria: Lanolin is great for your hands—you ought to try it. It's what's on
sheep wool naturally. How many shepherds have you seen with dry, chapped hands?
19. Lee: When I went in to the health service, I read some women's magazine that had the
results of a survey they'd done on women's attitudes towards men with beards. They
said that they received over 10,000 responses from their readers to the question in their
last issue, and 78% say they think that men with beards are really sexy! I'm definitely
going to grow a beard now.
20. My grandmother was diagnosed with cancer seven years ago. She refused any treatment
that was offered to her over the years. She's perfectly healthy and doing great. The
treatments for cancer are just a scam to get people's money.
21. Tom: Can you pick up that pro basketball player who's coming to the rally today?
Dick: I can't. Zoe's got the car. Why not ask Suzy?
Tom: She's got a Yoda hatchback. They're too small for someone over six foot tall.
22. (Overheard at a doctor's office) I won't have high blood pressure today because I got
enough sleep last night. The last two times you've taken my blood pressure I've rested
well the night before and both times it was normal.
23. Suzy: I've been studying this astrology book seriously. I think you should definitely go
into science.
Lee: I've been thinking of that, but what's astrology got to do with it?
Suzy: I remember your birthday is in late January, so you're an Aquarius?
Lee: Yeah, January 28.
Suzy: Well, Aquarians are generally scientific but eccentric.
Lee: C'mon. That can't be right.
Suzy: Sure it is. Copernicus, Galileo, and Thomas Edison were all Aquarians.
296 CHAPTER 14 Generalizing
24. Give the baby his pacifier so he'll stop crying. Every time I give him the pacifier he
stops crying.
25. We will be late for church because we have to wait for Gina. She's always late. She's
been late seven Sundays in a row.
26. Every time I or anyone else has looked into my refrigerator, the light is on. Therefore,
the light is always on in my refrigerator.
27. Every time I or anyone I know has seen a tree fall in the forest, it makes a sound.
Therefore, anytime a tree falls in the forest it makes a sound.
28. Biology breeds grumpy old men
Men lose brain tissue at almost three times the rate of women, curbing their memory,
concentration and reasoning power—and perhaps turning them into "grumpy old men"
—a researcher said Wednesday.
"Even in the age range of 18 to 45, you can see a steady decline in the ability to
perform such (attention-oriented) tasks in men," said Ruben C. Gur, a professor of
psychology at the University of Pennsylvania.
Gur said shrinking brains may make men grumpier because some of the tissue loss is
in the left frontal region of the brain, which seems to be connected to depression.
"Grumpy old men may be biological," said Gur, who is continuing to study whether
there is a connection.
However, one researcher not affiliated with the study said Wednesday that other
recent studies contradict Gur's findings on shrinkage.
The findings, which augment earlier research published by Gur and colleagues, are
the result of his studies of the brain functions of 24 women and 37 men over the past
decade. He measured the brain volume with an MRI machine and studied metabolism
rates. From young adulthood to middle age, men lose 15% of their frontal lobe volume,
8.5% of temporal lobe, he said. Women, while they have "very mild" shrinkage, lose
tissue in neither lobe. For the brain overall, men lose tissue three times faster.
Gur found that the most dramatic loss was in men's frontal lobes, which control
attention, abstract reasoning, mental flexibility and inhibition of impulses, and the
temporal lobe [which] governs memory.
Associated Press, April, 1996
29. Sex, lies, and HIV
Reducing the risk of human immunodeficiency virus (HIV) transmission among sexually
active teenagers and young adults is a major public health concern [reference supplied].
Young people are advised to select potential sexual partners from groups at lower risk
for HIV [reference supplied], in part by asking about partners' risk histories [reference
supplied]. Unfortunately, this advice overlooks the possibility that people may lie about
their risk history [reference supplied].
In a sample of 18-to-25-year-old students attending colleges in southern California
(n = 665), we found strong evidence that undermines faith in questioning partners as an
effective primary strategy of risk reduction. The young adults, of whom 442 were
sexually active, completed anonymous 18-page questionnaires assessing sexual
behavior, HIV-related risk reduction, and their experiences with deception when dating.
EXERCISES for Chapter 14 297
Variable
Men Women
( N = 1 9 6 ) (N = 226)
History of disclosure
percent
Has told a lie in order to have sex
34 10*
Li
ed about ejaculatory control or likelihood of pregnancy
38 14
Sexually active with more than one person
32 23$
Partner did not know
68 59
Experience of being lied to
Has been lied to for purposes of sex
47 60**
Partner lied about ejaculatory control or likelihood of pregnancy 34 46
Willingness to deceive***
Would lie about having negative HIV-antibody test
20 4*
Would lie about ejaculatory control or likelihood of pregnancy
29 2*
Would understate number of previous partners
47 42
Would disclose existence of other partner to new partner
Never
22 10*
After a while, when safe to do so
34 28*
Only if asked
31 33*
Yes
13 29*
Would disclose a single episode of sexual infidelity
Never
43 3 4 *
After a while, when safe to do so
21 20$
Only if asked
14 11*
Yes
22 3 5 *
* P < .001 by chi-square test % P < .05 by chi-square test ** P < .01 by chi-square test
*** Hypothetical scenarios were described in which honesty would threaten either the
opportunity to have sex or the maintenance of a sexually active relationship.
We found that sizable percentages of the 196 men and 226 women who were
sexually experienced reported having told a lie in order to have sex. Men reported
telling lies significantly more frequently than women (Table). Women more often
reported that they had been lied to by a dating partner. When asked what they would do
in hypothetical situations, both men and women frequently reported that they would
actively or passively deceive a dating partner, although again, men were significantly
more likely than women to indicate a willingness to do so.
Although we cannot be certain that our subjects were fully forthcoming in their
responses (e.g., they reported more frequent dishonesty from others than they admitted
to themselves), one can probably assume that their reports of their own dishonesty
underestimate rather than overestimate the problem. The implications of our findings
are clear. In counseling patients, particularly young adults, physicians need to consider
realistically the patients' capacity for assessing the risk of HIV in sexual partners
through questioning them [reference]. Patients should be cautioned that safe-sex
strategies are always advisable [references], despite arguments to the contrary from
partners. This is particularly important for heterosexuals in urban centers where
298 CHAPTER 14 Generalizing
distinctions between people at low risk and those at high risk may be less obvious
because of higher rates of experimentation with sex and the use of intravenous drugs and
undisclosed histories of high-risk behavior. Susan D Cochran and Vickie M. Mays,
Letter to the Editor,
New England Journal of Medicine, vol. 322, pp. 774-775, © 1990,
Massachusetts Medical Society. All rights reserved.
30. Sex unlikely to cause heart attacks
Sexual intercourse is unlikely to trigger a heart attack, even among people who have
already survived one, according to a study that is the first to examine this widespread
fear.
Only 1 percent of heart attacks were triggered by sexual activity in a nationwide
sample of nearly 900 heart attack survivors who said they were sexually active.
The odds of suffering a heart attack after engaging in sex are only about 2 in a
million, the study found—about twice as high as the average hourly risk of heart attack
among 50-year-old Americans with no overt sign of coronary artery disease.
"It's easy to get the message from movies, and even from Shakespeare, that sexual
activity can trigger heart attacks," said Dr. James Muller of New England Deaconess
Hospital in Boston, who led the study. "It's part of the mythology, and it's certainly in
the minds of many cardiac patients and their spouses."
"What has been lacking in the past are actual numbers. Now the numbers are
available, and the risk is quite, quite low."
Furthermore, regular exercise can substantially reduce the risk of a sex-triggered
heart attack.
Patients who never engaged in heavy physical exertion, or got vigorous exercise
only once a week, had a threefold risk of heart attack in the two hours after sexual
activity. But the relative risk dropped to twofold among patients who exercise twice a
week, and only 1.2 fold among those who exercised three or more times weekly.
The new figures, which appear in this week's Journal of the American Medical
Association, suggest that sexual activity triggers 15,000 of the 1.5 million heart attacks
that occur in this nation annually.
"Although sexual activity doubles the risk" of heart attack, the researchers noted, the
effect on annual risk "is negligible because the absolute risk difference is small, the risk
is transient and the activity is relatively infrequent."
For instance, for an individual without cardiac disease, weekly sexual activity would
increase the annual risk of a heart attack from 1 percent to 1.01 percent.
Richard Knox, Boston Globe, May, 1996
31. Would you try this new procedure? Explain.
Chili peppers a red hot cure for surgical pain
When burning pain lingers months after surgery, doctors say there is a red-hot cure: chili
peppers. In a study, an ointment made with capsaicin, the stuff that makes chili peppers
hot, brought relief to patients with tender surgical scars, apparently by short-circuiting
the pain.
Patients undergoing major cancer surgery, such as mastectomies or lung operations,
are sometimes beset by sharp, burning pain in their surgical scars that lasts for months,
EXERCISES for Chapter 14 299
even years. Sometimes the misery is so bad that sufferers cannot even stand the weight
of clothing on their scar, even though it is fully healed.
The condition, seen in about 5 percent or fewer of all cases, results from damage to
the nerves during surgery. Ordinary pain killers don't work, and the standard treatment
is antidepressant drugs.
However, these powerful drugs have side effects. So in search of a better
alternative, doctors tested a cream made with capsaicin on 99 patients who typically
had suffered painful surgical scars at least six months.
Patients preferred capsaicin over a dummy cream by 3-to-l.
"The therapy clearly worked," said Dr. Charles L. Loprinzi, head of medical
oncology at the Mayo Clinic. He released his data Monday at the annual meeting of the
American Society for Clinical Oncology.
Capsaicin is believed to work by blocking substance P, a natural chemical that
carries pain impulses between nerve cells. That same blocking effect may explain why
people who eat hot peppers all the time develop a tolerance to the burn.
Dr. Alan Lyss of Missouri Baptist Medical Center in St. Louis called it "a creative,
new and very inexpensive way to take care of some kinds of cancer pain."
Capsaicin is sold in drug stores without a prescription, and a tube that lasts a month
; costs about $ 1 6 . . . .
In the study, the patients were randomly assigned to capsaicin cream or the look-
alike placebo four times a day for eight-week intervals. Until the study was over, no one
knew which was which.
Patients kept score of their pain. It went down 53 percent while using capsaicin but
only 17 percent while on the placebo. About 10 percent said their pain disappeared
completely.
The doctors followed the patients for two months after they stopped using capsaicin
and found that pain did not come back. Longer follow-up will be necessary to see if the
treatment relieves the pain permanently. Associated Press, May 21, 1996
For Exercises 32-34 identify the analogy and explain how a generalization is required.
32. Dick: What do you think about getting one of those Blauspot rice cookers?
Zoe: It's not a good idea. Remember, Maria got one and she had to return it twice to
get it fixed.
33. Of chimpanzees fed one pound of chocolate per day in addition to their usual diet,
72% became obese within two months. Therefore, it is likely that most humans who eat
2% of their body weight in chocolate daily will become obese within two months.
34. Zoe: Suzy invited us over to dinner tonight. We've got to be there at 6 p.m.
Dick: I'm not going over there. The last time we went she served some concoction
she'd read about in a cookbook, and I had the runs for two days.
F u r t h e r Study Courses on statistics explain the nature of sampling and generalizing.
A course on inductive logic in a philosophy department will study more fully the
topics of this chapter and the next. A course on philosophy of science will study the
300 CHAPTER 14 Generalizing
role of generalizations in science, which you can also read about in my Five Ways of
Saying "Therefore." Many disciplines, such as sociology, marketing, or the health
sciences give courses on the use of sampling and generalizing that are specific to
their subject.
Two books about statistics in reasoning with lots of examples are Flaws and
Fallacies in Statistical Thinking, by Stephen K. Campbell and How to Lie with
Statistics, by Darrell Huff.
15 Cause
and Effect
A. What is the Cause?
1. Causes and effects 302
2. The normal conditions 303
3. Particular causes, generalizations, and general causes 303
•Exercises for Sections A. 1-A.3 304
4. The cause precedes the effect 305
Richard L Epstein Page 38