Meaning & use
fortiori argument
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Meanings
nouncountableformaltechnical
A way of arguing that if something is true in one case, it must be even more true in a stronger or clearer case.
Grammar: Countable: you can say 'an a fortiori argument' or 'a fortiori arguments' when discussing more than one.
Patterns
- a fortiori argument for something
- make an a fortiori argument
- an a fortiori argument that ...
The lawyer made an a fortiori argument: if the company is liable for a small leak, it is surely liable for a flood.
Her a fortiori argument was that if even experts find the rule confusing, beginners will find it impossible.
They used an a fortiori argument to show that the stricter rule must also apply here.
nouncountableformaltechnical
A conclusion reached by reasoning from a weaker case to a stronger one, often used in law and philosophy.
Grammar: Often appears in academic writing after verbs like 'use', 'offer' or 'accept'.
Patterns
- accept an a fortiori argument
- offer an a fortiori argument
- by a fortiori argument
The judge accepted the a fortiori argument and ruled in favor of the smaller claim.
In her essay she offers an a fortiori argument that moves from a mild example to an extreme one.
By a fortiori argument, if the basic test is failed, the advanced test must also be failed.
Word forms
| plural | a fortiori arguments |
|---|
Common combinations
- make an a fortiori argument
- The defense made an a fortiori argument to show that the harsher penalty was unjust.
- a fortiori reasoning
- A fortiori reasoning led them from the simple case to the difficult one.
- a fortiori argument in law
- Students learn the a fortiori argument in law because it appears in many court opinions.
- accept an a fortiori argument
- The panel accepted the a fortiori argument without much debate.
- a fortiori conclusion
- The a fortiori conclusion was that if one mistake is bad, two are worse.
Synonyms and how they differ
- argument from the stronger reason
- A descriptive phrase rather than a fixed term; it explains the same idea in plain English.
- inference
- Broader and more general: any conclusion drawn from evidence, not specifically the stronger-case pattern.
- deduction
- Focuses on logical steps from general rules to specific results, while an a fortiori argument focuses on greater strength of a case.
Word family
- a fortiori adverb
- By even stronger reason; the short form used on its own.
- fortiori adjective
- Rare shorthand for the same idea, usually only in technical writing.
Commonly confused: fortiori argument or a priori? fortiori argument or ad hominem?
fortiori argument vs a priori
A priori means based on theory rather than experience; a fortiori means with even stronger reason. They sound similar but describe different kinds of reasoning.
fortiori argument vs ad hominem
An ad hominem argument attacks the person rather than the point; an a fortiori argument compares the strength of two cases.
Practice
Which sentence uses 'a fortiori argument' correctly?
Choose one answer.
An a fortiori argument moves from a weaker case to a stronger one, so option 0 fits. Option 1 describes an ad hominem attack, option 2 is too casual and lacks the stronger-case structure, and option 3 is nonsense.
Make it your own
Write a sentence using “fortiori argument”, then check it and compare it with the examples above.