Medium LSAT Strengthen vs Weaken Questions Practice Questions

70% of Law School Admission Test (LSAT) Logical Reasoning sections consist of questions that ask you to manipulate an argument's validity. These specific tasks require you to either bolster or undermine the logical connection between a set of premises and a conclusion. Mastering LSAT Prep involves recognizing that these questions do not ask if the conclusion is true, but rather how new information affects the probability that the conclusion follows from the evidence. By engaging with Medium LSAT Strengthen vs Weaken Questions Practice Questions, you can refine your ability to spot logical gaps and identify the precise information needed to bridge or widen those gaps.

Concept Explanation

LSAT Strengthen and Weaken questions are logical reasoning tasks that require you to identify an answer choice that either increases or decreases the likelihood that a conclusion is validly drawn from its premises. In a Strengthen question, you look for a piece of evidence that supports an unstated assumption or eliminates an alternative explanation. Conversely, a Weaken question asks you to find a fact that highlights a flaw, introduces a competing cause, or shows that the premises do not necessarily lead to the conclusion. Both question types rely heavily on your ability to isolate the conclusion and identify the "gap" in the author’s reasoning. To succeed, you must treat the answer choices as true—even if they introduce entirely new information—and evaluate their impact on the existing argument. This process is distinct from "Inference" questions, where you must find what follows from the text. Here, you are bringing outside information to the text. Using tools like an AI Exam Simulator can help you practice this distinction under timed conditions, ensuring you don't confuse supporting an argument with simply restating it.

Solved Examples

1. Strengthen Example: Argument: A recent study showed that children who play chess score higher on standardized math tests than those who do not. Therefore, playing chess improves mathematical ability. Task: Strengthen the argument.

1. Identify the Conclusion: Playing chess improves mathematical ability.
2. Identify the Gap: The study shows a correlation, but it might be that kids who are already good at math are more likely to play chess.
3. Find the Support: An answer choice that rules out the reverse causality or shows the mechanism helps. Correct Answer: A longitudinal study found that students' math scores rose significantly only after they began a chess program.

2. Weaken Example: Argument: The city's new bike lanes have caused an increase in traffic congestion because average commute times for drivers have risen by 10% since the lanes were installed. Task: Weaken the argument.

1. Identify the Conclusion: Bike lanes caused the traffic congestion.
2. Identify the Gap: The increase in commute times could be caused by something else that happened at the same time.
3. Find the Weakener: Correct Answer: Major road construction on the city's primary highway began simultaneously with the installation of the bike lanes. (This provides an alternative cause).

3. Strengthen Example (Causal): Argument: The rare Golden Toad went extinct shortly after a period of unusually high temperatures. Scientists conclude that the heat directly caused the extinction. Task: Strengthen the argument.

1. Identify the Conclusion: Heat caused the extinction.
2. Identify the Gap: Maybe a disease or a predator killed them during that time.
3. Find the Support: Correct Answer: Laboratory tests show that Golden Toad embryos cannot survive in temperatures exceeding the average recorded during the period of extinction.

Practice Questions

1. (Medium) A nutritional study found that individuals who consume at least two apples a day have significantly lower cholesterol levels than those who eat no apples. The researchers concluded that the pectin in apples is responsible for lowering cholesterol. Which of the following, if true, most strengthens the researchers' conclusion? 2. (Medium) The local government of Westville recently increased the fine for littering. Since then, the amount of litter collected by city workers has decreased by 30%. The mayor claims that the higher fines have successfully deterred people from littering. Which of the following, if true, most weakens the mayor's claim? 3. (Medium) Studies show that companies with diverse boards of directors are 20% more profitable than companies with homogenous boards. Therefore, if a company wants to increase its profits, it should diversify its board. Which of the following, if true, most strengthens the argument? 4. (Medium) A tech company introduced a new software tool designed to increase employee productivity. Six months later, the company reported a record-breaking number of projects completed. The CEO credited the new software for this success. Which of the following, if true, most weakens the CEO's conclusion? 5. (Hard) Astronomers have observed that Planet X has a much thinner atmosphere than expected given its size. They hypothesize that frequent solar flares from its nearby star have stripped the atmosphere away over millions of years. Which of the following, if true, most strengthens the astronomers' hypothesis? 6. (Medium) A law firm recently started allowing its associates to work from home two days a week. Since then, the firm’s billable hours have increased. The managing partner concludes that working from home has made the associates more efficient. Which of the following, if true, most weakens the partner's conclusion? 7. (Medium) In a survey, 80% of residents in Oakwood reported that they feel safer now than they did five years ago. During this same period, the city installed 500 new streetlights. The city council claims the streetlights are the reason for the increased sense of safety. Which of the following, if true, most strengthens the council's claim? 8. (Hard) Historically, the price of gold rises when the stock market is volatile. Currently, the stock market is experiencing record-low volatility. Therefore, the price of gold is unlikely to rise in the near future. Which of the following, if true, most weakens the argument?

Answers & Explanations

1. Answer: An answer choice showing that pectin supplements alone, without apple consumption, also lead to lower cholesterol. Explanation: This strengthens the specific causal mechanism (pectin) by showing that the variable isolated by the researchers produces the effect even in the absence of other apple components. 2. Answer: Due to budget cuts, the city reduced the number of city workers responsible for collecting litter by 50%. Explanation: This weakens the claim by providing an alternative explanation for the 30% decrease in collected litter; it's not that there is less litter, but that there are fewer people to pick it up. 3. Answer: A study of the same companies before and after diversification showed that profit margins began to rise only after the board became diverse. Explanation: This strengthens the causal link by establishing a temporal sequence, making it less likely that high profits were the cause of board diversification (reverse causality). 4. Answer: The company hired 25% more employees during the same six-month period. Explanation: This weakens the CEO's conclusion by offering an alternative cause for the record-breaking number of projects: a larger workforce. 5. Answer: Other planets of similar size in the same system that are further away from the star have significantly thicker atmospheres. Explanation: This strengthens the hypothesis through a "control group" comparison, suggesting that proximity to the star (and its flares) is the differentiating factor. 6. Answer: The firm also hired several high-profile partners who brought a large volume of new clients during the same period. Explanation: This provides an alternative explanation for the increase in billable hours, suggesting the increase was due to more work being available, not necessarily increased efficiency from working at home. 7. Answer: A follow-up survey found that residents specifically cited better visibility at night as the primary reason they felt safer. Explanation: This connects the streetlights (which provide visibility) directly to the residents' feelings, strengthening the link between the cause and the effect. 8. Answer: Global political instability, which is currently at an all-time high, is a stronger driver of gold prices than stock market volatility. Explanation: This weakens the conclusion by introducing another factor that could cause gold prices to rise, even if the stock market factor is absent.

Frequently Asked Questions

What is the most common mistake on LSAT Strengthen questions?

Many students mistakenly choose an answer that is consistent with the conclusion but does not actually provide new support for it. To avoid this, always look for the option that bridges the gap between the specific evidence provided and the claim being made.

Can a Weaken answer choice be outside the scope of the argument?

Yes, Weaken answers almost always introduce new information that was not mentioned in the original stimulus. As long as that new information makes the conclusion less likely to be true, it is relevant and potentially the correct answer.

How do I handle "Except" questions in this category?

In a "Strengthen Except" question, four choices will strengthen the argument and one will either weaken it or have no effect. Your goal is to eliminate the four that help the argument, leaving the one that is neutral or harmful to the logic.

Are these questions similar to those on the GRE?

Yes, the logical reasoning skills tested here are very similar to those found in Hard GRE Reading Exam Questions. Both exams require you to analyze the underlying structure of arguments and evaluate how new data affects them.

Should I look for the "perfect" answer?

No, you should look for the "most" effective answer among the five choices provided. Sometimes the correct answer only weakens or strengthens the argument slightly, but if it does so more than the other four options, it is the right choice.

How can I improve my speed on these questions?

Practice identifying the conclusion immediately. Once you know exactly what the author is trying to prove, the gaps in the premises become much more obvious, allowing you to predict the type of information needed to strengthen or weaken the claim. You can use an AI Question Generator to create infinite variations of these logical structures for practice.