LSAT Argument Flaw Identification 3 — Questions and Answers
Question 1: Advertiser: Nine out of ten dentists recommend Bright Smile toothpaste. Therefore, Bright Smile is the best toothpaste available. What is the flaw?
- It treats a popular endorsement as proof of objective superiority (Correct answer)
- It attacks the credibility of the minority dentist
- It confuses correlation with causation
- It presents a false dilemma between toothpaste brands
Correct answer: It treats a popular endorsement as proof of objective superiority
Professional endorsement reflects preference or recommendation, not an objective measurement of superiority over all other options.
Question 2: Politician: If we allow same-sex marriage, soon people will want to marry animals. We must not allow same-sex marriage. What flaw does this illustrate?
- Ad hominem — attacking those who support same-sex marriage
- Slippery slope — assuming one change inevitably leads to an extreme outcome (Correct answer)
- Straw man — misrepresenting the proponents' position
- Equivocation — using 'marriage' in two different senses
Correct answer: Slippery slope — assuming one change inevitably leads to an extreme outcome
The argument claims one policy change will inevitably lead to extreme outcomes without providing evidence for each causal link.
Question 3: Executive: Our company has been profitable every year that Jenkins has been CEO. Jenkins must be the reason for our profitability. What is the flaw?
- Circular reasoning — the conclusion restates the premise
- Post hoc fallacy — assuming temporal association implies causation (Correct answer)
- False dichotomy — ignoring other leadership possibilities
- Hasty generalization — too small a sample of CEOs
Correct answer: Post hoc fallacy — assuming temporal association implies causation
Profitability occurring during Jenkins's tenure does not establish that Jenkins caused the profitability.
Question 4: Critic: You argue that we should fund the arts, but you yourself can't even draw a straight line. Your opinion is worthless. What flaw is present?
- Straw man — distorting the argument to make it easier to attack
- Ad hominem — dismissing a claim based on the person's irrelevant characteristics (Correct answer)
- Appeal to authority — citing an unqualified expert on artistic funding
- False analogy — comparing unlike funding situations
Correct answer: Ad hominem — dismissing a claim based on the person's irrelevant characteristics
The ability to draw has no bearing on whether arts funding arguments are logically sound.
Question 5: Investor: Either this company will become profitable or it will go bankrupt. It has not gone bankrupt. Therefore, it must now be profitable. What is the flaw?
- False dichotomy — ignoring intermediate states like break-even or stagnation (Correct answer)
- Denying the antecedent — incorrectly negating the first condition
- Circular reasoning — the premise and conclusion say the same thing
- Hasty generalization — based on limited financial data
Correct answer: False dichotomy — ignoring intermediate states like break-even or stagnation
A company can exist in states between profitability and bankruptcy, such as operating at break-even or surviving on loans.
Question 6: Scientist: Our lab tests showed that the drug worked on mice. Therefore, it will work on humans. What is the primary flaw?
- It draws an inference from a source that may not be analogous to humans (Correct answer)
- It appeals to scientific authority without providing peer-reviewed data
- It commits a circular argument by assuming the drug works
- It confuses necessary and sufficient conditions for drug efficacy
Correct answer: It draws an inference from a source that may not be analogous to humans
The physiological differences between mice and humans make generalizing results across species an unreliable inference.
Question 7: Parent: My son says he didn't steal the cookie, so he didn't steal it. Which reasoning flaw is illustrated?
- Circular reasoning — using the claim itself as the only evidence for the claim (Correct answer)
- Ad hominem — attacking those who accuse the son
- Slippery slope — assuming one theft leads to worse crimes
- False analogy — comparing the son to an honest person without basis
Correct answer: Circular reasoning — using the claim itself as the only evidence for the claim
The argument uses the son's denial as both the premise and the conclusion, providing no independent evidence.
LSAT Argument Flaw Identification 3
Advertiser: Nine out of ten dentists recommend Bright Smile toothpaste.
Therefore, Bright Smile is the best toothpaste available.
What is the flaw?