Formal Logic

Formal logic is the LSAT’s system of if-then rules, contrapositives, and quantifiers like some and most. It shows up in sufficient assumption, parallel reasoning, and some inference questions. Diagramming the statements makes the valid moves visible.

Example

Translating "No lawyers are chefs" and "Some chefs are runners" into diagrams to see what follows.

See also

• Conditional Statement
• Valid Argument
• Some and Most Statements

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Last updated October 12, 2026