Medium LSAT Strengthen and Weaken Practice Questions Practice Questions

Concept Explanation

Strengthen and Weaken questions require you to identify a piece of information that either bolsters or undermines the relationship between an argument's premises and its conclusion.

On the LSAT Prep journey, these question types are foundational because they test your ability to spot assumptions and gaps in logic. In a Strengthen question, your goal is to find an answer choice that makes the conclusion more likely to be true based on the provided evidence. Conversely, a Weaken question asks you to find information that makes the conclusion less likely to follow from the premises. These questions often involve causal reasoning, where the author assumes that because two things happened together, one caused the other. To strengthen such an argument, you might eliminate an alternative cause; to weaken it, you might suggest a third factor is responsible. Success on Medium LSAT Strengthen and Weaken Practice Questions depends on your ability to isolate the conclusion and identify the specific link—or lack thereof—between it and the supporting facts. High-authority resources like LSAC emphasize that these questions do not require the answer to prove or disprove the conclusion definitively, but merely to move the needle of probability in one direction.

Solved Examples

1. Example 1: Strengthening Causal Links
   Argument: A recent study found that people who eat breakfast every day have lower cholesterol levels than those who skip it. Therefore, eating breakfast causes a reduction in cholesterol.
   Question: Which of the following most strengthens the argument?
   Solution:
   1. Identify the conclusion: Eating breakfast causes a reduction in cholesterol.
   2. Identify the gap: The study shows a correlation, but not necessarily causation.
   3. Look for an answer that supports the causal link: "A separate clinical trial showed that individuals who started eating breakfast saw their cholesterol drop, even when their other habits remained the same." This eliminates the possibility that other habits were the true cause.
2. Example 2: Weakening by Alternative Explanation
   Argument: The city's new bike lanes have led to an increase in traffic accidents. Since the lanes were installed, accidents on those streets have risen by 15%.
   Question: Which of the following most weakens the argument?
   Solution:
   1. Identify the conclusion: Bike lanes caused the increase in accidents.
   2. Identify the premise: Accidents rose by 15% after installation.
   3. Find an alternative cause: "During the same period the bike lanes were installed, the city also redirected all heavy freight truck traffic onto those specific streets." This suggests the trucks, not the bike lanes, might be the cause.
3. Example 3: Strengthening via Assumption Validation
   Argument: Our company should switch to remote work permanently. Last month, while working remotely, our productivity increased by 10%.
   Question: Which of the following most strengthens the argument?
   Solution:
   1. Conclusion: The company should switch to remote work permanently.
   2. Premise: Productivity rose during a one-month remote trial.
   3. Validate the premise's relevance: "The productivity increase seen last month was not due to a temporary 'crunch' period for a specific project." This ensures the data wasn't an anomaly.

Practice Questions

1. Local farmers claim that the recent drought is the sole reason for the 20% increase in corn prices. However, during previous droughts of similar severity, prices only rose by 5%. Therefore, factors other than the drought must be contributing to the current price hike.

Which of the following, if true, most strengthens the argument?

2. A new law requires all high school students to participate in 20 hours of community service to graduate. Proponents argue this will make students more civic-minded. However, since students are being forced to participate, they will likely develop a resentment toward community service, making them less civic-minded in the long run.

Which of the following, if true, most weakens the argument?

3. Recent data shows that cities with more public parks have lower rates of heart disease. This suggests that the presence of green space encourages residents to exercise more, leading to better cardiovascular health.

Which of the following, if true, most strengthens the argument?

4. Many tea drinkers believe that herbal tea helps them sleep. However, a study showed that participants who drank herbal tea before bed took just as long to fall asleep as those who drank plain warm water. Thus, herbal tea has no effect on sleep onset.

Which of the following, if true, most weakens the argument?

5. The mayor wants to increase the number of police officers on foot patrol to reduce crime. However, last year, when foot patrols were doubled in the North District, the crime rate there remained unchanged. Therefore, increasing foot patrols is an ineffective way to reduce crime.

Which of the following, if true, most strengthens the argument?

6. Scientists have found that children who play musical instruments perform better on math tests. They conclude that musical training develops the same spatial-temporal reasoning skills required for mathematics.

Which of the following, if true, most weakens the argument?

7. A tech company found that employees who take a 15-minute nap in the afternoon are more productive than those who do not. The company concludes that napping improves cognitive function and should be encouraged for all staff.

Which of the following, if true, most strengthens the argument?

8. Retailers noticed that sales of luxury watches increase significantly in December. They attribute this to customers buying gifts for the holiday season. However, sales of luxury watches also spike in June.

Which of the following, if true, most weakens the retailers' holiday gift-giving explanation for the December spike?

Answers & Explanations

1. Answer: This is strengthened by showing that the current market has more supply than previous drought years. If there is more corn available now than in past droughts, yet the price is higher, it strongly suggests that non-drought factors (like inflation or fuel costs) are driving the price up.

2. Answer: The argument is weakened by evidence that students who are initially forced into volunteering often continue to do so voluntarily later. This suggests that the "resentment" predicted by the author does not materialize or is outweighed by the positive experience.

3. Answer: To strengthen this, we could use a AI Question Generator to find similar patterns, such as: "In cities where new parks were built, heart disease rates dropped even among residents who did not change their diet." This isolates the park/exercise variable.

4. Answer: The argument is weakened if we find that the "plain warm water" group also showed improved sleep onset compared to their usual habits. This would suggest that warm liquids in general help, and the study failed to use a proper control group (like room-temperature water).

5. Answer: This is strengthened if we learn that the North District's crime rate was actually projected to increase by 20% due to external factors, but the foot patrols kept it steady. This shows the patrols were effective at preventing an increase, even if the rate didn't "drop."

6. Answer: The argument is weakened by a classic correlation/causation reversal: "Children with high spatial-temporal reasoning skills are more likely to be drawn to and successful at playing musical instruments." This suggests the skill leads to the music, not vice versa.

7. Answer: To strengthen, we need to show that napping caused the productivity. If a study shows that the same employees were less productive on days they were prevented from napping, the causal link is much stronger.

8. Answer: If June is the peak month for weddings and graduations, the June spike can be explained by other gift-giving occasions. This supports the idea that watches are "gift items," potentially weakening the idea that the December spike is unique or caused by something other than gifts.

Frequently Asked Questions

What is the difference between a Strengthen and an Assumption question?

An assumption is something the argument must believe to be true for the logic to hold, whereas a strengthener is just any information that helps the argument, even if it isn't strictly necessary. You can use the AI MasterPlan to schedule specific drills for both types to see the subtle differences in phrasing.

Can a strengthener be a new piece of information not mentioned in the passage?

Yes, Strengthen and Weaken questions explicitly ask you to assume the answer choices are true, even if they introduce entirely new facts. The goal is to see how that new information interacts with the existing logic of the stimulus.

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

In a "Strengthen Except" question, four choices will strengthen the argument, and the correct answer will either weaken it or have no effect at all. Always categorize each choice as (+), (-), or (0) to keep track of their impact.

Does a weakener have to make the conclusion impossible?

No, a weakener only needs to cast doubt on the conclusion or make it less likely. It does not need to completely destroy the argument; it just needs to show that the premises don't support the conclusion as strongly as the author thinks.

Why are causal arguments so common in these questions?

Causal arguments are popular because they are inherently vulnerable to many logical attacks, such as alternative causes, reverse causation, or coincidental correlation. This variety makes them perfect for testing a student's ability to evaluate evidence and logic according to Wikipedia's overview of LSAT logical reasoning.