Question Database: Critical Thinking
Conditionals
Which of the following argument patterns are valid?
I.
1. If P, then Q
2. P
Therefore:
C. Q
II.
1. If P, then Q
2. Q
Therefore:
C. P
III.
1. If P, then Q
2. Not P
Therefore:
C. Not Q
IV.
1. If P, then Q
2. Not Q
Therefore:
C. Not P
A. I and II only.
B. I and IV only.
C. I only.
D. I and III only.
Answer: B
Topic:
Conditionals.
Course Level:
First year, critical thinking.
Notes:
1. Capital punishment is justified if it actually deters people from committing crimes
2. Capital punishment does not deter people from committing crimes
Therefore:
C. Capital punishment is not justified.
A. Valid
B. Invalid
Answer: B
Topic:
Condtionals. Necessary and sufficient conditions.
Course Level:
First year, critical thinking.
Notes:
1. Sarah won't go to the party, if Sue is coming.
2. Sue is coming to the party.
Therefore:
C. Sarah won't go to the party.
A. Valid
B. Invalid
Answer: A
Topic:
Condtionals. Necessary and sufficient conditions.
Course Level:
First year, critical thinking.
Notes:
1. If Jane is at the party, Brian will be there too.
2. Brian is at the party.
Therefore:
C. Jane is at the party.
A. Valid
B. Invalid
Answer: B
Topic:
Condtionals. Necessary and sufficient conditions.
Course Level:
First year, critical thinking.
Notes:
1. If Bob is a marathon runner, he will have well developed leg muscles.
2. Bob does not have well developed leg muscles.
Therefore:
C. Bob is not a marathon runner.
A. Valid
B. Invalid
Answer: A
Topic:
Condtionals. Necessary and sufficient conditions.
Course Level:
First year, critical thinking.
Notes
A unless B
Examples:
You will fail the course unless you submit the final assignment.
The bulbs won’t produce flowers unless they are chilled.
A unless B is equivalent to:
A. If not B, then A
B. If not B, then not A
C. If A then B
D. If B then A
Answer: A
Topic:
Conditionals
Course Level:
First year, critical thinking.
Notes:
You will fail the course unless you submit the final assignment = If you do NOT submit the final assignment, you will fail the course.
The bulbs won’t produce flowers unless they are chilled = If the bulbs are not chilled, they won’t produce flowers.
A unless B is equivalent to:
If not B, then A = If not A, then B
A only if B
Examples:
There is rain only if there is cloud.
The rules allow you to enter only if you are over 18.
A only if B is equivalent to:
A. If A then B
B. If B then A
C. If not A then B
D. If not B then A
Answer: A
Topic:
Conditionals
Course Level:
First year, critical thinking.
Notes:
There is rain only if there is cloud = If there is rain, then there is cloud.
The rules allow you to enter only if you are over 18 = If the rules allow you to enter, then you are over 18.
A only if B is equivalent to: If A then B