Definition:A Fortiori

Definition
A fortiori knowledge arises from stronger facts already established.

For example, in:


 * "I am too old for this game; therefore, my father is also too old."

the knowledge:


 * "My father is too old for this game."

arises a fortiori from the stronger knowledge that:


 * "I am too old for this game."

An a fortiori argument is most commonly used by applying a general fact in a particular case.