GMAT Review: Analysis of an Argument (Critiquing Reasoning, Identifying Flaws, Structuring Response)

GMAT – Analysis of an Argument (Critiquing Reasoning, Identifying Flaws, Structuring Response)

GMAT Study Guide – Analysis of an Argument (Critical‑Reasoning)

What This Is

Analysis of an argument asks you to evaluate the logic of a short passage, pinpoint the flaw (or strengthen/ weaken it), and choose the answer that best critiques the reasoning. It appears on the Verbal section and tests the same skills you’ll need in business school: spotting unsupported assumptions, recognizing irrelevant evidence, and constructing a concise, well‑structured response.

Typical stem: “The city council argues that building a new subway line will reduce traffic congestion because it will shift commuters from cars to trains. Which of the following, if true, most seriously weakens the council’s argument?”

Key Terms & Rules

• Assumption (Unstated Premise): The hidden statement that must be true for the argument’s conclusion to hold. E.g., “Commuters will actually use the subway.”
• Strengthening vs. Weakening: A strengthening answer makes the assumption more likely true; a weakening answer shows the assumption can be false.
• Flaw Types:
• Causal Fallacy: Mistaking correlation for causation.
• Insufficient Evidence: The data given does not fully support the claim.
• Circular Reasoning: The conclusion is restated as a premise.
• Argument Structure: Premise → (Implicit) Assumption → Conclusion. Identify each piece before scanning answer choices.
• “Most Effectively” vs. “Most Seriously”: “Most effectively” = strengthen; “most seriously” = weaken.
• Answer‑Choice Elimination Rule: If a choice does not address the core assumption, discard it immediately.
• “All of the above” Trap: GMAT never uses “all of the above”; each answer must stand alone as the best single option.
• Time‑Saving Shortcut – “Two‑Step” Method: (1) Locate the key assumption; (2) pick the answer that directly attacks or supports that assumption.
• “But‑For” Test: Ask, “But for which statement would the conclusion fail?” The answer that, if true, makes the conclusion false is the correct weakening choice.

Step‑by‑Step / Process Flow

1. Read the argument quickly (30‑45 sec). Highlight the premise(s) and the conclusion; underline any quantitative data.
2. Identify the implicit assumption – ask yourself, “What must be true for the conclusion to follow?” Write a one‑sentence paraphrase.
3. Classify the flaw (causal, insufficient evidence, etc.) – this guides which answer‑type you need (strengthen vs. weaken).
4. Scan the answer choices for the “but‑for” language. Eliminate any that do not touch the assumption or that introduce new, unrelated information.
5. Select the best answer and, if time permits, re‑read the stem to confirm the choice directly impacts the argument’s logic.

Common Mistakes

• Mistake: Choosing an answer that adds new evidence instead of attacking the assumption.
  Correction: The correct answer must challenge the hidden premise; extra facts that are true but irrelevant do not weaken the argument.

• Mistake: Assuming the argument’s premise is false.
  Correction: You are not asked to evaluate the truth of the premise—only whether the reasoning is valid. Focus on the logical link, not factual accuracy.

• Mistake: Selecting a “strengthening” answer when the question asks for the “most seriously weakens.”
  Correction: Pay close attention to the wording of the stem; “most seriously” = weakening, “most effectively” = strengthening.

• Mistake: Over‑reading and trying to incorporate every detail.
  Correction: Strip the argument to its core (premise‑assumption‑conclusion). Discard peripheral details that do not affect the logical chain.

• Mistake: Failing to notice a “but‑for” condition.
  Correction: Test each answer by asking, “If this were true, would the conclusion still hold?” The answer that makes the conclusion fail is the correct weakening choice.

Exam Insights

1. Most‑tested flaw: Insufficient evidence – the GMAT loves to give a plausible‑sounding premise and then ask you to expose the missing link.
2. Distractor pattern: Choices that restate the conclusion or add a new, unrelated fact are common traps.
3. Answer‑choice length cue: The correct answer is often shorter because it directly targets the assumption without extra fluff.
4. “But‑for” vs. “If‑then” – the GMAT frequently frames the weakening choice as an “if‑then” statement; spotting the conditional structure speeds up elimination.

Quick Check Questions

1. Passage: “A tech startup claims that offering a 30‑day free trial will increase its subscriber base because users who try the product will become paying customers.”
   Question: Which of the following, if true, most seriously weakens the startup’s claim?
2. A) 70 % of trial users never convert to paid plans.
3. B) Competitors offer a 60‑day trial.
4. C) The product’s price is higher than most alternatives.
5. D) The company’s marketing budget is limited.
6. E) The trial period can be extended upon request.

Answer: A – Shows that the assumed conversion from trial to paid is far lower than implied, directly undermining the premise.

1. Passage: “The university argues that increasing tuition by 5 % will not affect enrollment because the school’s reputation attracts enough applicants.”
   Question: Which statement, if true, most effectively strengthens the university’s argument?
2. A) Enrollment has risen 2 % each year for the past five years.
3. B) Tuition at peer institutions has risen 7 % on average.
4. C) The university’s graduation rate is 95 %.
5. D) Student loan interest rates are expected to drop.
6. E) The university’s endowment grew by 10 % last year.

Answer: A – Demonstrates that enrollment is already increasing, supporting the claim that a modest tuition hike won’t deter applicants.

1. Passage: “A city council says that installing more bike lanes will reduce traffic accidents because cyclists will be safer.”
   Question: Which of the following, if true, most seriously weakens the council’s reasoning?
2. A) Most traffic accidents involve pedestrians, not cyclists.
3. B) The city has a high rate of car ownership.
4. C) Bike lanes are funded by a federal grant.
5. D) Cyclists currently use the roads at night.
6. E) The city plans to add more pedestrian crosswalks.

Answer: A – Shows that the primary cause of accidents isn’t addressed by bike lanes, breaking the causal link.

Last‑Minute Cram Sheet (10 One‑Liners)

1. ⚠️ Never assume a premise is false – the GMAT tests logic, not factual accuracy.
2. Identify the hidden assumption → “What must be true for the conclusion to follow?”
3. “But‑for” test: If the answer were true, would the conclusion still hold?
4. Weakening = “most seriously”, strengthening = “most effectively.”
5. Causal fallacy = confusing correlation with cause; look for “because” without proof.
6. Insufficient evidence = premise doesn’t fully support conclusion; the answer will expose the missing link.
7. Answer‑choice length cue: The correct answer is usually the shortest that directly attacks the assumption.
8. Eliminate any choice that merely restates the conclusion – it never fixes the flaw.
9. Two‑Step Method: (1) Find the assumption; (2) pick the answer that attacks/supports it.
10. ⚠️ Watch for “but‑for” vs. “if‑then” wording – the correct weakening answer often appears as an “if … then …” conditional.

Good luck—master the logic, and the GMAT’s Critical‑Reasoning questions will become a breeze!