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Parallel Flaw

34 questions

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Question 1Question →

Evaluate the flawed logic presented in the arguments below. Connect each specific argument to the generalized description of its underlying error.

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Items

Whenever a software development team relies heavily on automated testing, they produce highly stable applications. The new mobile app from Zenith Tech is highly stable, which proves that Zenith Tech's developers relied heavily on automated testing.
Historical data indicates that civilizations located near major river systems typically develop complex agricultural economies. It is therefore evident that settling near a major river system is what directly causes a civilization to develop a complex agricultural economy.
Any student who receives personal tutoring in mathematics will pass the final exam. Unfortunately, David did not receive any personal tutoring in mathematics this semester. We can conclude that David will fail the final exam.
Every single brick used in the construction of the historical monument is incredibly light and easy to carry. Therefore, the historical monument as a whole must be incredibly light and easy to carry.

Matches

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Answer

The arguments match their abstract flaws as follows: The software testing argument matches treating a sufficient condition as necessary. The river civilization argument matches inferring causation from association. The math tutoring argument matches concluding a result will not occur because a sufficient condition is absent. The brick monument argument matches assuming a characteristic of parts applies to the whole.
Each argument contains a distinct, identifiable logical error. The software argument affirms the consequent (illegal reversal). The river argument confuses correlation with causation. The tutoring argument denies the antecedent (illegal negation). The brick argument commits the fallacy of composition (part-to-whole). The correct pairings accurately align each argument's specific error with its generalized logical description.

Step-by-Step Solution

1
Analyze the software development argument.
Identified a conditional reasoning flaw where the premise 'A implies B' is incorrectly reversed to 'B implies A' (affirming the consequent).
To match the argument with the generalized description of treating a sufficient condition as necessary.
2
Examine the river systems argument.
Identified a causal reasoning flaw where a correlation between rivers and agriculture is incorrectly treated as a definitive cause-and-effect relationship.
To find the abstract description describing causal inference drawn from mere association.
3
Analyze the mathematics tutoring argument.
Identified a conditional reasoning flaw where the premise 'A implies B' is incorrectly manipulated to 'Not A implies Not B' (denying the antecedent).
To match the argument with the description of concluding a result won't occur because a sufficient condition is absent.
4
Evaluate the historical monument argument.
Identified a composition flaw where the physical properties of a building's materials are improperly attributed to the building as a whole.
To find the abstract description of assuming parts apply unconditionally to the whole.

Key Concept

Parallel Flaw
Question 2Question →

The annual spring festival will definitely not be held in the town square this year. We know this because the festival is held in the square whenever the municipal budget runs a surplus and the mayor's office approves the permit. However, the municipal budget is not running a surplus this year.

Which one of the following arguments exhibits a flawed pattern of reasoning most similar to that exhibited by the argument above?

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Answer: Whenever the beta testing phase finds no critical bugs and the marketing campaign is finalized, the new software update is released on schedule. Yet, because the marketing campaign has not been finalized, the software update will not be released on schedule.

Answer

The argument concluding that the software update will not be released on schedule because the marketing campaign has not been finalized.
The stimulus commits an illegal negation by treating a compound sufficient condition as a necessary one. It establishes that two things together (budget surplus AND permit approval) guarantee an outcome. It then points out that one of those things didn't happen, and concludes the outcome won't happen. The correct answer has the exact same structure: it establishes that two things (no bugs AND marketing finalized) guarantee an outcome (released on schedule), notes that one didn't happen (marketing not finalized), and relies on flawed logic to conclude the outcome will not happen.

Step-by-Step Solution

1
Analyze the stimulus to identify the conclusion and premises.
Conclusion: The festival will not be held in the square. Premise 1: If budget runs a surplus AND permit is approved, then the festival is held in the square. Premise 2: The budget is not running a surplus.
Deconstructing the argument into formal logic is necessary to identify the exact structural flaw before examining the choices.
2
Identify the logical flaw in the stimulus.
The flaw is an illegal negation of a compound sufficient condition. The argument assumes that because one required part of the sufficient condition failed, the necessary result cannot occur, ignoring that there could be alternate ways to trigger the result.
Knowing the precise flaw prevents being distracted by arguments that are flawed but structurally different.
3
Evaluate the answer choices to find the matching abstract structure.
The software update argument matches: Premise 1 is (No bugs AND marketing finalized) -> released on schedule. Premise 2 is ~Marketing finalized. Conclusion is ~Released on schedule.
The correct answer in a Parallel Flaw question must match both the specific logical error and the structural components of the original argument.

Key Concept

Parallel Flaw - Illegal Negation of a Compound Condition
Question 3Question →

We can conclude that the majority of modernist civic centers designed in the mid-twentieth century suffer from severe thermal regulation issues. After all, most of these civic centers incorporate extensive raw concrete facades, and it is well documented that most structures incorporating extensive raw concrete facades suffer from such thermal issues.

Which of the following arguments contains a flawed pattern of reasoning most similar to the one exhibited in the argument above?

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Answer: Most hybrid sedans currently on the market are equipped with regenerative braking systems. Therefore, most hybrid sedans require specialized mechanic certification to service, since the majority of vehicles equipped with regenerative braking systems require such certification.

Answer

The argument about hybrid sedans and regenerative braking systems.
The correct answer accurately replicates the 'chaining mosts' quantifier flaw seen in the stimulus. In the stimulus, the argument assumes that because most civic centers (A) have concrete facades (B), and most structures with concrete facades (B) have thermal issues (C), then most civic centers (A) must have thermal issues (C). The correct answer uses the exact same flawed reasoning: Most hybrid sedans (A) have regenerative braking (B), and most vehicles with regenerative braking (B) need certification (C), therefore most hybrid sedans (A) need certification (C). The order of the sentences is slightly varied, but the logical dependencies are identical.

Step-by-Step Solution

1
Abstract the logical structure of the stimulus.
Conclusion: Most A are C. Premise 1: Most A are B. Premise 2: Most B are C.
Identifying the formal structure allows for an objective comparison of reasoning patterns, independent of the subject matter.
2
Identify the specific logical flaw in the abstracted structure.
The flaw is Quantifier Overreach. Just because Most A are B, and Most B are C, it does not guarantee that the A's and C's overlap. (e.g., Most dogs are pets. Most pets are cats. Therefore, most dogs are cats. - Invalid).
Understanding why the stimulus is flawed ensures the correct answer choice is selected for the right structural reason.
3
Evaluate the answer choices to find the exact structural match.
The correct option abstract is: Premise 1: Most A are B. Conclusion: Most A are C. Premise 2: Most B are C. Despite a different ordering of premises and conclusion, the logical linkage and the flaw perfectly match the stimulus.
Parallel reasoning questions often vary the presentation order to test true structural understanding rather than superficial reading.

Key Concept

Parallel Flaw - Quantifier Overreach
Question 4Question →

A municipal government's achievement of a significantly reduced budget deficit is strictly contingent upon the implementation of comprehensive tax reforms. The implementation of such reforms, in turn, invariably precipitates widespread public dissatisfaction in the short term. Consequently, any municipality currently experiencing widespread short-term public dissatisfaction must have succeeded in significantly reducing its budget deficit.

Which one of the following arguments contains a flawed pattern of reasoning most similar to the one in the argument above?

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Answer: Consistently attending the weekly seminar invariably guarantees that a student will receive a glowing letter of recommendation from the department chair. Furthermore, a student's mastery of the advanced physics curriculum is strictly contingent upon their consistent attendance at this seminar. It follows that any student in possession of such a recommendation letter must have mastered the advanced physics curriculum.

Answer

The correct argument is the one concluding that any student possessing a recommendation letter must have mastered the advanced physics curriculum.
The stimulus exhibits an Illegal Reversal of a transitive conditional chain. It establishes that reducing a deficit (A) requires tax reforms (B), and tax reforms (B) always lead to dissatisfaction (C). The valid inference is A -> C. However, the stimulus concludes that experiencing dissatisfaction (C) proves the deficit was reduced (A). The correct answer structurally replicates this exact flaw: it establishes that mastery (A) requires attendance (B), and attendance (B) guarantees a letter (C). It then incorrectly concludes that having a letter (C) guarantees mastery (A). Although the premises in the correct option are presented in reverse order compared to the stimulus, the underlying flawed logical structure (A -> B, B -> C, therefore C -> A) is identical.

Step-by-Step Solution

1
Analyze the stimulus structure
The stimulus creates a conditional chain: Reduced Deficit -> Tax Reforms, and Tax Reforms -> Public Dissatisfaction. Therefore, the valid chain is: Reduced Deficit -> Public Dissatisfaction.
Mapping the exact conditional relationships between the premises is required before diagnosing the flaw.
2
Identify the logical flaw in the stimulus
The stimulus concludes that Public Dissatisfaction -> Reduced Deficit. This is an Illegal Reversal of the entire transitive chain.
You must pinpoint the exact nature of the error in abstract terms to find its structural parallel.
3
Evaluate the options for a matching structure
Look for an option that presents a chain (A -> B and B -> C) but concludes C -> A. The correct option regarding the physics curriculum has this exact structural error.
Parallel reasoning requires matching the abstract logical error, regardless of the subject matter or the order in which the premises are presented.

Key Concept

Parallel Flaw - Transitive Illegal Reversal
Question 5Question →

Assess the following four excerpts drawn from various specialized fields. Match each argument with the abstract description that most precisely identifies its logical vulnerability.

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Items

In modern architectural design, every individual load-bearing column used in the museum's new wing has been subjected to rigorous stress tests to ensure maximum tensile strength. From this, the chief architect has deduced that the entire architectural framework of the wing possesses maximum tensile strength.
Preserving the delicate ecological balance of the wetland reserve during periods of severe drought demands the systematic introduction of drought-resistant flora. The conservation authority has comprehensively introduced such flora throughout the reserve this season; hence, the wetland's ecological balance will certainly be preserved.
An extensive epidemiological study found that individuals who consume high amounts of synthetic antioxidants exhibit a notably lower incidence of degenerative joint diseases than those who do not. This conclusively demonstrates that the ingestion of synthetic antioxidants prevents the deterioration of joint cartilage.
The municipal zoning code explicitly states that exemptions for commercial building height restrictions are granted only to structures serving a 'public interest'. The proposed luxury high-rise will generate massive public interest due to its controversial design and celebrity architect. Consequently, the high-rise qualifies for the height restriction exemption.

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Answer

The architectural argument exhibits a Composition flaw; the wetland argument exhibits a Necessary vs. Sufficient flaw; the epidemiological argument exhibits a Correlation vs. Causation flaw; and the zoning argument exhibits an Equivocation flaw.
Each excerpt perfectly maps to a foundational logical fallacy: generalizing from parts to a whole (Composition), treating a requirement as a guarantee (Necessary vs. Sufficient), inferring causation strictly from correlation, and shifting the definition of a key term mid-argument (Equivocation).

Step-by-Step Solution

1
Analyze the architectural argument's structural shift.
The premise addresses individual columns, but the conclusion addresses the entire framework.
Identifying the shift from component parts to the entire integrated system isolates the Part-to-Whole (Composition) logical error.
2
Analyze the conditional logic in the wetland argument.
The argument states introducing flora is required ('demands') but concludes it guarantees the outcome ('will certainly be preserved').
Recognizing the conflation of a requirement with a guarantee pinpoints the Confusion of Necessary and Sufficient conditions.
3
Evaluate the evidence-to-conclusion leap in the epidemiological argument.
The evidence is a statistical association, yet the conclusion asserts a direct preventative mechanism.
Noting the transition from correlational data to a definitive causal claim highlights the Correlation vs. Causation fallacy.
4
Examine the usage of key terminology in the zoning argument.
The phrase 'public interest' shifts from meaning civic utility in the premise to meaning widespread curiosity in the conclusion.
Spotting the semantic manipulation of a single phrase reveals the Equivocation fallacy.

Key Concept

Identifying and abstracting formal logical flaws (Parallel Flaw)
Question 6Question →

If a software application incorporates end-to-end encryption, it cannot be effortlessly intercepted by third-party eavesdroppers. The new messaging platform 'ChatSecure' cannot be effortlessly intercepted by third-party eavesdroppers. Therefore, 'ChatSecure' must incorporate end-to-end encryption.

Which one of the following arguments contains a flawed pattern of reasoning most similar to the one exhibited in the argument above?

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Answer: If a novel wins the prestigious Booker Prize, it will experience a massive surge in sales. The debut novel 'Echoes' recently experienced a massive surge in sales. Hence, 'Echoes' must have won the Booker Prize.

Answer

The argument concluding that a novel must have won the Booker Prize because it experienced a surge in sales.
The correct answer accurately mirrors the illegal reversal (affirming the consequent) found in the stimulus. The stimulus establishes a conditional statement 'If A (encryption), then B (no interception)', notes that B occurred, and incorrectly concludes A must have occurred. Similarly, the correct choice establishes 'If A (Booker Prize), then B (sales surge)', notes that B occurred (Echoes had a sales surge), and identically missteps by concluding A occurred (Echoes won the Booker).

Step-by-Step Solution

1
Analyze the logical structure of the stimulus argument.
Premise 1: If end-to-end encryption (A), then cannot be intercepted (B). Premise 2: ChatSecure cannot be intercepted (B). Conclusion: Therefore, ChatSecure uses end-to-end encryption (A).
Breaking down the argument into abstract conditional components makes it easier to identify the structural flaw.
2
Identify the specific logical flaw committed in the stimulus.
The argument commits a conditional logic error known as an illegal reversal, or affirming the consequent. It incorrectly assumes that because the necessary condition (B) is met, the sufficient condition (A) must have occurred.
Knowing the exact name and mechanism of the flaw is required to find its parallel.
3
Evaluate the answer choices to find the exact structural match.
The argument regarding the Booker Prize follows the exact same pattern: If Booker Prize (A), then sales surge (B). Sales surged (B). Therefore, Booker Prize (A).
Parallel flaw questions require matching the underlying abstract structure exactly, regardless of whether the subject matter is entirely different.

Key Concept

Illegal Reversal (Affirming the Consequent) in Conditional Logic
Estimated Time:1m 30s
Question 7Question →

Read the four short passages below, drawn from diverse fields of study. Each passage contains a specific error in reasoning. Select the abstract description that best identifies the structural flaw present in each argument.

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Items

If a cryptographic network implements decentralized hash verifications, it will successfully repel coordinated denial-of-service attacks. The 'Aegis' network recently repelled a massive, coordinated denial-of-service attack. Therefore, the Aegis network must have implemented decentralized hash verifications.
Every individual vocalization identified in the newly recorded dialect of the isolated mountain community is a variation of standard lowland vowels. Consequently, the dialect as a whole must simply be a variation of the standard lowland language.
Whenever ocean temperatures drop below the historical average in the equatorial Pacific, migratory patterns of the Bluefin tuna are severely disrupted. Forecasts indicate that equatorial Pacific temperatures will remain well above the historical average this year. We can therefore conclude that the migratory patterns of the Bluefin tuna will not be severely disrupted.
Archaeological surveys demonstrate that in medieval settlements where rye cultivation was prevalent, incidences of joint disease were remarkably low. This strongly suggests that a diet rich in rye actively prevents the onset of joint disease.

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Answer

The cryptographic network argument pairs with inferring a condition from its result; the dialect argument pairs with drawing conclusions about a whole from its parts; the oceanography argument pairs with assuming an outcome is avoided if one sufficient condition is absent; and the archaeology argument pairs with mistaking correlation for causation.
Each abstract description perfectly captures the logical error committed in its corresponding argument without relying on the specific vocabulary of the argument's topic. By mapping the conditional, compositional, and causal errors to their respective formal descriptions, the underlying flaw is correctly identified.

Step-by-Step Solution

1
Analyze the cryptographic network argument.
Identified structure: A ensures B. B occurred. Therefore, A occurred.
This reveals an 'Illegal Reversal' flaw, which confuses a sufficient condition with a necessary condition.
2
Analyze the linguistic dialect argument.
Identified structure: All parts (vocalizations) have trait X. Therefore, the whole (dialect) is X.
This represents the 'Fallacy of Composition', attributing a property of parts to the entirety of a system.
3
Analyze the oceanography argument.
Identified structure: A causes B. Not A. Therefore, Not B.
This represents an 'Illegal Negation' flaw, incorrectly assuming that avoiding one sufficient trigger guarantees the outcome will not happen.
4
Analyze the archaeology argument.
Identified structure: Phenomenon A and Phenomenon B occur together. Therefore, A causes B.
This matches a basic correlation-to-causation fallacy.

Key Concept

Identifying abstract logical flaws across different topics by recognizing underlying structural patterns.
Estimated Time:2m 0s
Question 8Question →

Match each flawed argument on the left with the abstract description of its logical error on the right.

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Items

If a commercial airline upgrades its fleet to next-generation jets, its fuel efficiency will inevitably improve. Skyline Airways has reported improved fuel efficiency this year. Therefore, Skyline Airways must have upgraded its fleet to next-generation jets.
Recent labor market data reveals that regions with the highest number of co-working spaces also experience the highest rates of freelance job growth. Therefore, opening more co-working spaces directly causes freelance job growth in a region.
Every individual brick used in the exterior facade of the new stadium is extremely light and can be easily lifted by one person. Consequently, the fully assembled stadium facade must also be extremely light and easily lifted by one person.
The national constitution guarantees the right to a free press. Since the dominant media conglomerate charges exorbitant subscription fees for its daily newspaper, it is clearly violating the constitution.

Matches

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Answer

The correct matches are: the airline argument matches the sufficient/necessary flaw, the labor market argument matches the correlation/causation flaw, the stadium argument matches the whole/part flaw, and the newspaper argument matches the shifting meaning flaw.
Each argument contains a specific, distinct logical error that maps exactly to one abstract description. The airline argument illegally reverses a conditional statement. The labor market argument confuses correlation for causation. The stadium argument commits a part-to-whole composition error. Finally, the newspaper argument equivocates on the meaning of the word 'free'.

Step-by-Step Solution

1
Analyze the airline argument for its logical structure.
The argument assumes that since the result (fuel efficiency) happened, the stated trigger (jet upgrades) must have been the cause.
Identifying the formal logic structure reveals an illegal reversal of a conditional statement.
2
Analyze the labor market argument.
The argument takes an observed coincidence (co-working spaces and job growth happening together) as absolute proof of causation.
Separating the premise (correlation) from the conclusion (causation) isolates the causal flaw.
3
Analyze the stadium argument.
The argument assumes a property of the individual bricks (being light) must apply to the entire completed facade.
Recognizing the shift in scope from components to the aggregate identifies a composition flaw.
4
Analyze the newspaper argument.
The argument shifts from 'free' meaning unrestricted speech to 'free' meaning no financial cost.
Tracking the definition of key terms uncovers an equivocation flaw.

Key Concept

Identifying abstract descriptions of logical flaws (Parallel Flaw)
Question 9Question →

The following arguments each demonstrate a common logical vulnerability. Which abstract description best identifies the flawed pattern of reasoning used in each argument?

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Items

A thriving marine ecosystem invariably features a diverse population of apex predators, as these predators regulate the populations of smaller marine life. Survey data from the Emerald Reef indicates a highly diverse population of apex predators currently inhabits the area. Therefore, the Emerald Reef must be a thriving marine ecosystem.
To stabilize the endangered wolf population, wildlife officials must introduce captive-bred wolves into the wild. After all, the only other suggestion—restricting human development in the wolves' natural habitat—has been repeatedly rejected by the regional legislature. Thus, introducing captive-bred wolves is the only path forward.
The globally renowned Horizon Tech Corporation has consistently been recognized as the most innovative tech company of the decade, pioneering breakthroughs in quantum computing and artificial intelligence. Consequently, Elias Vance, who works as a junior accountant at Horizon Tech, must be an exceptionally innovative employee.
A comprehensive dietary study found that individuals who consume high amounts of artificially sweetened beverages suffer from chronic fatigue syndrome at triple the rate of those who do not. This demonstrates that consuming artificially sweetened beverages directly contributes to the onset of chronic fatigue syndrome.

Matches

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Answer

The arguments logically pair as follows: The marine ecosystem argument matches the description of confusing a necessary condition with a sufficient one. The wolf population argument matches the description of a false dilemma. The tech company argument matches the description of a part-to-whole (division) error. The dietary study argument matches the description of confusing correlation with causation.
Each argument contains exactly one distinct logical error that perfectly mirrors the corresponding abstract description. The marine ecosystem argument demonstrates an illegal reversal (necessary vs. sufficient). The wolf argument demonstrates a false dichotomy. The tech company argument demonstrates a flaw of division. The dietary argument demonstrates a correlation-causation fallacy.

Step-by-Step Solution

1
Analyze the marine ecosystem argument.
Identified that the premise states 'thriving ecosystem -> diverse predators', but the conclusion reverses this to 'diverse predators -> thriving ecosystem'.
Recognizing conditional logic errors is crucial for matching it to the abstract description regarding necessary and sufficient conditions.
2
Analyze the wolf population argument.
Noted that it dismisses one option and automatically defaults to a second option, ignoring the possibility of any third alternative.
This structural pattern defines a false dilemma, matching the description about unstated assumptions regarding alternatives.
3
Analyze the tech company argument.
Observed that it attributes the broad characteristic of a company ('innovative') to a specific individual part of that company (an accountant).
This is the classic definition of the logical flaw of division, matching the description of presuming a collective attribute applies to constituent parts.
4
Analyze the dietary study argument.
Recognized that it jumps from a 'found correlation' (triple the rate) to a 'direct contribution' (causation) without eliminating other factors.
This error directly corresponds to the description of taking statistical correlation as definitive proof of causation.

Key Concept

Identifying and abstracting logical reasoning errors
Question 10Question →

Any city that successfully implements a comprehensive public transit system will see a significant reduction in traffic congestion. Therefore, since the city of Oakhaven has recently seen a significant reduction in traffic congestion, it must have successfully implemented a comprehensive public transit system.

The flawed pattern of reasoning in the argument above is most similar to that in which one of the following?

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Answer: All successful startup founders possess a high tolerance for risk. Thus, because Julian possesses a high tolerance for risk, he must be a successful startup founder.

Answer

The option stating that Julian must be a successful startup founder because he possesses a high tolerance for risk.
The original argument commits an illegal reversal flaw: it treats a necessary condition (reduced congestion) as if it were a sufficient condition, arguing that because the result occurred, the specific trigger must have caused it. The correct option perfectly mirrors this structure by establishing that being a successful founder guarantees high risk tolerance, and then flawed inferences that Julian's high risk tolerance guarantees he is a successful founder.

Step-by-Step Solution

1
Analyze the logical structure and identify the flaw in the stimulus argument.
The stimulus establishes a conditional premise: If a city implements a transit system (A), it sees reduced congestion (B). It then observes the result (B) and concludes the condition (A). This is an illegal reversal: assuming that a necessary condition is a sufficient one.
Correctly identifying the abstract structure of the flaw is required to find its parallel among the answer choices.
2
Evaluate the answer choices to find the one with the exact same structural flaw (Illegal Reversal: If A then B; B, therefore A).
The correct argument states: If one is a successful founder (A), one has high risk tolerance (B). Julian has high risk tolerance (B), therefore Julian is a successful founder (A).
Matching the abstract logical format ensures the correct answer contains an identical pattern of faulty reasoning, ignoring differences in subject matter.

Key Concept

Parallel Flaw - Illegal Reversal
Question 11Question →

Chef: To bake a flawless soufflé, a baker must use room-temperature eggs and precisely fold the egg whites into the batter. Marcus precisely folded the egg whites into his batter. Therefore, if Marcus fails to bake a flawless soufflé, it must be because he did not use room-temperature eggs.

Which one of the following arguments exhibits a flawed pattern of reasoning most similar to that in the chef's argument?

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Answer: Botanist: For a desert orchid to bloom, it must receive ample direct sunlight and be planted in well-draining soil. This particular desert orchid is planted in well-draining soil. Hence, if it fails to bloom, it must be because it is not receiving ample direct sunlight.

Answer

The argument about the botanist and the desert orchid exhibits the exact same flawed pattern of reasoning.
The correct answer exactly mirrors the highly specific, flawed logical structure of the stimulus. The stimulus establishes two necessary conditions for a goal (room-temperature eggs and precise folding for a flawless soufflé). It then states that one condition is met, and concludes that if the goal fails, it must be due to the absence of the other stated condition. This is flawed because it ignores the possibility of other unstated necessary conditions causing the failure (e.g., wrong oven temperature). Similarly, the correct answer establishes two necessary conditions for a goal (sunlight and well-draining soil for an orchid to bloom). It states that one condition is met (soil), and falsely concludes that if the goal fails (no bloom), it must be due to the absence of the other stated condition (sunlight), ignoring other possible causes for failure.

Step-by-Step Solution

1
Analyze the logical structure of the stimulus argument.
Structure: Goal (flawless soufflé) -> Necessary Condition 1 (room-temp eggs) AND Necessary Condition 2 (precisely fold).
Identifying the formal conditional logic is the first step in parallel reasoning.
2
Identify how the premises are applied to the specific case in the stimulus.
The argument states that Marcus met Necessary Condition 2 (precisely folded).
We must map the specific scenario to the abstract structure.
3
Analyze the conclusion to identify the exact logical flaw.
Conclusion: If Goal fails (Not Goal), it must be because of Not Necessary Condition 1. The flaw is assuming the stated necessary conditions are exhaustive. The soufflé could fail for an unstated reason (e.g., incorrect oven temperature) despite having room-temperature eggs.
Understanding the precise nature of the error is required to find its parallel.
4
Evaluate the answer choices for an identical structure.
The correct option states: Goal (bloom) -> N1 (sunlight) AND N2 (soil). Has N2 (soil). Concludes: If Not Goal, then Not N1. This is a perfect structural match.
The correct answer must match both the conditional premise structure and the exact flawed application in the conclusion.

Key Concept

Parallel Flaw - Assuming Stated Necessary Conditions are Exhaustive
Question 12Question →

If a startup company secures venture capital funding, it will rapidly expand its operations. The tech startup Zephyr Innovations did not secure venture capital funding. Therefore, Zephyr Innovations will not rapidly expand its operations.

Which of the following arguments exhibits a flawed pattern of reasoning most similar to the one exhibited in the argument above?

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Answer: If a museum acquires a highly anticipated exhibit, its daily visitor numbers will increase. The city art museum did not acquire a highly anticipated exhibit. Thus, its daily visitor numbers will not increase.

Answer

The argument concluding that the city art museum's visitor numbers will not increase because it did not acquire a highly anticipated exhibit.
The stimulus argument commits the fallacy of illegal negation (denying the antecedent). It establishes a conditional relationship (If A, then B), states that the sufficient condition (A) did not occur, and wrongly concludes that the necessary condition (B) cannot occur. The correct answer follows this exact flawed structure: it establishes that acquiring an exhibit leads to increased visitors, notes that the museum did not acquire an exhibit, and improperly concludes that visitors will not increase.

Step-by-Step Solution

1
Map the logical structure of the stimulus argument.
Premise 1: If Venture Capital (VC) -> Rapid Expansion (RE). Premise 2: Not VC. Conclusion: Therefore, Not RE.
Identifying the formal structure is necessary to pinpoint the exact logical flaw.
2
Identify the type of logical flaw committed in the stimulus.
The argument commits an illegal negation (denying the antecedent). It assumes that if the sufficient condition fails, the necessary condition must also fail.
Parallel flaw questions require matching the specific abstract type of erroneous reasoning.
3
Evaluate the answer choices to find the one with the identical flawed structure.
The museum argument matches exactly: Premise 1: If Acquire Exhibit (AE) -> Increase Visitors (IV). Premise 2: Not AE. Conclusion: Therefore, Not IV.
The correct answer must replicate the abstract structure of the original flaw, regardless of the subject matter.

Key Concept

Parallel Flaw: Illegal Negation
Question 13Question →

If a job applicant has a master's degree, they will be offered a second interview. Therefore, since Emily was offered a second interview, she must have a master's degree.

Which of the following contains a flawed pattern of reasoning most similar to that in the argument above?

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Answer: The old library must be historically significant. After all, if a building is historically significant, it will be protected by the city council, and the old library is indeed protected.

Answer

The option concluding that the old library must be historically significant because it is protected.
The correct answer perfectly replicates the illegal reversal flaw seen in the stimulus. The stimulus argues: If Master's (A) -> Interview (B). Emily got an Interview (B), therefore she has a Master's (A). The correct option argues: If Historically Significant (A) -> Protected (B). The library is Protected (B), therefore it is Historically Significant (A). Both erroneously confuse a necessary condition for a sufficient one.

Step-by-Step Solution

1
Analyze the logical structure and flaw of the stimulus.
The argument takes the conditional form: If A (has master's) then B (second interview). It states B is true (Emily offered a second interview), and concludes A is true (she has a master's).
Identifying the abstract structure is necessary to find a matching pattern.
2
Name the specific logical flaw.
The argument commits an illegal reversal. It treats a necessary condition (getting an interview) as if it were a sufficient condition to prove the original trigger (having a master's degree).
In parallel flaw questions, the correct answer must commit the exact same logical error.
3
Evaluate the options to find the identical structural flaw, ignoring the order of premises.
The option regarding the historically significant building takes the form: Conclusion A is true (it is historically significant) because if A then B (if historically significant, then protected), and B is true (it is protected).
This precisely matches the 'If A then B. B. Therefore A' illegal reversal structure of the original argument, despite the conclusion being stated first.

Key Concept

Parallel Flaw - Illegal Reversal
Question 14Question →

Match each flawed argument below to the abstract description that most accurately identifies its logical error.

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Items

Anyone who gets the promotion will buy a new car. Therefore, since Sarah bought a new car, she must have gotten the promotion.
If the company increases its marketing budget, profits will rise. However, the company will not increase its marketing budget, so profits will certainly not rise.
The symphony orchestra is known worldwide for its flawless timing. Therefore, the orchestra's newly hired violinist must have flawless timing.
We should reject Dr. Smith's findings regarding the new food additive. After all, Dr. Smith was recently involved in a highly publicized tax evasion scandal.

Matches

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Answer

Argument 1 matches with treating a necessary condition as sufficient; Argument 2 matches with confusing the lack of a sufficient condition for the lack of a necessary condition; Argument 3 matches with the whole-to-part composition error; Argument 4 matches with the ad hominem source attack.
Each argument perfectly models one of the classic logical flaws tested on the LSAT: illegal reversal, illegal negation, composition (whole-to-part), and ad hominem. The corresponding abstract descriptions accurately summarize these precise structural errors without relying on the specific subject matter.

Step-by-Step Solution

1
Analyze the first argument's conditional structure.
Identify it as a conditional reasoning flaw where the necessary condition is used to incorrectly guarantee the sufficient condition.
To match it with the 'necessary treated as sufficient' description.
2
Analyze the second argument's conditional structure.
Identify it as a conditional reasoning flaw where the denial of the sufficient condition is incorrectly used to deny the necessary condition.
To match it with the 'sufficient condition not met' description.
3
Analyze the scope of the third argument.
Identify it as a composition flaw where an attribute of the orchestra is incorrectly applied to an individual member.
To match it with the 'characteristic of a group applied to a member' description.
4
Analyze the focus of the fourth argument.
Identify it as a source argument flaw where the author attacks the researcher instead of the research.
To match it with the 'dismissing a conclusion based on personal flaws' description.

Key Concept

Identifying abstract logical flaws within varied arguments.
Question 15Question →

Botanist: If a plant species originates in a tropical climate, it requires high humidity to thrive. The newly discovered Silvervine plant does not originate in a tropical climate. Therefore, the Silvervine plant does not require high humidity to thrive.

Which one of the following arguments exhibits a flawed pattern of reasoning most similar to that exhibited by the botanist's argument?

Show answer & explanation

Answer: If a vehicle is a commercial airplane, it has wings. This passenger train is not a commercial airplane. Therefore, this passenger train does not have wings.

Answer

The argument about the passenger train and wings perfectly mirrors the flawed structure of the botanist's argument.
The original argument exhibits a formal logic flaw known as illegal negation. It establishes a conditional statement (If Tropical -> High Humidity), states that the sufficient condition is not met (Not Tropical), and improperly concludes that the necessary condition is also not met (Therefore, Not High Humidity). The correct argument perfectly mirrors this flawed structure: it sets a rule (If Airplane -> Wings), negates the sufficient condition (Not Airplane), and falsely concludes the negation of the necessary condition (Therefore, Not Wings).

Step-by-Step Solution

1
Identify the logical structure and specific flaw in the botanist's argument.
Premise 1: Tropical -> High Humidity. Premise 2: Not Tropical. Conclusion: Not High Humidity. This is an Illegal Negation.
To find a parallel flaw, you must first precisely abstract the original argument's logical structure.
2
Evaluate the choices to eliminate arguments that use valid reasoning or different types of flaws.
The arguments about the greyhound and the indoor plant commit an Illegal Reversal. The basketball argument is a Part-to-Whole flaw. The smartphone argument is logically valid.
Options with different structural errors or no errors at all are incorrect in a Parallel Flaw question.
3
Match the exact abstract structure (Illegal Negation) to the remaining options.
The argument about the commercial airplane translates to: Airplane -> Wings. Not Airplane. Therefore, Not Wings.
The correct answer must replicate the exact logical pattern (If A -> B; Not A -> Not B) regardless of the subject matter.

Key Concept

Parallel Flaw: Illegal Negation
Question 16Question →

Pair each of the following flawed arguments with the argument that exhibits an identical pattern of faulty reasoning.

Click a left item, then click its matching right item

Items

If a city has a subway system, it experiences less traffic congestion. Springfield is currently experiencing less traffic congestion. Therefore, Springfield must have built a subway system.
Every individual puzzle piece in this box is shaped like a square. Consequently, when the puzzle is completely assembled, the final image will be shaped like a square.
Studies show that employees who take frequent walks report higher job satisfaction. Therefore, taking frequent walks directly increases an employee's job satisfaction.

Matches

Show answer & explanation

Answer

The city subway argument matches the baking powder argument (Illegal Reversal). The puzzle piece argument matches the brick building argument (Part-to-Whole). The employee walks argument matches the streetlight argument (Correlation vs. Causation).
Each pair correctly links a stimulus argument with a target argument that shares the exact same logical vulnerability: illegal reversal, part-to-whole composition, and confusing correlation with causation, respectively.

Step-by-Step Solution

1
Analyze the first argument about the city subway system.
Identify the flaw as an illegal reversal: 'If A (subway) then B (less traffic). B (less traffic) is true, so A (subway) must be true.'
Understanding the abstract structure of the error is required to find its match.
2
Find the matching flaw among the available options.
The baking powder argument uses the exact same structure: 'If A (baking powder) then B (cake rises). B (cake rises) is true, so A (baking powder) must be true.'
This establishes the first parallel flaw pair.
3
Analyze the second argument about the puzzle pieces.
Identify the flaw as a part-to-whole error (composition): assuming the whole has a property just because its constituent parts do.
Extracting the logical error allows for structural comparison.
4
Find the corresponding part-to-whole error.
The brick building argument assumes the whole building is light because individual bricks are light, directly matching the puzzle argument.
This establishes the second parallel flaw pair.
5
Analyze the third argument about employee walks.
Identify the flaw as confusing correlation with causation: assuming walks cause satisfaction simply because the two are linked.
Identifying the causal assumption isolates the final abstract flaw type.
6
Match the final argument.
The streetlight argument assumes streetlights cause lower crime just because they are correlated, which perfectly matches the employee walks argument.
This confirms and completes all parallel flaw pairings.

Key Concept

Parallel Flaw
Question 17Question →

Sociologist: Most of the residents in this neighborhood commute by train. Furthermore, most of the residents in this neighborhood regularly vote in local elections. Consequently, it must be the case that most of the residents in this neighborhood who commute by train regularly vote in local elections.

The flawed pattern of reasoning in the sociologist's argument is most closely paralleled by which one of the following?

Show answer & explanation

Answer: Most of the novels on the bestseller list are thrillers. Additionally, most of the novels on the bestseller list are written by debut authors. Hence, most of the thrillers on the bestseller list must be written by debut authors.

Answer

The correct answer is the option stating that most of the novels on the bestseller list are thrillers and most are written by debut authors, concluding that most of the thrillers on the list must be written by debut authors.
The correct answer exactly replicates the flawed logical structure of the stimulus: 'Most X are Y, and most X are Z. Therefore, most X that are Y must also be Z.' In the stimulus, X is residents, Y is commuting by train, and Z is voting. In this option, X is novels on the bestseller list, Y is thrillers, and Z is written by debut authors. Both arguments erroneously assume that the intersection of two majorities must itself constitute a majority of the first subgroup.

Step-by-Step Solution

1
Analyze the premises and conclusion of the original argument.
Premise 1: Most A are B. Premise 2: Most A are C. Conclusion: Most of the A that are B, are C.
To find a parallel flaw, we must first abstract the exact structural pattern of the argument.
2
Evaluate the validity of the abstracted structure to identify the flaw.
The argument is flawed because two 'most' statements about a single group do not guarantee that a majority of the first subgroup belongs to the second subgroup.
For example, if 51% of group A are B, and 51% of group A are C, they might only overlap by 2%. Thus, we cannot logically deduce that 'most' of B are C.
3
Examine the answer choices to find the one that matches this specific flawed structure.
The option about novels and thrillers perfectly matches the 'Most A are B, Most A are C, therefore Most of A that are B are C' structure.
Parallel flaw questions require matching both the logical mechanics and the specific type of error committed, ignoring surface-level subject matter traps.

Key Concept

Identifying and matching flawed quantifier logic (specifically involving overlapping 'most' statements).
Question 18Question →

Analyze the reasoning in each of the following short arguments. Pair each argument with the abstract description that most accurately identifies its primary logical vulnerability.

Click a left item, then click its matching right item

Items

If a municipality enacts restrictive zoning ordinances, local property values will invariably rise. Over the past decade, property values in the township of Oakhaven have risen dramatically. Thus, Oakhaven must have enacted restrictive zoning ordinances.
Every individual member of the Metropolitan String Quartet is an internationally renowned virtuoso. It logically follows that the Metropolitan String Quartet itself is an internationally renowned ensemble.
Recent sociological data reveals that regions with higher rates of daily internet consumption also report higher incidences of generalized anxiety. Therefore, it is evident that excessive internet consumption induces anxiety.
The two independent art critics we surveyed found the new abstract installation completely devoid of meaning. This definitively proves that no patron visiting the gallery will be able to derive meaning from the installation.

Matches

Show answer & explanation

Answer

The correct pairings match each specific flawed argument to its corresponding logical fallacy: the zoning argument contains an illegal reversal (sufficient/necessary flaw), the quartet argument commits a composition fallacy (part-to-whole), the internet argument confuses correlation with causation, and the art exhibit argument relies on an unrepresentative sample.
Each pairing accurately maps the specific logical vulnerability of the argument to its formal definition. The zoning argument confuses necessary and sufficient conditions. The quartet argument falsely equates the properties of individual parts to the whole. The internet argument jumps from correlation to causation. The art exhibit argument overgeneralizes from an exceptionally small sample.

Step-by-Step Solution

1
Analyze each stimulus argument on the left to isolate its premises and its conclusion.
The core reasoning structure of each argument is identified, stripping away the specific subject matter.
Parallel flaw analysis requires understanding the structural relationship between premises and conclusions, rather than the topical content.
2
Identify the specific logical gap or unwarranted assumption bridging the premises and conclusion in each argument.
The distinct fallacies are isolated: conditional reasoning reversal, part-to-whole projection, correlation-to-causation leap, and small sample generalization.
Pinpointing the exact nature of the flaw is necessary to find its abstract description.
3
Evaluate the abstract descriptions on the right and pair them with the arguments that exhibit the matching structural flaw.
Each argument is successfully mapped to its abstract logical error.
This completes the matching process by linking the applied reasoning to formal logical taxonomy.

Key Concept

Parallel Flaw - Identifying Abstract Logical Structures
Question 19Question →

To successfully cultivate the rare ghost orchid, one must precisely control the humidity of the greenhouse and use a specialized fungal fertilizer. The botanical garden has maintained precise humidity control in its new greenhouse and applied the specialized fungal fertilizer. Thus, the garden will certainly succeed in cultivating the ghost orchid.

Which of the following arguments exhibits a flawed pattern of reasoning most similar to that exhibited by the argument above?

Show answer & explanation

Answer: Sarah finished the qualifying race in two hours and fifty minutes and received a clean bill of health from her doctor. Consequently, Sarah will qualify for the marathon, because anyone who qualifies for the marathon must complete the qualifying race under three hours and pass a rigorous medical examination.

Answer

The argument concerning Sarah qualifying for the marathon replicates the identical flawed pattern of reasoning.
The correct answer replicates the illegal reversal of compound necessary conditions found in the stimulus. In the stimulus, the argument establishes that achieving a result (cultivating the orchid) requires two necessary conditions (humidity control and fertilizer), and then falsely concludes that meeting those conditions is sufficient to guarantee the result. The correct choice similarly states that qualifying for a marathon requires two conditions (time limit and medical exam), establishes that these conditions are met, and falsely concludes that this guarantees qualification. It perfectly mimics the logical structure while varying the order in which the premises and conclusion are presented to avoid superficial matching.

Step-by-Step Solution

1
Analyze the logical structure of the stimulus argument.
Premise 1: Successfully cultivating the orchid (A) requires humidity control (B) and fertilizer (C). [If A, then B and C]. Premise 2: The garden has humidity control (B) and fertilizer (C). Conclusion: The garden will succeed (A).
Identifying the formal abstract structure is required before evaluating the answer choices.
2
Identify the logical flaw in the stimulus.
The argument commits an illegal reversal (affirming the consequent). It treats two necessary conditions (humidity and fertilizer) as if they were jointly sufficient to guarantee success.
We must find an answer choice that commits this exact same abstract logical error.
3
Evaluate the answer choices to find a matching flawed structure, paying attention to reordered premises.
The correct argument states that qualifying for a marathon (A) requires a sub-three-hour race (B) and a medical exam (C). It notes Sarah achieved B and C, and concludes she will achieve A. This perfectly matches the [If A, then B and C; B and C, therefore A] structure.
The correct choice must replicate the compound necessary condition reversal, regardless of the order in which the sentences are presented.

Key Concept

Parallel Flaw - Confusing Necessary and Sufficient Conditions
Question 20Question →

Analyze the reasoning in each of the following flawed arguments. Match each argument with the abstract description that most accurately identifies its logical flaw.

Click a left item, then click its matching right item

Items

Every brick used in the construction of the new civic center is exceptionally small and fragile. It necessarily follows that the civic center as a whole will be exceptionally small and fragile.
Some of the firm's legal advisors are proficient in corporate tax law, and some of the people proficient in corporate tax law are also expert litigators. Thus, at least some of the firm's legal advisors must be expert litigators.
A recent public health study revealed that municipalities with a high concentration of fitness centers also have unusually high rates of locally-owned health food stores. This demonstrates that opening fitness centers in a municipality stimulates the creation of health food stores.
To receive a highly competitive research grant from the foundation, a scientist must have conducted experiments involving human subjects. Dr. Vance has conducted multiple experiments involving human subjects. Therefore, Dr. Vance will certainly be awarded the research grant.

Matches

Show answer & explanation

Answer

The civic center argument matches the part-to-whole flaw. The legal advisors argument matches the overlapping sets quantifier flaw. The fitness centers argument matches the correlation-causation flaw. The research grant argument matches the necessary/sufficient condition flaw.
Each argument represents a classic logical flaw commonly tested on the LSAT. By abstracting the specific subject matter and focusing entirely on the reasoning structure of each stimulus, we can accurately identify the corresponding abstract flaw description. This is a matching question, so all valid rationales are detailed in the correct pairs.

Step-by-Step Solution

1
Analyze the first argument regarding the civic center's bricks.
The argument moves from a characteristic of the components to a characteristic of the entire structure.
Identifying the premise-to-conclusion relationship reveals a classic part-to-whole (composition) flaw.
2
Analyze the second argument regarding the legal advisors and litigators.
The argument incorrectly assumes two distinct groups must overlap just because they both overlap with a common third group.
Diagramming the 'some' statements shows that the intersection of the two outer groups is logically unsupported.
3
Analyze the third argument regarding fitness centers and health food stores.
The argument takes a statistical correlation and concludes there is a direct causal relationship.
The premise only establishes that two things happen simultaneously, but the conclusion unjustifiably claims one causes the other without ruling out alternative explanations.
4
Analyze the fourth argument regarding the research grant.
The argument treats a strict requirement for an outcome as a guarantee of that outcome.
Translating the conditional language reveals an illegal reversal flaw, confusing necessary and sufficient conditions.

Key Concept

Parallel Flaw
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