How to Weaken an Argument on the LSAT: A Repeatable Method
Weaken questions reward attacking the gap between premises and conclusion — not the facts. Learn a four-step method, with worked examples and the trap answers to avoid.
2026-06-01 · 8 min read
What a weaken question is really asking
A weaken question gives you an argument and asks which answer, if true, most undermines it. The key word is "argument." You are not attacking the conclusion directly, and you are not arguing that the premises are false. You are showing that the premises do less to support the conclusion than the author assumed.
Every LSAT argument relies on an unstated assumption — a bridge between what the author proves and what the author claims. The fastest way to weaken an argument is to attack that bridge.
The four-step method
Step 1: Find the conclusion. The conclusion is the claim the author wants you to accept; everything else is support.
Step 2: Find the support. Note exactly what evidence is offered.
Step 3: Name the gap. Ask, "What is the author assuming to get from this evidence to this conclusion?" That assumption is the target.
Step 4: Attack the gap. The correct answer usually introduces an alternative explanation, a counterexample, or new information that makes the conclusion less likely given the same evidence.
Worked example
Argument: "After the city installed brighter streetlights downtown, reported thefts fell by 20 percent. The brighter lights must have deterred thieves."
Conclusion: brighter lights deterred thieves. Support: thefts fell after the lights went in. The gap: the author assumes nothing else changed that could explain the drop.
A strong weakener: "During the same period, the city doubled the number of police patrols downtown." This offers an alternative cause for the drop, so the lights are no longer the obvious explanation. Notice it does not say the lights did nothing — it just loosens the link.
Trap answers to avoid
Out of scope: an answer about a different city, a different crime, or a different time period feels relevant but does not touch this argument.
Strengtheners in disguise: under time pressure it is easy to pick an answer that actually supports the conclusion. Always re-read the question stem.
Too weak or too strong: an answer that merely "could" matter in some unstated scenario is usually weaker than one that gives a concrete alternative cause.
Practice the habit, not just the question
Weakening is the same skill across strengthen, assumption, and flaw questions: locate the gap between evidence and conclusion. If you train that one move until it is automatic, four question types get easier at once. Verbloom drills argument structure visually so the gap becomes something you see rather than something you hunt for.
Frequently asked questions
Do I assume the answer choices are true in a weaken question?
Yes. LSAT weaken (and strengthen) stems say "if true." You accept each answer as fact and ask only whether it makes the conclusion less likely.
What is the most common correct-answer pattern for weaken questions?
Introducing an alternative cause or explanation for the evidence. If the argument says A caused B because B followed A, an answer that supplies another plausible cause of B is usually the credited response.
Should I eliminate answers that are out of scope first?
Yes. Quickly cutting answers that discuss a different topic, group, or time frame narrows the field so you can compare the remaining contenders against the specific gap you identified.
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