LSAT Logical Reasoning
Strengthen

Master the art of identifying which answer choice most strengthens an argument: the single most common question type on the LSAT.

LSAT Logical Reasoning

What Is a Strengthen Question?

A Strengthen question presents a short argument and asks you to choose the answer that makes the conclusion more likely to be true. You are not proving the conclusion: you are giving it additional support.

Anatomy of an Argument

Recognizing the Question Stem

Before you read the stimulus, identify the question type from the stem. Strengthen stems use characteristic language:

Classic Stems

"Which of the following, if true, most strengthens the argument?"

Variations

"Which most supports the conclusion?" or "provides the strongest additional evidence?"

Subtle Forms

"Which would be most useful to know to evaluate?" can sometimes function as strengthen.

The Core Principle

How Strengthening Works

There are several mechanisms by which an answer can strengthen an argument. Recognizing these patterns helps you evaluate choices faster:

1

Support the assumption: Directly affirm the unstated link that the argument relies on.

2

Eliminate an alternative explanation: Rule out a competing cause or interpretation of the evidence.

3

Provide additional evidence: Offer a new fact that makes the conclusion more plausible.

4

Rule out a potential objection: Anticipate and dismiss a reason the conclusion might fail.

Strengthen vs. Weaken

Strengthen and Weaken questions are mirror images. Understanding the contrast sharpens your ability on both types:

	Strengthen	Weaken
Goal	Make conclusion more likely	Make conclusion less likely
Assumption	Support it	Attack it
Alternative causes	Eliminate them	Introduce them
Additional evidence	Favors the conclusion	Favors the opposite
Standard	"Most" strengthens/weakens: need not be conclusive

Step-by-Step Approach

1

Read the question stem first. Confirm it is a Strengthen question so you know what to look for.

2

Identify the conclusion. What is the author trying to convince you of? Look for indicator words: "therefore," "thus," "consequently."

3

Identify the premises. What evidence or facts are given? What reasoning connects them to the conclusion?

4

Find the gap (assumption). Ask: "What must be true for this conclusion to follow?" The unstated assumption is your target.

5

Evaluate each answer. Pick the choice that best supports the assumption or adds evidence favoring the conclusion.

Worked Example 1

Worked Example 2

The gap: The argument assumes no other factor caused the increase: perhaps gas prices rose, or new EV models became available nationwide.

✓ Strengthens

"Neighboring cities without the tax credit saw no increase in EV sales during the same period." This rules out external factors.

✕ Does not strengthen

"Electric vehicles are better for the environment than gas vehicles." Irrelevant to whether the tax credit caused the increase.

Worked Example 3: Harder Stimulus

The assumption: Similar tools imply direct contact rather than independent invention or contact via an intermediary culture.

Types of Strengthening Answers

Affirm Assumption

Directly states what the argument takes for granted. The most common correct answer type.

Eliminate Alternative

Rules out a competing explanation, cause, or interpretation of the evidence.

Add Evidence

Introduces a new fact, analogy, or data point that makes the conclusion more plausible.

Trap Answer Patterns

1

Restates a premise: Repeats information already given. This adds nothing new and does not strengthen.

2

Irrelevant scope: Discusses something outside the argument's topic. Tempting because it sounds related.

3

Weakens instead: Actually undermines the conclusion. Read carefully: "strengthen" and "weaken" answers can look similar.

4

Too extreme: Proves too much or introduces an absolute claim. Correct answers are usually moderate.

Common Mistakes

✕ Picking "True" Over "Strengthens"

An answer can be factually true and still not strengthen the argument. The answer must connect to the conclusion's reasoning.

✕ Ignoring the Conclusion

Students sometimes pick an answer that supports a premise but not the overall conclusion. Always trace back to the main claim.

✕ Seeking Proof, Not Support

The correct answer only needs to make the conclusion slightly more likely. You do not need to prove it beyond all doubt.

Summary Checklist

Step	Action	Purpose
1	Read stem first	Confirm it is Strengthen
2	Find the conclusion	Know what needs support
3	Identify premises	Understand the evidence
4	Spot the assumption	Find the gap to fill
5	Predict before reading choices	Avoid trap answers
6	Choose "most strengthens"	Slight support is enough

Question 1 of 5

A new study shows that students who take handwritten notes perform better on conceptual exam questions than students who type their notes on laptops. The researchers conclude that handwriting notes causes deeper processing of the material.

▼ Tap to read passage

Which of the following, if true, most strengthens the researchers' conclusion?

Choice (B) eliminates the alternative explanation that the advantage is merely about paraphrasing vs. transcribing. Even when laptop users paraphrase, handwriting still wins: this supports the claim that the physical act of handwriting itself causes deeper processing.

Question 2 of 5

A city's mayor argues that the newly installed speed cameras on Main Street have made the road safer, since traffic accidents on Main Street decreased by 30% in the year after the cameras were installed.

▼ Tap to read passage

Which of the following, if true, most strengthens the mayor's argument?

Choice (C) eliminates the alternative explanation that a broader trend (fewer cars, better weather, road repairs) caused the decrease. If similar streets stayed the same, the cameras are the likely cause. Choice (D) actually weakens the argument by suggesting regression to the mean.

Question 3 of 5

A pharmaceutical company tested a new drug for migraines. In the trial, 60% of patients receiving the drug reported relief within one hour, compared to 40% of patients receiving a placebo. The company concludes that the drug is effective at treating migraines.

▼ Tap to read passage

Which of the following, if true, most strengthens the company's conclusion?

Choice (D) provides additional evidence of the drug's effectiveness: it not only relieves individual migraines but also reduces their frequency. This makes the effectiveness claim more robust. Choices (A) and (B) are irrelevant to effectiveness, and (C) describes standard trial conditions.

Question 4 of 5

A school board argues that reducing class sizes from 30 to 20 students will improve educational outcomes, citing a district where such a reduction led to higher test scores.

▼ Tap to read passage

Which of the following, if true, most strengthens the school board's argument?

Choice (A) eliminates alternative explanations. If no other changes were made, the improvement is more likely caused by the class size reduction itself. (B) is about satisfaction, not educational outcomes. (C) is about cost, not effectiveness. (D) actually weakens the argument.

Question 5 of 5

An environmental group argues that a proposed dam on the Clearwater River should not be built because it would destroy the habitat of the endangered silver trout. A government official responds that the dam is necessary because the region needs more hydroelectric power to meet growing energy demands.

▼ Tap to read passage

Which of the following, if true, most strengthens the environmental group's position?

Choice (B) strengthens the environmental group's position by showing that building the dam would cause irreversible extinction of the silver trout: there is no alternative habitat. This makes the group's argument against the dam much more compelling. (A) supports the government's position, (C) is irrelevant, and (D) is an ad hominem attack.

LSAT Logical ReasoningStrengthen

What Is a Strengthen Question?

Anatomy of an Argument

Recognizing the Question Stem

The Core Principle

How Strengthening Works

Strengthen vs. Weaken

Step-by-Step Approach

Worked Example 1

Worked Example 2

Worked Example 3: Harder Stimulus

Types of Strengthening Answers

Trap Answer Patterns

Common Mistakes

Summary Checklist

Question 1 of 5

Question 2 of 5

Question 3 of 5

Question 4 of 5

Question 5 of 5

LSAT Logical Reasoning
Strengthen