Practice Test 1

Question 1

i. What are the two main elements of argument analysis?

Answer 1

Reconstruction and evaluation.

Question 2

ii. Could an argument be both rhetorically powerful and rationally strong, or are these exclusive features?

Answer 2

An argument is rhetorically powerful if it persuasive. It is rationally if strong it provides good reasons to believe that the conclusion is true. An argument that provides good reasons to believe the conclusion could be persauasive, indeed it should be. Therefore, these are not mutually exclusive features.

Question 3

iii. Does the truth value of “Nearly everybody believes that the earth is round” depend on what people think about the topic?

Answer 3

It truth value depends on what people think about the shape of the earth but it doesn’t depend on what people think about the proposition.

Question 4

iv. Suppose I like butter tarts and you don’t like butter tarts. Do we disagree about the truth value of any proposition?

Answer 4

No. When I say “I like butter tarts”, ‘I’ refers to me. If you say “It’s not the case that I like butter tarts”, ‘I’ refers to you. Thus we do not disagree about the truth value of the proposition asserted by “I like butter tarts”. One might argue that we disagree about the proposition asserted by “Butter tarts taste good,” but in fact we don’t. When I assert “Butter tarts taste good,” I’m really only saying that I like the taste of butter tarts.

Question 5

v. Two arguments may satisfy the condition for being strong (for a certain person), but one of the arguments may be stronger than the other. How can this happen?

Answer 5

If the two arguments are deductively strong, one can be stronger than the other if the premises of one are more reasonable to believe than the other. If the two arguments are inductively strong, one can be stronger than the other, again, if the premises of one are more reasonable than the premises of the other. As well, the two arguments could differ in their degree of cogency.

Question 6

i. Suppose you know that an argument has all true premises and a true conclusion. What can you conclude about the status of the argument?
a. It’s valid
b. It’s cogent
c. It’s ill-formed
d. You can’t tell

Answer 6

Can’t Tell

Question 7

ii. Suppose you know that an argument has all false premises and a false conclusion. What can you conclude about the status of the argument?
a. It’s valid
b. It’s cogent
c. It’s ill-formed
d. You can’t tell

Answer 7

Can’t Tell

Question 8

iii. Suppose you know that an argument has all true premises and a false conclusion. What can you conclude about the status of the argument?
a. It’s valid
b. It’s cogent
c. It’s ill-formed
d. You can’t tell

Answer 8

Can’t Tell

Question 9

iv. Suppose you know that an argument has all false premises and a true conclusion. What can you conclude about the status of the argument?
a. It’s valid
b. It’s cogent
c. It’s ill-formed
d. You can’t tell

Answer 9

Can’t Tell

Question 10

v. Suppose you know that an argument is cogent and that its conclusion is false and that one of its two premises is true. What can you conclude about the truth value of its other premise?
a. Definitely true
b. Probably true
c. Probably false
d. Definitely false
e. Can’t tell

Answer 10

Can’t Tell

Question 11

Part 3. State whether the following argument is valid, cogent or ill-formed and give the argument’s pattern. If the argument is invalid, give an argument following the same pattern that clearly has true premises and a false conclusion.

1. Most logicians are highly intelligent.
2. Dr. Laverty is highly intelligent.
3. Dr. Laverty is a logician.

Answer 11

A: Logicians
B: People who are highly intelligent
x: Dr. Laverty

1. Most As are Bs.
2. x is a B.
3. x is an A.

Ill-formed

1. Most TTC drivers are male.
2. Stephen Harper is male.
3. Stephen Harper is a TTC driver.

Question 12

Part 4. Evaluate the following argument.

1. Most Canadians are not philosophers.
2. Dr. Laverty is Canadian.
3. Dr. Laverty is not a philosopher.

Answer 12

A: Canadians
B: Philosophers
x: Dr. Laverty

1. Most As are not Bs.
2. x is an A.
3. x is not a B.

The argument is cogent as it has a cogent pattern. Premise 1 is reasonable, there are far more Canadians that are not philosophers than Canadians that are philosophers. Premise 2 is reasonable. You know I teach at a Canadian university and most people who teach at Canadian universities are Canadian. However, you also know that I am a philosopher. Therefore you have evidence that shows that the conclusion is false. Therefore, the argument is defeated and hence weak.

Question 13

. Evaluate the following argument.

1. Grass is green unless Dr. Laverty is the pope.
2. Dr. Laverty is not the pope.
3. Grass is green.

Answer 13

P: Grass is green.
Q: Dr. Laverty is the pope.

1. P unless Q
2. ~Q
3. P

Written in standard form:

1. If ~Q then P
2. ~Q
3. P
   The argument is valid by affirming the antecedent. However, premise 1 is not reasonable to believe. The colour of grass has nothing to do with whether or not Dr. Laverty is the pope. Therefore, the argument is weak.

Question 14

. Evaluate the following argument.

1. The Leafs will win the Stanley Cup only if every other team loses.
2. Every other team will lose.
3. The Leafs will win the Stanley Cup.

Answer 14

P: The Leafs will win the Stanley Cup
Q: Every other team will lose.

1. P only if Q
2. Q
3. P

Written in standard form:

1. If P then Q.
2. Q.
3. P.

The argument is invalid by affirming the consequent. Therefore, the argument is weak.