LSAT Strengthen and Weaken Practice Questions Practice Questions with Answers

LSAT Strengthen and Weaken Practice Questions Practice Questions with Answers

Logical Reasoning sections on the Law School Admission Test (LSAT) allocate nearly 50% of their content to questions that require you to evaluate how new information impacts an argument's validity. Success in these sections depends on your ability to identify the underlying assumptions and select the most impactful evidence. This guide provides comprehensive LSAT Strengthen and Weaken Practice Questions to help you refine your logical analysis and improve your overall score.

Concept Explanation

LSAT Strengthen and Weaken questions are tasks that require you to identify a piece of new information that either increases or decreases the likelihood that a conclusion follows logically from its premises. These question types focus on the "gap" or assumption within an argument. In a Strengthen question, your goal is to find a premise that bridges this gap or provides additional support for the author's claim. Conversely, in a Weaken question, you must identify an answer choice that exposes a flaw, introduces a counter-example, or provides an alternative explanation for the observed phenomenon. According to the Law School Admission Council (LSAC), these questions test your ability to evaluate evidence critically, a skill essential for legal practice. For those looking to structure their study time effectively, using an AI MasterPlan can help balance these reasoning tasks with other sections like Reading Comprehension.

Key Strategies for Success

• Identify the Conclusion: Always isolate the main point of the argument first. The conclusion is what you are trying to support or attack.
• Find the Gap: Look for the unstated assumption that connects the premises to the conclusion.
• Accept Choices as True: The prompt usually says "which one of the following, if true..." Treat every answer choice as a factual statement, even if it seems unlikely.
• Focus on Impact: The correct answer doesn't have to prove or disprove the conclusion entirely; it just needs to make it more or less likely.

Solved Examples

Below are three worked examples demonstrating how to approach these logical reasoning tasks systematically.

1. Strengthen Example:

   Argument: Recent studies show that people who drink green tea daily have lower rates of heart disease. Therefore, green tea contains antioxidants that directly prevent heart conditions.

   Step 1: Identify the conclusion—Green tea prevents heart disease via antioxidants.

   Step 2: Identify the gap—The study shows a correlation, but the conclusion assumes causation and a specific mechanism (antioxidants).

   Step 3: Strengthen the link—An answer choice stating that "laboratory tests confirm the specific antioxidants in green tea inhibit arterial plaque buildup" would strengthen the argument by providing the missing causal mechanism.

2. Weaken Example:

   Argument: The city of Riverdale saw a 20% decrease in crime after installing new streetlights. Thus, the streetlights were responsible for the drop in crime.

   Step 1: Identify the conclusion—Streetlights caused the crime drop.

   Step 2: Identify the gap—The argument assumes no other factors were at play.

   Step 3: Weaken the link—An answer choice stating that "Riverdale doubled its police patrol presence at the same time the lights were installed" weakens the argument by providing an alternative cause for the effect.

3. Strengthen Example (Comparison):

   Argument: Brand X batteries lasted 10 hours in a flashlight, while Brand Y lasted only 5 hours. Therefore, Brand X is the superior battery for all electronic devices.

   Step 1: Identify the conclusion—Brand X is better for all devices.

   Step 2: Identify the gap—The evidence is limited to flashlights; other devices might have different power draws.

   Step 3: Strengthen the link—An answer choice stating that "the power discharge pattern of a flashlight is identical to that of 90% of all portable electronic devices" helps generalize the finding.

Practice Questions

Apply your skills to the following LSAT Strengthen and Weaken Practice Questions. These range from basic causal arguments to complex statistical interpretations.

1. (Strengthen) A local university found that students who attended optional review sessions scored 15 points higher on the final exam than those who did not. The university concluded that the review sessions were highly effective at teaching the course material.

2. (Weaken) Legislator: Our state’s economy is thriving because we lowered the corporate tax rate last year. Since the tax cut, 5,000 new jobs have been created in the manufacturing sector.

3. (Strengthen) Nutritionist: People who eat breakfast every morning are less likely to be overweight than those who skip it. Therefore, eating breakfast helps regulate metabolism and prevents weight gain.

4. (Weaken) Archaeologists found ancient tools in a cave in France dated to 40,000 years ago. Because similar tools were found in Spain dated to 35,000 years ago, the archaeologists concluded that the tool-making technology migrated from France to Spain.

5. (Strengthen) A study of 1,000 drivers found that those who listen to classical music have 30% fewer accidents than those who listen to rock music. The researchers concluded that classical music promotes a calmer driving style.

6. (Weaken) The new "Smart-Grow" fertilizer led to a record-breaking corn harvest in Iowa this year. Therefore, farmers in arid regions like Arizona should switch to "Smart-Grow" to increase their crop yields.

7. (Strengthen) Over the last decade, the number of migratory birds in the wetlands has declined. Biologists claim that the construction of a nearby highway is the primary cause of this decline.

8. (Weaken) A company implemented a four-day work week, and productivity increased by 10%. The CEO concluded that the shorter work week made employees more focused and efficient.

Answers & Explanations

Review the reasoning behind each answer to ensure you are identifying the correct logical gaps. If you find yourself struggling with the vocabulary or phrasing of these questions, practicing with vocabulary-in-context strategies can often clarify the nuances of the arguments.

1. Answer: An answer choice stating that the review sessions covered specific exam questions not found in the textbook would strengthen the link between the session and the score. Alternatively, showing that students in both groups had similar baseline GPAs before the session eliminates the "self-selection" bias.
2. Answer: To weaken this, you could point out that a national economic boom occurred at the same time, or that a major competitor in a neighboring state closed down, forcing 5,000 workers to relocate to the legislator's state.
3. Answer: This is strengthened by a study showing that skipping breakfast leads to hormonal imbalances that trigger overeating later in the day, providing a biological mechanism for the claim.
4. Answer: To weaken this, evidence could show that the tools in Spain were actually made of a material found only in Spain and were developed independently, or that even older versions of the tools (50,000 years old) were found in Italy.
5. Answer: The argument is strengthened if a controlled experiment shows that drivers' heart rates and stress levels decrease significantly when classical music is played compared to rock music.
6. Answer: This is weakened by noting that "Smart-Grow" fertilizer requires three times the amount of water as standard fertilizers to be effective, making it unsuitable for arid Arizona.
7. Answer: Evidence showing that the decline in bird population began exactly when the highway construction started, and that bird populations remained stable in similar wetlands without highways, strengthens the causal claim.
8. Answer: To weaken this, one could show that the company also installed new high-speed computers during the same period, which accounted for the entire 10% productivity gain.

Frequently Asked Questions

What is the difference between a Strengthen question and a Most Strongly Supported question?

Strengthen questions ask you to find new information that supports the argument's conclusion, while Most Strongly Supported questions ask you to identify which conclusion follows most logically from the information already provided in the stimulus. In the former, you go from the answers to the stimulus; in the latter, you go from the stimulus to the answers.

Do I need to find an answer that proves the conclusion is 100% true?

No, the correct answer in a Strengthen question only needs to make the conclusion more likely than it was before. Even a small increase in probability is sufficient if it is the most effective choice among the options provided.

How do I handle answer choices that seem irrelevant?

Many LSAT distractors provide information that is true in the real world but has no logical impact on the specific "gap" in the argument. If an answer choice does not touch upon the relationship between the premises and the conclusion, it is likely incorrect.

Can a Weaken answer choice attack the premises directly?

While most Weaken questions target the assumption or the link between premises and conclusion, an answer choice that calls the validity of a premise into question can occasionally be the correct answer. However, the LSAT usually asks you to accept the premises as given and attack the inference drawn from them.

What is the "No Cause, No Effect" rule?

This is a powerful technique for Strengthen and Weaken questions involving causality. To strengthen a causal claim, show that when the cause is absent, the effect is also absent; to weaken it, show that the effect occurs even when the cause is missing.