LNAT Critical Analysis 5 — Questions and Answers
Question 1: A newspaper editorial states: 'Nine out of ten dentists recommend this toothpaste, so it must be the best.' What is the weakest point of this argument?
- Dentists are not qualified to evaluate toothpaste
- The sample of dentists and the criteria for 'best' are not specified (Correct answer)
- Toothpaste quality is entirely subjective
- Nine out of ten is not a meaningful statistic
Correct answer: The sample of dentists and the criteria for 'best' are not specified
Without knowing how dentists were selected or what 'best' means, the claim cannot be properly evaluated.
Question 2: Which of the following most accurately distinguishes between 'deductive' and 'inductive' reasoning?
- Deductive reasoning moves from specific cases to general principles; inductive reasoning does the opposite
- Deductive reasoning guarantees a true conclusion if premises are true; inductive reasoning only makes the conclusion probable (Correct answer)
- Deductive reasoning is used in science; inductive reasoning is used in law
- Inductive reasoning is always stronger than deductive reasoning
Correct answer: Deductive reasoning guarantees a true conclusion if premises are true; inductive reasoning only makes the conclusion probable
In valid deductive reasoning, true premises guarantee a true conclusion, while inductive reasoning yields only probable conclusions based on evidence.
Question 3: A court decision states: 'Because this defendant confessed, and confessions are reliable, he is guilty.' What assumption is the court relying on?
- The defendant had legal representation
- All confessions are always true and never coerced (Correct answer)
- Guilt requires more than a single piece of evidence
- The crime carries a custodial sentence
Correct answer: All confessions are always true and never coerced
The argument assumes confessions are inherently reliable, ignoring the possibility of false or coerced confessions.
Question 4: A commentator writes: 'Professor Smith supports rent control. But Smith was once arrested for tax evasion, so his economic views cannot be trusted.' This argument commits which fallacy?
- Appeal to authority
- Ad hominem (Correct answer)
- Tu quoque
- Genetic fallacy
Correct answer: Ad hominem
Attacking the professor's past conduct rather than addressing the merits of his economic argument is an ad hominem fallacy.
Question 5: Which of the following would most weaken the argument: 'Higher minimum wages cause unemployment because businesses cannot afford more labor costs'?
- Some businesses have large profit margins and can absorb higher wages without cutting jobs (Correct answer)
- Workers prefer higher wages to better working conditions
- Minimum wage laws vary by state
- Higher wages reduce worker turnover
Correct answer: Some businesses have large profit margins and can absorb higher wages without cutting jobs
If many businesses have sufficient margins to absorb higher wages, the premise that they cannot afford higher costs—and must cut jobs—is undermined.
Question 6: A passage concludes that a proposed policy is wrong because it was championed by a discredited politician. What type of fallacy is present?
- Appeal to nature
- Genetic fallacy (Correct answer)
- False analogy
- Equivocation
Correct answer: Genetic fallacy
The genetic fallacy dismisses an idea based on its origin or who supports it, rather than evaluating the idea on its own merits.
Question 7: An LNAT passage presents an argument with premises P1 and P2 leading to conclusion C. A student wants to show the argument is unsound. Which strategy is most effective?
- Argue that the conclusion C is undesirable
- Show that at least one premise is false or that C does not follow from P1 and P2 (Correct answer)
- Find a different argument that reaches a different conclusion
- Claim the author is biased
Correct answer: Show that at least one premise is false or that C does not follow from P1 and P2
Demonstrating that a premise is false or that the reasoning is invalid directly undermines the soundness of the argument.
LNAT Critical Analysis 5
A newspaper editorial states: 'Nine out of ten dentists recommend this toothpaste, so it must be the best.' What is the weakest point of this argument?