Rank 11 by frequency | 51 questions in corpus (2.1% of all questions)
Weaken questions ask you to find a statement that, if true, would most undermine, challenge, or cast doubt on an argument inside the passage. Unlike its Logical Reasoning cousin, which operates on a short standalone argument, RC Weaken operates on an argument embedded in a longer text — you first locate the targeted position inside the passage, then evaluate which hypothetical new fact does the most damage to it.
A Weaken stem hands you a hypothetical: if the following were true, which would most undermine the passage's argument? You are not challenging what the passage already says — you are evaluating five brand-new pieces of information from outside the passage and asking which one, if added, most decreases confidence in the targeted claim.
The skill being tested is critical reasoning: seeing where an argument is vulnerable, what it is secretly assuming, and what kind of outside evidence would expose its weak points. You also need direction sensitivity — distinguishing between evidence that genuinely damages a claim and evidence that merely sits near the topic, or worse, supports the argument. Because these are always hypotheticals, the correct answer doesn't need to refute the conclusion. It just has to move the needle in the undermining direction more than any other choice.
RC Weaken is the mirror image of RC Strengthen — same hypothetical framing, opposite direction. It also closely resembles LR Weaken, with one key difference: in LR you are handed a compact, self-contained argument; in RC you first have to locate the targeted argument inside a long passage. The targeted argument is usually a small, specific claim in a single paragraph rather than the passage's overall thesis.
Before you can find the right weakener, you need a mental catalog of the kinds of things that can damage an argument. The correct answer on any given question will usually fall into one of three families.
Provide an alternative explanation. Many passage arguments propose a causal or interpretive claim (X caused Y, this pattern is best explained by Z). An answer that introduces a plausible rival cause — something else that could have produced the same observation — undermines the claim by showing the evidence doesn't uniquely point to the author's explanation. A classic example: a scientific hypothesis weakened by a study showing a different mechanism produces the same outcome.
Present counter-evidence. Sometimes the argument is vulnerable to a direct factual blow — a counterexample where its prediction fails, a case that contradicts the premise, or data that points the opposite way. An answer that shows the argument's predicted effect didn't actually occur, or that the stated cause was absent in a case where the effect appeared, strikes at the argument's evidentiary base.
Undercut an assumption. Every argument rests on unstated premises. An answer that contradicts one of those hidden assumptions breaks the logical chain from evidence to conclusion. If an argument that a tax will make industry switch fuels quietly assumes that the taxed fuel is more expensive, an answer showing the taxed fuel actually costs less destroys the argument without contradicting any explicit claim.
Weaken stems come in five recognizable flavors based on how aggressive the attack language is. They test the same underlying skill; the wording choice is mostly stylistic, though the softer versions are slightly more common.
Variation A — "Most weaken / most seriously weaken" (18 questions, 35%). The most direct phrasing. "Which one of the following, if true, would most weaken the author's argument?" or "Which one of the following, if true, most seriously weakens the author's claim?" "Weaken" is the operative word.
Variation B — "Undermine / call into question / cast doubt" (23 questions, 45%). The most common subtype, using softer attack language. "Which one of the following, if true, would most seriously undermine [X]?" or "Which one of the following, if true, would cast the most doubt on [X]?" These verbs signal that the answer doesn't need to destroy the argument — just make it less convincing.
Variation C — "Challenge / counter / argue against" (4 questions, 8%). Confrontational language. "Which one of the following, if true, most challenges the author's contention?" or "Which one of the following, if true, would present the greatest challenge to the new proposal?" "Challenge" implies more direct confrontation — the answer actively opposes rather than merely erodes.
Variation D — "Vulnerable to criticism / objection" (1 question, 2%). Asks about vulnerabilities. "Which one of the following, if true, would provide the strongest objection to the criticism in the passage?"
Variation E — Other (5 questions, 10%). Mixed phrasings: "most clearly weakens [X]," "would cast the most doubt on [X]'s argument." Functionally equivalent to Variations A and B.
A four-step process works for every variation. The critical discipline is not to read the answer choices first — Weaken choices are designed to look plausible in isolation, and the only way to separate them cleanly is to know the argument's vulnerability before you look at them.
Step 1 — Find the target argument. The stem usually names a specific claim, paragraph, or person. Go back to the passage and locate it. This is rarely the passage's overall main point — RC Weaken almost always tackles a small, specific argument that lives in one paragraph. Isolate the sub-argument you're being asked to damage.
Step 2 — Identify the argument's structure. Is it a causal claim, a theoretical prediction, a historical explanation, a policy recommendation, or an evaluative comparison? Identify the conclusion and the evidence offered for it.
Step 3 — Predict the vulnerability. Ask what the argument is assuming, what alternative explanations it hasn't ruled out, and where its evidence is thin. Form a rough idea of the weakener — "an answer that introduces an alternative cause," or "an answer that contradicts the assumption that the taxed fuel costs more."
Step 4 — Evaluate each choice for direction and degree. First ask: does it weaken, strengthen, or do nothing? Eliminate anything that isn't a weakener. Among the remaining weakeners, the correct answer is the one that damages the argument most — the one that targets the most critical vulnerability.
Correct answers average about 19.9 words and read as self-contained factual claims — a study result, an observed pattern, a historical fact. They are always external to the passage: if you recognize the content as something the passage already said, it is not the answer.
The correct answer usually targets the argument's causal link or its key assumption, not a peripheral detail. Common patterns include the alternative cause (X causes Y? here's something else that also causes Y), the broken mechanism (the stated process doesn't actually work as claimed), the counterexample (a case where the prediction fails), the undermined premise (a key factual claim turns out to be false), the scope limitation (the argument doesn't apply as broadly as claimed), and the reversed correlation (the relationship runs the other way).
The bar is most weakens, not refutes. An answer that lands a clean blow on the conclusion's main support beats an answer that makes some noise at the edges of the argument, even if the second one feels more dramatic.
Wrong answers on Weaken questions follow predictable patterns. Seeing them as patterns makes them easier to cut.
Trap 1 — Irrelevant but topical. The answer shares vocabulary with the passage and sounds "about" the right subject, but it doesn't actually affect the targeted argument. If the passage argues about why birds migrate, an interesting fact about bird feeding habits is topically related but logically inert. Defense: don't reward topical overlap — ask whether the fact actually moves the argument's conclusion.
Trap 2 — Actually strengthens. The answer provides evidence that supports rather than undermines the argument. Test-takers who don't pause to check direction can pick a strong-sounding supporter because it looks substantive. Defense: after identifying your candidate, explicitly ask "does this make the conclusion more or less likely?"
Trap 3 — Weakens the wrong claim. The answer powerfully undercuts some argument in the passage, just not the one the stem asked about. Especially common in passages with multiple embedded arguments. Defense: keep the specific target statement in view while evaluating each choice.
Trap 4 — Weak weakener. The answer technically damages the argument, but another choice damages it much more. LSAC uses "most" deliberately. Defense: don't stop at the first plausible weakener — check the remaining choices and pick the strongest blow.
Weaken has a base difficulty of 4 — higher than Strengthen, in part because the vulnerabilities in passage arguments are often subtle.
Difficulty 3 — clear target. When the argument is simple (single cause-effect) and the correct weakener is a direct counterexample, the question drops to 3.
Difficulty 4 — non-obvious vulnerability. The argument has multiple components, and the correct weakener targets a vulnerability that isn't the first one you notice. You have to work through the argument's structure to see which assumption matters most.
Difficulty 5 — indirect mechanism or ranking problem. The argument uses multi-step reasoning, the weakener works through an indirect logical path, or multiple answers seem to weaken and you must identify which weakens most. This is where the word "most" does real work and half-weakeners feel like valid answers.
RC Weaken is heavily skewed toward single passages: 48 questions (94%), vs. 3 (6%) on comparative passages. Because the targeted argument usually lives in a single paragraph, the question is cleanest when there is only one passage to work from.
Any of the following stems signal a Weaken question. Recognize them instantly and switch into the four-step workflow: locate the target, structure the argument, predict the vulnerability, then rank the choices by direction and degree.