Solutions Manual
INTroducTIoN To
Logic
FIFTEENTH EdITIoN
irving M. copi
carl cohen
Victor Rodych
, chapter 1
Section 1.2 Identify Premises and Conclusions
Exercises on pages 9–11
1. Premise: A well-regulated militia is necessary for the security of a free state.
Conclusion: The right of the people to keep and bear arms shall not be infringed.
2. Premises:
(1) It’s easier (than photocopying) to buy your friend a paperback copy of a book.
(2) A paperback copy of the book is inexpensive.
Conclusion: What stops many people from photocopying a book and giving it
to a pal is not integrity but logistics.
3. Premise: Human intelligence is a gift from God.
Conclusion: To apply human intelligence to understand the world is not an
affront to God, but is pleasing to him.
4. Premise: Sir Edmund Hilary dedicated his life to helping build schools and hospitals
for the Sherpas who helped him to climb Mount Everest.
Conclusion: He is, for that reason, a hero.
5. Premises:
(1) Standardized tests have a disparate racial impact, as illustrated by the differ-
ence in the average scores of different ethnic groups.
(2) Ethnic differences arise on all kinds of tests, at all levels.
Conclusion: If a racial gap is evidence of discrimination, then all tests discriminate.
6. Premise: Everybody thinks himself so abundantly provided with good sense that
even those most difficult to please in all other matters do not commonly desire
more of it than they already possess.
Conclusion: Good sense is, of all things in the world, the most equally distributed.
7. Premise: Any words new to the United States are either stupid or foreign.
Conclusion: There is no such thing as the American language; there’s just bad
English.
8. Premise: In New York State alone taxpayers spent more than $200 million in a failed
death penalty experiment, with no one executed.
Conclusion: The death penalty is too costly.
Premise: [There has been] an epidemic of exonerations of death row inmates
upon post-conviction investigation, including ten New York inmates freed in the
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Introduction to Logic
last eighteen months from long sentences being served for murders or rapes they
did not commit.
Conclusion: Capital punishment is unfair in its application, in addition to being
too costly.
9. Premise: Houses are built to live in, not to look on.
Conclusion: Use is to be preferred before [i.e., above] uniformity.
10. Premises:
(1) A boycott, although not violent, can cause economic harm to many.
(2) The greater the impact of a boycott, the more impressive is the statement it
makes.
(3) The economic consequences of a boycott are likely to be felt by innocent
bystanders, who suffer loss of income because of it.
Conclusion: The boycott weapon ought to be used sparingly.
11. Premises:
(1) In the early part of the 20th century forced population shifts were not
uncommon.
(2) In that period multicultural empires crumbled and nationalism drove the for-
mation of new, ethnically homogenous countries.
Conclusion: Ethnic cleansing was viewed not so long ago as a legitimate tool of
foreign policy.
12. Premises:
(1) If a jury is sufficiently unhappy with the government’s case or the govern-
ment’s conduct, it can simply refuse to convict.
(2) This possibility puts powerful pressure on the state to behave properly.
Conclusion: A jury is one of the most important protections of a democracy.
13. Premises:
(1) Orangutans spend more than 95 percent of their time in the trees, which,
along with vines and termites, provide more than 99 percent of their food.
(2) Their only habitat is formed by the tropical rain forests of Borneo and
Sumatra.
Conclusion: Without forests, orangutans cannot survive.
14. Premise: If God is omniscient, he must already know how he is going to intervene
to change the course of history using his omnipotence.
Conclusion: God cannot change his mind about his intervention.
Premise: God cannot change his mind about his intervention.
Conclusion: If God is omniscient he is not omnipotent.
Premise: If God is omniscient he is not omnipotent.
Conclusion: Omniscient and omnipotence are mutually incompatible.
15. Premises:
(1)
Reason never comes to the aid of spiritual things.
(2)
More frequently than not, reason struggles against the divine Word, treating
all that comes from God with contempt.
Conclusion: Reason is the greatest enemy that faith has.
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Solutions Manual
Section 1.4 Arguments and Explanations
Exercises on pages 19–22
1. This is essentially an explanation. What is being explained is the fact that humans
have varying skin colors. The explanation is that different skin colors evolved as
humans came to live at different distances from the Equator and hence needed
different degrees of protection from the rays of the sun. One might interpret the
passage as an argument whose conclusion is that skin color is not a permanent trait
of all humans. Under this interpretation, all the propositions preceding the final
sentence of the passage serve as premises.
2. This is an argument whose conclusion is that the victories of American labor through
the passage of ostensibly neutral laws regulating labor, were seriously adverse to the
interests of blacks, and resulted in the now longstanding gap between black and
white unemployment rates. One might interpret the passage simply as an explana-
tion, in which what is being explained is that gap, but this interpretation leaves
aside the many ramifications of the argument.
3. This is an explanation. What is being explained is why sex feels good. The expla-
nation is that those animals in which it does feel good have more offspring, and
therefore more evolutionary success, than those animals in which sex does not so
effectively motivate. If we did not know that sex feels good, this might be consid-
ered an argument to show that it does; but since the pleasure of sex is a fact not in
serious question here, the passage is best viewed as an explanation of that reality.
4. This is an argument. Its premises are that (1) changes are real and (2) changes are
only possible in time. The conclusion is that time must be something real.
5. This may be interpreted either as an explanation or as an argument. Viewed as an
explanation, what is being explained is the fact, not doubted here, that the nursing
shortage has turned into a crisis. The explanation of that fact is a combination of
observations, including the fact that fewer young people are going into nursing,
that many older nurses are on the verge of retirement, that nurses often report
high rates of job dissatisfaction and plan to leave the profession, and that hospitals
routinely cancel or delay surgical cases because of a lack of nursing staff. Viewed
as an argument, all these factors are premises supporting the conclusion that the
shortage of nurses has indeed turned into a crisis.
6. This is an argument. Dewey is calling attention to the fact that to show what caused
an event is not sufficient to justify it or to condemn it, because justification or con-
demnation comes (in his view) only through the consequences of the event, not
its origin.
7. This passage is mainly an argument, whose conclusion is that a king cannot be
subject to his own laws. Its premises are: (1) it is impossible to bind oneself in
any matter which is the subject of one’s own free exercise of will, and (2) the laws
are no more than the product of the king’s free will. The passage also serves as an
explanation of the words commonly used in completing edicts and ordinances of a
king: “for such is our good pleasure.” This reinforces the argument above, since the
king plainly cannot be bound by that which is determined only by his own good
pleasure.
8. This is a bit of Oscar Wilde’s humor that can be interpreted in various ways—as a sar-
donic argument attacking Wagner’s music, perhaps, or as a lighthearted explanation
