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The Logical Reasoning (LR) section tests your ability to evaluate, analyze, and complete arguments.
Logical Reasoning questions present short passages, usually arguments, followed by a question that asks you to analyze, strengthen, weaken, or draw a conclusion from the argument.
These questions assess how well you understand the structure of reasoning and your ability to spot assumptions, flaws, or inferences. Each LSAT typically includes two scored LR sections, and together they account for about half your total score, making mastery of this section crucial.
Each Logical Reasoning question begins with a short passage, typically an argument but sometimes a set of facts, followed by a question stem and five answer choices. The first step to solving any LR question is identifying the question type, as each one asks you to perform a different logical task. Common types include:
Look closely at the language in the question stem. Phrases like “Which of the following, if true, most strengthens…” signal a Strengthen question. If it says “The reasoning is flawed because…,” it’s a Flaw question. Recognizing these clues is essential because each type demands a different approach.
Once you’ve identified the question type, here’s how to find the correct answer:
With practice, you'll start to recognize recurring patterns and logical structures, which makes identifying and attacking each question much more manageable.
Here are 10 sample Logical Reasoning questions with a detailed explanation for each answer.
“Scientist: Earth’s average annual temperature has increased by about 0.5 degrees Celsius over the last century. This warming is primarily the result of the buildup of minor gases in the atmosphere, blocking the outward flow of heat from the planet.”
Which one of the following, if true, would count as evidence against the scientist’s explanation of Earth’s warming?
(A) Only some of the minor gases whose presence in the atmosphere allegedly resulted in the phenomenon described by the scientist were produced by industrial pollution.
(B) Most of the warming occurred before 1940, while most of the buildup of minor gases in the atmosphere occurred after 1940.
(C) Over the last century, Earth received slightly more solar radiation in certain years than it did in others.
(D) Volcanic dust and other particles in the atmosphere reflect much of the Sun’s radiation back into space before it can reach Earth’s surface.
(E) The accumulation of minor gases in the atmosphere has been greater over the last century than at any other time in Earth’s history.
Answer
A. Incorrect. The scientist does not address pollution, and the source of the gases is irrelevant to her conclusion. This option tries to mislead by introducing external associations like pollution and global warming, but the gases could come from natural sources as well.
B. Correct. This choice effectively undermines the argument by showing that the proposed cause and the observed effect did not occur simultaneously. That weakens the claim that the gases caused the warming, suggesting another factor may be responsible.
C. Incorrect. This misses the point. A 0.5-degree increase is significant, and the phrase “slightly more solar radiation” downplays that. Plus, the argument concerns long-term average temperatures, which can trend upward even if only some years receive more radiation. The answer doesn’t claim a consistent increase in solar radiation.
D. Incorrect. The argument links atmospheric changes to temperature rise. This option fails to mention any change in volcanic dust or particles over the past century, so it doesn’t address the argument's causal link.
E. Incorrect. This somewhat supports the argument, as a sharp rise in minor gases could logically lead to greater warming, strengthening the scientist’s conclusion rather than weakening it.
“Columnist: Research shows significant reductions in the number of people smoking, and especially in the number of first-time smokers in those countries that have imposed stringent restrictions on tobacco advertising. This provides substantial grounds for disputing tobacco companies’ claims that advertising has no significant causal impact on the tendency to smoke.”
Which one of the following, if true, most undermines the columnist’s reasoning?
(A) People who smoke are unlikely to quit merely because they are no longer exposed to tobacco advertising.
(B) Broadcast media tend to have stricter restrictions on tobacco advertising than do print media.
(C) Restrictions on tobacco advertising are imposed only in countries where a negative attitude toward tobacco use is already widespread and increasing.
(D) Most people who begin smoking during adolescence continue to smoke throughout their lives.
(E) People who are largely unaffected by tobacco advertising tend to be unaffected by other kinds of advertising as well.
Answer:
A. Incorrect. This choice uses the absolute term “unlikely,” while the stimulus refers to a relative change—“less likely.” Someone can remain unlikely to quit smoking, yet still be more likely to quit than before. The distinction between absolute and relative likelihood is important here.
B. Incorrect. This focuses on the legal nature of the advertising restrictions, which is irrelevant. The argument is concerned with the effects of the restrictions, not their legal classification.
C. Correct. This introduces a plausible alternative explanation. If negative public attitudes toward smoking led to both the advertising restrictions and the decline in first-time smoking, then the restrictions may not be the true cause of the reduction. This is the third type of weakener: proposing a third variable responsible for both the supposed cause and effect.
D. Incorrect. The argument is about the number of first-time smokers. What happens after someone starts smoking doesn’t impact that point. Additionally, this choice doesn’t address whether advertising influences attitudes toward smoking, which is central to the argument.
E. Incorrect. This offers an unrelated detail about advertising. For this to be relevant, we’d need information about how many people are unaffected by tobacco ads. Mentioning other forms of advertising doesn’t help evaluate the argument.
If you feel like you’re still getting stuck on weaken LSAT questions, reviewing additional examples and explanations can help!
“The Land Party achieved its only national victory in Banestria in 1935. It received most of its support that year in rural and semirural areas, where the bulk of Banestria’s population lived at the time. The economic woes of the years surrounding that election hit agricultural and small business interests the hardest, and the Land Party specifically targeted those groups in 1935. I conclude that the success of the Land Party that year was due to the combination of the Land Party’s specifically addressing the concerns of these groups and the depth of the economic problems people in these groups were facing.”
Each of the following, if true, strengthens the historian’s argument except:
(A) In preceding elections the Land Party made no attempt to address the interests of economically distressed urban groups.
(B) Voters are more likely to vote for a political party that focuses on their problems.
(C) The Land Party had most of its successes when there was economic distress in the agricultural sector.
(D) No other major party in Banestria specifically addressed the issues of people who lived in semirural areas in 1935.
(E) The greater the degree of economic distress someone is in, the more likely that person is to vote.
Answer:
A. Correct. This weakens the argument by introducing irrelevant information. Past elections don’t matter; we’re only interested in the outcome of the 1935 election. For all we know, the Land Party didn’t exist before 1935. If this option had included data from that specific election, showing a correlation between campaign presence and votes, it might have supported the argument.
B. Incorrect. This strengthens the historian’s claim. It reinforces the idea that the Land Party’s focus on agricultural and small business concerns influenced those voters to support them.
C. Incorrect. This also supports the argument. It suggests a link between economic hardship among rural groups and their support for the Land Party, which backs up the historian’s claim that economic struggles contributed to the party’s success.
D. Incorrect. If the Land Party was uniquely responsive to the concerns of agricultural and small business voters, it makes sense those voters would support it. That directly strengthens the claim that the party won by addressing those groups' issues.
E. Incorrect. This, too, supports the argument. It connects economic distress to increased voter turnout among affected groups. If those voters were inclined toward the Land Party, greater turnout would logically mean more support for that party.
“Consumer: The latest Connorly Report suggests that Ocksenfrey prepackaged meals are virtually devoid of nutritional value. But the Connorly Report is commissioned by Danto Foods, Ocksenfrey’s largest corporate rival, and early drafts of the report are submitted for approval to Danto Foods’ public relations department. Because of the obvious bias of this report, it is clear that Ocksenfrey’s prepackaged meals really are nutritious.”
The reasoning in the consumer’s argument is most vulnerable to criticism on the grounds that the argument
(A) treats evidence that there is an apparent bias as evidence that the Connorly Report’s claims are false
(B) draws a conclusion based solely on an unrepresentative sample of Ocksenfrey’s products
(C) fails to take into account the possibility that Ocksenfrey has just as much motivation to create negative publicity for Danto as Danto has to create negative publicity for Ocksenfrey
(D) fails to provide evidence that Danto Foods’ prepackaged meals are not more nutritious than Ocksenfrey’s are
(E) presumes, without providing justification, that Danto Foods’ public relations department would not approve a draft of a report that was hostile to Danto Foods’ products
Answer:
A. Correct. This accurately identifies the flaw in the argument—an ad hominem attack. The consumer criticizes the company itself rather than addressing the quality of its products with substantive evidence.
B. Incorrect. Unrepresentative samples involve drawing conclusions from only part of a group. In this case, the consumer is referencing all of Ocksenfrey’s prepackaged meals, not just a subset. A true unrepresentative sample would be judging all meals based on just one bad example.
C. Incorrect. While Ocksenfrey may have biases, their own claims are not the focus of this argument. The flaw lies in the consumer’s reasoning, not in anything Ocksenfrey has said or claimed.
D. Incorrect. The argument doesn’t mention Danto’s products at all. It focuses entirely on Ocksenfrey. So the quality of Danto’s offerings isn’t relevant to evaluating the consumer’s reasoning.
E. Incorrect. Although this choice might sound relevant, it misses the mark. The consumer isn’t referencing negative reports about Danto—only criticizing Ocksenfrey. Hostile reports about competitors are not part of the argument here.
“Some video game makers have sold the movie rights for popular games. However, this move is rarely good from a business perspective. After all, StarQuanta sold the movie rights to its popular game Nostroma, but the poorly made film adaptation of the game was hated by critics and the public alike. Subsequent versions of the Nostroma video game, although better than the original, sold poorly.”
The reasoning in the argument is most vulnerable to criticism in that the argument
(A) draws a general conclusion on the basis of just one individual case
(B) infers that a product will be disliked by the public merely from the claim that the product was disliked by critics
(C) restates as a conclusion a claim earlier presented as evidence for that conclusion
(D) takes for granted that products with similar content that are in different media will be of roughly equal popularity
(E) treats a requirement for a product to be popular as something that ensures that a product will be popular
Answer:
A. Correct. This highlights the flaw of drawing a broad conclusion from only one example. To support a general claim, you need more than a single case.
B. Incorrect. This goes against what the stimulus says, which clearly stated the movie was disliked by both critics and the public. Also, the argument does not involve a prediction. It describes something that already happened. A flawed version of this reasoning would be: "Critics hated this game, so the public will hate it too."
C. Incorrect. This choice refers to circular reasoning, which is not present here. Circular reasoning is when the conclusion is simply a restatement of a premise. For example: "Selling movie rights is bad because it is never a good idea to sell movie rights."
D. Incorrect. This option is unclear and seems unrelated to the argument. It may be trying to describe a faulty analogy, which would involve comparing two unrelated things. For instance: "This movie with lots of sex scenes was popular, so this video game with sex scenes will be popular too."
E. Incorrect. This describes a confusion between necessary and sufficient conditions, which does not apply here. A typical example of this flaw would be: "Good games must be challenging. This game is challenging, so it must be good.
Looking for more practice? Here are additional answers and explanations for Flaw LSAT questions to help you perfect your skills!
“An undergraduate degree is necessary for appointment to the executive board. Further, no one with a felony conviction can be appointed to the board. Thus, Murray, an accountant with both a bachelor’s and a master’s degree, cannot be accepted for the position of Executive Administrator, since he has a felony conviction.”
The argument’s conclusion follows logically if which one of the following is assumed?
(A) Anyone with a master’s degree and without a felony conviction is eligible for appointment to the executive board.
(B) Only candidates eligible for appointment to the executive board can be accepted for the position of Executive Administrator.
(C) An undergraduate degree is not necessary for acceptance for the position of Executive Administrator.
(D) If Murray did not have a felony conviction, he would be accepted for the position of Executive Administrator.
(E) The felony charge on which Murray was convicted is relevant to the duties of the position of Executive Administrator.
Answer:
A. This gives sufficient conditions for being eligible for the board. When you take the contrapositive, it says: If someone is not eligible for the board, then they either lack a master’s degree or have a felony conviction. That doesn’t help. We already know Murray has a felony conviction, so this adds nothing new.
B. Correct. This directly links board eligibility to eligibility for the Executive Administrator role. Since Murray is not eligible for the board due to his conviction, and this answer states that only those eligible for the board can be Executive Administrator, it follows that Murray is also ineligible for that role.
C. This doesn’t rule out Murray’s eligibility. It simply says that an undergraduate degree isn’t required. That doesn’t weaken the argument. It’s like saying, “Having a perfect LSAT score isn’t required for law school, so having one doesn’t help.” The logic doesn’t follow.
D. This is just a faulty negation of the argument’s conclusion. Even if the felony conviction isn’t the reason Murray can’t be Executive Administrator, that doesn’t prove he can be. It’s still possible he would be ineligible for other reasons.
E. Just because the felony conviction isn’t necessarily disqualifying doesn’t mean it isn’t in this case. This answer doesn’t rule out the possibility that it still prevents Murray from being appointed.
Sufficient assumption questions like this often trip students up and can lead to lower scores. Review more sample answers to build confidence and boost your performance!
“Editorial: The city has chosen a contractor to upgrade the heating systems in public buildings. Only 40 percent of the technicians employed by this contractor are certified by the Heating Technicians Association. So the city selected a contractor 60 percent of whose technicians are unqualified, which is an outrage.”
Which one of the following is an assumption required by the argument in the editorial?
(A) Certified technicians receive higher pay than uncertified technicians.
(B) There are no contractors with fewer than 40 percent of their technicians certified.
(C) Technicians who lack certification are not qualified technicians.
(D) Qualified technicians installed the heating systems to be upgraded.
(E) The contractor hired by the city has personal ties to city officials.
Answer:
A. The argument says nothing about technician pay, so this is irrelevant. Whether certified technicians earn more doesn't help determine if they’re more qualified.
Negation: Certified technicians do not receive higher pay than uncertified ones.
B. Comparing the contractor to others in general doesn’t address the core issue. It only matters if there are more qualified technicians elsewhere, not just fewer certified ones.
Negation: One contractor in Ecuador has 39% certified technicians, while all others have 40%.
C. Correct. This points to the key assumption. The argument treats certification as evidence of qualification but doesn’t justify that link.
Negation: Technicians can be qualified even without certification.
D.Who installed the systems in the past is unrelated. The argument is about whether the current technicians are qualified.
Negation: The heating system was installed by trained monkeys.
E. Any potential conflict of interest doesn't affect whether the technicians are qualified. That issue is outside the scope of the argument.
Negation: The contractor has no personal ties to city officials.
“Biologist: Marine animals known as box jellyfish have eyes with well-formed lenses capable of producing sharp images that reveal fine detail. But the box jellyfish’s retinas are too far forward to receive a clear image, so these jellyfish can receive only a blurry image that reveals prominent features of objects but not fine detail. This example shows that eyes are adapted only to an animal’s needs rather than to some abstract sense of how a good eye would be designed.”
The argument requires assuming which one of the following?
(A) Box jellyfish are the only kind of jellyfish with retinas that do not focus clearly.
(B) Box jellyfish have a need to detect prominent features of objects but not fine details.
(C) Box jellyfish would benefit from having retinas that allowed their eyes to focus more sharply.
(D) Box jellyfish developed from jellyfish whose retinas received clear images.
(E) Box jellyfish use vision as their main means of detecting prey.
Answer:
A. What other jellyfish can or can't do isn't relevant. The argument is focused solely on the box jellyfish.
Negation: At least one other type of jellyfish cannot focus clearly.
B. Correct. This addresses the central assumption. The conclusion claims that box jellyfish don’t need better vision, but the argument never establishes what their actual needs are. This choice helps link their visual abilities to what they require.
Negation: Box jellyfish do need to detect fine details of objects.
C. This assumption actually weakens the argument. If box jellyfish would benefit from better vision, that undermines the idea that they don’t need it. The negation strengthens the conclusion, which means this can’t be the correct assumption.
Negation: Box jellyfish wouldn’t benefit from better vision.
D. This introduces an unrelated idea. If an ancestor had better eyes, that raises new questions about why the box jellyfish lost that ability. But the argument is about why the box jellyfish never developed better vision in the first place, not whether it lost it.
E. Whether box jellyfish use other ways to detect objects doesn’t affect the point. The argument hinges on whether their visual limitations mean they don’t need better vision, regardless of what else they can do.
With enough practice, you’ll start to spot and answer necessary assumption questions more easily.
“Modern science is built on the process of posing hypotheses and testing them against observations—in essence, attempting to show that the hypotheses are incorrect. Nothing brings more recognition than overthrowing conventional wisdom. It is accordingly unsurprising that some scientists are skeptical of the widely accepted predictions of global warming. What is instead remarkable is that with hundreds of researchers striving to make breakthroughs in climatology, very few find evidence that global warming is unlikely.”
The information above provides the most support for which one of the following statements?
(A) Most scientists who are reluctant to accept the global warming hypothesis are not acting in accordance with the accepted standards of scientific debate.
(B) Most researchers in climatology have substantial motive to find evidence that would discredit the global warming hypothesis.
(C) There is evidence that conclusively shows that the global warming hypothesis is true.
(D) Scientists who are skeptical about global warming have not offered any alternative hypotheses to explain climatological data.
(E) Research in global warming is primarily driven by a desire for recognition in the scientific community.
Answer:
A. The argument doesn’t mention anything about an "accepted standard of scientific debate." This choice likely tries to evoke the idea of “scientific consensus,” a term often used in public discussions, but it’s not relevant to the reasoning in the stimulus.
B. Correct. This is a reasonable assumption. It’s natural to think scientists value recognition for their work. Since predictions of global warming are widely accepted, anyone who could successfully disprove them would be challenging mainstream thought—something the stimulus says brings significant recognition.
C. The argument notes that global warming predictions are widely accepted and haven’t been disproven, but that doesn’t mean they’ve been definitively proven. A lack of disproof isn’t the same as conclusive evidence for a theory.
D. This is a trap. The stimulus says that skeptical scientists haven’t found evidence against global warming predictions, but that doesn’t mean they don’t have alternative theories. They just lack the evidence to support them.
E. The passage doesn’t make any claims about what motivates scientific research. It only states that recognition comes from overturning conventional views, not from supporting them. So we can’t assume that most research is driven by a desire for recognition or that confirming mainstream theories offers the same reward.
Trap answers frequently appear in "most strongly supported" questions, so it's helpful to go over more sample questions to get familiar with them.
“Principle: The executive in a given company whose compensation package is determined by the advice of an external consultant is likely to be overcompensated if the consultant also has business interests with the company the executive manages.”
Which one of the following judgments conforms most closely to the principle stated above?
(A) The president of the Troskco Corporation is definitely overpaid, since he receives in salary and benefits almost 40 times more than the average employee of Troskco receives.
(B) The president of the Troskco Corporation is probably overpaid, since his total annual compensation package was determined five years ago, when the company’s profits were at an all-time high.
(C) The president of the Troskco Corporation is probably not overpaid, since his total compensation package was determined by the Troskco board of directors without retaining the services of an external compensation consultant.
(D) The president of Troskco Corporation is probably overpaid, since the Troskco board of directors determined his compensation by following the advice of an external consultant who has many other contracts with Troskco.
(E) The president of Troskco Corporation is definitely not overpaid, since the external consultant the board of directors retained to advise on executive salaries has no other contracts with Troskco.
Answer:
A. The principle does not support a firm conclusion that an executive is overpaid. It only allows us to conclude they are probably overpaid under certain conditions. This answer goes too far.
B. This starts in the right direction but fails to mention consultants. The principle only applies when an executive’s salary is set by a consultant who has business ties to the company. Without that detail, the principle doesn’t apply.
C. The principle doesn’t allow us to conclude that someone is probably not overpaid. It only supports the conclusion that someone is probably overpaid when specific conditions are met.
D. Correct. This matches the principle exactly. It provides the required condition—a consultant with business ties determining the salary—and correctly draws the conclusion that the executive is probably overpaid.
E. This answer concludes that the executive is not overpaid, which is stronger than what the principle allows. The principle only supports a probable conclusion under the right circumstances, and only in the direction of being overpaid.
Keep your prep going with more examples and explanations of principle-based question types.
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Reviewed by:
Senior Law School Admissions Advisor, Tel Aviv University Law School
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