{{Short description|Two types of knowledge, justification, or argument}} {{Redirect2|A priori|A posteriori||A priori (disambiguation)|and|A posteriori (disambiguation)}} {{DISPLAYTITLE:''A priori'' and ''a posteriori''}} {{Use dmy dates|date=February 2023}} {{Use shortened footnotes|date=September 2021}} {{Epistemology sidebar}}
'''{{lang|la|A priori}}''' (‘from the earlier’) and '''{{lang|la|a posteriori}}''' (‘from the later’) are Latin phrases used in philosophy and linguistics to distinguish types of knowledge, justification, or argument by their reliance on experience. Roughly speaking, a proposition is known or justified ''a priori'' if it is known or justified independently of any experience (beyond the experience necessary to understand the proposition);<ref>Galen Strawson has stated that an {{lang|la|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." ({{harvnb|Sommers|2003}})</ref> instead, it is known or justified ''a posteriori'' if its knowledge and/or justification depends on empirical evidence. For example, the proposition ‘It is sunny in London today’ can be known (if true) ''a posteriori'', whereas the proposition ‘Either it is sunny or it is not sunny in London today’ can be known ''a priori''.
Fields of knowledge where ''a priori'' justification is predominant are, for example, mathematics<ref>Though some associationist philosophers have contended that mathematics comes from experience and is not a form of any ''a priori'' knowledge ({{harvnb|Macleod|2016}})</ref> and formal logic; by contrast, most of the sciences generally involve ''a posteriori'' justification.
In the history of philosophy, the ''a priori–a posteriori'' distinction first appeared in the writings of the 14th century logician Albert of Saxony, where the phrases were used to distinguish between arguments ‘from causes to effects’ (''a priori'') and ‘from effects to causes’ (''a posteriori'').<ref name=":0">{{Cite web |date=20 July 1998 |title=A priori knowledge |url=https://www.britannica.com/topic/a-priori-knowledge |url-status=live |archive-url=https://web.archive.org/web/20260410144527/https://www.britannica.com/topic/a-priori-knowledge |archive-date=10 April 2026 |access-date=10 April 2026 |website=Britannica}}</ref> As an epistemological distinction it became prominent with Immanuel Kant's ''Critique of Pure Reason'',<ref name=":0" /><ref>{{Cite book |last=Cassullo |first=Albert |title=A Priori Justification |publisher=Oxford University Press |year=2003 |isbn=9780195115055 |location=Oxford |pages=4}}</ref> where its relation to the analytic–synthetic distinction is discussed.
==Examples== === A priori ===
==== Philosophical a priori example ==== Consider the proposition: "If George V reigned at least four days, then he reigned more than three days." This is an ''a priori'' statement, as it can be known through reason alone.
==== Linguistic a priori example ==== Consider the proposition: Most nonsense words are created from scratch. Klingon, Aui and Solresol are completely made-up.
=== A posteriori ===
==== Philosophical a posteriori example ==== Consider the proposition: "George V reigned from 1910 to 1936." This is something that (if true) one must come to know ''a posteriori'' because it expresses an empirical fact unknowable by reason alone.
==== Linguistic a posteriori example ==== Consider the proposition: When making an artificial language, all words are from other languages but the affixes are completely made-up.
== Aprioricity, analyticity and necessity ==
===Relation to the analytic–synthetic distinction=== {{Further|Analytic–synthetic distinction}}
Several philosophers, in reaction to Immanuel Kant, sought to explain ''a priori'' knowledge without appealing to what Paul Boghossian describes as "a special faculty [intuition]{{Nbsp}}... that has never been described in satisfactory terms."<ref name="Boghossianj_1996">{{harvnb|Boghossian|2003|p=363}}</ref> One theory, popular among the logical positivists of the early 20th century, is what Boghossian calls the "analytic explanation of the a priori".<ref name="Boghossianj_1996" /> The distinction between analytic and synthetic propositions was first introduced by Kant. While his original distinction was primarily drawn in terms of conceptual containment, the contemporary version of such distinction primarily involves, as American philosopher Willard Van Orman Quine put it, the notions of "true by virtue of meanings and independently of fact."<ref name=Q21>{{harvnb|Quine|1951|p=21}}</ref>
'''Analytic propositions''' are considered true by virtue of their meaning alone, while ''a posteriori'' propositions by virtue of their meaning and of certain facts about the world. According to the analytic explanation of the ''a priori'', all ''a priori'' knowledge is analytic; so ''a priori'' knowledge need not require a special faculty of pure intuition, since it can be accounted for simply by one's ability to understand the meaning of the proposition in question. More simply, proponents of this explanation claimed to have reduced a dubious metaphysical faculty of pure reason to a legitimate linguistic notion of analyticity.
The analytic explanation of ''a priori'' knowledge has undergone several criticisms. Most notably, Quine argues that the analytic–synthetic distinction is illegitimate:<ref>{{harvnb|Quine|1951|p=34}}</ref><blockquote>But for all its a priori reasonableness, a boundary between analytic and synthetic statements simply has not been drawn. That there is such a distinction to be drawn at all is an unempirical dogma of empiricists, a metaphysical article of faith.</blockquote>
Although the soundness of Quine's proposition remains uncertain, it had a powerful effect on the project of explaining the ''a priori'' in terms of the analytic.<ref>{{cite book |last1=Fred-Rivera |first1=Ivette |title=A Historical and Systematic Perspective on A Priori Knowledge and Justification |date=10 August 2022 |publisher=Springer Nature |isbn=978-3-031-06874-4 |pages=40–45 |url=https://books.google.com/books?id=MamAEAAAQBAJ&pg=PA43 |language=en |archive-date=2 October 2024 |access-date=26 August 2024 |archive-url=https://web.archive.org/web/20241002185310/https://books.google.com/books?id=MamAEAAAQBAJ&pg=PA43 |url-status=live }}</ref>
=== Relation to the necessary truths and contingent truths=== The metaphysical distinction between ''necessary'' and ''contingent'' truths has also been related to ''a priori'' and ''a posteriori'' knowledge.
A proposition that is necessarily true is one in which its negation is self-contradictory; it is true in every possible world. For example, considering the proposition "all bachelors are unmarried:" its negation (i.e. the proposition that some bachelors are married) is incoherent due to the concept of being unmarried (or the meaning of the word "unmarried") being tied to part of the concept of being a bachelor (or part of the definition of the word "bachelor"). To the extent that contradictions are impossible, self-contradictory propositions are necessarily false as it is impossible for them to be true. The negation of a self-contradictory proposition is, therefore, supposed to be necessarily true.
By contrast, a proposition that is '''contingently true''' is one in which its negation is not self-contradictory. Thus, it is said ''not'' to be true in every possible world. As Jason Baehr suggests, it seems plausible that all necessary propositions are known ''a priori'', because "[s]ense experience can tell us only about the actual world and hence about what is the case; it can say nothing about what must or must not be the case."<ref>{{harvnb|Baehr|2006}}, §3</ref>
Following Kant, some philosophers have considered the relationship between ''aprioricity'', ''analyticity,'' and ''necessity'' to be extremely close. According to Jerry Fodor, "positivism, in particular, took it for granted that ''a priori'' truths must be necessary."<ref>{{harvnb|Fodor|1998|p=86}}</ref> Since Kant, the distinction between analytic and synthetic propositions has slightly changed. Analytic propositions were largely taken to be "true by virtue of meanings and independently of fact",<ref name=Q21/> while synthetic propositions were not—one must conduct some sort of empirical investigation, looking to the world, to determine the truth-value of synthetic propositions.
===Separation=== Aprioricity, analyticity and necessity have since been more clearly separated from each other. American philosopher Saul Kripke (1972), for example, provides strong arguments against this position, whereby he contends that there are necessary ''a posteriori'' truths. For example, the proposition that water is H<sub>2</sub>O (if it is true): According to Kripke, this statement is both ''necessarily true'', because water and H<sub>2</sub>O are the same thing, they are identical in every possible world, and truths of identity are logically necessary; and ''a posteriori'', because it is known only through empirical investigation. Following such considerations of Kripke and others (see Hilary Putnam), philosophers tend to distinguish the notion of aprioricity more clearly from that of necessity and analyticity.
Kripke's definitions of these terms diverge in subtle ways from Kant's. Taking these differences into account, Kripke's controversial analysis of naming as contingent and ''a priori'' would, according to Stephen Palmquist, best fit into Kant's epistemological framework by calling it "analytic a posteriori."<ref group="lower-roman">In this pair of articles, Stephen Palmquist demonstrates that the context often determines how a particular proposition should be classified. A proposition that is synthetic ''a posteriori'' in one context might be analytic ''a priori'' in another. ({{harvnb|Palmquist|1987b|pp=269, 273}})</ref> Aaron Sloman presented a brief defence of Kant's three distinctions (analytic/synthetic, apriori/empirical and necessary/contingent), in that it did not assume "possible world semantics" for the third distinction, merely that some part of ''this'' world might have been different.{{sfn|Sloman|1965}}
The relationship between aprioricity, necessity and analyticity is not easy to discern. Most philosophers at least seem to agree that while the various distinctions may overlap, the notions are clearly not identical: the ''a priori''/''a posteriori'' distinction is epistemological; the analytic/synthetic distinction is linguistic; and the necessary/contingent distinction is metaphysical.<ref>{{harvnb|Baehr|2006}}, §2-3</ref>
==History== ===Early uses=== The term ''a priori'' is Latin for 'from what comes before' (or, less literally, 'from first principles, before experience'). In contrast, the term ''a posteriori'' is Latin for 'from what comes later' (or 'after experience').
They appear in Latin translations of Euclid's ''Elements'', a work widely considered during the early European modern period as the model for precise thinking.
An early philosophical use of what might be considered a notion of ''a priori'' knowledge (though not called by that name) is Plato's ''theory of recollection'', related in the dialogue ''Meno'', according to which something like ''a priori'' knowledge is knowledge inherent, intrinsic in the human mind.{{source needed|date=June 2023}}
Albert of Saxony, a 14th-century logician, wrote on both ''a priori'' and ''a posteriori''.<ref name=EB>{{harvnb|Hoiberg|2010|p=1}}</ref>
The early modern Thomistic philosopher John Sergeant differentiates the terms by the direction of inference regarding proper causes and effects. To demonstrate something ''a priori'' is to "Demonstrate Proper Effects from Proper Efficient Causes" and likewise to demonstrate ''a posteriori'' is to demonstrate "Proper Efficient Causes from Proper Effects", according to his 1696 work ''The Method to Science'' Book III, Lesson IV, Section 7.
G. W. Leibniz introduced a distinction between ''a priori'' and ''a posteriori'' criteria for the possibility of a notion in his short treatise "Meditations on Knowledge, Truth, and Ideas" (1684). ''A priori'' and ''a posteriori'' arguments for the existence of God appear in his ''Monadology'' (1714).{{sfn|Look|2007}}
George Berkeley outlined the distinction in his 1710 work ''A Treatise Concerning the Principles of Human Knowledge'' (para. XXI).
===Immanuel Kant=== The 18th-century German philosopher Immanuel Kant (1781) advocated a blend of rationalist and empiricist theories. Kant says, "Although all our cognition begins with experience, it does not follow that it arises from [is caused by] experience."<ref name="kant_1781">{{harvnb|Kant|1781|p=1}}</ref> According to Kant, ''a priori'' cognition is transcendental, or based on the ''form'' of all possible experience, while ''a posteriori'' cognition is empirical, based on the ''content'' of experience:<ref name="kant_1781"/> <blockquote>It is quite possible that our empirical knowledge is a compound of that which we receive through impressions, and that which the faculty of cognition supplies from itself sensuous impressions [sense data] giving merely the ''occasion'' [opportunity for a cause to produce its effect]. </blockquote>Contrary to contemporary usages of the term, Kant believes that ''a priori'' knowledge is not entirely independent of the content of experience. Unlike the rationalists, Kant thinks that ''a priori'' cognition, in its pure form, that is without the admixture of any empirical content, is limited to the deduction of the conditions of possible experience. These ''a priori'', or transcendental, conditions are seated in one's cognitive faculties, and are not provided by experience in general or any experience in particular (although an argument exists that ''a priori'' intuitions can be "triggered" by experience).
Kant nominated and explored the possibility of a transcendental logic with which to consider the deduction of the ''a priori'' in its pure form. Space, time and causality are considered pure ''a priori'' intuitions. Kant reasoned that the pure ''a priori'' intuitions are established via his transcendental aesthetic and transcendental logic. He claimed that the human subject would not have the kind of experience that it has were these ''a priori'' forms not in some way constitutive of him as a human subject. For instance, a person would not experience the world as an orderly, rule-governed place unless time, space and causality were determinant functions in the form of perceptual faculties, i. e., there can be no experience in general without space, time or causality as particular determinants thereon. The claim is more formally known as Kant's transcendental deduction and it is the central argument of his major work, the ''Critique of Pure Reason''. The transcendental deduction argues that time, space and causality are ideal as much as real. In consideration of a possible logic of the ''a priori'', this most famous of Kant's deductions has made the successful attempt in the case for the fact of subjectivity, what constitutes subjectivity and what relation it holds with objectivity and the empirical.
===Johann Fichte=== After Kant's death, a number of philosophers saw themselves as correcting and expanding his philosophy, leading to the various forms of German Idealism. One of these philosophers was Johann Fichte. His student (and critic), Arthur Schopenhauer, accused him of rejecting the distinction between ''a priori'' and ''a posteriori'' knowledge:
{{Blockquote|... Fichte who, because the thing-in-itself had just been discredited, at once prepared a system without any thing-in-itself. Consequently, he rejected the assumption of anything that was not through and through merely our representation, and therefore let the knowing subject be all in all or at any rate produce everything from its own resources. For this purpose, he at once did away with the essential and most meritorious part of the Kantian doctrine, the distinction between ''a priori'' and ''a posteriori'' and thus that between the phenomenon and the thing-in-itself. For he declared everything to be ''a priori'', naturally without any evidence for such a monstrous assertion; instead of these, he gave sophisms and even crazy sham demonstrations whose absurdity was concealed under the mask of profundity and of the incomprehensibility ostensibly arising therefrom. Moreover, he appealed boldly and openly to intellectual intuition, that is, really to inspiration.|Schopenhauer|''Parerga and Paralipomena'', Vol. I, §13}}
==See also== <!-- Please keep entries in alphabetical order --> {{div col|colwidth=18em}} * A priori probability * A posteriori necessity * ''Ab initio'' * Abductive reasoning * Abstract and concrete * Analytic–synthetic distinction * Deductive reasoning * Inductive reasoning * Off the verandah * Relativized a priori * ''Tabula rasa'' * Transcendental empiricism * Transcendental hermeneutic phenomenology * Transcendental nominalism * Vorstellung {{div col end}} <!-- please keep entries in alphabetical order -->
== References ==
=== Notes === {{Reflist|group=lower-roman}}
=== Citations === {{Reflist}}
=== Sources === {{Refbegin}} * {{cite web | last = Baehr | first = Jason S. | title = A Priori and A Posteriori | website = Internet Encyclopedia of Philosophy | year = 2006 | url = http://www.iep.utm.edu/apriori/ | access-date = 10 February 2014 | archive-date = 9 March 2010 | archive-url = https://web.archive.org/web/20100309135741/http://www.iep.utm.edu/apriori/ | url-status = live }} * {{cite book |first = Graham |last = Bird |editor-first = Ted |editor-last = Honderich |title = The Oxford Companion to Philosophy |publisher = Oxford University Press |location = Oxford |year = 1995 |isbn = 0-19-866132-0 |url = https://archive.org/details/oxfordcompaniont00hond/page/439 }} * {{cite book | last = Boghossian | first = Paul Artin | editor1-last = Hale | editor1-first = Bob | editor2-last = Wright | editor2-first = Crispin | chapter = 14: Analyticity | title = A Companion to the Philosophy of Language | series = Blackwell Companions to Philosophy | year = 2003 | orig-year = 1997 | publisher = Blackwell Publishing | location = Malden, MA | isbn = 978-0631213260}} * {{cite book | last = Fodor | first = Jerry | year = 1998 | title = Concepts: Where Cognitive Science Went Wrong | location = New York, NY | publisher = Oxford University Press | isbn = 978-0198236368}} * {{cite encyclopedia | editor-last = Hoiberg | editor-first = Dale H. | encyclopedia = Encyclopædia Britannica, Vol. I: A-Ak – Bayes | title = a priori knowledge | edition = 15th | year = 2010 | location = Chicago, Illinois | isbn = 978-1-59339-837-8 | url = https://archive.org/details/newencyclopaedia2009ency }} * {{cite book | last = Kant | first = Immanuel | title = Kritik der reinen Vernunft | trans-title = Critique of Pure Reason | year = 1781 | publisher = Im Insel-Verlag | url = https://books.google.com/books?id=b7w8AAAAYAAJ&q=critique+of+pure+reason&pg=PA15 }} * {{cite book | last = Kitcher | first = Philip | editor1-last = Boghossian | editor1-first = Paul | editor2-last = Peacocke | editor2-first = Christopher | chapter = A Priori Knowledge Revisited | chapter-url = https://books.google.com/books?id=AKwmGycd6yYC&pg=PA65 | title = New Essays on the A Priori | publisher = Oxford University Press | location = Oxford, England | year = 2001 | isbn = 978-0199241279 }}{{failed verification|date=February 2014}} * {{cite encyclopedia |last=Look |first=Brandon C. |date=22 December 2007 |title=Gottfried Wilhelm Leibniz |encyclopedia=The Stanford Encyclopedia of Philosophy |edition=Spring 2020 |editor-first=Edward N. |editor-last=Zalta |via=Metaphysics Research Lab, Stanford University |url=https://plato.stanford.edu/archives/spr2020/entries/leibniz/ |access-date=22 May 2020 |archive-date=30 June 2020 |archive-url=https://web.archive.org/web/20200630092046/https://plato.stanford.edu/archives/spr2020/entries/leibniz/ |url-status=live }} * {{cite encyclopedia |last=Macleod |first=Christopher |date=25 August 2016 |title=John Stuart Mill |encyclopedia=The Stanford Encyclopedia of Philosophy |edition=Summer 2020 |editor-first=Edward N. |editor-last=Zalta |via=Metaphysics Research Lab, Stanford University |url=https://plato.stanford.edu/archives/sum2020/entries/mill/ |access-date=19 August 2020 |archive-date=30 January 2021 |archive-url=https://web.archive.org/web/20210130185100/https://plato.stanford.edu/archives/sum2020/entries/mill/ |url-status=live }} * {{cite journal | last = Palmquist | first = Stephen | journal = The Review of Metaphysics | volume = 41 | issue = 2 | title = ''A Priori'' Knowledge in Perspective: (II) Naming, Necessity and the Analytic A Posteriori |date = December 1987b | pages = 255–282}} * {{cite journal | last = Quine | first = Willard Van Orman | title = Two Dogmas of Empiricism | journal = The Philosophical Review | pages = 20–43 | year = 1951 | volume = 60 | issue = 1 | url = http://www.ditext.com/quine/quine.html | doi = 10.2307/2181906 | jstor = 2181906 | url-access = subscription | archive-date = 13 November 2017 | access-date = 27 August 2006 | archive-url = https://web.archive.org/web/20171113060456/http://www.ditext.com/quine/quine.html | url-status = live }} * {{cite journal |last=Sloman |first=A. |date=1965-10-01 |title='Necessary', 'a priori' and 'analytic' |journal=Analysis |volume=26 |issue=1 |pages=12–16 |doi=10.1093/analys/26.1.12 |s2cid=17118371}} * {{cite journal | last = Sommers | first = Tamler | editor-last = Jarman | editor-first = Casey | url = http://www.believermag.com/issues/200303/?read=interview_strawson | title = Galen Strawson (interview) | publisher = McSweeney's McMullens | location = San Francisco, CA | journal = Believer Magazine | date = March 2003 | access-date = 10 July 2013 | volume = 1 | issue = 1 | archive-date = 25 February 2012 | archive-url = https://web.archive.org/web/20120225043625/http://www.believermag.com/issues/200303/?read=interview_strawson | url-status = live }} {{Refend}}
==Further reading== {{Refbegin}} * {{cite book |last=Descartes |first=René |year=1641 |url=http://www.wright.edu/cola/descartes/ |title=Meditationes de prima philosophia, in qua Dei existentia et animæ immortalitas demonstratur |trans-title=Meditations on First Philosophy |editor=In Cottingham |display-editors=etal |access-date=25 August 2006 |archive-url=https://web.archive.org/web/20130715042128/http://www.wright.edu/cola/descartes/ |archive-date=15 July 2013 |url-status=dead}} * {{cite book |last=Descartes |first=René |title=The Philosophical Writings of Descartes |publisher=Cambridge University Press |year=1984 |isbn=978-0521288088 |volume=2 |location=Cambridge, UK |author-mask=1}} * {{cite journal |last=Fodor |first=Jerry |title=Water's Water Everywhere |journal=London Review of Books |volume=26 |issue=21 |date=21 October 2004}}. * {{cite book |last=Greenberg |first=Robert |url=http://www.psupress.psu.edu/books/titles/0-271-02083-0.html |title=Kant's Theory of a Priori Knowledge |publisher=Penn State Press |year=2001 |isbn=978-0271020839 |location=University Park, PA |access-date=30 May 2007 |archive-url=https://web.archive.org/web/20060901081051/http://www.psupress.psu.edu/books/titles/0-271-02083-0.html |archive-date=1 September 2006 |url-status=dead}} * {{cite book |last=Heisenberg |first=Werner |year=2007 |orig-year=1958 |title=Physics and Philosophy: The Revolution in Modern Science |url=https://archive.org/details/physicsphilosoph00heis_128 |url-access=limited |pages=[https://archive.org/details/physicsphilosoph00heis_128/page/n94 76]–92 |location=New York, NY |publisher=Harper Perennial Modern Classics |isbn=978-0061209192}} * {{cite book |last=Hume |first=David |orig-year=1777 |url=http://eserver.org/18th/hume-enquiry.html |title=An Enquiry concerning Human Understanding |editor-last=Millican |editor-first=Peter |publisher=Oxford university Press |location=Oxford, UK |isbn=978-0199549900 |year=2008 |access-date=28 August 2006 |archive-url=https://web.archive.org/web/20081007110136/http://eserver.org/18th/hume-enquiry.html |archive-date=7 October 2008 |url-status=dead}} * {{cite journal |last=Jenkins |first=C. S. |date=May 2008 |url=http://www3.interscience.wiley.com/journal/119423031/abstract?CRETRY=1&SRETRY=0 |archive-url=https://archive.today/20130105084101/http://www3.interscience.wiley.com/journal/119423031/abstract?CRETRY=1&SRETRY=0 |url-status=dead |archive-date=2013-01-05 |title=A Priori Knowledge: Debates and Developments |journal=Philosophy Compass |volume=3 |issue=3 |pages=436–450 |doi=10.1111/j.1747-9991.2008.00136.x |url-access=subscription}} * {{cite book |last=Kant |first=Immanuel |year=1783 |title=Prolegomena zu einer jeden künftigen Metaphysik |trans-title=Prolegomena to any Future Metaphysics |url=http://eserver.org/philosophy/kant-prolegomena.txt |archive-url=https://web.archive.org/web/20000831211542/http://eserver.org/philosophy/kant-prolegomena.txt |archive-date=31 August 2000 |url-status=dead}} * {{cite book |last=Kripke |first=Saul |orig-year=1972 |chapter=Naming and Necessity |title=Semantics of Natural Language |year=2013 |series=Synthese Library |publisher=Springer |edition=2nd |isbn=978-9027703101}} * {{cite book |last=Leibniz |first=Gottfried |orig-year=1714 |chapter-url=https://archive.org/details/philosophicalpap0000leib |chapter=Monadology |title=Philosophical Papers and Letters: A Selection |series=Synthese Historical Library |volume=2 |isbn=978-9027706935 |year=1976 |edition=2nd |editor-first=Leroy E. |editor-last=Loemker |publisher=Kluwer Academic Publishers |location=Dordrecht |chapter-url-access=registration}} * {{cite book |last=Locke |first=John |year=1689 |url=http://www.ilt.columbia.edu/publications/locke_understanding.html |title=An Essay Concerning Human Understanding |publisher=Oxford University Press |location=Oxford, UK |isbn=978-0198245957 |series=Clarendon Edition of the Works of John Locke |editor-first=Peter H. |editor-last=Nidditch |access-date=29 August 2006 |archive-url=https://web.archive.org/web/20060829173733/http://www.ilt.columbia.edu/Publications/locke_understanding.html |archive-date=29 August 2006 |url-status=dead}} * {{cite journal |last=Palmquist |first=Stephen |journal=The Review of Metaphysics |volume=41 |issue=1 |title=''A Priori'' Knowledge in Perspective: (I) Mathematics, Method and Pure Intuition |date=September 1987a |pages=3–22}} * {{cite book |last=Plato |orig-year=380 B.C. |chapter-url=https://archive.org/details/completeworks00plat |chapter=Meno |title=Plato: Complete Works |editor1-last=Cooper |editor1-first=John M. |editor2-first=D. S. |editor2-last=Hutchinson |location=Indianapolis, IN |publisher=Hackett Publishing Co. |year=1997 |isbn=978-0872203495}} {{Refend}}
== External links == {{Commons category|A priori}} {{Wikiquote}} * {{cite SEP |url-id=apriori |title=''A Priori'' Justification and Knowledge}} * {{InPho|taxonomy|2381|''A priori'' and ''a posteriori''}} * {{PhilPapers|category|the-a-priori|''A priori'' and ''a posteriori''}} * {{IEP|url-id=apriori}} * [http://www.philosophypages.com/dy/a5.htm#a-pr ''A priori'' / ''a posteriori''] – in the Philosophical Dictionary online. * [http://plato.stanford.edu/entries/rationalism-empiricism/ "Rationalism vs. Empiricism"] – an article by Peter Markie in the ''Stanford Encyclopedia of Philosophy''.
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