Identify the Principle
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LSAT Logical Reasoning › Identify the Principle
Which one of the following principles, if valid, most justifies Dr. Lin's decision?
A claim should not be believed until every lab has replicated it.
Consumers are typically skeptical of early scientific claims.
If a study is likely to be replicated, its results are necessarily trustworthy.
One should refrain from publicizing tentative claims when doing so risks misleading the public and verification is reasonably forthcoming.
Scientists should always avoid media interactions about their research.
Explanation
The correct principle supports withholding tentative claims when there is risk of public misunderstanding and timely verification is available. The distractors are irrelevant, overgeneralized, or assert an unwarranted standard.
Which one of the following conforms most closely to the principle stated above?
A fashion vlogger accepted clothing from the brand she reviewed, did not disclose it in the video, and viewers concluded her review was not reliable.
A film critic accepted travel funding from a studio but disclosed it a week after the review appeared; the review was regarded as reliable.
A tech blogger refused a free device and posted a review without any disclosure; readers deemed the review unreliable for lacking disclosure.
A food critic accepted a gift from a restaurant she does not review; she posted a review of another restaurant without disclosure and was criticized as unreliable for failing to disclose.
A book reviewer disclosed that a publisher once sponsored a conference they attended, but having refused benefits for the particular book, the review was still considered unreliable.
Explanation
The principle requires disclosure when benefits are accepted from the company being reviewed and deems the evaluation unreliable if disclosure is not made, which E exemplifies. The other choices either treat nonrequired disclosures as necessary or treat belated or missing required disclosures as compatible with reliability.
A gardener claims: All plants that are native to this region can survive the winter here without being brought indoors. The silver sage is native to this region. So the silver sage can survive the winter here without being brought indoors. The gardener admits that some nonnative plants also survive if protected, but says that does not matter for the silver sage.
Which one of the following principles, if valid, most justifies the reasoning above?
If an ability is valuable, then it should be the only factor in choosing among alternatives.
If something can survive a winter, then it must be native to the region where it survives.
If something is native to a region, then it will thrive there under all conditions.
If some members of a group have a certain ability, then any member of that group has that ability.
If every member of a group has a certain ability, then any member of that group has that ability.
Explanation
The gardener claims that all native plants survive local winters outdoors, so the native silver sage will, undeterred by some nonnatives surviving with protection. This uses conditional reasoning where nativity sufficiently ensures survival. The principle must affirm that group membership guarantees the ability for any member. Choice A fits the logic and scope, emphasizing universality without implying exclusivity. A tempting wrong is C, which narrows to a reverse (survival implies nativity), failing to support the argument's direction. Match principles to the argument's reasoning mechanism, such as from category to attribute, rather than to exceptions or converse logic.
A homeowner argues that installing a programmable thermostat is worthwhile. The homeowner notes that, in homes where the thermostat automatically lowers the temperature while occupants are asleep or away, heating systems run fewer hours. The homeowner also notes that running the heating system fewer hours generally reduces energy bills. Therefore, the homeowner concludes that installing a programmable thermostat will reduce the home’s energy bills. The reasoning assumes that if a device reliably causes a reduction in usage of a cost-driving system, then the device will tend to reduce the associated costs.
If a device reduces the use of a system that drives costs, then using that device will generally reduce those costs.
If a system runs fewer hours, then it will never require maintenance.
If energy bills are reduced, then the home must be more comfortable for everyone living there.
If a person wants to save money, then that person should avoid buying any new device.
If a product is advertised as efficient, then it will always reduce costs in every household.
Explanation
The homeowner's argument follows a cost-reduction logic based on decreased system usage. The homeowner notes that programmable thermostats in other homes automatically lower temperatures when appropriate, causing heating systems to run fewer hours, which generally reduces energy bills. The conclusion is that installing such a thermostat will reduce their energy bills. This reasoning assumes that devices reliably reducing usage of cost-driving systems will tend to reduce associated costs. The principle treats reduced system operation as a pathway to cost savings that will generally hold across similar situations. Answer choice C is tempting because it mentions efficiency advertising, but the argument is based on observed mechanical relationships between usage and costs, not advertising claims. The key insight is that principle questions about practical benefits often test whether you can identify the logical mechanism connecting an intervention to its predicted outcome.
A professor claims that Mira deserves an extension on the final paper. Mira emailed the professor two days before the deadline explaining that a close family member had been hospitalized, and she provided documentation from the hospital. In the past, whenever students have provided credible documentation of an unexpected emergency before a deadline, the professor has granted an extension. Therefore, the professor concludes that Mira should be granted an extension as well. The reasoning depends on applying a consistent policy: cases meeting the same relevant conditions should be treated the same way.
If an emergency is unexpected, then it excuses any failure to meet any obligation, regardless of timing.
If a person asks politely, then refusing the request would be unfair.
Whenever a person provides any documentation, that person should receive whatever request is being made.
If a rule has exceptions, then it should not be enforced in any case.
If a decision-maker has treated certain cases one way, then any future case with the same relevant features should be treated that way.
Explanation
The professor's argument exemplifies consistency-based reasoning in decision-making. The professor established a precedent of granting extensions to students who provide credible documentation of unexpected emergencies before deadlines. Mira meets these exact conditions: she provided hospital documentation of a family emergency before the deadline. The professor concludes Mira deserves an extension based on treating similar cases similarly. This reasoning depends on the principle that decision-makers should apply consistent policies—cases with the same relevant features should receive the same treatment. Answer choice A is too broad because it suggests any documentation warrants any request, ignoring the specific conditions the professor has established. The key test-taking insight is that principle questions about fairness and consistency often hinge on applying established criteria uniformly rather than making arbitrary distinctions.
During a staff meeting, a manager argued: Last quarter, our customer-support tickets were resolved faster on days when the team used the new triage checklist. Also, the checklist does not add any steps to the process; it merely orders existing steps. Finally, whenever a work tool improves speed without increasing workload, adopting it companywide is the sensible choice. Therefore, we should require every support team, not just ours, to use the new triage checklist.
Any procedure that reorganizes existing steps without adding new ones will improve efficiency in any workplace setting.
If a tool improves speed, it is sensible to recommend it, but not to require it, unless it also reduces errors.
If a tool improves performance in one department, it should be adopted by every department, regardless of whether their tasks are similar.
If a work tool improves speed without increasing workload for a group performing a given task, then it is sensible to require all groups performing that task to use the tool.
A tool should be required only after it has been tested in multiple teams over several quarters with consistent results.
Explanation
This argument follows a pattern of applying a general principle to justify a specific policy decision. The manager observes that the checklist improved speed without adding workload, then invokes the principle that tools meeting these criteria should be adopted companywide. The correct answer (C) captures both the specific conditions (improves speed without increasing workload) and the conclusion (should be required for all groups performing that task). This principle matches the scope—it applies to groups doing the same task, not different departments. Choice A is tempting but too broad, suggesting any improvement in one department justifies universal adoption regardless of task similarity. The key insight is that principle questions require matching both the logical structure and the specific scope of the argument's reasoning.
A technology officer argues that the company should require two-factor authentication (2FA) for employee accounts. The officer notes that, in departments that voluntarily adopted 2FA, the number of successful account takeovers dropped markedly. The officer also notes that account takeovers often lead to data breaches, and preventing breaches is a central security goal. Therefore, the officer concludes that requiring 2FA companywide will help prevent data breaches. The reasoning assumes that when a measure reliably reduces a common pathway to a harm, implementing it broadly will tend to reduce that harm.
If a security measure is inconvenient, then it should not be required even if it improves security.
If 2FA prevents some attacks, then it prevents all attacks and makes other security measures unnecessary.
If a department has fewer breaches, then its employees must be more honest than other employees.
If a measure reduces a frequent means by which a harm occurs, then adopting the measure will generally reduce the occurrence of that harm.
If a policy is adopted companywide, then it will be effective regardless of whether employees follow it.
Explanation
The technology officer's argument follows a harm prevention logic based on blocking a common pathway to problems. The officer notes that departments using two-factor authentication experienced fewer successful account takeovers, observes that account takeovers often lead to data breaches, and concludes that requiring 2FA companywide will help prevent breaches. This reasoning assumes that when a measure reliably reduces a frequent means by which harm occurs, implementing it broadly will tend to reduce that harm. The principle treats blocking common pathways to problems as an effective prevention strategy. Answer choice D is tempting because it mentions preventing attacks, but it's too absolute—the argument claims 2FA helps prevent breaches by reducing a common cause, not that it prevents all attacks or makes other measures unnecessary. The key insight for principle questions about security and prevention is to focus on how measures that reduce common risk pathways contribute to overall harm reduction.
A librarian states: Every book that is part of the “Reference Only” collection cannot be checked out. This atlas is part of the “Reference Only” collection. Therefore, the atlas cannot be checked out. The librarian adds that some other books also cannot be checked out because they are on reserve, but that does not change what follows from being “Reference Only.”
Which one of the following principles, if valid, most justifies the reasoning above?
If an item belongs to a category, then it shares every restriction that applies to any other restricted category.
If all items in a category are prohibited from an action, then any item in that category is prohibited from that action.
If an item is prohibited from an action, then it must belong to the category most commonly associated with that prohibition.
If some items are restricted for different reasons, then no restriction can be inferred from category membership.
If an item is useful to many people, then it should not be permitted to leave the building.
Explanation
The librarian reasons that every 'Reference Only' book cannot be checked out, so this atlas in that collection cannot, unaffected by other books restricted for different reasons. This is conditional logic: category membership sufficiently prohibits checkout. The principle needs to justify inferring the prohibition from category alone. Choice A captures this precisely, aligning with the argument's scope without overgeneralizing. Tempting choice B reverses the logic (prohibition implies category), which doesn't support the forward conclusion. In principle questions, connect to how the argument derives its restriction, like from membership to rule, not to alternatives or reversals.
A tenant argues that the landlord should replace the building’s broken exterior light. The tenant notes that the lease requires the landlord to maintain common-area lighting in working order. The tenant also notes that the exterior light is part of the common-area lighting and has been nonfunctional for weeks. Therefore, the tenant concludes that the landlord is obligated to replace the light. The reasoning relies on the idea that when a contract assigns an obligation to a party, that party must fulfill it whenever the specified conditions obtain.
If a light is broken, then it must have been broken by a tenant rather than by ordinary wear.
If a contract requires a party to do something under certain conditions, then that party is obligated to do it when those conditions are met.
If a tenant requests a repair, then the landlord must comply immediately regardless of the lease terms.
If a landlord is obligated to repair one item, then the landlord is obligated to repair all items, even those outside common areas.
If a contract contains any maintenance clause, then the landlord must renovate the entire building.
Explanation
The tenant's argument follows contractual obligation reasoning based on specified conditions being met. The tenant notes that the lease requires landlords to maintain common-area lighting in working order, identifies the exterior light as part of common-area lighting, and observes it has been nonfunctional for weeks. The conclusion is that the landlord is obligated to replace it. This reasoning assumes that when contracts assign obligations to parties under certain conditions, those parties must fulfill the obligations when the conditions obtain. The principle treats contractual language as creating binding duties that apply when their specified circumstances arise. Answer choice A is tempting because it mentions maintenance clauses, but it's too extreme—the argument is about fulfilling specific contractual obligations, not renovating entire buildings. The strategic insight is that principle questions about legal or contractual reasoning often test whether you understand how specific conditions trigger defined obligations.
Which one of the following principles, if valid, most justifies the judge's ruling?
Juries, not judges, should decide what evidence is reliable.
Eyewitness confidence is a reliable indicator of accuracy.
When the method of producing evidence is systematically biased and avoidable, the evidence should be excluded despite superficial indicators of credibility.
Evidence should be admitted as long as it has some probative value.
All eyewitness identifications should be excluded.
Explanation
The correct principle supports excluding evidence generated by avoidably biased procedures, which is the judge's reason. The remaining options contradict that rationale or are overbroad.