LSAT Inference
Questions
Master the art of identifying what must be true based on the information provided: the core skill behind LSAT inference questions.
What Is an Inference?
In everyday language, "inference" means a guess or a conclusion you draw. But on the LSAT, the word has a much stricter meaning. An inference is a statement that must be true based on the information given in the stimulus.
Recognizing Inference Stems
Inference questions use specific language in the question stem. Learning to spot these phrases is your first step toward consistent accuracy.
The Logic Behind Inference
Inference questions test your ability to combine premises and derive what logically follows. You are not adding outside knowledge: you are working strictly within the text.
The Core Rule of Inference
Must Be True vs. Most Strongly Supported
These two question types are closely related, but they differ in how strict the logical standard is. Understanding this distinction prevents costly errors.
| Must Be True | Most Strongly Supported | |
|---|---|---|
| Standard | 100% guaranteed | Very well supported |
| Allows Slight Leap? | No | A very small one |
| Wrong Answers | Could be false | Weakly or not supported |
| Frequency | Very common | Common |
Key Inference Triggers
Certain logical structures in the stimulus frequently generate inferences. Learning to spot these patterns speeds up your analysis.
Step-by-Step Approach
Worked Example: Conditional Chain
Worked Example: Quantifier Overlap
Worked Example: Contrapositive
Eliminating Wrong Answers
Wrong answers on inference questions fall into predictable categories. Recognizing these traps makes elimination faster and more confident.
Common Mistakes
Quantifier Strength Scale
The LSAT cares deeply about the strength of quantifiers. A valid inference can never be stronger than its weakest premise. Memorize this scale.
Inference Cheat Sheet
| Pattern | Structure | Inference |
|---|---|---|
| Conditional Chain | \( A \rightarrow B, B \rightarrow C \) | \( A \rightarrow C \) |
| Contrapositive | \( A \rightarrow B \) | \( \neg B \rightarrow \neg A \) |
| Quantifier Overlap | All \(X\) are \(Y\), Some \(X\) are \(Z\) | Some \(Z\) are \(Y\) |
| Combined Quantifiers | Most \(A\) are \(B\), All \(B\) are \(C\) | Most \(A\) are \(C\) |
| Converse (Invalid) | \( A \rightarrow B \) | \( B \rightarrow A \) (wrong) |
Question 1 of 5
Every student who passes the bar exam has completed law school. Jordan has not completed law school.
If the statements above are true, which of the following must be true?
Question 2 of 5
Most of the paintings in the gallery are by local artists. All paintings by local artists are available for purchase. Some of the paintings in the gallery are landscapes.
Which one of the following can be properly inferred from the statements above?
Question 3 of 5
No one who lacks a security clearance can access the classified files. Chen accessed the classified files last Tuesday. Anyone with a security clearance has undergone a background check.
If all of the statements above are true, which one of the following must also be true?
Question 4 of 5
Critic: The new film adaptation fails because it omits the novel's central theme of moral ambiguity. Without that theme, the story is reduced to a simplistic good-versus-evil narrative.
Director: The film succeeds on its own terms. Audiences do not need to have read the novel, and the film's focus on visual storytelling creates a different but equally valid artistic experience.
The critic and director disagree about whether:
Question 5 of 5
Some of the city's parks have been renovated this year. All parks that have been renovated now include accessible playgrounds. Every park with an accessible playground has seen increased weekend attendance.
The statements above, if true, most strongly support which of the following?