Quick answer: a Sufficient Assumption question asks which answer, if added, would make the conclusion follow for sure. Find the idea in the conclusion that is missing from the evidence, then pick the answer that links them. Strong language is often fine here.
How to Spot Sufficient Assumption Questions
Look for question stems like these:
- The conclusion follows logically if which one of the following is assumed?
- Which one of the following, if assumed, enables the conclusion to be properly drawn?
- Which one of the following, if assumed, allows the conclusion to be properly inferred?
How to Solve Sufficient Assumption Questions
- Write the evidence and the conclusion in short form.
- Find the new idea in the conclusion.
- Build the missing link from the evidence to that idea.
- Pick the answer that gives that exact link.
- Add it to the evidence and check that the conclusion now has to be true.
Sufficient Assumption Questions Example
This is a practice example we wrote to show the idea. It is not a real LSAT question.
Argument: Lena speaks Spanish. So Lena will be hired.
Question: The conclusion follows logically if which one of the following is assumed?
Best answer: Anyone who speaks Spanish will be hired.
Why: Add that rule to the evidence and the conclusion has to follow. It is strong, and that is fine, because this answer only has to be enough.
Common Traps
- The reverse rule: “Anyone who is hired speaks Spanish.” It does not prove the conclusion.
- Answers that make the conclusion likely but not certain.
- Rejecting a strong answer because it sounds extreme.
Sufficient Assumption Questions FAQ
Can a sufficient assumption be extreme?
Yes. It only has to be enough to prove the conclusion.
Does the negation test work here?
No. Use the negation test for necessary assumptions. Here, add the answer and see if the conclusion must follow.
Do I need formal logic?
Basic if then rules help a lot, especially reversing them correctly.
See all Logical Reasoning question types, read the Logical Reasoning guide, and practice with LSAC’s free official PrepTests.
Related LSAT Section Guides
- All LSAT section and question type guides
- LSAT Logical Reasoning guide
- Logical Reasoning question types
- LSAT Reading Comprehension guide
- Reading Comprehension question types
Sufficient assumption questions rely on conditional rules. Review LSAT conditional logic with unless, if, and only if.