Practice Test 2

Question 1

1. Because this is such an easy question, most students will get the right answer.

Answer 1

This question is an easy question. (EP)
2. All easy questions are questions that most students will get the right answer. (IP)
3. This question is a question that most students will get the right answer. (1,2)
Pattern:
1. x is an A.
2. All As are Bs.
3. x is a B.
This is a valid pattern, therefore the argument is valid. The premises are
reasonable to believe. Therefore, the argument is deductively strong.

Question 2

2. Most students who don’t do the assignments don’t know how to reconstruct arguments. So, if you didn’t do the assignments you’ll probably fail the test.

Answer 2

1. Most students who don’t do the assignments don’t know how to reconstruct arguments. (EP)
2. All students that don’t know how to reconstruct arguments will fail the test. (IP)
3. Most students who don’t do the assignments will fail the test. (1,2)
   The arguments pattern is:
4. Most As are Bs.
5. All Bs are Cs.
6. Most As are Cs.
   This is a valid argument pattern, so the argument is valid. I would say the premises are
   reasonable given my teaching experience. Therefore, the argument is deductively strong.

Question 3

3. Some metals are rare and costly. Therefore, some welder’s materials are rare and costly.

Answer 3

1. Some metals are rare and costly. (EP)
2. If some metals are rare and costly, then some welder’s materials are rare and costly. (IP)
3. Some welder’s materials are rare and costly. (1,2)
   Pattern:
4. P
5. If P then Q
6. Q
   The argument is valid by affirming the antecedent, but the P2 is unreasonable. Even
   though welders use metals, the metals they use may not be the metals that are rare and
   costly. Therefore, the argument is weak.

Question 4

4. I don’t believe that people are inherently selfish. Even though some people behave selfishly, my evidence suggests most people are generous and kind.

Answer 4

1. Most people are generous and kind. (EP)
2. All people that are generous and kind are not inherently selfish. (IP)
3. Most people are not inherently selfish. (1,2)
4. If 3, then 5.(IP)
5. All people are not inherently selfish. (3,4)
   The argument is valid. The pattern for the subargument is:
6. Most As are Bs
7. All Bs are Cs
8. Most As are Cs
   The argument pattern for the main is affirming the consequent. The premises are
   reasonable to believe. Therefore, the argument is deductively strong.

Question 5

5. Since reasons can be given for pieces of behaviour we usually call “irrational”, even this behaviour is rational, but at the subconscious level. It follows that irrational behaviour is “really” rational; thus, we are more rational than we usually suppose.

Answer 5

1. Reasons can be given for pieces of behaviour we usually call “irrational”. (EP)
2. If 1, then 3. (IP)
3. Pieces of behaviour we usually call “irrational” are rational. (1,2)
4. If 3, then 5. (IP)
5. Irrational behaviour is “really” rational. (3,4)
6. If 5, then 7. (IP)
7. We are more rational than we suppose. (5,6)
   The argument is valid by affirming the antecedent. P2 is unreasonable given our
   definition of rationality. Therefore, the argument is weak.

Question 6

6. Since people can do what they want to with their own bodies, a pregnant woman can get an abortion.

Answer 6

1. All people can (should be able to) do what they want to with their own bodies. (EP)
2. All pregnant women are people. (IP)
3. All pregnant women can do what they want with their own bodies. (1,2)
4. Having an abortion is doing something with your own body. (IP)
5. If 3 and 4, then 6. (IP)
6. All pregnant women can (should be able to) have an abortion. (3,4,5)
   The argument is valid. The pattern of the subargument is:
   All As are Bs
   All Bs are Cs
   All As are Cs
   The pattern of the main argument is affirming the antecedent.
7. is controversial. You could say it is unreasonable, reasonable, or suspend
   judgment, but need to give reason for your assessment. The argument is deductively
   weak or strong depending on what you said about the premises. Note: The
   conclusion is intended to be a normative claim, so Premise 1 should also be
   interpreted as such.

Question 7

1. No sane witnesses incriminate themselves. Some witnesses are just insane.

Answer 7

1. No sane witnesses incriminate themselves. (EP)
2. Some witnesses incriminate themselves. (IP)
3. Some witnesses are insane. (1,2)

Pattern:

1. No ABs are Cs
2. Some As are Cs
3. Some As are not Bs.

The argument is valid, but P1 is not reasonable to believe. P1 in standard form is: All witnesses who incriminate themselves are insane. Witness may incriminate themselves for reasons other than insanity (honesty, stupidity). Therefore, the argument is weak.

Question 8

2. Buildings over three hundred feet tall are skyscrapers, but there are buildings under three hundred feet tall, because skyscrapers are not the only examples of modern architecture.

Answer 8

1. All building over three hundred feet tall are skyscrapers. (EP)
2. Some buildings are not skyscrapers. (EP)
3. Some buildings are not over three hundred feet tall. (1,2)

Pattern:

1. All ABs are Cs
2. Some As are not Cs
3. Some As are not Bs

The argument is valid. P1 is reasonable, by the definition of skyscraper. My house is not a skyscraper, so P2 is reasonable. Therefore, the argument is deductively strong.

Question 9

3. I don’t think Stephen Harper is a good leader. He’s smart, but he only cares about the rich.

Answer 9

1. Stephen Harper only cares about the rich. (EP)
2. All people who only care about the rich are not good leaders. (IP)
3. Stephen Harper is not a good leader. (1,2)

Pattern:

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

The argument is valid. My evidence suggests both premises are reasonable to believe. Harper wants to lower the corporate tax rate which will only benefit the wealthy. A person who only cares about the rich, would be ignoring a significant portion of the population and thus would not be a good leader. Therefore the argument is deductively strong.

Question 10

4. You don’t really know anything. No matter what you believe you could be wrong.

Answer 10

1. All things you believe are things you could be wrong about. (EP)
2. All things you could be wrong about are things you don’t know. (IP)
3. All thing you believe are things you don’t know. (EP)

The argument is valid, its pattern is:

1. All As are Bs
2. All Bs are Cs
3. All As are Cs.

However, 2 is unreasonable. Logical truths are necessarily true.

Question 11

5. Since morals, therefore, have an influence on the actions and affections, it follows that they cannot be derived from reason; and that because reason alone, as we have already proved, can never have any such influence.

Answer 11

1. Morals have an influence on the actions and affections. (EP)
2. Reason alone can never influence the actions and affections. (EP)
3. If 1 and 2, then 4. (IP)
4. Morals cannot be derived from reason. (1-3)

The argument is valid by affirming the antecedent. P1 is reasonable: My moral beliefs effect what I do and what I like. P2 is reasonable: Logical truths cannot guide us in our actions or our likes. P3 is reasonable: If morals influence our actions and affections but reason alone does not, then it must be that morals cannot be derived from reason alone. Therefore, it is deductively strong.