4.2 Strengthening, Weakening & Evaluating Arguments

Manipulating Arguments

Once you can deconstruct an argument and identify its unstated assumptions, the next step is learning how to manipulate it. In the Executive Assessment, you will frequently be asked to Strengthen, Weaken, or Evaluate an argument.

Crucially, unlike Inference questions where you must rely strictly on the provided text, for Strengthen, Weaken, and Evaluate questions, you must accept the answer choices as true, even if they introduce entirely new information. Your job is to determine the effect of that new information on the argument's conclusion.

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Strengthening Arguments

Goal: Find the answer choice that makes the conclusion more likely to be true.

Strengthening an argument does not mean proving it with 100% certainty. It just means providing support that shores up the logic. You are essentially looking for an answer choice that confirms one of the author's unstated assumptions.

Strategies for Strengthening

1. Eliminate Alternative Causes: If the argument claims that A caused B, an answer choice that rules out C, D, or E as the cause of B will strengthen the claim that A is the true cause.
2. Provide Supporting Examples or Data: An answer choice that shows the same cause-and-effect relationship happening elsewhere, or provides new data corroborating the premise, strengthens the argument.
3. Validate the Reliability of Data: If the argument relies on a survey or study, an answer choice stating that the study was conducted properly and without bias strengthens the conclusion.
4. Bridge the Gap (Supporter): Explicitly state the missing link between the premise and the conclusion.

Trap Answers in Strengthen Questions:

• Opposite: Weakens the argument.
• Restatement: Merely repeats a premise without adding new support.
• Out of Scope: Provides positive information about the topic that doesn't actually impact the specific conclusion.

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Weakening Arguments

Goal: Find the answer choice that makes the conclusion less likely to be true.

Weakening an argument requires you to attack the author's assumptions. You are looking for the "fatal flaw" in the reasoning. You do not need to prove the conclusion false, only cast serious doubt on its validity.

Strategies for Weakening

1. Introduce Alternative Explanations: If the argument claims A caused B, showing that C actually caused B destroys the argument.
2. Show Cause Without Effect (or Effect Without Cause): If the argument claims a new policy will increase sales, an answer choice showing a similar policy elsewhere that resulted in stagnant sales weakens the argument.
3. Attack the Sample or Data: Show that the survey was biased, the sample size was too small, or the comparison group was not representative. (e.g., "The survey of commuter preferences only interviewed people who ride the train.")
4. Highlight Unforeseen Negative Consequences: Show that the proposed plan will trigger secondary effects that negate the intended benefits.

Example: Argument: The city should implement a toll on the downtown bridge to reduce traffic congestion. Weaken: Drivers will simply bypass the toll bridge and use the already-crowded tunnel, making overall downtown congestion worse.

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Evaluating Arguments

Goal: Identify the question or piece of information that is most critical to determining whether the argument is logically sound.

Evaluate questions are essentially a hybrid of Strengthen and Weaken questions. The correct answer will highlight the core assumption of the argument and ask whether that assumption is true or false.

The Variance Test

The most effective strategy for Evaluate questions is the Variance Test. The correct answer choice will usually be phrased as a question or an assessment (e.g., "Whether...", "The extent to which...").

To apply the Variance Test, supply two polar opposite responses to the answer choice (e.g., "Yes" and "No", or "0%" and "100%").

• If one response significantly strengthens the argument, AND the opposite response significantly weakens the argument, you have found the correct answer.
• If both responses have the same effect (or no effect) on the argument, the answer choice is incorrect.

Example Application: Argument: Switching to solar power will save the factory money in the long run because solar panels are cheaper to maintain than the current coal generators. Contender A: Whether the factory operates on weekends. Contender B: Whether the initial cost of installing solar panels outweighs the long-term savings in maintenance.

Applying the Variance Test to B:

• Response 1 (Yes): The initial cost does outweigh the maintenance savings. (Effect: Weakens the conclusion that they will save money.)
• Response 2 (No): The initial cost does not outweigh the maintenance savings. (Effect: Strengthens the conclusion that they will save money.) Because the two extreme responses have opposite effects on the conclusion, B is the correct evaluation factor.