5 Steps to Solving Strengthen Logical Reasoning Questions

What do you do when you see a Strengthen Logical Reasoning question?

Remember that Logical Reasoning makes up half the exam, and Strengthen Logical Reasoning questions are common. Here's a step-by-step guide to help you solve them.

1. Recognize that it's a Strengthen question.
Some strengthen question stems:

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

"Which of the following, if true, would most justify the conclusion?"

2. Look for the main flaw (if present).
It will make some unwarranted (and unstated) assumption - the missing (and weakest) link between premises/evidence and conclusion.

3. Support the assumption and scan for answer choice that helps patch up the argument.
After you find the central flaw of the argument, fix it. Bridge the gap between evidence and conclusion. The correct answer may protect the argument against the flaw by:

-denying an alternative possibility

-promoting the evidence's relevance to the conclusion

-supporting the evidence's validity (such as by saying a survey or study was properly conducted)

-providing additional evidence to support the conclusion

4. Remember that the answer choices can contain information not mentioned in the stimulus.
Why? Because the question stem says "if true," which allows the possibility of new information.

5. Remember that in "Strengthen EXCEPT" questions, 4 will strengthen the argument, and 1 will not.
The 1 that doesn't strengthen will either weaken or have no effect. In logic, the opposite of strengthen is "not strengthen."


Contrast with Sufficient Assumption (aka Justify) question stems:

"Which one of the following, if true, allows the conclusion to be properly drawn?"

"The conclusion follows logically if which one of the following is assumed?"

Sufficient Assumption questions do strengthen the argument. In fact, they fully justify it by guaranteeing that the conclusion logically follows.

However, they should be approached differently than Strengthen questions. The major difference is that Sufficient Assumption (Justify) questions often reward a formal-logic approach, while Strengthen questions reward an informal-logic approach.

For more on how to approach Sufficient Assumption questions, check out:

Sufficient Assumption Questions | Tips and Categorization

Logical Reasoning | Sufficient Assumption (Justify) Questions


  1. Hey Steve, in reference to your strengthen questions right answers list, is it okay for the right answer to support evidence's validity? Aren't premises/evidence presumed to be true on the LSAT, so why would a strengthen question right answer support the premise's validity.

    1. That's the case with Necessary, Sufficient, and almost every Flaw question. Strengthen and Weaken can have ACs that influence the premise in a way, so long as they actually influence the overall reasoning

  2. Thanks Buddy ths was really helpful !!