Strengthen Questions on the LSAT: How to Find the Right Answer

Strengthen questions in LSAT Logical Reasoning ask you to find the answer choice that most helps the argument — not one that makes it airtight, and not one that proves the conclusion is true.

Common question stems: 'Which of the following, if true, most strengthens the argument?' or 'Which of the following, if true, provides the most support for the conclusion?' or 'Which of the following, if assumed, most helps to justify the conclusion?'

The key phrase is 'if true.' You accept every answer choice as true for the purpose of this question. Your job is to find which one, treated as a new piece of evidence, does the most to support the argument's conclusion from its premises.

Students often confuse strengthen questions with sufficient assumption questions. A sufficient assumption makes the conclusion logically guaranteed. A strengthen answer just makes the argument better — it does not have to close the gap entirely.

Every strengthen question follows the same pattern. The stimulus contains an argument: one or more premises that support a conclusion. The argument has a gap — a logical leap between what the evidence shows and what the conclusion claims.

The correct answer closes that gap, at least partially. It adds a piece of information that makes the connection between the evidence and the conclusion more plausible or more direct.

Your first job is to identify the conclusion and the gap before reading the answer choices. If you know what the argument needs, you can evaluate each answer choice against that specific need.

Example: 'A new study found that employees who take walking breaks during the workday report fewer headaches. Therefore, walking breaks reduce workplace headaches.' The gap: the study shows a correlation (association) but the conclusion claims causation. A strengthener would need to make the causal claim more plausible — for instance, by ruling out that workers who take walking breaks are already healthier, or by providing a mechanism through which walking reduces headache frequency.

The correct strengthen answer does one of a few things: it provides evidence for a missing link the argument assumes, it rules out an alternative explanation, it supports a key causal claim, or it establishes that a principle the argument relies on is true.

It does not have to prove the conclusion. It does not have to be the most important or dramatic piece of evidence imaginable. It just has to make the argument better than it was before.

On a causal argument: a correct strengthener often rules out the most obvious alternative explanation (reverse causation, common cause, or coincidence), or it provides a plausible mechanism through which the cause produces the effect.

On an argument that assumes a principle: a correct strengthener often confirms that the principle is true or that the relevant case falls under it.

On an argument that assumes similarity between two groups or situations: a correct strengthener often establishes that the two groups are in fact comparable in the relevant way.

This is where many students go wrong. A sufficient assumption makes the argument logically valid — if the assumption is true, the conclusion must follow. A strengthen answer just increases the likelihood that the conclusion is true. The bar is lower.

Example argument: 'Every student who used the new tutoring software passed the certification exam. Therefore, the tutoring software is effective for exam preparation.'

Sufficient assumption: 'Passing the certification exam is a reliable measure of preparation effectiveness.' If this is true, the conclusion follows with certainty.

Strengthen answer: 'Students who used the tutoring software performed better than students who prepared using only textbooks.' This makes the argument better without guaranteeing the conclusion.

On a strengthen question, reject answers that feel too strong or that seem to prove the conclusion outright — you may be looking at a sufficient assumption-style answer, which could be a trap if it relies on information not in the argument. The correct strengthen answer adds evidence; it does not close the entire logical gap.

Out of scope: the answer mentions something related to the topic but does not bear on the specific logical gap the argument contains. If the argument is about whether walking reduces headaches, an answer about the benefits of fresh air for mood does not strengthen it — even if it sounds related to wellness.

Weakener disguised as strengthener: the answer is true and related but actually makes the conclusion less likely. On strengthen questions, wrong answers can be weakeners — especially if you misidentified the conclusion or misread the direction of the gap.

Restates the evidence: the answer essentially repeats what the premises already say in different words. Adding nothing new to the argument adds no strength.

Too strong: the answer claims more than the argument needs, and in a way that introduces new logical problems. A correct strengthen answer is targeted and precise.

Irrelevant comparison: the answer compares the argument's subject to something else in a way that does not support the specific conclusion.

Argument: 'The city's new bike-share program launched in neighborhoods with the highest rates of car ownership. Within six months, traffic congestion in those neighborhoods dropped measurably. The bike-share program must have caused the reduction in congestion.'

Conclusion: The bike-share program caused the congestion reduction.

Premises: The program launched in high-car-ownership neighborhoods. Congestion dropped after launch.

Gap: Classic correlation-causation flaw. The drop in congestion might be explained by something else — a road construction project completing, an economic shift reducing commutes, or seasonal variation.

Which answer strengthens? Option: 'No major road construction projects were completed in those neighborhoods during the six months following the program's launch.' This rules out one plausible alternative explanation for the congestion drop. It makes the causal claim more defensible.

Which answer is a trap? Option: 'Bike-share programs have been shown to reduce car use in cities around the world.' This is tempting but does not address whether this specific program caused this specific drop in these specific neighborhoods. It is too general to close the gap.

Before reading the answer choices, identify the gap and ask yourself: what piece of information would make this argument significantly more convincing?

For causal arguments: 'What alternative explanation could I rule out? What mechanism could I provide?'

For analogical arguments: 'What could confirm that the two cases are similar in the relevant way?'

For principle-based arguments: 'What could confirm that the principle holds here, or that this case falls under the principle?'

For statistical arguments: 'What could confirm that the sample is representative, or that the numbers are being interpreted correctly?'

You will not always predict the exact correct answer. But having a clear sense of what you are looking for protects you from attractive wrong answers that address a different part of the argument than the one that matters.

Strengthen and weaken questions are mirror images of each other. Both require you to understand the argument's structure and gap. Both require you to evaluate how an answer choice interacts with that gap.

On a weaken question, you are looking for an answer that opens a hole in the argument — typically by providing an alternative explanation, showing the evidence is misleading, or attacking a hidden assumption.

On a strengthen question, you are looking for an answer that patches a hole — by ruling out alternative explanations, supporting a hidden assumption, or providing a mechanism.

The same wrong answer traps appear on both types: out-of-scope answers, answers that go in the opposite direction, and answers that merely restate the evidence. Learn to recognize both directions of the same skill.

Q: Can a correct strengthen answer be something that does not directly mention the conclusion? Yes. The correct answer often addresses a premise or a gap that is not explicitly stated in the conclusion. What matters is whether it makes the overall argument better, not whether it mentions the conclusion's specific wording.

Q: How much does a correct strengthen answer have to strengthen the argument? It just has to make the argument better than it was — even slightly. On the LSAT, you choose the answer that most strengthens among the five, so relative comparisons matter when two answers both seem to help.

Q: Is the 'if true' phrasing important? Very. You do not need to evaluate whether an answer is plausible or realistic. You accept it as true and then ask: given that this is true, does it help the argument?

Q: If I can't identify the gap, how do I approach strengthen questions? Process of elimination works. Ask of each answer: does this make the connection between the evidence and the conclusion stronger? If it seems unrelated to the argument, cross it off. If it seems to hurt the argument, cross it off. If it merely repeats the evidence, cross it off.

Strengthen questions are among the most common question types in LSAT Logical Reasoning. They appear in almost every section, and they reward students who can identify the logical gap in an argument quickly and precisely.

Verbloom's Logical Reasoning practice includes strengthen questions with detailed explanations covering why the correct answer helps and why each wrong answer fails — including the direction each answer choice pushes the argument.

Build this skill at verbloom.dev.