Practice Flaws & Assumptions questions for the Law School Admission Test. Every question includes a full explanation of why the correct answer is right and why the tempting distractors are wrong.
10 example questions with full explanations. Use the interactive practice above to work through the complete set.
Question 1medium
An argument states: 'Every member of the city council voted in favor of the new zoning law. Therefore, the city council, as a governing body, unanimously endorses unrestricted urban expansion.' The reasoning in this argument commits the composition fallacy by inferring that a property of the individual members — voting for the law — is shared by the council as a collective entity in a broader sense than the evidence supports.
Correct answer: B
The flaw here is actually a scope shift, not the composition fallacy. The composition fallacy would involve inferring a collective property from individual properties (e.g., 'each member is intelligent, so the council is intelligent'). In this argument, the individual members did vote for the law, and it is technically valid to say the council voted unanimously. The real problem is that the conclusion shifts scope: voting for a specific zoning law is extrapolated to mean endorsing the much broader concept of 'unrestricted urban expansion,' which is not supported by the premise. This scope shift — moving from a narrow action to a sweeping policy position — is the actual flaw, making the statement that this is a composition fallacy False.
Question 2medium
Consider this argument: 'Studies show that neighborhoods with more coffee shops have lower crime rates. Therefore, opening more coffee shops in high-crime areas will reduce crime.' A critic argues that this reasoning is flawed because it confuses a necessary condition with a sufficient one — having coffee shops is necessary for low crime, but not sufficient. This critic's diagnosis of the flaw is correct.
Correct answer: B
The critic's diagnosis is incorrect. The actual flaw in the argument is a correlation-versus-causation error: the argument observes that coffee shops and low crime co-occur and then assumes that coffee shops cause lower crime. The critic's claim — that the argument confuses necessary and sufficient conditions — does not accurately describe what is happening. The argument makes no conditional claim about necessity at all; it simply assumes that a correlated variable is causally responsible. Because the critic misidentifies the flaw, the statement is False.
Question 3medium
A politician argues: 'My opponent has proposed reducing the defense budget. But my opponent was cited for a minor traffic violation last year, so we should not trust his judgment on national security.' This argument is an example of an ad hominem attack, and ad hominem attacks are always logically invalid because a person's character or past behavior can never be relevant to evaluating their arguments or proposals.
Correct answer: B
The first part of the statement is correct — the politician's argument is indeed an ad hominem attack, using an irrelevant personal fact to dismiss the opponent's policy proposal. However, the second part of the statement is false: ad hominem attacks are not *always* logically invalid in every conceivable context. In some cases, a person's character or past behavior can be legitimately relevant — for example, when assessing a witness's credibility or evaluating whether someone has a conflict of interest. Because the blanket claim that personal information is *never* relevant is an overstatement, the full statement is False.
Question 4medium
An editorial argues: 'For decades, this city's public transit system was reliable and efficient. Therefore, the current administration's plan to overhaul the system is unnecessary — what worked before will continue to work today.' This argument contains a temporal flaw, and the conclusion would be strengthened if the arguer provided evidence that the conditions underlying the transit system's past success have not materially changed.
Correct answer: A
Both parts of this statement are correct. The argument does commit a temporal flaw: it assumes that because the system worked well in the past, it will continue to work well now and in the future, without accounting for changes in population, infrastructure aging, technology, or ridership patterns. This is a classic example of applying past conditions to present circumstances without justification. The second part is also correct: demonstrating that the underlying conditions have remained stable would directly address and weaken the temporal flaw, thereby strengthening the conclusion. The statement is True.
Question 5medium
A nutritionist argues: 'A diet high in antioxidants is healthy for the body's cells. Blueberries are high in antioxidants. Therefore, a person who eats only blueberries will be perfectly healthy.' A student identifies this as a hasty generalization because the nutritionist is drawing a broad conclusion from a single food source. This identification is accurate.
Correct answer: B
The student's identification is inaccurate. Hasty generalization occurs when a conclusion about a broad population or category is drawn from too small or unrepresentative a sample. That is not what happens here. The actual flaw is a scope shift combined with a false sufficiency assumption: the premise establishes that antioxidants are healthy for cells, but the conclusion leaps to the claim that a diet consisting exclusively of blueberries produces *perfect* health — ignoring that overall health requires protein, fats, vitamins, and other nutrients not found adequately in blueberries alone. The argument doesn't generalize from a small sample; it wrongly equates one beneficial property with complete nutritional sufficiency. Therefore, the student's diagnosis is wrong, and the statement is False.
Question 6easy
A politician argues: 'We must either raise taxes or cut public services. Since no one wants their taxes raised, we must cut public services.' Which of the following most accurately describes the flaw in this argument?
- A.The argument presents only two options as if no other alternatives exist, when additional options may be available.✓
- B.The argument attacks the character of those who support tax increases rather than addressing their position.
- C.The argument assumes that what is true of individual citizens must be true of the government as a whole.
- D.The argument uses the word 'want' in two different senses across its premises.
Correct answer: A
The argument commits a false dichotomy by presenting only two options — raise taxes or cut public services — as if these are the only possibilities. In reality, there could be other options such as reducing government waste, borrowing, or restructuring spending. Answer A describes ad hominem, which is not present here. Answer C describes a composition/division flaw, which is not applicable. Answer D describes equivocation, but 'want' is used consistently throughout the argument.
Question 7easy
A nutrition blogger writes: 'You should follow Dr. Henderson's advice to eat six small meals per day. Dr. Henderson is a world-renowned cardiologist who has published dozens of papers on heart disease.' The reasoning is flawed because:
- A.The argument draws a broad conclusion from a single case study.
- B.The argument relies on the opinion of an expert in a field unrelated to the claim being made.✓
- C.The argument mistakes a correlation between meal frequency and health for a causal relationship.
- D.The argument assumes that what worked in the past will necessarily work in the present.
Correct answer: B
This is a classic appeal to authority flaw. Dr. Henderson is cited as an expert in cardiology, not nutrition or dietary science, so his authority does not directly support advice about meal frequency. Being an expert in one field does not confer expertise in a related but distinct field. Answer A describes hasty generalization, which is not applicable here since no sample is referenced. Answer C describes correlation vs. causation, which is not the issue. Answer D describes a temporal flaw, which is also not present.
Question 8easy
An advertising executive says: 'Our new office building is the most energy-efficient in the city. Every floor uses LED lighting, recycled materials, and smart thermostats. Therefore, the building as a whole consumes less energy than any other building in the city.' The flaw in this reasoning is that:
- A.The argument confuses the cause of energy efficiency with its effects.
- B.The argument uses 'energy-efficient' to mean two different things in the same passage.
- C.The argument assumes that because each part of the building has efficient features, the entire building must be more efficient overall than other buildings.✓
- D.The argument relies on the testimony of a biased source to support its conclusion.
Correct answer: C
This is a composition flaw: the argument assumes that because each individual component of the building (floors) has energy-efficient features, the building as a whole must be the most energy-efficient in the city. However, a building could have efficient individual parts yet still consume more energy overall due to its size, usage, or number of floors. Answer A describes correlation vs. causation, which is not relevant. Answer B describes equivocation, which is not present here. Answer D describes appeal to authority or biased source, which is not applicable.
Question 9easy
A debate coach tells her students: 'A sharp mind is essential for winning debates. Steel is one of the sharpest materials known. Therefore, steel has a sharp mind.' The most accurate description of the flaw in this argument is:
- A.The argument draws a conclusion about all debates from evidence about only a few specific cases.
- B.The argument assumes that because winning debates is desirable, all means of achieving it are equally valid.
- C.The argument presents an either/or choice where more options are available.
- D.The argument uses the word 'sharp' in two different senses — intellectual acuity and physical sharpness — treating them as if they mean the same thing.✓
Correct answer: D
This argument commits equivocation by using the word 'sharp' in two entirely different senses. In the first premise, 'sharp' refers to mental acuity or intelligence. In the second premise, 'sharp' refers to a physical property of a material. By treating these two meanings as identical, the argument arrives at a nonsensical conclusion. Answer A describes hasty generalization, which is not present. Answer B introduces a false premise about means and ends not found in the argument. Answer C describes a false dichotomy, which is absent.
Question 10easy
A student argues: 'If you study hard, you will pass the exam. Maria passed the exam. Therefore, Maria must have studied hard.' Which of the following most accurately describes the flaw in this reasoning?
- A.The argument mistakes a sufficient condition for a necessary condition, assuming that because studying hard guarantees passing, passing must require studying hard.✓
- B.The argument draws a conclusion about Maria based on a sample that is too small to be representative.
- C.The argument attacks Maria's character rather than addressing the logic of the situation.
- D.The argument assumes that what was true of past students must be true of Maria today.
Correct answer: A
The argument confuses a sufficient condition with a necessary condition. 'Studying hard' is presented as sufficient for passing (if you study hard, you pass), but the argument then treats it as necessary (if you passed, you must have studied hard). This is the classic 'affirming the consequent' error. Option B is wrong because the argument makes no appeal to a sample group. Option C is wrong because no personal attack is made. Option D is wrong because no temporal comparison is involved.