A priori and a posteriori

two types of knowledge, justification, or argument

A priori ("from the earlier") and a posteriori ("from the later") are Latin phrases used in philosophy to see what is different between some types of knowledge, reasoning, or argument by their reliance on evidence or experience based on experience. A priori knowledge is independent from current experience (e.g., as part of a new study). Examples include mathematics,[lower-roman 1] tautologies, and deduction from pure reason.[lower-roman 2] A posteriori knowledge depends on empirical evidence [en]. Examples include most fields of science and aspects of personal knowledge [en].

The terms originate from the analytic methods found in Organon, a collection of works by Aristotle. Prior analytics (a priori) is about deductive logic, which comes from definitions and first principles. Posterior analytics (a posteriori) is about inductive logic, which comes from observational evidence.

Both terms appear in Euclid's Elements and were popularized by Immanuel Kant's Critique of Pure Reason, an influential work in the history of philosophy.[1] Both terms are primarily used as modifiers [en] to the noun "knowledge" (i.e. "a priori knowledge"). A priori can be used to modify other nouns such as "truth". Philosophers may use apriority, apriorist, and aprioricity as nouns referring to the quality of being a priori.[2]

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References

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  1. Some associationist [en] philosophers have contended that mathematics comes from experience and is not a form of any a priori knowledge (Macleod 2016)
  2. Galen Strawson [en] has stated that an a priori argument is one in which "you can see that it is true just lying on your couch. You don't have to get up off your couch and go outside and examine the way things are in the physical world. You don't have to do any science." (Sommers 2003)
  • Bird, Graham (1995). Honderich, Ted (ed.). The Oxford Companion to Philosophy. Oxford: Oxford University Press. ISBN 0-19-866132-0.
  • Kitcher, Philip (2001). "A Priori Knowledge Revisited". In Boghossian, Paul; Peacocke, Christopher (eds.). New Essays on the A Priori. Oxford, England: Oxford University Press. ISBN 978-0199241279.[not in the source given]
  • Macleod, Christopher (Aug 25, 2016). "John Stuart Mill". In Zalta, Edward N. (ed.). The Stanford Encyclopedia of Philosophy (Summer 2020 ed.) – via Metaphysics Research Lab, Stanford University.
  • Sommers, Tamler (March 2003). Jarman, Casey (ed.). "Galen Strawson (interview)". Believer Magazine. 1 (1). San Francisco, CA: McSweeney's McMullens. Retrieved 10 July 2013.