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Chapter 11
Inductive Reasoning
Chapter Recap
• An argument from an analogy is an argument that something has an attribute because a
similar thing has that attribute.
• Thinking critically about arguments from analogy involves the principles stated on page
343.
• The time-honored strategy for rebutting an argument from analogy is to “attack the
analogy” by calling attention to important dissimilarities between the premise-analogue
and the conclusion-analogue.
• Scientific generalizing from samples differs from the everyday variety in that everyday
samples are not scientifically selected to eliminate bias, and probabilities in everyday
generalizations cannot be calculated precisely.
• Statistical syllogisms have this form: Most Xs are Ys; this is an X; therefore this is a Y.
• The strength of a statistical syllogism is distinct from the probability of its conclusion
everything considered.
• Arguments and causal statements often use the same vocabulary.
• Causal statements can be conclusions or premises in arguments, but not entire arguments.
• A causal hypothesis is a tentative causal statement offered for further investigation or
testing.
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occurrence of mutually exclusive events, conditional probabilities, and expectation value.
• The legal cause of an effect often requires a judgment regarding what causal agent is most
relevant.
Answers to Text Exercises
Exercise 11-1
1. ▲A
8. A
9. B
Exercise 11-2
1. ▲The premise-analogue is rats. The conclusion-analogue is humans. The attribute of
interest is saccharin as a cause of cancer.
2. The analogues are Gray’s performance as a businessman and as a mayor. The attribute of
interest is being successful. Gray’s performance as a businessman is said to have the
attribute; Gray’s performance as mayor is predicted to have it.
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is whether I will like it. His last movie is said to have this attribute; the current movie is
predicted to have it.
7. ▲The premise-analogue is December’s heating bill. The conclusion-analogue is January’s
Exercise 11-3
1. ▲The premise-analogue is iPods. The conclusion-analogue is iPads. The attribute of
interest is usability.
2. The analogues are almonds and hazelnuts. The attribute of interest is whether they are
upsetting to my stomach. Almonds are said to have the attribute; hazelnuts are predicted to
have it.
7. ▲The premise-analogue is auto insurance. The conclusion-analogue is health insurance.
The attribute of interest is that of being a good thing.
8. The analogues are the Greek economy and this economy. The attribute of interest is
collapse because of all the government pensions. The Greek economy is said to have the
attribute; this economy is predicted to have it.
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▲Exercise 11-4
Exercise 11-6
1. ▲This is stronger than a parallel argument that uses “Neptune” rather than “Mars” as an
analogue.
2. This is stronger than a parallel argument that uses “an office” rather than “an auto parts
store” as an analogue.
6. This is a little weaker than a parallel argument that uses “golf” rather than “bowling” as an
analogue.
Exercise 11-8
1. ▲The new supposition introduces a difference between past crops and this crop, so it
weakens the argument. Kirk should be less confident the new crop will be like the previous
crops.
2. The new supposition diversifies the past three occasions, increasing the likelihood the new
crop will replicate a condition of a mildewed crop. Kirk should be more confident the new
crop will be like past crops.
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This makes it less likely this year’s crop will be like previous crops.
5. The new supposition introduces a contrary analogue, which makes it less likely the new
crop will have mildew.
Exercise 11-9
1. ▲Not a general statement
Exercise 11-10
1. ▲Generalization from a sample
2. Statistical syllogism
9. Generalization from a sample
10. ▲Statistical syllogism
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Exercise 11-11
1. ▲A
2. B
9. B
10. ▲A
Exercise 11-12
1. ▲Most (all, nearly all, etc.) Otterhounds don’t fetch.
2. Most people who jog ten miles a day don’t have high blood pressure.
9. Most people would be upset by a husband who treats them in that way.
10. ▲Chabot Gap is a small town.
Exercise 11-13
1. ▲Most professional dancers are pretty athletic.
9. One often encounters trouble finding parking on New Year’s Eve.
10. ▲Christie probably won’t be a very good president.
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Exercise 11-14
1. ▲The sample is the ten Disney movies I have seen. The population is Disney movies. The
attribute of interest is that of being nonviolent.
2. The sample is my professors. The population is professors. The attribute of interest is that
of wearing glasses.
6. The sample is pianos the department sold last time. The population is pianos sold by the
department. The attribute of interest is that of being very overpriced.
7. ▲The sample is Costco store-brand coffee. The population is Costco store-brand products.
The attribute of interest is that of being as good as name-brand products.
Exercise 11-15
1. ▲The sample is a quart of milk. The population is things for sale at “this joint.” The
attribute of interest is that of being overpriced.
2. The sample is people from the Hamptons I’ve encountered. The population is people from
the Hamptons. The attribute of interest is that of being snobs.
7. ▲The sample is my performance on the first test. The population is my performance on
assessments in this class. The attribute of interest is that of having done well.
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8. The sample is the doorbell and the hot water heater in this house. The population is every
item in this house. The attribute of interest is that they are not working.
▲Exercise 11-16
1. Episodes of Survivor
▲Exercise 11-17
1. Olympic shot-putters
▲Exercise 11-18
1. Cowboys who are teachers
Exercise 11-19
1. ▲We’d speculate that a disproportionate number of Lexus drivers (a) own swimming
pools, (b) have a college degree, (c) are over 40 years old, and (d) think of themselves as
knowledgeable about politics.
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who has no teeth cavities, and (c) not be frequent imbibers of soft drinks or desserts.
4. ▲The population of people who are susceptible to poison ivy or poison oak might perhaps
include a disproportionate number of people (a) who are fair-skinned and (b) who are not
elderly. Dog owners and hikers are more apt to have cases of poison oak or poison ivy,
although they wouldn’t necessarily be more susceptible to the plight.
5. Handgun owners may disproportionately (a) own other firearms, (b) hunt, (c) fish, (d)
identify themselves as political conservatives, and (e) belong to the NRA.
11. We speculate that iPad owners might disproportionately (a) own iPhones, (b) have at least
some level of college education, (c) be under 55, and (d) consider themselves technically
Exercise 11-20
1. ▲a
Exercise 11-21
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1. ▲Given this supposition, the speaker should be less confident that most Ohio State
students say they believe in God.
2. Given this supposition, the speaker should be less confident that most Ohio State students
say they believe in God.
Exercise 11-22
1. ▲The six students who turned in written evaluations
2. Ludlum’s students
Exercise 11-23
1. ▲The speaker is implying that, in general, Dodge builds tough trucks. This evidently
means that Dodge trucks can be driven many miles on the original engine. This conclusion
2. This argument is relatively weak. The sample is small and potentially atypical.
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the sample is biased and for reason two is not very strong.
5. This is a weak argument. It is a potentially atypical sample.
6. This is a sweeping generalization about a diversified population based on a relatively tiny
Exercise 11-24
1. ▲Causal statement
2. Argument
10. ▲This is a causal statement, but the lateness of the hour could have been offered as
evidence that the bars are closed.
Exercise 11-25
1. ▲Causal statement (behavioral variety)
8. Causal statement