Strengthen & Weaken Arguments

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Strengthen & Weaken Arguments — Key Facts for LSAT India Core concept: These questions ask what would make an argument more (or less) logically convincing High-yield point: Always identify the argument’s unstated assumption first — that is the most likely target for strengthen/weaken answers ⚡ Exam tip: The correct answer often targets the assumption, not the explicit premises

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Strengthen & Weaken Arguments — LSAT India Study Guide

Strengthen and Weaken in the RC Context

In the Reading Comprehension section, Strengthen and Weaken questions ask you to evaluate the logical robustness of the author’s argument. Unlike Logical Reasoning section questions where you evaluate a standalone argument, in RC you are working within the context of a passage — which means you must first reconstruct the argument before you can evaluate it.

These questions appear less frequently than Main Point or Inference questions — typically 1–2 times per passage when they appear at all — but they are consistently among the most challenging RC question types because they require active logical thinking rather than mere text retrieval.

Identifying Strengthen Questions

Strengthen questions typically use one of these stems:

• “Which of the following, if true, would most strengthen the author’s argument?”
• “The author’s argument would be most strengthened if which of the following were true?”
• “Which of the following would provide the best support for the author’s conclusion?”
• “The passage’s argument is most vulnerable to criticism on which of the following grounds?” (This is a weaken question in disguise — it asks what would weaken the argument)

Identifying Weaken Questions

Weaken questions typically use one of these stems:

• “Which of the following, if true, would most weaken the author’s argument?”
• “The author’s argument would be weakened most by which of the following?”
• “Which of the following, if true, would cast the most doubt on the author’s conclusion?”
• “The reasoning in the passage is most vulnerable to which of the following objections?”

The Logic of Strengthening

A correct Strengthen answer makes the argument’s conclusion more likely to be true. This can happen in three ways:

1. Supporting an Unstated Assumption

If the argument’s conclusion depends on an unstated assumption, evidence that the assumption is true strengthens the argument.

Example argument:

“Company X’s profits increased last year. Therefore, Company X must have improved its operational efficiency.”

Unstated assumption: Profit increases were caused by improved operational efficiency (not, say, a one-time asset sale or favorable market conditions).

Strengthen answer: “Company X did not sell any significant assets last year, and its revenue increase was not driven by favorable market conditions.”

2. Providing Additional Supporting Evidence

New evidence that directly supports the conclusion — or supports a key premise — strengthens the argument.

3. Ruling Out an Alternative Explanation

If a weakened or alternative explanation for the evidence exists, evidence that rules out that alternative strengthens the original argument.

The Logic of Weakening

A correct Weaken answer makes the argument’s conclusion less likely to be true. This can happen in several ways:

1. Undermining an Unstated Assumption

If the argument’s conclusion depends on an unstated assumption, evidence that the assumption is false (or probably false) weakens the argument.

2. Introducing or Supporting an Alternative Explanation

If there is another explanation for the observed facts, the original conclusion becomes less compelling.

3. Undermining the Evidence or Premises

If the evidence supporting the conclusion is shown to be unreliable, incomplete, or misrepresented, the argument weakens.

4. Showing That the Evidence Supports a Different Conclusion

If the evidence is equally consistent with a different conclusion, the original conclusion is weakened.

A Worked Example

Passage:

“The growing popularity of plant-based meat alternatives represents a fundamental shift in consumer preferences. Sales of plant-based burgers and sausages have increased by over 200% in the past five years, and major restaurant chains have responded by adding plant-based options to their menus. However, this trend should not be interpreted as a signal that consumers are prioritizing environmental sustainability. Research indicates that most consumers who purchase plant-based meats do so primarily for health reasons, not environmental ones. The environmental benefits of plant-based meats, while real, are a secondary consideration for the vast majority of buyers.”

Question: “Which of the following, if true, would most weaken the author’s argument that the growth in plant-based meat sales should not be interpreted as a signal that consumers are prioritizing environmental sustainability?”

Analyzing the argument:

• Conclusion: Growth in plant-based meat sales should NOT be interpreted as a signal of environmental prioritization.
• Primary evidence: Most consumers who buy plant-based meats do so for health reasons.
• Unstated assumption: Consumer motivations, as expressed in surveys or purchase data, are an accurate indicator of their underlying priorities.

Evaluating answer choices:

(A) “Plant-based meat sales have increased even among consumers who explicitly cite environmental concerns as their primary motivation.” This supports the author’s position — it shows that even among environmentally motivated consumers, purchases are growing. It does not weaken the argument.

(B) “Consumer surveys about motivation are often unreliable because respondents tend to give socially desirable answers.” This weakens the argument by undermining the reliability of the evidence (consumer surveys) used to support the premise that consumers buy for health reasons, not environmental ones. If the surveys are unreliable, the premise is weakened, and with it the conclusion.

(C) “The environmental impact of plant-based meat production is significantly lower than that of conventional animal-based meat.” This is a factual claim about environmental impact. It does not address whether the growth in sales reflects environmental prioritization. It is irrelevant to the argument’s logical structure.

(D) “Health concerns about processed foods have led some consumers to return to conventional animal-based meats.” This discusses a different trend and does not address the environmental interpretation of plant-based meat growth.

Correct answer: (B)

How to Approach Strengthen/Weaken Questions

Step 1: Reconstruct the Argument

Before you can strengthen or weaken an argument, you must clearly identify:

• What is the conclusion?
• What are the stated premises?
• What is the unstated assumption?

Your answer to these questions is your target. The correct answer will directly address one of these elements.

Step 2: Formulate What Would Strengthen/Weaken

Before looking at the answer choices, think about what kind of information would affect the argument. Write down or mentally note what you are looking for.

For a Strengthen question: “I need evidence that supports the conclusion or its key assumption.” For a Weaken question: “I need evidence that undermines the conclusion or its key assumption.”

Step 3: Evaluate Each Answer Choice Against Your Target

For each answer choice, ask:

• Does this support the conclusion? (Strengthen)
• Does this undermine the conclusion or its assumption? (Weaken)
• Is this relevant to the argument’s logical structure?

Step 4: Eliminate Answer Choices That Don’t Connect to the Argument

Many wrong answers on Strengthen/Weaken questions are irrelevant — they may be true, interesting, or even related to the passage’s topic, but they do not address the specific logical structure of the argument. Eliminate them.

Common Weakens: The “Other Explanation” Pattern

One of the most common and effective weaken strategies is to provide an alternative explanation for the evidence. If the passage says “X happened, therefore Y must be true,” a strong weaken answer says “Actually, X happened because of Z, which has nothing to do with Y.”

Watch for this pattern on both Strengthen and Weaken questions.

Common Strengthens: The “Ruling Out Alternatives” Pattern

The counterpart to the “other explanation” weaken is the “ruling out alternatives” strengthen. If the passage argues that X caused Y, a strong strengthen answer says “There is no other plausible explanation for Y besides X.”

The Assumption Is Usually the Target

In most Strengthen/Weaken questions, the unstated assumption is the most vulnerable part of the argument and the most likely target for both correct answers and correct eliminations. Always identify the assumption before answering.

Exam Strategy Summary

• Identify the argument’s conclusion, premises, and unstated assumption
• Formulate what would strengthen or weaken the argument before looking at choices
• Target the assumption — correct answers almost always address the assumption, not just the stated premises
• Eliminate answers that are irrelevant to the argument’s logical structure
• Be wary of answers that are factually true but logically peripheral
• Trust your logical instinct — if an answer choice feels like it addresses the argument’s weak point, it probably does

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