Strengthen Questions
The argument has a gap. Your job is to find the fact that fills it.
Two tools pair with this method. The miss-pattern analyzer shows which question types cost you the most points, and the blind review worksheet gives you a second pass at every miss.
What the question asks
The question asks which answer most strengthens the argument. The stem says something like "Which one of the following, if true, most strengthens the argument?"
The new fact does not have to prove the conclusion. It just has to help. Think of it as adding weight to the author’s side of the scale.
Step-by-step method
- Find the conclusion and the evidence. Write them down in short form. The argument is almost always: evidence, therefore conclusion.
- Find the gap. Ask what the author is taking for granted. Strengthen answers almost always address this gap directly.
- Predict the help. Before reading the choices, say what kind of fact would help. Three common kinds: a missing link between evidence and conclusion, a ruled-out alternate explanation, or proof the sample is representative.
- Pick the choice that matches. The right answer makes the conclusion more likely, even if only a little. Do not demand proof. A small boost is enough.
Worked examples
Both examples are original. They are not real LSAT questions.
Example 1
Ridgedale installed new parking meters last year, and downtown revenue rose 12 percent. The meters must have caused the increase.
Which one of the following, if true, most strengthens the argument?
The answer: No other new revenue sources were added downtown that year.
Why: This rules out the main alternate explanation. If nothing else changed, the meters are the likely cause. The link between the meters and the revenue gets stronger.
Example 2
Patients who took the new supplement reported fewer colds than patients who did not. The supplement must boost immunity.
Which one of the following, if true, most strengthens the argument?
The answer: Both groups were similar in age, diet, and health before the study began.
Why: This answers the worry that the supplement group was healthier to start with. Comparable groups make the result trustworthy, so the conclusion gains support.
What a good strengthener actually does
A strengthener does not need to prove the conclusion. It only needs to make the reasoning harder to attack. Think of the gap between the evidence and the conclusion as a bridge with a loose plank. The right answer tightens that plank. It does not build a second bridge.
The most common mistake is picking an answer that makes you feel better about the conclusion without touching the gap. If the argument says the new policy will cut traffic because a similar policy worked in one city, an answer that says traffic is a serious problem strengthens nothing. It agrees with the topic. It does not close the gap between "worked there" and "will work here."
Strong language is fine in a strengthener. Unlike necessary assumption questions, there is no penalty for going further than needed. But strength is not the test. Relevance to the gap is the test. A mild answer that rules out an alternative explanation beats a dramatic answer about something the argument never claimed.
Common traps
- A choice that strengthens a different conclusion. Check which claim the argument actually makes.
- A choice that repeats a premise in new words. Restating evidence adds nothing.
- A choice that is true but irrelevant to the gap. Feel-good facts are not support.
- A choice that weakens the argument. Read the stem twice. One word decides the job.
Practice the method
The free diagnostic scores every LR question type and shows exactly where you are losing points.