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CHAPTER 2
Identifying
Arguments
The
starred items are also contained in the Answer Key at the back of The Power of Logic.
Exercise 2.1
Part A: Arguments and Nonarguments
*1. Nonargument
(explanation).
2. Nonargument
(conditional statement).
3. Nonargument
(report).
*4. Argument. Conclusion:
Waging war is always wrong.
5. Nonargument
(explanation).
6. Argument. Conclusion:
Today the principal threat to America is America
*7. Argument. Conclusion:
Pluto doesn’t act much like a
planet.
8. Nonargument
(conditional statement).
9. Nonargument
(report).
*10. Nonargument
(explanation).
11. Nonargument
(explanation).
12. Argument. Conclusion:
The population of the world
has grown both steadily and rapidly since 1950.
(Could also be read as a nonargument illustration.)
*13. Nonargument
(report).
14. Argument. Conclusion:
James died because he was
hanged.
15. Argument. Conclusion:
Not all tyrants avoid
prosecution.
*16. Nonargument
(illustration).
17. Nonargument
(conditional).
18. Nonargument
(illustration).
*19. Nonargument
(conditional).
20. Argument. Conclusion:
The U.S.
21. Nonargument
(conditional).
*22. Argument. Conclusion:
The good don’t always die
young.
23. Nonargument
(explanation).
24. Argument. Conclusion:
Some metals are liquids at
room temperature.
25. Argument. Conclusion:
Stealing is wrong simply
because society disapproves of it.
Part B: Constructing Arguments
*1. It
is morally permissible to experiment on nonhuman animals.
Premises: If it is not morally
permissible to experiment on nonhuman animals, then all new medical treatments
must be tried out initially on human subjects. But surely not all new medical
treatments must be tried out initially on human subjects.
2. It
is wrong to eat animals.
Premises: Most people do not eat
meat because they need it to live; rather, they eat meat because they like the
taste. But this is not a good enough reason to justify killing animals.
3. Marijuana
should be legalized.
Premise: The prohibition of
marijuana creates a lucrative underground market that is characterized by
violence.
*4. Only
violent criminals should be imprisoned.
Premises: Sending people to prison
tends to make them worse. And there are ways of controlling non-violent
criminals without sending them to prison.
5. Handguns
should be outlawed.
Premise: The vast majority of people
who are either murdered or killed accidentally are shot with handguns.
6. Society
has an obligation to provide housing for the homeless.
Premise: In general, we have an
obligation to help those less fortunate than ourselves.
*7. Americans
are too individualistic.
Premises: Most Americans insist on
using their own vehicles as opposed to public transportation. And this pattern
of behavior causes severe damage to the environment.
8. The
world is overpopulated with humans.
Premises: Environmental problems
result when too many people live in a given geographical area. And there are
currently serious environmental problems in virtually every country around the
globe.
9. It
is foolish to live in a modern city.
Premises: In a modern city the pace
of life is inhuman, the crime rate is high, the air quality is often poor, and
the traffic is dangerous.
*10. Beauty
is in the eye of the beholder.
Premise: People often disagree about
whether a given person or work of art is beautiful, whereas they seldom
disagree about the shape or weight of an object.
11. Large
corporations have too much political power.
Premises: Corporations can influence
politics quite significantly by contributing large financial gifts to those
running for public office. And what’s good for large corporations isn’t
necessarily good for the average citizen.
12. Nuclear
deterrence is irrational.
Premises: The effects of a nuclear
war are well known and simply horrible. It is irrational for nations to
threaten each other with nuclear weapons when the obvious alternative of
multilateral disarmament is available.
*13. It
is wrong to misrepresent one’s income on a tax form.
Premises: Lying is wrong, and
misrepresenting one’s income on a tax form is lying.
14. It
is not always wrong for a nation to wage war.
Premise: Surely a nation is not
morally obligated to surrender to every aggressive nation that goes on the
attack.
15. Torture
is never morally permissible.
Premise: Torture causes excruciating
pain that debases both victim and torturer.
Exercise 2.2
Part A: Identifying Arguments
*1. 1. The defendant is insane.
So,
2. The defendant is not guilty of
murder.
2. Not an argument
3. 1. American and Britain
2. Britain
So, (3) The United States should avoid
reducing the power of the state. (from 1 and 2)
*4.
1. The U.N. Food and Agriculture Organization
(FAO) reports that current food production can sustain world food needs even
for the 8 billion people who are projected to inhabit the planet in 2030.
So,
2. All the world’s farms currently
produce enough food to make every person on the globe fat.
5. 1. People fear death more than they fear life
imprisonment.
So,
2. The death penalty is a greater
deterrent than life imprisonment.
6. Not an argument.
*7. 1. Affirmative action involves giving a less
qualified person the job.
2. The most qualified person deserves the job.
So,
3. Affirmative action is unjust.
8. Not an argument
9. 1. If alcoholism is a disease, then it is
treated medically.
2. The primary mode of treatment is the 12-step
program of Alcoholics Anonymous.
3. AA’s 12-step program is religious in nature.
So,
4. Alcoholism is not treated medically.
(from 2 and 3)
So,
5. Alcoholism is not a disease. (from 1
and 4)
*10. Not an argument
11. Not an argument
12. 1. Most murderers, at the time when they commit
the act, are so full of hate or anger that they are completely unconcerned with
the long-term consequences of their actions.
So,
2. The death penalty does not deter
murder.
*13. Not an argument.
14. 1. Pacifists are either deeply insightful or
greatly mistaken.
2. If pacifists are deeply insightful, then it
is immoral for a policeman to kill a sniper who is firing at schoolchildren.
3. It is not immoral for a policeman to kill a
sniper who is firing at schoolchildren.
So,
4. Pacifists are not deeply insightful.
So,
5. Pacifists are greatly mistaken.
15. Not an argument
*16. 1. Empirical data are scientific.
2. Only what can in principle be shown false is
scientific.
So,
3. Empirical data can in principle be
shown false.
17. Not an argument.
18. 1. The probability of life evolving from nonlife
is so low as to be in the category of the miraculous.
2. If evolution is true, then there are “missing
links.”
3. The fossil record contains no missing links.
So,
4. There are no “missing links.” (from
3)
So,
5. The theory of evolution is highly
questionable. (from 1, 2, and 4)
*19. Not an argument
20. 1. Faculty salaries differ markedly by
discipline.
So,
2. If colleges gave equal pay for equal
work, then they would either (a) go broke paying all faculty high salaries or
(b) demoralize the more highly-paid faculty with severe pay cuts.
3. (a) would be disastrous, and so would (b).
So,
4. If the principle of equal pay for
equal work were applied to colleges, it would have disastrous consequences.
So,
5. The principle of equal pay for equal
work is untrue.
Part B: Identifying Missing Premises
*1. 1. Every woman has the right to do what she
wants with her own body.
2. Abortion is a use of one’s own body.
So, 3. Every woman has the right to an abortion.
2. 1. Abortion kills unborn human beings
2. It is wrong to kill unborn human beings.
So, 3. Abortion is wrong.
3. 1. Kurt is a cardiologist.
2. Cardiologists are usually smart.
So, 3. Kurt must be smart.
*4. 1. Harry is the hero of the story.
2. Heroes of stories are rarely killed early in books.
So, 3. Harry will not be killed at the beginning of
book 2.
5. 1. God created us.
2. If God created us, then we have an obligation to do what he tells
us to do.
So, 3. We have an obligation to do what God tells us
to do.
6. 1. I washed the dishes yesterday.
2. If I washed the dishes yesterday, then it is not my turn to wash
them (today).
So, 3. It is not my turn to wash the dishes (today).
4. Either it is my turn to wash the dishes (today), or it is your
turn.
So, 5. It is your turn to wash the dishes (today).
*7. 1. There have been documented cases of an
innocent person being wrongly convicted and executed.
2. If so, then capital punishment is unjust.
So, 3. Capital punishment is unjust.
4. Unjust forms of punishment should be abolished.
So, 5. Capital punishment should be abolished.
Or,
more simply:
1. There have been documented cases of an innocent person being
wrongly convicted and executed.
2. If so, then capital punishment should be abolished.
So, 3. Capital punishment should be abolished.
8. 1. The evidence regarding the deterrence effect
of capital punishment is inconclusive.
2. If the evidence regarding the deterrence effect of capital
punishment is inconclusive, then there is a chance that capital punishment
saves lives.
So, 3. There is a chance that capital punishment
saves lives.
4. If there is a chance that capital punishment saves lives, then we
should continue to practice it.
So, 5. We should continue to practice capital
punishment.
9. 1. William Shakspere of Stratford-on-Avon was an
uneducated man who had an illiterate daughter and owned no books.
2. No uneducated man with illiterate children and no books could have
written Hamlet, MacBeth and so forth.
So,
3. William Shakspere of
Stratford-on-Avon couldn’t have been the author of Hamlet, Macbeth, etc.
*10. 1. I find this class very boring.
2. Activities that we find boring are frequently too easy for us.
So, 3. This class is too easy for me.
Note that reversing the stated
premise and conclusion, here, makes the passage read more like a
nonargumentative statement.
11. 1. I cannot think of any reason that would
justify God in allowing so many horrible instances of suffering.
2. If I cannot think of any such reasons, then there are none.
So,
3. There is no reason that would justify
God in allowing so many horrible instances of suffering.
Note that “I cannot think of any”
cannot be here treated as a hedge without trivializing the argument.
12. 1. The only persons who did well in history 307
wrote essays that simply parroted the professor’s opinions.
2. Janice did well in history 307.
So, 3. Janice simply parroted the professor’s
opinions in her essays in history 307.
*13. 1. Well-behaved women rarely make history.
2. If well-behaved women rarely make history, then I (a woman) should
not behave myself.
So, 3. I should not behave myself.
Part C: More Identifying Arguments
*1. Not an argument
2. 1. Literary study is an education in how to
picture and understand human situations.
So,
2. The most essential and fundamental
aspect of culture is the study of literature.
3. 1. Naturalism is true.
2. If Naturalism is true, then the only facts we should believe in
are those compatible with the results of science.
So, 3. If moral realism requires facts
that are incompatible with science, then it is false.
*4. 1. Americans consume about 400 gallons of oil a
year per citizen – about 17% of our nation’s energy use – for agriculture,
aclose second to our vehicular use.
So,
2. Americans put almost as much fossil
fuel into our refrigerators as our cars.
5. Not an argument
6. 1. God exists.
2. If God exists, then a perfect being exists.
So,
3. A perfect being exists.
4. If God exists, then God created the world.
So,
5. A perfect being created the world
(from 1, 2, and 4)
6. If a perfect being created the world, then we
live in the best of all possible worlds.
So,
7. We live in the best of all possible
worlds. (from 5 and 6)
*7. 1. If each culture should be judged only by its
own moral standards, then no culture’s moral standards should be criticized.
2. Some cultures permit slavery, cannibalism,
and/or the oppression of women.
So,
3. The moral standards of some cultures
should be criticized. (from 2)
So,
4. It is not the case that each culture
should be judged only by its own moral standards.
8. 1. Good fiction is written more often than it is
read.
So,
2. As long as the appearance of a really
fine work of fiction is so rare on the best-seller lists, the nation’s teachers
of English have no right to be complacent about their service to literature.
So,
3. The blame for the failure to study
literature in a technical way may be shared by teachers and students.
9. Not an argument
*10. Not an argument
11. 1. Either murderers are rational enough to be
deterred by the death penalty or they are not.
2. If they are not rational enough to be
deterred by the death penalty, then the death penalty is not necessary.
3. If murderers are rational enough to be
deterred by the death penalty, then they are rational enough to be deterred by
life imprisonment.
4. If murderers are rational enough to be
deterred by life imprisonment, then capital punishment is not necessary.
So,
5. The death penalty is not necessary.
6. If the death penalty is not necessary, then
it should be abolished.
So,
7. The death penalty should be
abolished. (from 5 and 6)
12. There is room here for disagreement about
whether the passage is an argument. If it is an argument, the well-crafted form
would be along these lines:
1. If a person does not perform good actions
(just actions, temperate actions), then he or she will not become good (just,
temperate, etc.).
2. Philosophizing about being good will not
produce a healthy state of the soul any more than merely listening to a
doctor’s advice but not taking it will produce a healthy state of the body.
So,
3. A good (just, temperate, etc.) person
becomes good by doing what is good (just, temperate, etc.).
*13. 1. Deductive reasoning cannot have certainty
about its premises.
2. Inductive reasoning cannot have certainty
about its conclusions.
So,
3. Absolute proof is something which the
human being does not and cannot have.
14. 1. If a woman has an unlimited right over what
happens in and to her own body, then she has the right to drink heavily during
pregnancy.
2. If drinking alcohol heavily during pregnancy
causes birth defects, then a woman does not have the right to drink heavily
during pregnancy.
3. Drinking alcohol heavily during pregnancy
causes birth defects.
So,
4. A woman does not have the right to
drink heavily during pregnancy.
(from 2 and 3)
(from 2 and 3)
So,
5. A woman does not have an unlimited
right over what happens in and to her own body. (from 1 and 4)
15. 1. Children are not moral agents until they act
in a nonracist fashion even when discipline (rewards and punishments) is not in
view, and act in this way by acting on the principle of love and respect.
So,
2. Rewards and punishments do not by
themselves yield the moral life.
*16. 1. The civil disobedient withholds taxes or
violates state laws knowing he is legally wrong but believing he is morally
right.
2. M. L. King led his followers in violation of
state laws he believed were contrary to the federal Constitution.
3. Supreme Court decisions generally upheld
King’s many actions.
So,
4. M. L. King should not be considered a
true civil disobedient.
17. 1. In 1992 a small group of researchers in England
So,
2. There is no (natural) talent.
18. 1. Terrorism is the threat or use of violence
against noncombatants for political purposes.
2. In ordinary war, the deaths of civilians are
side effects of military operations directed against military targets.
3. In terrorist operations, the civilian is the
direct and intentional target of attack.
So,
4. George Washington was not a
terrorist; but neither were the truck-bombers who attacked the Marine compound
in Beirut in 1983; on the other hand, when states use murder and torture to
crush political dissent, they engage in terrorism.
*19. Not an argument
20. 1. Segregation gives the segregator a false
sense of superiority, and the segregated a false sense of inferiority.
So,
2. Segregation distorts the soul and
damages the personality.
So,
3. All segregation statutes are unjust.
4. Segregation ends up relegating persons to the
status of things.
So,
5. Segregation is not only politically,
economically, and sociologically unsound, but it is morally wrong and sinful.
(from 3 and 4)
So,
6. I (Martin Luther King, Jr.) can
(rightly) urge men to disobey segregation.
Part D: Argument Forms and Well-Crafted Arguments
*1. 1. H.
So,
2. If M, then L.
3. M.
So,
4. L 2, 3, modus ponens
2. 1. W.
2. If W, then A.
So,
3. A. 1, 2, modus ponens
4. If A, then I.
So,
5. I. 3, 4, modus ponens
3. 1. If
D, then T.
2. If R, then P.
3. Either D or R.
So,
4. Either T or P. 1, 2, 3, constructive dilemma
*4. 1. If
P, then C.
2. If C, then F.
So,
3. If P, then F. 1, 2, hypothetical syllogism
4. Not F.
So,
5. Not P. 3, 4, modus tollens
5. 1. If
M, then E.
2. Not E.
So,
3. Not M. 1, 2, modus tollens
6. 1. O
or D.
2. Not O.
So,
3. D. 1, 2, disjunctive syllogism
4. If D, then G.
So,
5. G. 3, 4, modus ponens
*7. 1. Either
E or A.
2. Not
A.
So,
3. E 1, 2, disjunctive syllogism
8. 1. G
or I.
2. If G, then D.
3. If I, then H.
So,
4. D or H. 1, 2, 3, constructive dilemma
5. If
E, then not D.
6. E.
So,
7. Not D. 5, 6, modus ponens
So,
8. H. 4, 7, disjunctive syllogism
9. 1. If
B, then D.
2. If D, then F.
So,
3. If B, then F. 1, 2, hypothetical syllogism
4. Not F.
So,
5. Not B. 3, 4, modus tollens
6. If not B, then S.
So,
7. S. 5, 6, modus ponens
*10. 1. If
S, then C.
2. If C, then A.
So,
3. If S, then A. 1, 2, hypothetical syllogism
4. If A, then U.
So,
5. If S, then U. 3, 4, hypothetical syllogism
6. If U, then W.
So,
7. If S, then W. 5, 6, hypothetical syllogism
Exercise
2.3
Note: Given the vagaries of the natural language, a certain amount of
interpretation is required in some of the following exercises.
Part A: Argument Diagrams
*1. 1[Photography
makes representational art obsolete] because 2[no one, not even the
best artist, can be more accurate than a camera.]
2
↓
1
2. In
spite of the fact that 1[electrons are physical entities,] 2[they
cannot be seen.] For 3[electrons are too small to deflect photons
(i.e., light particles).] Hence, 4[electrons are invisible.]
3
↓
2
3. 1[There
is a healthy kind of individualism—the kind that is resistant to group
tyranny. . . .] But 2[capitalist individualism is not concerned about promoting the growth of the person into emotional, intellectual, ethical and cultural fullness;] rather, 3[it fosters the development of individual traits only so far as these are useful for maximizing profits.] Thus, ironically, 4[capitalist individualism turns into a group despotism under which personal becoming is sacrificed to the external tyrannies of material gain.]
tyranny. . . .] But 2[capitalist individualism is not concerned about promoting the growth of the person into emotional, intellectual, ethical and cultural fullness;] rather, 3[it fosters the development of individual traits only so far as these are useful for maximizing profits.] Thus, ironically, 4[capitalist individualism turns into a group despotism under which personal becoming is sacrificed to the external tyrannies of material gain.]
2 + 3
↓
4
Note: The logical form of this
passage might be interpreted differently, such that (2) and (3) represent
distinct arguments for (4).
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