A Fortiori Definition and Legal Meaning

On this page, you'll find the legal definition and meaning of A Fortiori, written in plain English, along with examples of how it is used.

What is A Fortiori?

prep. latin phrase meaning “from the stronger” – loosely used to mean “with even stronger reason”. Often used to lead from a less certain proposition to a more evident inference that follows directly from the other proposition.

History and Meaning of A Fortiori

A fortiori, a Latin phrase meaning "from the stronger," is a legal term that has been in use since ancient Roman times. Its origin can be traced back to the works of prominent Roman orators and scholars, such as Cicero and Seneca, who used the term to strengthen arguments and make decisive points. In legal discourse, a fortiori is employed to demonstrate the stronger reason for inferring one fact from another. In other words, the term is applied when asserting that if one fact is true, another, even more obvious fact, must also be true.

Through the centuries, a fortiori has been adopted by diverse fields such as law, philosophy, and mathematics, and its usage has evolved accordingly. Despite this evolution, the core meaning of the phrase remains the same—drawing attention to a more substantial argument or conclusion based on the establishment of a lesser, related point.

Examples of A Fortiori

  1. If it is established that a person commits a crime by stealing a small item, a fortiori, that same person would be more culpable for stealing something of greater value.

  2. In a contract dispute case, a court finds that a party has breached the agreement by not meeting a secondary obligation, so a fortiori, the same party would be in breach if they failed to fulfill the primary obligation.

  3. If a 17-year-old is considered too young to vote, a fortiori, a 15-year-old would also be deemed ineligible.

  4. When a law recognizes that citizens have the right to express their political opinions, a fortiori, they have the freedom to express non-political opinions as well.

  5. If a person is held liable for negligence while driving a car, a fortiori, they would be considered even more liable if they were driving recklessly.

Legal Terms Similar to A Fortiori

  1. A priori: A term of Latin origin, which means "from the earlier" and is used to describe knowledge or justifications that are independent of experience or observation.

  2. A posteriori: Another Latin term, meaning "from the later" or "from the more recent," it signifies knowledge or justification derived from experience or empirical evidence.

  3. Q.E.D.: Short for "quod erat demonstrandum," the Latin phrase translates to "that which was to be demonstrated" and is typically used at the end of a logical argument to signify that the intended point has been proven.

  4. Ad absurdum: A Latin phrase meaning "to the point of absurdity," it is used to argue that a proposition leads to absurd or illogical conclusions, thereby demonstrating its falseness.