LSAT Argument Flaw Identification 2 — Questions and Answers
Question 1: Mayor: Our city's crime rate dropped 15% after we installed new streetlights. Therefore, the streetlights caused the reduction in crime. Which flaw does this argument commit?
- It confuses correlation with causation (Correct answer)
- It attacks the credibility of police officers
- It generalizes from an unrepresentative sample
- It relies on circular reasoning
Correct answer: It confuses correlation with causation
The argument assumes that because one event followed another, the first caused the second — a classic post hoc ergo propter hoc fallacy.
Question 2: Nutritionist: Either you eat a balanced diet or you will develop serious health problems. You eat a balanced diet. Therefore, you will not develop serious health problems. What is the flaw?
- It affirms the antecedent incorrectly
- It denies the consequent
- It affirms the disjunct, ignoring that both conditions can be false simultaneously
- It affirms the disjunct, ignoring that other causes of health problems exist (Correct answer)
Correct answer: It affirms the disjunct, ignoring that other causes of health problems exist
The argument treats 'balanced diet' as the only factor preventing health problems, ignoring genetics, exercise, and other variables.
Question 3: Senator: My opponent argues we should raise the minimum wage, but he has accepted donations from labor unions. His argument should therefore be dismissed. What flaw is present?
- Straw man — misrepresenting the opponent's position
- Ad hominem — attacking the source rather than the argument (Correct answer)
- False dichotomy — presenting only two options
- Appeal to authority — citing an unqualified expert
Correct answer: Ad hominem — attacking the source rather than the argument
The senator attacks the opponent's funding source rather than addressing the actual merits of the minimum wage argument.
Question 4: Coach: All of last year's championship teams had rigorous training programs. Our team has a rigorous training program. So our team will win the championship. What is the logical flaw?
- Affirming the consequent — treating a sufficient condition as necessary (Correct answer)
- Denying the antecedent — concluding incorrectly from a negation
- Hasty generalization — drawing conclusions from too few cases
- Equivocation — using 'rigorous' in two different senses
Correct answer: Affirming the consequent — treating a sufficient condition as necessary
Rigorous training may be a feature of championship teams without being sufficient alone to guarantee a championship.
Question 5: Philosopher: This action is moral because wise people throughout history have always done it. What is the primary flaw in this reasoning?
- It commits a false dichotomy between wisdom and morality
- It appeals to tradition as a substitute for moral argument (Correct answer)
- It attacks the character of those who disagree
- It equivocates on the meaning of 'moral'
Correct answer: It appeals to tradition as a substitute for moral argument
The argument uses historical practice as evidence of correctness without providing a reasoned justification for why tradition equals morality.
Question 6: Researcher: We surveyed 200 gym members and found they exercise four times per week on average. We can conclude that Americans exercise four times per week on average. What flaw does this contain?
- It argues from authority without citing credentials
- It draws a conclusion from an unrepresentative sample (Correct answer)
- It confuses necessary and sufficient conditions
- It commits a circular argument
Correct answer: It draws a conclusion from an unrepresentative sample
Gym members are not representative of all Americans; they are already a self-selected group predisposed to exercise.
Question 7: Editor: No great novel has ever been written quickly. This author took three years on her book. Therefore, her book must be great. Identify the flaw.
- It confuses a necessary condition for greatness with a sufficient one (Correct answer)
- It generalizes from the behavior of a single author
- It appeals to the popularity of slow-written novels
- It relies on an ambiguous definition of 'quickly'
Correct answer: It confuses a necessary condition for greatness with a sufficient one
Taking a long time might be necessary for greatness without being enough on its own to guarantee it.
LSAT Argument Flaw Identification 2
Mayor: Our city's crime rate dropped 15% after we installed new streetlights.
Therefore, the streetlights caused the reduction in crime.
Which flaw does this argument commit?