Deck 7: Syllogisms in Ordinary Language

Question 1

"No physicians are poverty-stricken.Some residents of Chicago are MDs.Therefore, some Chicagoans are not poor."
What, if anything, must be done to put this syllogism in the proper form to test it for validity?

A)Nothing.It is perfectly valid as it is.
B)The two terms in the conclusion are not represented exactly in the premises. "Residents of Chicago" needs to be replaced with "Chicagoans" and "poverty-
stricken" with "poor."
C)This syllogism contains six terms three pairs of which are synonyms.All three pairs must be reduced to one term each.
D)There is nothing that can be done to make this syllogism valid.

Answer 1

This syllogism contains six terms three pairs of which are synonyms.All three pairs must be reduced to one term each.

Question 2

"All logic professors are funny individuals.No businessman is a funny individual. Therefore, all businessmen are non-logic professors."
Is this argument ready for testing, or does it need to be rewritten?

A)No.It is clearly valid as it is.
B)The conclusion should be changed to its logically equivalent form "No busi- nessman is a logic professor."
C)The conclusion should be changed to its logically equivalent form "No non- logic professor is a businessman."
D)This syllogism is clearly invalid.No further testing is necessary.

Answer 2

The conclusion should be changed to its logically equivalent form "No busi- nessman is a logic professor."

Question 3

Consider a syllogism with the premise "Some logic professors are unreasonable." What, if anything, needs to be done to get it into standard form?

A)Nothing needs to be done.The terms are "logic professors" and "unreasonable."
B)Nothing can be done with this proposition because there are not really two different terms here.
C)Both terms of this proposition must be rewritten to eliminate adjectives. However when you do this the premise contains three terms not two.
D)The predicate term must be converted to a noun phrase, such as "unreasonable people."

Answer 3

The predicate term must be converted to a noun phrase, such as "unreasonable people."

Question 4

What is the correct standard-form translation of "Not every animal is a vicious beast"?

A)No animal is a vicious beast.
B)Some animal is a vicious beast.
C)Some vicious beast is not an animal.
D)Some animal is not a vicious beast.

Question 5

What is the standard-form translation of "None but qualified people need apply"?

A)All people who may apply are qualified people.
B)No non-applicants are not qualified people.
C)No person who is qualified is not a person who may apply.
D)All qualified people are people who may apply.

Question 6

In testing an enthymeme for validity, the logician must:

A)supply any missing information that logic requires and then treat it exactly as any other syllogism.
B)be careful to remember not to "read into" the material anything that is not explicitly stated.
C)supply any missing parts to the argument making allowances for the fact that this may make the argument slightly less plausible than might be desired.
D)supply any missing premises required by the logic of the argument, but remem- ber not to supply a missing conclusion; this is the same mistake committed
when the conclusion is diagrammed with a Venn diagram.

Question 7

"No person who cries is a person who can be trusted.Fred is a logic professor.No untrustworthy person is a logic professor.Therefore, Fred does not cry." To tell if this argument is valid, we must:

A)choose the relevant premises for deriving the conclusion and test the resulting syllogism for validity.The other premises are not relevant and need not be tested.
B)first derive the conclusion "some logic professors do not cry" and test that syllogism for validity.
C)first derive the conclusion "Fred is a trustworthy person" and test that syl- logism for validity.Then test a second syllogism which has that conclusion as a premise.
D)do nothing, since this argument is illogical.The conclusion cannot be derived from what is given.

Question 8

"Either I play ball, or I keep my new shoes clean.I can't resist playing ball, so I guess my new shoes will be getting dirty."
How should we label this argument?

A)an invalid argument that contains extraneous material
B)denying the antecedent
C)modus tollens
D)disjunctive syllogism

Question 9

Starting with the major premise, "If the heater is turned on, then the house will get warm," which of the following completed arguments commits the fallacy of
affirming the consequent?

A)The heater is turned on so the house is warm.
B)No one turned the heater on so the house must be cold.
C)The house is warm so someone must have turned on the heater.
D)The house is cold, so we know that no one turned on the heater.

Question 10

"Either I keep eating beef and get a heart attack, or I quit and eat yucky vegetables. Since I know I must either eat beef or not, I know I will be stuck either with yucky vegetables or a heart attack."
To escape between the horns of this dilemma, I might argue:

A)I haven't really considered the alternatives though.I can always learn to exer- cise more so that eating beef won't give me a heart attack.
B)Now that I think of it the outlook isn't so bleak.Lots of people manage on vegetables.I'll start eating more vegetables now so that I can avoid heart dis-ease later.
C)Let's look at it in a new light.Either I eat just enough beef to make my vegeta- bles taste OK now or I quit eating beef now and concentrate on looking for better food.Either way I end up with a different diet.
D)Of course, the choice shouldn't be between beef and vegetables.What I really need is to find more variety in foods.

Question 11

A second-order enthymeme is one in which the major premise is left unstated.

Question 12

In a disjunctive syllogism, one premise is a disjunction and the other premise denies
the truth of one of the disjuncts.

Question 13

"They told me that if I ran the mile in under four minutes, I'd be on the team.Well,
I did! So I am!"
This argument contains a pure hypothetical syllogism.

Question 14

"If someone turns on the sprinklers, my paint job will get wet.No one turned them
on, so I know my paint job is dry."
This argument is an example of modus tollens.

Question 15

The point of posing a counterdilemma is not usually to invalidate an opponent's
dilemma.

Question 16

Matching:

-An argument is a(n) ________ argument if it can be translated into a standard-form categorical syllogism.

A)syllogistic
B)valid
C)invalid

Question 17

Matching:

-In a ________ -order enthymeme, the minor premise is unstated.

A)third
B)second
C)First

Question 18

Matching:

-When you deny the consequent, you use the logical technique called modus ________.

A)tollens
B)ponens
C)operandi

Question 19

Matching:

-________ syllogisms contain "if ...then" propositions.

A)Hypothetical
B)Categorical
C)Disjunctive

Question 20

Matching:

-To "grasp a dilemma by the horns," you must show that one of the ________ it con- tains is false.

A)disjuncts
B)conjuncts
C)ambiguities