# a priori

Pronunciation: US say "ay pry-OR-ee" /ˌeɪ pɹaɪˈɔːɹi/; UK say "ay pry-AW-ry" /ˌeɪ pɹaɪˈɔːɹaɪ/

## Adjective

1. Reasoned out from theory and hypothesis, without depending on experiment or other empirical evidence.
   - Simple: Based on ideas and theory, not on experiments or on what people have seen and measured.
   - _Philosophers still argue over whether the truths of arithmetic count as a priori knowledge._
   - _The economist rejected the policy on a priori grounds, before any data from the pilot program had come in._
2. Assumed to be true or correct without first being examined or analyzed.
   - Simple: Believed to be true without anyone checking or thinking it through.
   - _Investigators cautioned reporters against drawing any a priori conclusion about the cause of the fire._
   - _The team's a priori assumption that users wanted more features went unexamined until sales collapsed._
4. Evident without needing proof or argument, and obvious by intuition alone.
   - Simple: So clearly true that you just know it without any proof.
   - _That a promise should be kept seemed a priori to him, too obvious to need any defense._
   - _To a native speaker, the word order feels a priori, obvious in a way that no lesson ever had to explain._
5. Of a constructed language: created entirely from scratch rather than derived from any existing language.
   - Simple: Describes an invented language that is made from nothing, not based on any language that already exists.
   - _She spent six years developing an a priori language for her fantasy novels, coining every root herself._
   - _The film's alien tongue is fully a priori: none of its vocabulary traces back to any human language._

## Adverb

3. In a manner grounded in theoretical deduction rather than in empirical observation.
   - Simple: By working things out from theory, not by watching or testing what happens.
   - _Some philosophers hold that basic moral principles can be known a priori._
   - _The physicist argued a priori that the effect must exist, years before any instrument could detect it._

## Origin

First recorded in 1610, it is a learned borrowing from Medieval Latin ā priōrī, literally "from the former," which meant "involving reasoning from cause to effect; from first principles."

Source: DictionaryAI, https://dictionaryai.com/define/a-priori (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).