1.
Language is the incarnation of the mentality of the
race which fashioned it. Every phrase and word embodies some habitual idea of a
set of particular communities of men and women as they ploughed their fields,
tended their homes, and built their cities. For this reason, precise translations
of words and phrases from one language to another aren’t really possible.
2. Abraham Lincoln died because John Wilkes
Booth shot him with a pistol.
This is an explanation, since it is
common knowledge that Abraham Lincoln died.
2.
Experience has shown that international cooperation
to resolve global issues is possible, but states must recognize their
responsibilities toward one another if they are to live together peacefully.
There is no
inferential claim here, so this is not an argument. These are loosely-associated statements.
3.
Neither the chameleon nor the hypocrite can have
self-respect. Self-respect requires personal integrity: abiding
convictions, and action in agreement with convictions. Lacking firm convictions
and abiding affections, the chameleon-like person tailors his or her views to
fit changing circumstances. The hypocrite, in contrast, has lasting convictions
and emotional bonds, but betrays those convictions and bonds in his or her
conduct.
4.
Since the
This is a single statement. The word “since” here has a temporal meaning;
it is not a premise indicator.
PART II. (30
points, 6 points each) Determine whether the following arguments are inductive
or deductive. If inductive, determine whether strong or weak. If deductive,
determine whether valid or invalid. Explain
your answers. HINT: You can often use the general type of argumentation — argument from analogy, generalization from
a sample, causal argument, argument from signs, argument from authority,
categorical syllogism, disjunctive syllogism, hypothetical syllogism, etc. — to
help determine whether the argument is inductive or deductive. See the following examples.
FIRST EXAMPLE:
Question: “Most
Why? The arguer claims that the premises, if true,
make the conclusion likely. This is the
defining characteristic of inductive arguments.
Logically correct? (I.e., if deductive, valid or invalid;
if inductive, strong or weak – choose one)?
(You write) Strong
Why/ why not? In this
argument, the conclusion really would be likely if the premises were true. The first premise (“Most Americans live in
SECOND
EXAMPLE
Question: “All
Why? The argument is a disjunctive syllogism – one
of the forms that signifies deduction.
Logically correct? (valid or invalid, strong or weak –
choose one)? (You write) valid
Why/ why not? Disjunctive
syllogism is a valid form so all its substitution instances are valid
arguments The first premise (“All
Americans currently live either in Nevada or California”) is clearly false,
however, so the argument cannot be sound.
1. This morning there were drops of oil on the
pavement, right under the hood of Tom’s car. The drops were not there last night.
Probably Tom’s car has begun to leak oil.
Inductive or deductive? Inductive
Why?
This
is a causal argument.
Logically correct (valid or invalid,
strong or weak)? Strong
Why / why not? The conclusion is likely if the premises are
true. While it is possible the oil got
there some other way (e.g., practical joke, space aliens), the most likely
cause is an oil leak.
2. All mammals are cats. All cats are animals. So all mammals are animals.
Inductive or deductive? Deductive
Why?
This
is a categorical syllogism.
Logically correct (valid or invalid,
strong or weak)? Valid
Why / why not? The
conclusion has to be true if the premises are true. The argument is not sound, however, because
the premise “All mammals are cats” is false.
3. A porpoise is similar to a human being. It has lungs rather than gills. It is
warm-blooded rather than cold-blooded.
And porpoises nurse their young with milk. Therefore, porpoises, like
humans, are probably capable of speaking languages.
Inductive or deductive? Inductive
Why? (HINT: What type of argument is
this?) This is an argument by analogy.
Logically correct (valid or invalid,
strong or weak)? Weak
Why / why not? Many
relevant differences between porpoises and human beings make the conclusion
unlikely even if the premises are true. The similarities mentioned in the argument
(lungs, warm blood, nursing young) are due to the fact that humans and porpoises are both mammals. The ability to speak languages requires
specific anatomical structures
over and above those associated with mammals.
Possibly the argument is stronger if you define “speaking” and “language” very broadly, to include the sorts of vocalizations that some animals use in their communication.
4. The headline of
today’s New York Times says that
yesterday a hurricane struck
Inductive or deductive? Inductive
Why? This
is an appeal to authority. The arguer claims the hurricane report is true
because the New York Times reported it.
Logically correct (valid or invalid,
strong or weak)? Strong
Why / why not? The
New York Times is a reliable authority.
It is very unlikely the Times would invent a story like this.
5. If beings from other planets have visited us
and there is an official government cover-up, then the government would, of
course, deny any knowledge of these alien visits. The government does deny knowledge of these alien visits.
Therefore, creatures from other planets must have visited us and there is an
official government cover-up.
Inductive or deductive? Deductive
Why?
This is an argument
containing a conditional (if … then) statement.
Logically correct (valid or invalid,
strong or weak)? Invalid
Why
/ why not? The conclusion might be false even if the premises are
true.The government might deny knowledge of alien visits simply because
the government in fact has no such
knowledge.
Furthermore, this argument has the form
affirming the consequent, which is an invalid form,
and all arguments of this form are invalid.
PART III.
(20
points, 10 points each) Use the counterexample method to prove the following
arguments invalid.
1. All planets are round, so the earth must
be a planet, since the earth is round.
The conclusion is “the earth must be a
planet”. You know this because of the
conclusion indicator words
“so” and “must”.
Substitute
“WVC students” for “planets”
“humans” for “round”
“George W. Bush” for
“the earth”
Reorder the statement so the conclusion
comes last, but maintain the structure.
You get All
WVC students are humans. (true)
George W. Bush is a
human. (true)
Therefore George W. Bush
must be a WVC student. (false)
In the new argument the premises are
obviously true and the conclusion is obviously false.
Therefore, the original argument must be
invalid. If its form had been valid, the
conclusion could not be false
if all premises are true.
2. If
Substitute “
“Lindsay
Lohan” for “Becky”
You get
If
Arnold Schwartzenegger is married to Lindsay
Lohan, then Arnold Schwartzenegger is not a bachelor.
(true)
Arnold Schwartzenegger is not married to
Lindsay Lohan. (true)
Therefore, Arnold Schwartzenegger is
a bachelor. (false at the time this exam was given)
The premises are obviously true and
the conclusion is obviously false. (At the time this exam was given, it was common knowledge that Arnold Schwartzenegger was married to Maria Shriver.) PART IV. Multiple choice. (12 points, 2
points each) 1. Which of the following is a sufficient
condition for winning a football game? A. at the end of the game, having earned three
points more than the other team B. avoiding injury during play C. having a defense that is at least as good as
your offense D. showing up to play the game E. getting
at least one touchdown 2. Which of the following is a necessary
condition for passing a test? A. studying the material the night before B. showing up to take the test C. bringing “crib notes” to the test D. participating in a study group E. earning a score of at least C+ 3. Which of the following never occurs in an
invalid argument? A. true premises, true conclusion B. true premises, false conclusion C. false premises, false conclusion D. false premises, true conclusion E. invalid arguments can have any of the above
combinations 4. Which of the following statements is false? A. A sound argument may have a false premise. B. A sound argument must be valid. C. A sound argument cannot be an argument from
analogy. D. A sound argument cannot be strong. E. A sound argument cannot have a false
conclusion. 5. Which of the
following is not a premise indicator? A. implies that B. since C. for the reason that D. because E. for 6. Which of the following sentences is a
statement? A. No dogs are collies. B. How many dogs do you own? C. Get your dog off my lawn! D. Let’s get a dog. 7. If a deductive
argument has a true conclusion, then we know the argument is A. sound B. valid C. strong D. cogent E. none of the above 8. If a deductive
argument has a false premise, what do we know about the argument? A. It’s invalid B. It’s weak C. It’s unsound D. The conclusion is false E. None of the above PART V. True or
false? (28 points, 2 points each) 1. _____ If
a valid argument has only true premises, then it must have a true conclusion. True 2. _____ Every
invalid argument is unsound. True 3. _____
If an argument is not cogent, one or more of its premises must be false. False. An argument could fail to be cogent because
it is weak but all premises are
true. 4. _____
The inferential (logical) claim in an inductive argument is that it is
impossible for the premises to be true and the
conclusion false. False 5. _____ Some
arguments are false. False. Only 6. _____
Every valid argument with a true conclusion is sound. False 7. _____
Every valid argument with a false conclusion has at least one false premise. True 8. _____
The following argument is an argument from analogy: “According to Flew’s Dictionary of Philosophy, the British philosopher Bertrand Russell
died in 1970. So Bertrand Russell died in 1970.” False. It’s an appeal to authority. 9. _____ A
weak argument is one in which an arguer claims a conclusion is likely if some premises are true, and the
arguer’s claim is incorrect: i.e., the conclusion really isn’t likely if those
premises are true. True 10. ____ The
following argument is cogent: “Most humans fear death. Woody Allen (a real living human) is a human. Therefore Woody Allen fears death.” True 11. ____ It
is possible for a cogent argument to have a false conclusion. True 12. ____ A
statement is the kind of sentence that can have a truth value. True 13. ____ The
following inductive argument is weak: “There is intelligent life on all the following planets: Mercury,
Venus, Earth, Jupiter, Saturn, Uranus, Neptune. So it’s likely there is intelligent life
on Mars.” False. This is actually a strong inductive argument, because the premise (if true) makes the conclusion reasonable to believe. The problem here is that the
premises are false. This argument is strong but not cogent. 14. ____ A
conditional statement asserts that the consequent is necessary for the antecedent. True
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