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Logical Flaws

245 questions

All types245Multiple choice128Multiple select41True / False16Matching60
Question 241Question →

Educational Researcher: A nationwide review of high schools reveals a strong positive correlation between schools offering competitive debate programs and schools reporting above-average scores on standardized mathematics assessments. Based on this data, the review concludes that participating in competitive debate inherently develops analytical skills that directly improve a student's mathematical reasoning.

Which one of the following most accurately describes a flaw in the researcher's argument?

Show answer & explanation

Answer: It infers that a particular educational program causes an improvement in academic performance based solely on an observed positive association between the two.

Answer

The argument is flawed because it infers that a particular educational program causes an improvement in academic performance based solely on an observed positive association between the two.
The correct answer accurately diagnoses the fundamental error in the researcher's reasoning: assuming that because two phenomena consistently appear together (debate programs and high math scores), one must be directly causing the other. It completely ignores the possibility of a third variable, such as school district wealth, which could simultaneously cause a school to afford both a debate team and better math resources.

Step-by-Step Solution

1
Analyze the argument's structure to identify the premises and the main conclusion.
Premise: There is a correlation between schools offering debate programs and higher math scores. Conclusion: Debate programs cause improved mathematical reasoning.
Separating facts from claims is the first step in identifying a logical flaw.
2
Evaluate the logical relationship between the premise and the conclusion to find the logical gap.
The premise only establishes that two things happen together (statistical association), but the conclusion makes a definitive causal claim.
Identifying the difference between what is proven (correlation) and what is claimed (causation) reveals the central vulnerability.
3
Match the identified flaw with the abstract descriptions provided in the answer choices.
The correct choice accurately describes inferring causation directly from an observed positive correlation.
LSAT flaw questions require translating the specific logical gap into a generalized description of the reasoning error.

Key Concept

Correlation vs. Causation
Question 242Question →

Infrastructure Commissioner: Our region's highway system is currently overwhelmed by the sheer volume of daily commuter traffic. To prevent a complete gridlock that would paralyze the local economy, we must immediately implement a strict congestion pricing system for all vehicles entering the metropolitan area. Therefore, since allowing our economy to be paralyzed is not an acceptable outcome, we have no choice but to enact the congestion pricing system.

Which one of the following most accurately describes a flaw in the infrastructure commissioner's reasoning?

Show answer & explanation

Answer: fails to consider the possibility that measures other than congestion pricing could effectively resolve the region's highway traffic issues

Answer

The correct answer identifies that the argument ignores alternative solutions, failing to consider that measures other than congestion pricing could resolve the traffic issues.
The author presents a binary choice: either implement congestion pricing, or suffer economic paralysis due to complete traffic gridlock. This reasoning is flawed because it assumes, without justification, that no other interventions—such as expanding public transportation, building new roads, or incentivizing remote work—could effectively prevent the gridlock. By ignoring these middle-ground or alternative possibilities, the argument commits a False Dilemma fallacy.

Step-by-Step Solution

1
Identify the argument's main conclusion.
The conclusion is that the city has no choice but to enact the congestion pricing system.
Understanding the final claim is necessary to evaluate the logic used to reach it.
2
Identify the premises supporting this conclusion.
Premise 1: Congestion pricing must be implemented to prevent complete gridlock. Premise 2: Complete gridlock would paralyze the economy, which is unacceptable.
Evaluating the reasoning requires mapping how the premises are supposed to guarantee the conclusion.
3
Analyze the logical gap between the premises and the conclusion.
The argument assumes that congestion pricing is the singular possible way to prevent traffic gridlock, ruling out any other alternatives.
Identifying unstated assumptions reveals vulnerabilities or flaws in the argument's structure.
4
Select the option that accurately describes this logical gap.
The correct option points out the failure to consider other measures to resolve the traffic issue.
The question asks for the flaw, which in this case is a false dilemma (ignoring alternative solutions to a problem).

Key Concept

False Dilemma (False Dichotomy)
Estimated Time:1m 30s
Question 243Question →

Evaluate the reasoning in the following four arguments. Pair each argument with the statement that most accurately describes the specific causal fallacy it commits.

Click a left item, then click its matching right item

Items

Data from coastal resorts indicates that weeks with the highest ice cream sales invariably experience the most shark sightings. Consequently, the local council determined that shark sightings induce psychological stress that tourists attempt to alleviate by consuming more ice cream.
Urban records reveal that historical districts with dense concentrations of coffee shops experience exceptionally high pedestrian traffic. City planners have therefore concluded that the establishment of new coffee shops is the primary driver generating this increased pedestrian traffic.
Over the past two decades, the global sale of printed encyclopedias has declined at exactly the same rate as the number of active landline telephones. This undeniable statistical alignment demonstrates that the shift away from landline communication directly decreases the desire to read physical books.
An office study revealed that employees who volunteered to use standing desks report significantly higher daily productivity than their seated colleagues. Management concluded that replacing all seated desks with standing desks will inherently boost the productivity of the entire workforce.

Matches

Show answer & explanation

Answer

The coastal resort argument matches the 'common underlying cause' flaw; the coffee shop argument matches the 'effect mistaken for cause' flaw; the encyclopedia argument matches the 'parallel trajectories' flaw; and the standing desk argument matches the 'self-selection' flaw.
Each argument represents a distinct variation of the correlation-to-causation error. The coastal resort argument illustrates a third-variable flaw (weather causes both). The historical district argument illustrates reverse causation (traffic causes shops). The encyclopedia argument illustrates coincidental alignment (both are victims of the broader digital age, not each other). The office study argument illustrates selection bias (productive people choose standing desks).

Step-by-Step Solution

1
Analyze the causal claim in the coastal resort argument (ice cream and sharks).
It claims sharks cause ice cream consumption, ignoring that summer heat drives both.
Identifying a missing third variable reveals the 'common underlying cause' fallacy.
2
Analyze the causal claim in the urban records argument (coffee shops and pedestrians).
It claims coffee shops generate pedestrian traffic, overlooking that businesses intentionally open where pedestrians already are.
Recognizing the flipped relationship reveals the 'effect mistaken for cause' (reverse causation) fallacy.
3
Analyze the causal claim in the encyclopedia and landline argument.
It links two declining technologies causally just because they happen at the same time.
Identifying unrelated long-term trends reveals the 'parallel trajectories' (coincidental correlation) fallacy.
4
Analyze the causal claim in the office standing desk argument.
It assumes forcing desks on everyone will yield the same results seen in volunteers.
Noticing that the initial group volunteered reveals the 'self-selection bias' fallacy.

Key Concept

Variations of the Correlation vs. Causation Fallacy
Question 244Question →

Op-ed: The regional forestry commission recently suggested restricting commercial logging in the old-growth sectors of the Whispering Pines reserve during the spring nesting season of the spotted owl. The commission's proposal is completely unreasonable. Banning all timber harvesting in the region permanently would devastate the local economy and leave hundreds of mill workers unemployed. We simply cannot afford to shut down the entire timber industry.

Which one of the following most accurately describes a flaw in the op-ed columnist's argument?

Show answer & explanation

Answer: It refutes an exaggerated version of the commission's proposal rather than addressing the specific limitations that were actually suggested.

Answer

The correct answer is the option indicating that the argument refutes an exaggerated version of the commission's proposal rather than addressing the specific limitations that were actually suggested.
This option perfectly describes the Straw Man fallacy present in the stimulus. The original proposal is temporary (spring season) and localized (old-growth sectors). The columnist completely ignores these limitations, instead evaluating the economic impact of a permanent, region-wide ban. By substituting an extreme policy for a moderate one, the columnist makes the proposal much easier to defeat.

Step-by-Step Solution

1
Analyze the scope of the original proposal.
The forestry commission's plan is heavily restricted: it applies only to 'commercial logging,' only in 'old-growth sectors,' and only 'during the spring nesting season.'
Identifying the exact parameters of the initial claim is essential to evaluating whether the rebuttal addresses it fairly.
2
Analyze the scope of the columnist's rebuttal.
The columnist attacks a policy of 'banning all timber harvesting in the region permanently' and shutting down 'the entire timber industry.'
Comparing the rebuttal to the original claim reveals any logical disconnects or distortions.
3
Identify the logical flaw committed by the columnist.
The columnist drastically broadens the scope and duration of the proposed restrictions, making the policy seem far more economically devastating than it would actually be.
Attacking a distorted, extreme version of an opponent's argument instead of the actual argument is the definition of a Straw Man fallacy.

Key Concept

Straw Man Fallacy
Question 245Question →

Dr. Lin: Currently, our conservation strategy for the silver-spotted salamander involves prohibiting public access to all major hiking trails in the valley. A more reasonable approach would be to close only those specific trails that pass within fifty meters of known breeding pools, and only during the spring mating season.

Dr. Vance: Your proposal is utterly irresponsible. If we simply abandon our conservation efforts and prioritize recreational hiking over the survival of an endangered species, the silver-spotted salamander will be extinct within a decade.

Which of the following most accurately describes the logical flaw in Dr. Vance's reasoning?

Show answer & explanation

Answer: attacks a distorted representation of the opponent's proposal rather than the actual proposal itself

Answer

The correct answer is the option stating that the reasoning attacks a distorted representation of the opponent's proposal rather than the actual proposal itself.
The correct answer accurately describes the Straw Man fallacy present in the dialogue. Dr. Lin advocates for a more targeted conservation strategy that closes specific trails near breeding pools. Dr. Vance responds by arguing against a completely different, much more extreme policy: abandoning conservation efforts entirely. By mischaracterizing Dr. Lin's position to make it easier to attack, Dr. Vance commits a flaw in reasoning.

Step-by-Step Solution

1
Analyze Dr. Lin's initial argument.
Dr. Lin advocates for replacing a total ban on hiking with a targeted ban near breeding pools during the mating season.
Establishing the baseline proposal is necessary to evaluate the second speaker's response.
2
Analyze Dr. Vance's rebuttal.
Dr. Vance claims Dr. Lin is proposing to 'abandon our conservation efforts' and 'prioritize recreational hiking over the survival' of the species.
Identifying how the second speaker interprets and addresses the first speaker's claim reveals their method of reasoning.
3
Compare the rebuttal to the original argument to pinpoint the logical flaw.
Dr. Vance severely exaggerates Dr. Lin's proposal. He transforms a targeted, specific conservation strategy into a complete abandonment of all conservation efforts, thereby attacking a position Dr. Lin did not take.
This structural disconnect defines the classic Straw Man fallacy, matching the correct description of the flaw.

Key Concept

The Straw Man Fallacy occurs when a speaker mischaracterizes, exaggerates, or distorts an opponent's argument, making the fabricated position easier to attack than the actual position.
Estimated Time:1m 30s
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Logical Flaws Practice Questions — LSAT — Page 13 | Examkin