CLAST Logical Reasoning 3 — Questions and Answers
Question 1: Which of the following is the contrapositive of 'If it is raining, then the ground is wet'?
- If the ground is wet, then it is raining
- If it is not raining, then the ground is not wet
- If the ground is not wet, then it is not raining (Correct answer)
- If it is raining, then the ground is not wet
Correct answer: If the ground is not wet, then it is not raining
The contrapositive of 'If P then Q' is 'If not Q then not P,' which is logically equivalent to the original statement.
Question 2: An argument that jumps from a few observed cases to a universal conclusion is guilty of:
- Circular reasoning
- Hasty generalization (Correct answer)
- False dilemma
- Straw man fallacy
Correct answer: Hasty generalization
Hasty generalization draws a broad conclusion from an insufficient or unrepresentative sample of evidence.
Question 3: The 'straw man' fallacy occurs when someone:
- Misrepresents an opponent's argument to make it easier to attack (Correct answer)
- Uses emotional language to sway an audience
- Cites an irrelevant authority to support a claim
- Draws a conclusion that doesn't logically follow from the premises
Correct answer: Misrepresents an opponent's argument to make it easier to attack
A straw man distorts or exaggerates the opposing view, then attacks that distorted version rather than the actual argument.
Question 4: If 'Some students are athletes' is true, which statement CANNOT be true at the same time?
- Some athletes are students
- All students are athletes
- No students are athletes (Correct answer)
- Some students are not athletes
Correct answer: No students are athletes
If at least some students are athletes, it is impossible that no students are athletes — these statements are contradictory.
Question 5: Which of the following is an example of deductive reasoning?
- I have seen 50 white swans, so probably all swans are white
- All mammals breathe air; dolphins are mammals; therefore dolphins breathe air (Correct answer)
- The last three winters were mild, so next winter will be mild
- Most students pass this test, so I will probably pass it
Correct answer: All mammals breathe air; dolphins are mammals; therefore dolphins breathe air
Deductive reasoning moves from general premises to a specific, logically guaranteed conclusion, as in the classic syllogism form.
Question 6: A politician says, 'You're either with us or against us.' This is an example of which fallacy?
- Ad hominem
- Slippery slope
- False dilemma (Correct answer)
- Appeal to authority
Correct answer: False dilemma
False dilemma (either/or fallacy) presents only two options as if they are the only possibilities, ignoring other alternatives.
Question 7: Which of the following arguments uses the valid form known as modus tollens?
- If P then Q; P; therefore Q
- If P then Q; not Q; therefore not P (Correct answer)
- If P then Q; Q; therefore P
- If P then Q; not P; therefore not Q
Correct answer: If P then Q; not Q; therefore not P
Modus tollens has the form 'If P then Q; not Q; therefore not P,' which is logically valid by denying the consequent.
CLAST Logical Reasoning 3
Which of the following is the contrapositive of 'If it is raining, then the ground is wet'?