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Question 41Question →

Economist: Technological automation in the manufacturing sector has historically led to a temporary displacement of workers, followed by long-term employment growth. As machines take over routine tasks, production costs fall, lowering prices and increasing consumer demand, which ultimately creates new jobs in sales, distribution, and machine maintenance. Therefore, the current rapid adoption of artificial intelligence in the service sector will eventually result in a net increase in service-sector jobs, despite initial layoffs.

Which of the following, if true, most seriously weakens the economist's argument?

Show answer & explanation

Answer: Unlike physical goods, AI-generated services can be scaled instantly to meet surging consumer demand without any proportional increase in human labor for distribution or delivery.

Answer

Unlike physical goods, AI-generated services can be scaled instantly to meet surging consumer demand without any proportional increase in human labor for distribution or delivery.
The argument relies on an analogy: just as automation in manufacturing ultimately created jobs by increasing consumer demand (which required more humans for sales and distribution), AI in the service sector will do the same. The correct answer attacks this analogy by pointing out a crucial difference between the two sectors: unlike manufactured goods, AI services can scale rapidly to meet higher demand without needing additional human labor. If this is true, the fundamental mechanism that created jobs in manufacturing will not function in the service sector, severely weakening the economist's conclusion.

Step-by-Step Solution

1
Identify the main conclusion of the argument.
The conclusion is that the adoption of AI in the service sector will eventually result in a net increase in service-sector jobs.
Locating the conclusion is necessary to understand exactly what claim needs to be weakened.
2
Identify the premises supporting the conclusion.
The author uses an analogy to the manufacturing sector, where automation lowered costs and prices, increased demand, and subsequently created new jobs in sales, distribution, and maintenance.
Understanding the supporting logic reveals the specific mechanism the author relies on.
3
Identify the logical flaw or unstated assumption.
The argument assumes that the job-creation mechanism in manufacturing (where scaling physical goods requires human labor for distribution/sales) will identically apply to AI in the service sector.
Finding the gap between the premises and the conclusion highlights how to successfully attack the argument.
4
Evaluate the options to find one that attacks this specific assumption.
The option stating that AI-generated services can scale without a proportional increase in human labor for distribution severs the causal link assumed by the analogy.
A valid weakener must undermine the logical connection between the evidence and the conclusion, not just contradict a premise or change the subject.

Key Concept

Weakening Arguments Involving False Analogies
Question 42Question →

Marine Biologist: Deep-sea coral colonies situated adjacent to hydrothermal vents exhibit significantly faster calcification rates than colonies in non-volcanic regions. Because hydrothermal vents continuously release dissolved iron and silicate compounds into the surrounding water, the high concentration of these specific minerals must be the primary cause of the accelerated growth rates observed in these vent-adjacent corals.

Which of the following, if true, most seriously weakens the marine biologist's argument?

Show answer & explanation

Answer: In controlled laboratory conditions, deep-sea corals exposed to vent-level concentrations of dissolved iron and silicate compounds exhibit no increase in their calcification rates.

Answer

The statement showing that deep-sea corals exposed to vent-level mineral concentrations in controlled conditions experience no increase in calcification rates most seriously undermines the argument.
The argument concludes that elevated concentrations of dissolved iron and silicates cause accelerated calcification based solely on the correlation between vent proximity and growth rates. The correct answer weakens this causal claim by providing direct experimental evidence that exposing corals to these exact mineral concentrations does not increase calcification, proving the proposed cause is ineffective.

Step-by-Step Solution

1
Identify the conclusion and premises of the argument.
Premise: Corals near hydrothermal vents calcify faster and vents release high levels of iron and silicate. Conclusion: High mineral concentration is the primary cause of the accelerated calcification.
Isolating the core causal claim reveals the logical gap between observed correlation and inferred causation.
2
Identify the unstated assumption linking the premises to the conclusion.
The author assumes that the elevated mineral levels actually stimulate coral calcification and that no alternative factor unique to the vents is responsible.
Weaken questions require targeting the unstated assumption that makes the causal conclusion vulnerable.
3
Evaluate the answer choices to find new information that severs this causal relationship.
Experimental evidence demonstrating that vent-level concentrations of iron and silicate do not increase calcification rates directly disproves the claimed causal mechanism.
Showing that the hypothesized cause fails to produce the effect under controlled conditions decisively weakens a causal claim.

Key Concept

Causal Reasoning and Severing Causal Mechanisms
Question 43Question →

Ornithologist: In a behavioral study, captive migratory songbirds placed inside an indoor planetarium failed to orient toward their southward route whenever the artificial night sky was darkened. This demonstrates that these songbirds rely exclusively on celestial patterns rather than geomagnetic fields to determine their migratory direction.

The claim that the planetarium testing room was encased in thick metal shielding that completely blocked Earth's ambient geomagnetic field, if true, weakens the ornithologist's argument.

Show answer & explanation

Answer: True

Answer

True. The supplementary statement introduces an alternative explanation that undermines the author's conclusion.
The statement is true because the presence of magnetic shielding invalidates the premise that geomagnetic cues were available as a backup. Because the birds were deprived of all navigation cues when the lights went out, their failure to orient does not demonstrate that they cannot use geomagnetic fields under normal conditions.

Step-by-Step Solution

1
Identify the author's premise and conclusion.
Premise: Songbirds failed to orient when visual star patterns were removed. Conclusion: Songbirds rely exclusively on stars and do not use geomagnetic fields.
Isolating the core reasoning step is necessary to determine what assumption the author relies upon.
2
Evaluate the logical effect of the new information.
If the testing facility blocked Earth's geomagnetic field, the birds lacked access to magnetic cues throughout the experiment. Their inability to navigate in the dark was therefore due to having neither visual nor magnetic cues available.
Revealing that the experimental environment eliminated the alternative navigational system directly challenges the inference that the birds lack magnetic navigational capabilities.

Key Concept

Weakening a causal conclusion by identifying an unaddressed experimental confound or alternative explanation.
Question 44Question →

Nutritionist: A recent study observed that households that regularly consume fermented tea report 40 percent fewer seasonal respiratory infections than households that do not consume fermented tea. The beverage contains high concentrations of antioxidants, which support immune function. Therefore, regular consumption of fermented tea directly reduces the likelihood of developing seasonal respiratory infections.

Which of the following, if true, most seriously weakens the nutritionist's argument?

Show answer & explanation

Answer: Households that regularly consume fermented tea are significantly more likely to engage in regular exercise and follow hygienic practices than households that do not.

Answer

Households that regularly consume fermented tea are significantly more likely to engage in regular exercise and follow hygienic practices than households that do not.
The correct response points out that households drinking fermented tea also practice other health-promoting behaviors, such as regular exercise and good hygiene. This provides an alternative explanation for their lower infection rate, demonstrating that the observed benefit may be due to general lifestyle factors rather than the fermented tea itself.

Step-by-Step Solution

1
Identify the premises and conclusion of the stimulus.
Premise: Fermented tea drinkers report 40% fewer respiratory infections and the tea has antioxidants. Conclusion: Drinking fermented tea directly causes a reduced likelihood of infection.
Isolating the core argument reveals the gap between an observed correlation and a direct causal claim.
2
Identify the underlying logical assumption.
The author assumes there is no confounding variable or alternative explanation accounting for the difference in infection rates between the two groups.
Causal arguments on the LSAT frequently assume that correlation implies causation and that other causative factors are absent.
3
Evaluate the answer choices for a statement that undermines this assumption.
The choice showing that fermented tea consumers also engage in more exercise and better hygiene provides a plausible alternative cause for their fewer infections.
Demonstrating a third variable that accounts for the observed effect severs the direct causal link asserted in the conclusion.

Key Concept

Alternative Explanations in Causal Reasoning
Question 45Question →

Paleoclimatologist: Core samples extracted from the Ellesmere Ice Shelf reveal an abrupt spike in micro-charcoal particle density dating to approximately 8,200 years ago. Because regional boreal forests produce high concentrations of airborne charcoal only during prolonged periods of severe drought and wildfire, researchers conclude that a catastrophic multi-decade megadrought afflicted the adjacent subarctic mainland during this era.

Which of the following statements, if true, most undermine the paleoclimatologist's conclusion? Select all that apply.

Select all that apply

Show answer & explanation

Answer: Around 8,200 years ago, annual snowfall over the Ellesmere Ice Shelf dropped by over 80 percent, dramatically reducing ice accumulation and concentrating standard atmospheric particulates into dense bands.; Geochemical analysis of the micro-charcoal in the ice layers shows an elemental composition characteristic of basaltic volcanic combustions from a distant ocean ridge rather than organic wood fires.

Answer

The statements establishing that a severe reduction in snowfall concentrated baseline atmospheric particles and that the charcoal originated from volcanic basalt rather than forest combustion both undermine the conclusion.
The argument assumes that an elevated density of charcoal particles in the ice core must reflect increased mainland forest burning caused by drought. The statement regarding reduced snowfall demonstrates an accumulation artifact where low precipitation concentrates normal baseline particles into high-density layers without any increase in fire activity. Similarly, the statement identifying a volcanic origin demonstrates that the charcoal did not come from burning boreal trees, severing the link to mainland forest conditions.

Step-by-Step Solution

1
Identify the main conclusion and core premises of the argument.
The premise is that an ice core shows a spike in micro-charcoal density and boreal forests produce high airborne charcoal during severe drought; the conclusion is that a catastrophic megadrought afflicted the adjacent mainland.
Isolating the conclusion allows detection of the key assumptions linking charcoal density in ice to regional drought conditions.
2
Identify the unstated assumptions and vulnerabilities in the author's reasoning.
The author assumes that high particle density reflects higher total charcoal output rather than an ice-accumulation artifact, and that the charcoal necessarily originated from regional mainland forest fires.
Weaken questions require identifying logical gaps or alternative explanations that break the link between the evidence and the conclusion.
3
Evaluate the answer choices to identify all statements that introduce facts undermining these key assumptions.
The statement showing reduced snowfall caused particle concentration and the statement showing a volcanic origin for the charcoal each independently undermine the author's causal claim.
Both findings provide alternative explanations that account for the data without requiring a mainland drought.

Key Concept

Alternative Causal Explanations and Data Measurement Confounders
Estimated Time:1m 30s
Question 46Question →

Consider the following argument:

Organizational Psychologist: In an initiative to curtail administrative burnout, a regional hospital network automated its patient intake record-keeping across half of its clinics, while the remaining clinics retained manual data entry. Over the subsequent eighteen months, clinicians at clinics with automated intake reported a 40 percent reduction in administrative fatigue, whereas clinicians at manual clinics reported no change. Thus, automating patient intake records is an effective method for reducing clinician administrative fatigue.

Evaluate whether the following statement is true or false:

The psychologist's conclusion is substantially undermined if, concurrent with the trial period, the hospital network systematically reassigned the most complex, documentation-intensive chronic care patients exclusively to the clinics retaining manual intake.

Show answer & explanation

Answer: True

Answer

True
The evaluated statement is correct in asserting that the argument is substantially weakened. The psychologist infers a direct causal relationship between intake automation and reduced clinician fatigue from a comparative study between automated and manual clinics. However, if the hospital network simultaneously shifted the most documentation-heavy cases away from automated clinics and into manual clinics, the automated clinics experienced an inherent decrease in overall paperwork demands independent of the software. This introduces a major confounding factor that explains the survey results without requiring the software to be effective, thereby undermining the author's causal claim.

Step-by-Step Solution

1
Deconstruct the stimulus argument into premises and main conclusion
Premise: Automated clinics saw a 40% reduction in fatigue, while manual clinics saw 0%. Conclusion: Automating patient intake is effective at reducing clinician administrative fatigue.
Isolating the core causal claim is essential for evaluating potential vulnerabilities in the reasoning.
2
Identify the unstated causal assumption in the argument
The author assumes that the two groups of clinics were comparable in all other respects affecting administrative workload and that no confounding variable accounts for the observed drop in fatigue.
Causal arguments rely on the assumption that alternative explanations and confounding differences between comparison groups have been ruled out.
3
Evaluate the impact of the supplementary fact on the causal claim
Reassigning complex, documentation-heavy patients exclusively to manual clinics means the automated clinics had a lighter paperwork burden regardless of software efficiency, presenting a viable alternative cause for their reduced fatigue.
Providing a strong rival explanation for the observed outcome directly weakens a causal conclusion.
4
Determine the truth value of the evaluation statement
Because the supplementary fact demonstrates a classic confounding variable flaw and weakens the conclusion, the statement asserting that it substantially undermines the argument is True.
Matching the weakening effect to the statement's claim confirms its validity.

Key Concept

Identifying confounding variables and alternative explanations to weaken a causal inference
Question 47Question →

City Planner: Last year, the city converted one vehicular traffic lane on Market Street into a protected bicycle lane. Over the subsequent twelve months, total retail sales along Market Street increased by 15 percent. Because the bicycle lane increased foot and bicycle traffic directly in front of storefronts, installing dedicated bicycle lanes on commercial corridors is an effective method for boosting local business revenue.

Which of the following statements, if true, each undermine the city planner's conclusion? (Select all that apply.)

Select all that apply

Show answer & explanation

Answer: During the same twelve-month period, broader regional economic growth caused retail sales across the entire city to rise by an average of 20 percent.; Six months before the bicycle lane was installed, the city reopened a major subway station on Market Street following an extensive two-year renovation.

Answer

The statements showing that citywide retail sales grew even faster (20 percent) due to general economic growth and that a major subway station reopened on Market Street following renovations each weaken the argument.
The conclusion asserts a direct causal link between the bicycle lane and increased business revenue. The argument is undermined by statements providing plausible alternative explanations: the finding that citywide retail grew by 20 percent indicates Market Street actually underperformed general market trends, and the reopening of a major subway station provides a distinct source of increased foot traffic.

Step-by-Step Solution

1
Identify the conclusion and the supporting evidence in the stimulus.
The author concludes that installing dedicated bicycle lanes boosts local business revenue, based solely on the correlation between the lane installation and a 15 percent sales increase on Market Street.
Weaken questions require identifying the gap between the stated evidence and the final causal claim.
2
Evaluate each choice to identify alternative explanations or confounding factors.
Two choices introduce external factors—a citywide economic boom and the reopening of a central transit hub—that explain the sales increase independently of the bicycle lane.
Demonstrating that an effect is likely attributable to another cause undermines a causal conclusion.

Key Concept

Causal reasoning and identifying alternative explanations for an observed correlation
Question 48Question →

Economist: Five years ago, the municipality of Oakridge instituted a subsidy program covering half the installation costs for businesses that install rooftop rainwater harvesting systems. Over the same five-year period, commercial municipal water consumption in Oakridge dropped by 30 percent. Because the price of municipal water remained constant throughout this period, the subsidy program clearly succeeded in significantly reducing commercial reliance on municipal water.

Which of the following, if true, most seriously undermines the economist's argument?

Show answer & explanation

Answer: During the five-year period, two large beverage bottling facilities that had historically accounted for nearly half of Oakridge's total commercial water consumption ceased operations.

Answer

The argument is most seriously undermined by establishing that during the five-year period, two large beverage bottling facilities accounting for nearly half of Oakridge's commercial water usage ceased operations.
The argument concludes that the subsidy program caused a 30 percent reduction in commercial municipal water consumption based solely on the correlation between the subsidy's implementation and the subsequent decline. The correct answer undermines this causal conclusion by introducing a compelling alternative explanation: the closure of two major beverage bottling facilities that previously comprised nearly half of the entire city's commercial water usage. If those massive consumers closed, total commercial water demand would naturally plummet regardless of whether any other business adopted rainwater harvesting.

Step-by-Step Solution

1
Identify the argument's premises and main conclusion.
Premises: Oakridge subsidized 50% of rainwater harvesting installations five years ago; commercial water consumption dropped 30% over that period; water prices stayed constant. Conclusion: The subsidy program caused the reduction in commercial water reliance.
Weaken questions require isolating the exact claim the author attempts to prove.
2
Identify the underlying logical flaw or causal gap.
The author commits a correlation-to-causation fallacy by assuming that because the subsidy coincided with a drop in municipal water consumption, the subsidy program must be the cause of that drop, overlooking alternative causes.
To weaken a causal argument, one must introduce an alternative explanation, show a confounding factor, or show the effect occurring without the cause.
3
Evaluate the answer choices for new information that provides a viable alternative cause.
The closure of two water-intensive industrial bottling plants directly accounts for the 30 percent decline in commercial water usage without attributing the change to the harvesting subsidies.
Providing a plausible alternative explanation severs the causal link between the subsidy and the observed reduction in water consumption.

Key Concept

Alternative Causal Explanations in Weaken Questions
Estimated Time:1m 15s
Question 49Question →

Archaeologist: Obsidian tools discovered at the inland Neolithic settlement of Karasura match the unique geochemical composition of deposits from the volcanic island of Milos, situated hundreds of kilometers away across open water. Since no watercraft from this era have been recovered in the regional archaeological record, several researchers maintain that the tools arrived via roundabout overland trading routes. However, traversing the rugged coastal mountain ranges on foot would have been vastly more perilous and resource-intensive than open-water seafaring. Therefore, the discovery of these tools at Karasura proves that the settlement's inhabitants possessed indigenous seafaring capabilities far earlier than conventional chronologies suggest.

Which of the following statements, if true, each weaken the archaeologist's argument? (Select all that apply)

Select all that apply

Show answer & explanation

Answer: Geochemical analyses of obsidian artifacts from several contemporary coastal island settlements reveal that their seafaring residents regularly acquired Milian obsidian and exchanged finished tools with mainland populations.; During the Neolithic period, an established network of regional down-the-line exchange allowed valuable raw materials to pass between adjacent neighboring communities over short distances without any single community traveling long distances or braving mountain terrain.

Answer

The statements showing that maritime islanders traded the tools to mainland communities and that down-the-line regional exchange moved goods across short distances without long journeys each weaken the argument.
The author concludes that Karasura's inhabitants must have independently developed seafaring capabilities based solely on the presence of island obsidian and the difficulty of overland travel. The statement describing intermediary coastal islanders who acquired the obsidian and traded it with mainland groups directly provides an alternative explanation that relieves Karasura's inhabitants of the need to sail. Similarly, the statement explaining down-the-line exchange shows that goods could move incrementally across adjacent communities without requiring any single community to navigate hazardous mountains or sail open seas.

Step-by-Step Solution

1
Identify the argument's premises and main conclusion
Premises establish that Milian obsidian was found at Karasura, no regional Neolithic boats have been found, and traversing overland mountains was far harder than seafaring. Main conclusion: The discovery proves Karasura's inhabitants possessed indigenous seafaring capabilities earlier than assumed.
Deconstructing the argument isolates the author's leap from the presence of island obsidian to the claim that the settlement's own inhabitants sailed to retrieve it.
2
Expose the unstated assumptions and false dilemma
The author assumes a false dilemma: either Karasura's people endured grueling overland treks or they independently built boats and sailed. This overlooks intermediary trade networks and third-party maritime groups.
Weakening an argument on the LSAT typically involves introducing alternative explanations that break the necessary link between the evidence and the conclusion.
3
Select the statements that provide viable alternative mechanisms
The statement showing intermediary island seafarers traded finished tools and the statement showing short-distance down-the-line land trade each explain the presence of obsidian without requiring Karasura's inhabitants to have seafaring technology.
Both statements independently undermine the conclusion that Karasura developed indigenous maritime capabilities.

Key Concept

Identifying alternative explanations and exposing false dilemmas in explanatory causal arguments
Question 50Question →

Archaeologist: Excavations at the Bronze Age settlement of Tell el-Marwa uncovered numerous ceramic vessels lined with beeswax. Because beeswax was widely used across antiquity as a waterproofing sealant for storing wine and olive oil, and because microscopic residue analysis inside these specific jars lacked lipid signatures characteristic of olive oil, the vessels must have been used almost exclusively for the storage and trade of fermented grape wine.

Which of the following, if true, most seriously weakens the archaeologist's argument?

Show answer & explanation

Answer: In the region surrounding Tell el-Marwa, beeswax was routinely applied to seal jars containing dry grains and legumes to protect them from ambient humidity.

Answer

The argument is most seriously weakened by evidence that beeswax was routinely applied to seal jars containing dry grains and legumes to protect them from ambient humidity.
The author concludes that the jars were used almost exclusively for fermented grape wine simply because olive oil residues were absent and beeswax was known to be used for wine and olive oil. This reasoning commits a false dilemma by presuming no other goods were stored in beeswax-lined containers. The correct option directly exposes this flaw by showing that beeswax was routinely used to seal dry grains and legumes against humidity, offering an alternative use that fully explains the physical evidence without supporting the wine conclusion.

Step-by-Step Solution

1
Identify the premises and conclusion of the argument.
Premises: The jars were lined with beeswax; beeswax was used to waterproof jars for wine and olive oil; the jars lacked olive oil lipid signatures. Main Conclusion: The jars must have been used almost exclusively for storing and trading fermented grape wine.
Deconstructing the argument structure allows identification of the underlying assumptions linking the evidence to the claim.
2
Identify the logical flaw and unstated assumption.
The author assumes a false dichotomy—that because beeswax was used for wine and olive oil, and olive oil is eliminated, wine is the only viable commodity stored in the jars.
To weaken an argument relying on process of elimination, one must show that other unconsidered alternatives exist.
3
Evaluate the answer choices to find new information that exploits this gap.
The finding that beeswax was regularly used to waterproof storage jars for dry grains and legumes provides a direct alternative use that explains the presence of beeswax without implying the presence of wine.
Providing an alternative cause or function severely undermines the exclusivity asserted in the conclusion.

Key Concept

Alternative Explanations in Causal and Eliminative Arguments
Estimated Time:1m 15s
Question 51Question →

Paleontologist: The extinction of the Megalodon was not caused by a sudden global cooling event. Fossils of marine mammals—the Megalodon's primary prey—show no population decline in geological strata corresponding to the extinction period. Since its prey thrived, the theory that a catastrophic plunge in ocean temperatures starved the Megalodon is unfounded.

Statement: The discovery that the Megalodon inhabited deep, temperature-stable ocean trenches, whereas its prey occupied highly temperature-variable surface waters, significantly weakens the paleontologist's argument.

Show answer & explanation

Answer: False

Answer

The statement is false. The proposed discovery actually strengthens the paleontologist's argument rather than weakening it.
The paleontologist concludes that global cooling did NOT cause the extinction. The new information shows the Megalodon lived in temperature-stable deep waters, meaning it would be physically insulated from a cooling event. This provides an additional, independent reason to believe cooling wasn't the cause. Because this fact bolsters the paleontologist's conclusion, it strengthens the argument. Therefore, the statement asserting that it weakens the argument is false.

Step-by-Step Solution

1
Identify the author's main conclusion.
The conclusion is negative: A sudden global cooling event did NOT cause the Megalodon's extinction.
Isolating the exact conclusion is necessary to determine what type of evidence would weaken it.
2
Analyze the premises provided.
The primary premise is that the Megalodon's food source (marine mammals) survived the period without population decline.
Understanding the evidence helps evaluate the argument's core assumptions and vulnerabilities.
3
Evaluate the impact of the new information in the statement.
The new fact indicates the Megalodon lived in temperature-stable environments, protecting it from sudden oceanic cooling events.
We must determine how this new fact structurally interacts with the author's negative conclusion.
4
Determine if the information weakens the conclusion.
Because the new fact makes it even less likely that cooling killed the Megalodon, it provides secondary support to the author's claim. It strengthens the argument, meaning the statement that it weakens the argument is false.
A fact that strengthens an argument cannot fulfill a weaken prompt.

Key Concept

Recognizing opposite-task traps in arguments with negative conclusions.
Estimated Time:1m 30s
Question 52Question →

Wildlife Biologist: To prevent the spread of a fungal pathogen among endangered cave bats, conservationists installed heated artificial roosts in several winter hibernacula. Because the pathogen cannot survive temperatures above 18 degrees Celsius, the heated roosts successfully prevented fungal colonization on the bats occupying them. Nevertheless, bats utilizing the heated roosts suffered higher winter mortality rates than bats hibernating in unheated, fungus-free caves. Therefore, some environmental hazard inherent to the heated roosts is responsible for the elevated mortality.

Which of the following, if true, most seriously weakens the wildlife biologist's argument?

Show answer & explanation

Answer: Bats that enter hibernation with depleted fat reserves and severe physiological stress actively seek out warmer microclimates.

Answer

Bats that enter hibernation with depleted fat reserves and severe physiological stress actively seek out warmer microclimates.
The correct answer weakens the argument by introducing an alternate cause rooted in selection bias. If bats that are already in critical metabolic distress preferentially seek warmer roosts, their higher mortality rate is a consequence of their prior health condition rather than an environmental hazard inherent to the heated roosts.

Step-by-Step Solution

1
Isolate the argument's premises and main conclusion.
Premise: Bats in heated roosts avoided fungal colonization but had higher winter mortality than bats in unheated fungus-free caves. Conclusion: An environmental hazard inherent to the heated roosts caused the higher mortality.
Identifying the exact gap between the observed correlation and the causal conclusion is necessary to determine what would weaken the inference.
2
Identify the unstated assumption in the causal reasoning.
The biologist assumes that the bats using the heated roosts and those using unheated caves were comparable in health and survival probability prior to entering their respective hibernacula.
Causal claims based on group comparisons are vulnerable to selection bias and confounding baseline differences.
3
Select the statement that provides an alternative explanation for the mortality difference.
If stressed, malnourished bats selectively enter heated roosts, their pre-existing weakness accounts for the elevated mortality, eliminating the need to posit a hazard inherent to the roosts.
Demonstrating that the outcome was driven by self-selection rather than the roost environment directly undermines the causal conclusion.

Key Concept

Causal Reasoning and Selection Bias
Estimated Time:1m 30s
Question 53Question →

Paleoecologist: Fossilized tooth enamel from dwarf hippopotamuses on the island of Minoria shows a sharp increase in micro-wear scratches and carbon-13 isotope levels dating to 12,000 years ago. Because this change coincides with the earliest archaeological evidence of human arrival on Minoria, and carbon-13 enrichment indicates the consumption of tough coastal scrub rather than lush inland vegetation, researchers conclude that hunting pressure from human arrivals forced the hippopotamuses from their inland forest habitats into marginal coastal zones, leading to their extinction.

Which of the following statements, if true, most seriously undermine the paleoecologist's argument? (Select all that apply.)

Select all that apply

Show answer & explanation

Answer: Sediment core data from Minoria show that an island-wide megadrought occurred 12,000 years ago, severely desiccating inland freshwater sources and wiping out the island's inland forest vegetation.; Fossilized dwarf hippopotamus remains recovered from inland caves on Minoria demonstrate elevated carbon-13 levels and identical micro-wear patterns dating to several hundred years before the earliest human arrival.

Answer

The statements that undermine the argument are the finding that an island-wide megadrought destroyed inland forests 12,000 years ago and the finding that the dietary shift occurred centuries prior to human arrival.
Both correct choices directly sever the proposed causal connection. One provides an alternative environmental cause (an island-wide drought that destroyed inland forests), showing that the dietary shift was driven by climatic destruction rather than human hunting pressure. The other demonstrates that the dietary shift occurred centuries before human arrival, showing that the phenomenon existed independently of any human presence.

Step-by-Step Solution

1
Identify the argument's premises and main conclusion
Premises: Minoria dwarf hippo enamel displays elevated carbon-13 and micro-wear at 12,000 BP (indicating a diet of coastal scrub), coinciding with human arrival. Conclusion: Human hunting pressure forced the hippos out of inland forests to coastal zones, causing extinction.
Deconstructing the argument isolates the causal leap from temporal correlation to human-induced displacement.
2
Determine the underlying causal assumptions and vulnerabilities
The author assumes human arrival caused the habitat displacement rather than an alternative environmental cause, and assumes the dietary shift did not precede human arrival.
Causal arguments on the LSAT are vulnerable to alternative causes, reversed causation, and pre-existing conditions.
3
Evaluate the choices for valid weaken mechanisms
The drought statement provides an alternative explanation for the loss of inland vegetation, and the pre-human fossil statement destroys the temporal correlation by demonstrating the shift happened before humans arrived.
Both findings directly invalidate the author's causal inference.

Key Concept

Weaking causal arguments via alternative explanations and pre-existing timeline disproof
Estimated Time:2m 0s
Question 54Question →

Traffic Safety Analyst: In an effort to reduce nighttime pedestrian collisions, the city of Bellview recently installed high-contrast reflective crosswalks at fifty major intersections. Over the subsequent six months, nighttime pedestrian collisions at these intersections decreased by twenty percent relative to the previous six months. Because no other roadway modifications were made at these intersections during this period, the new reflective crosswalks clearly caused the reduction in collisions by making pedestrians more visible to drivers.

Which one of the following, if true, most seriously undermines the traffic safety analyst's argument?

Show answer & explanation

Answer: Shortly before the crosswalks were installed, a nearby bridge closure permanently diverted over one-third of nighttime vehicular traffic away from the streets containing the fifty intersections.

Answer

The argument is most seriously weakened by demonstrating that a major bridge closure diverted over one-third of nighttime vehicular traffic away from the intersections, providing an alternate explanation for the collision reduction.
The analyst concludes that the crosswalk paint caused the reduction in pedestrian accidents by improving visibility. The statement detailing a major bridge closure that diverted over one-third of nighttime vehicular traffic away from these intersections directly undermines this conclusion by providing an obvious alternative explanation: with fewer cars on the road, collisions decreased regardless of driver visibility.

Step-by-Step Solution

1
Identify the premises and the main conclusion of the argument.
Premises: 50 intersections received reflective crosswalks, nighttime pedestrian collisions dropped 20% over six months, and no other road modifications occurred. Conclusion: The reflective crosswalks caused the reduction in collisions by increasing visibility.
Isolating the core causal claim is essential for identifying the logical gap.
2
Identify the unstated assumption linking the correlation to causation.
The author assumes that no other external factor (such as changes in traffic volume or pedestrian density) was responsible for the decline in nighttime collisions.
Causal arguments on the LSAT frequently overlook alternate causes or confounding variables.
3
Select the choice that provides an alternative explanation for the 20% decline in nighttime collisions.
A substantial diversion of nighttime traffic due to a bridge closure explains why fewer collisions occurred, independently of whether the crosswalks improved visibility.
Introducing an alternate cause breaks the inferred link between the reflective paint and the reduction in accidents.

Key Concept

Evaluating Alternate Explanations in Causal Arguments
Question 55Question →

Archaeologist: Microscopic analysis of dental calculus from Bronze Age human remains excavated at a high-altitude settlement in the Tian Shan mountains revealed starch granules from cultivated broomcorn millet. Because wild millet cannot grow at these elevations and historical linguistic models indicate that local populations lacked farming terminology until centuries later, the excavators concluded that these highlanders obtained all their millet through trade with distant lowland farming societies.

Which of the following statements, if true, most seriously undermine the excavators' conclusion? (Select all that apply.)

Select all that apply

Show answer & explanation

Answer: Strontium isotope analyses of the skeletal remains indicate that these individuals spent their childhood and early adulthood in lowland farming settlements before moving to the high-altitude site.; Microclimate analysis and soil cores from the mountain settlement demonstrate that sheltered micro-basins supported the opportunistic seasonal cultivation of early-maturing millet without specialized agricultural techniques.

Answer

The statements indicating that the individuals lived in lowland farming settlements prior to migrating to the mountain site, and that sheltered micro-basins at the site supported local cultivation of early-maturing millet, both undermine the conclusion.
Both correct statements introduce new evidence that directly challenges the author's inferential leaps: one establishes an alternative explanation for the dental calculus (that individuals ate millet while living in the lowlands before migrating to the highlands), and the other establishes that local cultivation was environmentally feasible in micro-basins despite the general regional elevation constraints and the absence of specialized agricultural vocabulary.

Step-by-Step Solution

1
Analyze the stimulus argument to isolate premises and the main conclusion.
Premises: Starch granules of broomcorn millet were identified in dental calculus from high-altitude human remains; wild millet cannot grow at high altitudes; linguistic reconstructions show no farming vocabulary until centuries later. Conclusion: Highlanders acquired all their millet via trade with distant lowland farmers.
Deconstructing the argument isolates the inferential gap between physical evidence of consumption and the claim of trade dependency.
2
Identify unstated assumptions and reasoning vulnerabilities.
The author assumes that calculus deposits reflect dietary intake solely during residence at the high-altitude site, that lack of formal farming vocabulary precludes all local cultivation, and that trade is the sole possible mechanism.
Uncovering implicit assumptions highlights how alternative explanations sever the link between premises and conclusion.
3
Evaluate each statement to determine whether it provides counter-evidence against the conclusion.
The statement showing prior lowland residence provides an alternative origin for the dental deposits (migration), and the statement showing micro-basin cultivation provides an alternative origin for the crop (local growing), both undermining the conclusion.
Multi-select weaken questions require identifying all independent choices that undermine the argument's central claim.

Key Concept

Weaken Arguments via Alternative Explanations and Unstated Assumptions
Estimated Time:2m 0s
Question 56Question →

Consider the following argument:

Marine Biologist: Deep-sea coral reefs off the southern Reykjanes Ridge experienced a 30 percent decline in skeletal calcification rates following a series of localized undersea seismic tremors. Because such tremors fracture hydrothermal fissures, releasing acidic mineral compounds into surrounding waters, researchers concluded that the increased acidity from these venting fissures was the direct cause of the diminished calcification in the coral colonies.

Statement: If true, the fact that the undersea tremors also triggered dense submarine sediment plumes that settled over the reefs and obstructed the nutrient filtration required for calcification weakens the researchers' conclusion.

Show answer & explanation

Answer: True

Answer

True
The statement is true because the stimulus commits a classic correlation-to-causation error. The author assumes that because calcification dropped following seismic activity, the acidic compounds released by the tremors must be the direct cause. Introducing evidence that the tremors concurrently created sediment plumes that physically impede the biological mechanism of calcification provides an alternative explanation for the decline, substantially weakening the author's conclusion.

Step-by-Step Solution

1
Identify the conclusion and supporting premises in the stimulus.
Conclusion: The increased acidity from venting fissures was the direct cause of the diminished coral calcification. Premise: A 30 percent calcification decline occurred after seismic tremors, which are known to fracture fissures and release acidic mineral compounds.
Accurately identifying the author's causal claim is necessary to determine what evidence would weaken it.
2
Identify the underlying reasoning gap in the argument.
The author assumes that because tremors release acidity and calcification subsequently declined, the acidity must be the specific factor responsible, overlooking other potential consequences of the tremors.
Causal arguments that infer causation from temporal correlation are vulnerable to plausible alternative explanations for the observed effect.
3
Evaluate whether the statement introduces an effective alternative cause.
The statement introduces a competing causal mechanism—sediment plumes caused by the same tremors that directly obstruct calcification—which accounts for the effect without relying on water acidity.
Providing a viable alternative cause directly undermines the claim that acidity was the direct cause, confirming that the statement weakens the conclusion.

Key Concept

Weakening causal arguments by introducing an alternative explanation for an observed correlation
Question 57Question →

Anthropologist: Kaelen's ancient society was highly unusual in that its wealthiest elite resided in a vulnerable low-lying river basin rather than on high ground. This is evident from recent architectural surveys of the ruins, which demonstrate that the most elaborately ornamented residential dwellings are concentrated in the basin. Conversely, the plain, strictly utilitarian structures are located exclusively on the elevated rocky plateaus overlooking the river, despite the fact that throughout antiquity, the social elite almost universally occupied elevated terrain to project dominance and ensure defensive superiority.

Which of the following, if true, most seriously weakens the anthropologist's argument?

Show answer & explanation

Answer: The low-lying basin experienced severe annual flooding that routinely destroyed buildings, forcing its impoverished residents to use easily carved but temporary wood, while the elite could afford the immense labor required to cut the permanent, unadorned basalt used for the plateau homes.

Answer

The option stating that impoverished basin residents used easily carved temporary wood while the elite afforded permanent, unadorned basalt on the plateaus is correct.
The correct answer destroys the author's core assumption that 'elaborately ornamented' equals 'wealthy.' By explaining that the basin residents used easily carved wood out of impoverished necessity, and that the plateau residents used expensive, hard-to-carve basalt, it provides a superior alternative explanation for the architectural differences. This strongly suggests the wealthy actually lived on the plateaus, entirely dismantling the anthropologist's conclusion.

Step-by-Step Solution

1
Identify the main conclusion of the argument.
The conclusion is the first sentence: Kaelen's wealthiest elite resided in the vulnerable low-lying river basin rather than on high ground.
This is the central claim the anthropologist is trying to prove using the architectural evidence.
2
Identify the premises supporting the conclusion.
Ornamented dwellings are found in the basin, while plain structures are found on the plateaus. Usually, elites live on high ground for dominance and defense.
These established facts form the foundation of the author's reasoning.
3
Identify the unstated assumption bridging the premises to the conclusion.
The argument assumes that 'elaborately ornamented' buildings are a definitive indicator of wealth, and that 'plain, strictly utilitarian' structures must belong to non-elites.
The author jumps from the physical appearance of the buildings directly to the social status of the inhabitants.
4
Evaluate the options to find the one that attacks this assumption.
The correct option demonstrates that the ornamentation was a feature of cheap, easily workable material used by the poor out of necessity, while the plainness was a feature of expensive, permanent stone used by the wealthy.
This severs the link between ornamentation and wealth, demonstrating that the wealthy actually lived on the plateaus, devastating the conclusion.

Key Concept

Identifying and attacking the unstated assumption linking evidence to the conclusion (Alternate Cause/Explanation).
Estimated Time:2m 0s
Question 58Question →

Agronomist: In a three-year trial across several commercial groves, citrus orchards intercropped with sweet alyssum experienced a 45 percent reduction in parasitic aphid infestations compared to adjacent monoculture orchards. Alyssum blooms are known to attract hoverflies, whose larvae prey voraciously on aphids. Thus, intercropping sweet alyssum reduces aphid infestations in citrus orchards specifically by boosting populations of natural predatory insects.

Which of the following statements, if true, most seriously undermine the agronomist's reasoning? (Select TWO correct answers.)

Select all that apply

Show answer & explanation

Answer: Sweet alyssum releases volatile organic compounds that directly deter adult aphids from landing on nearby citrus foliage, even in enclosures where predatory insects are entirely absent.; Adult hoverflies drawn to sweet alyssum lay their eggs almost exclusively on ground-level foliage and rarely migrate into the higher citrus tree canopies where the aphids reside.

Answer

The statements establishing that sweet alyssum directly repels aphids via chemical emissions and that hoverflies lay eggs only at ground level rather than in the citrus canopy.
The agronomist concludes that intercropping sweet alyssum reduces aphid infestations specifically by boosting populations of natural predatory insects. The option establishing that sweet alyssum directly repels aphids via chemical emissions provides an alternative explanation for the drop in pests, thereby undermining the predator hypothesis. The option showing that hoverfly larvae remain at ground level reveals that the predators do not reach the aphids in the tree canopies, directly breaking the proposed mechanism.

Step-by-Step Solution

1
Identify the conclusion and supporting premises of the argument.
Premise: Alyssum intercropping reduced aphids by 45 percent, and alyssum attracts predatory hoverflies. Conclusion: Alyssum reduces aphids specifically by boosting natural predator populations.
To weaken an argument, one must locate the precise leap from the observed correlation to the specific causal conclusion.
2
Identify potential weaknesses in the causal claim.
The argument assumes that hoverfly predation is the sole driver of the aphid reduction and that the attracted hoverflies actually prey on the aphids in the citrus trees.
Causal claims can be undermined by providing an alternative cause or by breaking the chain between the alleged cause and the effect.
3
Evaluate the choices to find statements that independently undermine the causal link.
The statement showing direct chemical deterrence provides an alternative cause, while the statement showing hoverfly larvae stay at ground level demonstrates that the proposed mechanism does not reach the tree canopy pests.
Both findings directly cast doubt on the conclusion that increased predator activity caused the aphid decline.

Key Concept

Weaken via Alternative Cause and Broken Causal Mechanism
Estimated Time:1m 15s
Question 59Question →

Transit Analyst: Following the introduction of a universal fare-free policy on Metroville's municipal bus network, total daily passenger boardings increased by 35 percent over eighteen months. The municipal transit board concluded that eliminating ticket fares was the direct cause of this ridership surge, proving that financial cost had been the primary deterrent to public transit usage.

Statement: The transit board's conclusion is significantly undermined if the city simultaneously closed two major vehicular bridges to private automobiles while doubling bus service frequency along those transit corridors.

Show answer & explanation

Answer: True

Answer

True
The evaluation that the statement undermines the argument is correct. The transit analyst commits a causal error by attributing a 35 percent ridership increase solely to the removal of fares. By demonstrating that the municipality enacted major disincentives to private driving (bridge closures) and drastically increased the convenience and availability of transit (doubled bus frequency) concurrently, the statement supplies compelling alternate causes for the surge, thereby weakening the board's conclusion.

Step-by-Step Solution

1
Identify the argument's core premises and conclusion
Premise: Bus boardings rose by 35% after fares were eliminated. Conclusion: Eliminating fares was the direct cause of the surge and financial cost was the primary deterrent.
Isolating the conclusion exposes the author's causal leap from a mere correlation (fare elimination and ridership rise) to an exclusive causal relationship.
2
Determine the central assumption and vulnerability
The transit board assumes that no other concurrent factors or service modifications caused the increase in bus boardings during the eighteen-month window.
Causal arguments on the LSAT are vulnerable to alternate causes and unaddressed confounding factors that occurred during the same timeframe.
3
Evaluate the impact of the supplementary statement
Restricting private automobile traffic on major bridges while doubling bus frequencies creates strong incentives and service improvements that explain higher bus usage independent of fare policy.
Providing a viable alternative explanation undermines the board's conclusion that fare elimination was the primary causal factor.

Key Concept

Weaken an argument by providing an alternative causal explanation for an observed correlation
Estimated Time:1m 30s
Question 60Question →

Food Scientist: Perishable fruits spoil primarily due to the accumulation of ethylene gas and moisture inside standard retail packaging. A newly developed bio-polymer film incorporates microporous zeolite minerals designed to continuously absorb ethylene and regulate internal humidity. In laboratory trials under standard refrigerated conditions, strawberries wrapped in this bio-polymer film remained fresh twice as long as strawberries wrapped in conventional plastic packaging. Therefore, commercial grocers can substantially reduce in-store strawberry spoilage by adopting this bio-polymer packaging.

Which of the following, if true, most seriously weakens the food scientist's argument?

Show answer & explanation

Answer: Unlike the dark refrigerated units used in the laboratory trials, typical grocery display cases subject packaged fruit to continuous fluorescent lighting, which triggers the bio-polymer to break down and release moisture that fosters fungal decay.

Answer

The argument is most seriously weakened by pointing out that typical grocery display cases expose packaged fruit to continuous lighting that breaks down the bio-polymer and accelerates fungal decay.
The correct answer provides evidence that the operating conditions of retail grocery stores differ in a crucial way from the laboratory test environment. Specifically, continuous fluorescent lighting in stores triggers a chemical breakdown in the bio-polymer that releases moisture and promotes fungal rot, thereby invalidating the conclusion that grocers will experience a net reduction in strawberry spoilage.

Step-by-Step Solution

1
Identify the premises and conclusion of the argument.
Premises: Ethylene and moisture cause fruit spoilage; the bio-polymer absorbs both; in refrigerated laboratory trials, strawberries wrapped in this film lasted twice as long as those in plastic. Conclusion: Commercial grocers can reduce in-store strawberry spoilage by adopting this packaging.
Weaken questions require identifying the gap between the evidence provided and the author's ultimate claim.
2
Analyze the underlying assumption bridging the experimental evidence to the real-world application.
The author assumes that the performance observed in dark, refrigerated laboratory conditions will translate directly to commercial grocery store environments without unanticipated failure modes.
Arguments that generalize from controlled laboratory tests to commercial use are vulnerable to unconsidered real-world differences.
3
Evaluate the answer choices for new information that breaks this assumption.
The option noting that retail fluorescent lighting causes the bio-polymer to degrade and release moisture that fosters decay demonstrates that in-store conditions will actively negate the preservation benefits observed in the laboratory.
Introducing an operational failure specific to commercial grocery environments directly undermines the recommendation.

Key Concept

Evaluating causal generalizations from controlled laboratory trials to real-world commercial environments
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