Necessary vs. Sufficient Conditions

A sufficient condition guarantees the outcome. A necessary condition is required for the outcome. Being a dog is sufficient for being a mammal but not necessary, while breathing is necessary for living but not sufficient. Mixing these two up is one of the most tested errors on the LSAT.

Example

A ticket is necessary to enter the theater, but it does not guarantee you a seat.

See also

• Conditional Statement
• Sufficient Assumption
• Necessary Assumption

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Last updated October 12, 2026