Quiz #1

Question 0

What are syllogisms?

Answer 0

Deductive arguments presented in the form of two supporting premises and a conclusion.

Question 1

Deductive arguments sometimes contain words or phrases such as…

Answer 1

Certainly
Definitely
Absolutely
Conclusively
Must be
It necessarily follows that

Question 2

A deductive argument is valid if…

Answer 2

The form of the argument is such that conclusion must be true if the premises are true.

For example:

P1: All cats are mammals.
P2: All tigers are cats.
C: Therefore, all tigers are mammals.

Question 3

What is form?

Answer 3

The pattern of reasoning in a deductive argument.

For example:

P1: All X are Y.
P2: All Z are X.
C: Therefore, all Z are Y.

Question 4

Does a false conclusion mean that the deductive argument is invalid?

Answer 4

No. The conclusion of a valid argument is false only if one of the premises are false.

For example:

P1: All men are tall people.
P2: Tom Cruise is a man.
C: Therefore, Tom Cruise is a tall person.

Question 5

An argument can also be invalid if…

Answer 5

Both premises are true and the conclusion is false.

For example:

All dogs are mammals.
Some mammals are not poodles.
Therefore, some poodles are not dogs.

Question 6

Is it also possible to have an invalid argument in which the premises are true and the conclusion happens to be true?

Answer 6

Yes, it is possible.

For example:

No seniors are freshmen.
All freshmen are college students.
Therefore, some college students are seniors.

Question 7

What is the following argument an example of?

P1: All men are mortal.
P2: All fathers are men.
C: Therefore, all fathers are mortal.

Answer 7

A valid argument. Is also a sound argument.

Question 8

An argument is sound if…

Answer 8

1) It is valid and 2) The premises are actually true.

Question 9

Argument by elimination

Answer 9

A deductive argument that rules out different possibilities until only one remains. Frequently used in everyday life.

Question 10

What is this an example of?

P1: My class is neither in room A, B, or C.
P2: My class is not in room A.
P3: My class is not in room B.
C: Therefore, my class must be in room C.

Answer 10

Argument by elimination

Question 11

Disjunctive syllogism

Answer 11

A type of deductive argument by elimination in which the premises present only two alternatives.

For example:

P1: Either A or B.
P2: Not A.
C: Therefore, B.

And vice versa.

Question 12

What is this an example of?

P1: Either Silver Blaze is at King’s Pyland or Silver Blaze is at Mapleton.
P2: Silver Blaze is not at King’s Pyland.
C: Therefore, Silver Blaze is at Mapleton.

Answer 12

Disjunctive syllogism

Question 13

What is a hypothetical syllogism?

Answer 13

A hypothetical syllogism is a form of deductive argument that contains two premises, at least one of which is a hypothetical or conditional “if… then” statement.

Question 14

How many basic patterns of hypothetical syllogisms are there? Which are they?

Answer 14

There are three: modus ponens, modus Tollens, and chain arguments.

Question 15

Modus Ponens

Answer 15

In this type of argument, there is one conditional premise, a second premise that states the antecedent, and a conclusion that asserts the truth of the consequent. Follows this form:

If A (antecedent), then B (consequent).
A.
Therefore, B.

Question 16

What is this an example of?

P1: If I get this raise at work, then I can pay off my credit-card bill.
P2: I got the raise at work.
C: Therefore, I can pay off my credit-card bill.

Answer 16

Modus ponens

Question 17

A modus ponens argument is invalid when…

Answer 17

The second premise affirms the consequent (B) rather than the antecedent (A).

For example:

If Oprah Winfrey is president, then she was born in the United States.
Oprah Winfrey was born in the United States.
Therefore, Oprah Winfrey is president.

Question 18

Modus tollens

Answer 18

The second premises denies the consequent, and the conclusion denies the truth of the antecedent.

If A (antecedent), then B (consequent).
Not B.
Therefore, not A.

Question 19

Here’s an example of _____.

If Morgan is a physician, then she has graduated from college.
Morgan did not graduate from college.
Therefore, Morgan is not a physician.

Answer 19

Modus tollens

Question 20

Arguments that are made up of three conditional propositions–two premises and one conclusion–linked together.

HINT:
If A, then B.
If B, then C.
Therefore, if A, then C.

Answer 20

Chain arguments. Here’s an example:

P1: If it rains tomorrow, then the beach party is cancelled.
P2: If the beach party is cancelled, we’re having a party at Rachel’s house.
C: Therefore, if it rains tomorrow, we’re having a party at Rachel’s house.

Question 21

What is the following an example of?

P1: If A, then B, and if C, then D.
P2: Either A or C.
C: So, either B or D.

Answer 21

Constructive Dilemma. Here’s an example:

P1: If it is hot, then I am grumpy and if it is raining, then I am happy.
P2: Either it is hot or it is raining.
C: Therefore, either I am grumpy or I am happy.