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IM – 4 | 1
Chapter 4
Credibility
Chapter Recap
This list summarizes the topics covered in this chapter.
• Claims lack credibility to the extent they conflict with our observations, experience, or
background information, or come from sources that lack credibility.
• The less initial plausibility a claim has, the more extraordinary it seems; and the less it fits
with our background information, the more suspicious we should be.
• Governments have been known to influence and even to manipulate the news.
• Sources like Wikipedia, institutional websites, and news organizations can be helpful, but
skepticism is the order of the day when we obtain information from unknown Internet
sources or advocacy TV.
What goes for advocacy television also goes for talk radio.
Advertising assaults us at every turn, attempting to sell us goods, services, beliefs,
and attitudes. Because substantial talent and resources are employed in this effort, we
need to ask ourselves constantly whether the products in question will really make
the differences in our lives that their advertising claims or hints they will make.
Advertisers are more concerned with selling something than with improving your
life. They are concerned with improving their own lives.
Answers to Text Exercises
▲Exercise 4-1
IM – 4 | 5
car as the former mechanic in a short time. We would not trust ourselves to be unbiased,
especially if the car is a sporty red convertible.
Exercise 4-12
1. ▲The most credible choices are either the FDA or Consumer Reports, both of which
investigate health claims of the sort in question with reasonable objectivity. The company
that makes the product is the least credible source because it is the most likely to be biased.
2. ▲It would probably be a mistake to consider any of the individuals on this list more expert
than the others, although different kinds and different levels of bias are fairly predictable
on the parts of the victim’s father, the NRA representative, and possibly the police chief.
3. ▲Although problem 2 hinges on a value judgment, this one calls for an interpretation of
the original intent of a constitutional amendment. Here, our choices would be either the
Supreme Court justice or the constitutional historian, with a slight preference for the latter
because Supreme Court justices are concerned more with constitutional issues as they have
been interpreted by other courts than with original intent. (And Supreme Court Justices are
Copyright ©2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill
Education.
4. We’d put the NIH and the New England Journal of Medicine at the top of our list. Time
5. Notice that this is not a biological question. If it were, a physician would be best at
answering it. Similarly, if it were a legal question, we’d trust the lawyer. But this is a
philosophical question, and we’d put the philosopher at the top of the list. The minister is
very likely to have theological prejudice on the issue, so we’d count him as probably
Exercise 4-13
2. Since he spent two years in Venezuela and is a consultant in “numerous developing
countries,” we think Pierce would be a credible source for both (a) and (b). His years in the
country would lead us to believe his opinion of both these matters would be worthwhile.
Exercise 4-15
1. ▲We’d accept this as probably true—but probably only approximately true. It’s difficult
to be precise about such matters; Campbell will most likely lay off about 650 workers,
including about 175 at its headquarters.
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provided here. Given the quotation from one of the parents who opposed Haskew, we
6. This is probably false.
7. This is probably false.
8. ▲We’d accept this as likely.
13. To the extent that we understand what the author is saying, we don’t believe it. These
observations conflict with the background knowledge of most sane people.
14. We are inclined to accept these claims because of the following reasons: (a) these claims
are made by staff writer for a reputable nontechnical science magazine (you can look him
up), who is probably well informed, (b) they are printed in Esquire, a magazine that is not
in general a suspicious source of information, and (c) they coincide with our own
observations that a person’s features seem to become more pronounced with age. The
claims are not particularly precise, and they are clearly general statements not intended to
apply to every individual to the same degree. All this said, we would be very pleased to see
a more authoritative source—for example a professor of physiology writing in a science
journal—pronounce them one and all false.
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story received much public confirmation from other sources.
18. There is probably some truth to the story, but we would not trust the details not to be
exaggerated and inflammatory.
Solution to triangle puzzle on page 100
If you look carefully, you’ll see that the hypotenuse (the topmost, longest line) of the two
Exercise 4-16
We think the credibility of the “Petition Project,” which Mr. Watts endorsed, is called into
Writing Exercises
Here are some things that can be said about these (although we usually leave this stuff up to you,
we just happen to have these remarks handy!).
1. We’re not reporting on a scientific poll when we say that more people believe that
professional “psychics” have supernatural powers than that stage magicians possess, but
we have asked number of classes of students and those seem to be the usual opinions. We
think there are a couple of explanations for the difference. For one thing, people are
accustomed to being fooled by one sort of trickery or another on television or on a stage.
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Copyright ©2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill
Education.
importance to their clients. Their subjects are ready to believe they are able to read the
future, contact the dead, find lost objects, and so on, because they really want to know their
futures, converse with their deceased loved ones, or find their lost objects. As is pointed
out in the text, we are much more likely to believe something we want to believe than
something in which we have less interest, even if the latter is accompanied by smoke,
bright lights, and white tigers.
2. We’re willing to concede that Charlie’s bringing us a photocopy or facsimile of a
newspaper adds somewhat to the story’s credibility, but since the story had so little
credibility to begin with, it remains highly dubious. We would say that it is still much more
likely to be false than true. One way to ask the crucial question is this: Which is more
likely—that there is fictitious evidence of an eighty-seven-year-old woman swimming
across Lake Michigan in the winter (e.g., a phony facsimile of the front page of a Chicago
newspaper) or that an eighty-seven-year-old woman actually made such a swim? Putting it
3. Students’ answers will vary.
