following criteria: he was properly referred for alcohol problems, was aged 20 to 65 and
married, did not have any progressive or painful physical disease or brain damage or
psychotic illness, and lived within a reasonable distance of the clinic (to allow for clinic
visits and follow-up home visits by social workers). A statistical randomization proce-
dure was used to divide the subjects into two groups comparable in the severity of their
drinking and their occupational status.
For subjects in one group (the "advice group"), the only formal therapeutic activity
was one session between the drinker, his wife, and the psychiatrist. The psychiatrist told
the couple that the husband was suffering from alcoholism and advised him to abstain
from all drink. The psychiatrist also encouraged the couple to attempt to keep their
marriage together. There was a free-ranging discussion and advice about the person-
alities and particularities of the situation, but the couple was told that this one session
was the only treatment the clinic would provide. They were told in sympathetic and
EXERCISES for Section D 329
constructive language that the "attainment of the stated goals lay in their hands and
could not be taken over by others."
Subjects in the second group (the "treatment group") were offered a year-long
program that began with a counseling session, an introduction to Alcoholics Anony-
mous, and prescriptions for drugs that would make alcohol unpalatable and drugs that
would alleviate withdrawal suffering. Each drinker then met with a psychiatrist to work
out a continuing outpatient treatment program, while the social worker made a similar
plan with the drinker's wife. The ongoing counseling was focused on practical problems
in the areas of alcohol abuse, marital relations, and other social or personal difficulties.
Drinkers who did not respond well were offered in-patient admissions, with full access
to the hospital's wide range of services.
Twelve months after the experiment began, both groups were assessed. No
significant differences were found between the two groups. Furthermore, drinkers in
the treatment group who stayed with it for the full period did not fare better than those
who dropped out. At the twelve-month point, only eleven of the one hundred drinkers
had become abstainers. Another dozen or so still drank but in sufficient moderation to
be considered "acceptable" by both husband and wife. Such rates of improvement are
not significantly better than those shown in studies of the spontaneous or natural
improvement of chronic drinkers not in treatment.
Herbert Fingarette, Heavy Drinking: The Myth of Alcoholism as Disease
Summary We encounter cause and effect claims every day. The best way to begin
to evaluate them is to describe the purported cause and effect with claims. Then we
can use much of what we know about how to reason with claims.
For there to be cause and effect, it must be (nearly) impossible for the claim
describing the cause to be true and effect false. That's the same relation as between
premises and conclusion of a valid or strong argument, except that here these claims
should already be plausible. As with arguments, we often need additional premises,
what we call the "normal conditions," to show that the inference is valid or strong.
Among those additional premises will often be a generalization establishing a
correlation.
Checking that the cause makes a difference is how we rule out other possible
causes. In addition, the cause has to precede the effect, and there must be no
common cause. Once we've checked that all these necessary conditions for cause
and effect hold, there's not much more we can do except make sure we haven't made
one of the common mistakes of reversing cause and effect or arguing post hoc ergo
propter hoc (after this, therefore because of this).
When we can't specify the normal conditions for a general causal claim, we
rely on statistical arguments to establish that there is some causal link. Three kinds
of experiments are important for those arguments: controlled cause-to-effect,
uncontrolled cause-to-effect, and uncontrolled effect-to-cause.
330 CHAPTER 15 Cause and Effect
Key Words causal claim
coincidence
cause
causal factor
effect
foreseeable consequence
normal conditions
intervening cause
particular cause and effect
cause in population
general cause and effect
control group
correlation
common thread
common cause
controlled cause-to-effect experiment
reversing cause and effect
uncontrolled cause-to-effect experiment
post hoc ergo propter hoc
uncontrolled effect-to-cause experiment
Further Study To read about cause and effect in scientific explanations, see the
Science Workbook for this text. For a fuller discussion of how to reason about cause
and effect, including reasoning in the sciences, see my Five Ways of Saying
"Therefore" also published by Wadsworth, which has many more examples and
a history of the subject back to Aristotle.
Writing Lesson 11
Below are two pairs of arguments. Each pair involves some causal claim. Choose
one of the pairs and prepare a full analysis in outline form of both arguments.
Then present the analyses in an essay, either agreeing with one of the arguments
or explaining why you should suspend judgment.
This will take all the skills you've learned in this course. For guidelines, see
"The steps in analyzing complex arguments" on p. 229 and the section "Evaluating
Reasoning" on p. 341 below.
1. Power lines and leukemia
A. Power lines and leukemia: beware of scientists bearing glad tidings
"No Adverse Health Effects Seen From Residential Exposure to Electromagnetic Fields,"
said the press release from the National Academy of Sciences (NAS). "Study Fails to
Link EMFs With Illnesses," repeated the Los Angeles Times. "Panel Sees No Proof of Health Hazards From Power Lines," "Electromagnetic research review finds no danger,"
"Power lines cleared as cause of cancer," "Power Line Hazard Called Small," echoed the New York Times, Boston Globe, San Francisco Examiner, and Washington Post.
Feel better now? No need to worry about buying or renting a home near high-
voltage electric power lines. Forget the scare stories about your children getting
leukemia (cancer of the blood), and worry about real problems like the kids being
abducted by aliens.
But the headlines lie. Digging a bit deeper reveals that the study issued last October
by a panel of 16 distinguished experts does not exonerate power lines, nor electromag-
netic fields (EMFs), from being a danger to human health. In fact, the report itself (as
opposed to the press release) summarizes the many existing epidemiological studies as
saying that proximity to high-voltage lines raises a child's chances of contracting
leukemia by 50%—hardly a negligible figure.
While making this admission, the report goes on to emphasize that childhood leu-
kemia is "a rare disease." This means about one case per 30,000 children in a year, says
> committee vice-chair David Savitz of the University of North Carolina. Since about
one-quarter of homes are exposed to power lines, a bit of arithmetic shows that raising
this rate by 50% could cause hundreds of additional deaths per year in the United States!
Perhaps not as frightening as destruction of the ozone layer, but far worse than some
other current scares, such as passenger-side air bags. How to reconcile the headlines
with the 50% increase? It seems that although statistical studies of humans demonstrate
an association between EMF strength and cancer, laboratory research has not found the
331
332 Writing Lesson 11
mechanism by which EMFs actually cause cancer. So while the epidemiologists believe
there is a problem, the physicists don't buy it.
The report, rather than focusing on this association, instead centers on the lack of
physical proof: "No clear, convincing evidence exists to show that residential exposure
to electric and magnetic fields are a threat to human health." Yet in a dissenting
statement three committee members point out that, "Even in the case of cigarette
smoking, it took nearly 50 years after the demonstration of a statistical association with
lung cancer for scientists to define a cellular mechanism by which compounds in smoke
could definitely cause the cellular changes associated with lung cancer."
The report's executive summary, and chair Charles Stevens, argue that the
association of power lines with cancer could be pure coincidence. Other factors, such as
"age of home, housing density, and neighborhood traffic density," could be the cause of
the higher rates of leukemia.
But epidemiologists say that these other factors have been investigated and no
relationship has been found. "There is no good evidence to suggest that it is something
else [other than EMFs]—socioeconomic status, traffic density, or the type of neighbor-
hood," says committee member Larry Anderson of Pacific Northwest Labs. And
member Daniel Driscoll of the New York State Department of Public Services agrees.
By adopting an extremely high standard of proof to reach a conclusion of "guilty"
the committee ensured that it would exonerate the defendant, says Louis Slessin, editor
of Microwave News. Stevens also used "the oldest trick in the book," by issuing a press release that did not reflect the more balanced comments in the full report, adds Slessin.
Whose interests would be threatened by a conclusion that EMFs cause leukemia?
The conventional view, seconded by Larry Anderson, is that the electric utilities have the
most at risk, since their power lines criss-cross the nation, entering every community.
But, claims Slessin, "We are talking about all the technologies of the 21st century.
The number one interest group is the military." The modern military, he argues, is fully
dependent on electromagnetic fields, for weapons, reconnaissance and communications.
Physicists, such as those on the committee, whose work is heavily funded by the
military, "are doing the work of the Department of Defense, either consciously or
unconsciously," says Slessin.
So don't believe the reassurances from the National Academy of Sciences. Until
further notice, if you can avoid living near a power line, do so. And while you're at it,
stay away from military bases.
Resources: Possible Health Effects of Exposure to Residential Electric and Magnetic Fields,
National Research Council (National Academy of Sciences), October, 1996; "NAS Finds No
EMF-Cancer Link; Report Stirs Controversy," Microwave News, Nov/Dec 1996.
Marc Breslow, Dollars & Sense, May/June 1997
Power lines not a cancer risk for children
Children who live near high-voltage power lines appear to be no more likely to get
leukemia than other kids, doctors report today in the most extensive study of the
controversial issue ever done. Researchers in nine states studied 629 children with
leukemia and 619 healthy children. No child was admitted to the study unless the
Writing Lesson 11 333
investigators could measure the electromagnetic fields (EMF) in homes where the
children had lived 70% of the time. In addition, the researchers:
• Measured EMF in all homes where children under 5 had lived more than 6
months.
• Measured the EMF in homes where the mothers of 460 children—half of whom
had cancer—lived for 5 months of their pregnancy.
• Placed dose meters in the children's bedrooms for a day.
They found that children without cancer were exposed to the same levels of
electromagnetic energy as children with cancer, effectively ruling out EMF as a cause.
"Overall, I believe this study demonstrates that exposure to electromagnetic fields
does not increase a child's risk of leukemia," says Leslie Robinson, of the University of
Minnesota and a co-author of the report in today's New England Journal of Medicine.
The study, sponsored by the National Cancer Institute, is the latest of hundreds to
examine EMF and cancer. Parents nationwide have been alarmed and concerns have
cost the nation an estimated $1 billion a year in diminished real estate prices and stalled
power-transmission projects.
All of the studies, including the 1979 report that triggered these worries had
drawbacks. Indeed, the National Research Council, an arm of the National Academy of
Sciences, reported eight months ago that 500 studies over 17 years yielded no conclusive
evidence that household EMF causes cancer.
The overall finding comes with a caveat. A handful of children exposed to
moderately elevated EMF appeared to be 1.7 times more likely to develop cancer. In
contrast, smokers face a 20-fold increase in cancer risk.
However, the children's risk increase was so small—14 of the 19 had cancer—that
researchers believe it's a matter of chance.
Even more telling was evidence indicating that children exposed to much more
powerful energy fields faced no risk. USA Today, July 3, 1997
2. Should AIDS exhibit be OK'd as school field trip?
(This pair of arguments is from the Las Vegas Sun, March, 1996)
A. Yes: Information is not false; trustees should reconsider their decision
Sandra Thompson, managing editor of the Las Vegas Sun
The message is written in a teenage scrawl: "A friend of mine is always having
unprotected sex. I hope she doesn't have AIDS."
One of many comments in a book at the AIDS exhibit in the Lied Discovery
Children's Museum, it sums up one of the purposes of the exhibit: To inform people that
if they have sex, they can get AIDS.
And that message is causing a ruckus in the community.
The School Board—without having seen the exhibit—on February 13 voted against
approving it as a field trip for students. Members may reconsider their decision at a
March 12 board meeting since several have seen the exhibit since their vote.
All members should see the exhibit for themselves and then approve it as a field-trip
option.
334
Writing Lesson 11
The operative word here is "option."
By its vote, the School Board in effect made the decision for every parent. Critics
counter that parents still have the choice—they can take their kids to the museums
themselves.
/>
Sure. And they could do other things with them, spend time with them and get
involved in their education and extracurricular activities.
The reality is that many parents don't even attend their own children's school
activities let alone take them to a museum.
I agree with Nevada Concerned Citizens that parents should take a more active role
in their children's lives, especially education. They should know what their children are
learning.
The furor over students seeing the traveling national AIDS exhibit centers on a
perception that it does not stress abstinence, and talks about the risks of unprotected sex.
Nevada Concerned Citizens objects to wording in the exhibit literature that says to
protect yourself against AIDS, don't share needles and wear a condom during sex.
Members say that's misinformation because just doing that won't protect you, won't
prevent AIDS. After all, condoms break.
The objection is based on semantics. The exhibit does not say taking such
precautions will protect you 100 percent. And several times it mentions abstinence as
the safest and best way to avoid AIDS.
I'm a great believer in youths abstaining from sex. But look around you: Kids are
sexually active. They need information contained in the exhibit. They need to know
what can happen if they fool around.
The exhibit does not promote sex. Nor does it promote a certain lifestyle connected
with AIDS such as homosexuality, promiscuity or drug use.
"Whenever you deal with issues like this you set up alarms," Emily Newberry says
of the "What About AIDS?" exhibit. "These are touchy issues. It's not the easiest topic to bring up."
Newberry is the public affairs coordinator for the Lied Discovery Children's
Museum. She says the exhibit, which opened Feb. 3, is a national touring exhibit that
does not contain any misinformation. A local advisory board of health-care
professionals, educators and others reviewed the exhibit to ensure that.
"We got this exhibit because we were the only science museum in the state," she
says, adding that it contains strong science content "with a compassionate side."
If school field trips were approved for the AIDS exhibit, Newberry says students
would be accompanied by teachers and a school nurse who could clear up any perceived
misinformation.
Richard L Epstein Page 43
