LSAT Logical Reasoning

Master the art of analyzing, evaluating, and constructing arguments for the LSAT and beyond.

Advanced Topics

Evaluating Assumptions

Digging Deeper into Assumptions

Every argument relies on assumptions—unstated links that connect the premises to the conclusion. On the LSAT, your job is to find these hidden bridges.

Types of Assumptions

  • Necessary Assumption: Must be true for the argument to work.
  • Sufficient Assumption: Guarantees the conclusion if true.

How to Uncover Assumptions

Try the "negation test": If negating a statement destroys the argument, it's likely a necessary assumption.

Real-World Relevance

Spotting assumptions helps you evaluate arguments in news, politics, and even casual conversations.

Key Formula

\[A \rightarrow B\]

Examples

  • If an argument claims, 'All cats are friendly because my cat is friendly,' the hidden assumption is that your cat is representative of all cats.

  • An ad says, 'This shampoo makes hair shiny,' assuming that all users have similar hair types.

In a Nutshell

Uncovering unstated assumptions is key to evaluating arguments.

Key Terms

Necessary Assumption
A statement that must be true for the argument to hold.
Sufficient Assumption
A statement that, if true, guarantees the argument's conclusion.