a posteriori

[ ey po-steer-ee-awr-ahy, -ohr-ahy, -awr-ee, -ohr-ee ]

adjective

1. from particular instances to a general principle or law; based upon actual observation or upon experimental data: Compare a priori ( def 1 ).

   an a posteriori argument that derives the theory from the evidence.

2. not existing in the mind prior to or independent of experience. Compare a priori ( def 2 ).

a posteriori

/ ɑː; -rɪ; eɪ pɒsˌtɛrɪˈɔːraɪ /

adjective

1. relating to or involving inductive reasoning from particular facts or effects to a general principle
2. derived from or requiring evidence for its validation or support; empirical; open to revision
3. statistics See posterior probability

Word History and Origins

Origin of a posteriori¹

1615–25; < Latin: literally, from the one behind. See a- ⁴, posterior

Word History and Origins

Origin of a posteriori¹

C18: from Latin, literally: from the latter (that is, from effect to cause)

Example Sentences

In scholastic terms this was a debate over the reliability of a posteriori reasoning; in our terms it is a debate over the evidence of things, or over Evidence-Indices.

From Literature

This a posteriori saga gives us a refreshed Raphael, whose psychological acuity feels newly approachable.

From New York Times

“There’s no rigorous mathematical argument you can write about one event evaluated a posteriori,” he said.

From Fox News

The maximum a posteriori value and minimal 68.3% credible interval from this posterior density function is .

From Nature

Although this specific interaction was not quantified in this example, we view this a posteriori justification of a stereochemical outcome as a foundation for future rational design of such interactions in catalytic systems.

From Nature

More About A Posteriori

What does a posteriori mean?

A posteriori is a term applied to knowledge considered to be true based on experience, observation, or existing data. In this sense, a posteriori describes knowledge that requires evidence.

A posteriori comes from Latin and literally translates as “from the latter” or “from the one behind.”

It’s often applied to things involving inductive reasoning, which uses specific instances to arrive at a general principle or law (from effect to cause).

It can be used as an adjective, as in a posteriori knowledge, or as an adverb, as in We acquire knowledge a posteriori—through experience.

A posteriori contrasts with a priori, which literally translates as “from the previous” or “from the one before” and is applied to things considered to be true without being based on previous experience or observation. A priori is applied to things that involve deductive reasoning, which uses general principles to arrive at specific facts or conclusions (from cause to effect).

Both a priori and a posteriori are used in the context of reasoning and philosophy, especially epistemology, which is the philosophical study of knowledge. Both can also be used generally, though they’re often used formally.

Example: It’s a scientist’s job to gather facts a posteriori by careful observation.

Where does a posteriori come from?

The first records of the use of a posteriori in English come from around 1620. The first part, a, means “from,” and posteriori means “behind” (the English word posterior is based on the same root).

The terms a priori and a posteriori were popularized by philosopher Immanuel Kant in his influential 1781 book Critique of Pure Reason, which focuses on the distinction between empirical and non-empirical knowledge.

A priori knowledge is independent of experience, while a posteriori knowledge is derived from experience or observation. Things that are claimed to be true a priori are often thought to be self-evident, while those claimed to be true a posteriori are based on what has been experienced or demonstrated to be true.

Did you know ... ?

What are some words that share a root or word element with a posteriori? 

• posterior

What are some words that often get used in discussing a posteriori?

 

• knowledge
• reasoning
• epistemology 
• philosophy
• induction
• argument
• experience

What are some words a posteriori may be commonly confused with?

• a priori

How is a posteriori used in real life?

A posteriori is primarily used in philosophy, but is also occasionally used in general conversation and writing.

My break up with someone’s son showed me that we had no business trying again. Lessons about love can only be a posteriori never a priori.

— Zinhle ka’Nobuhlaluse (@ConflictedBlkW) March 26, 2020

A posteriori knowledge or justification is dependent on experience or empirical evidence

— Philosophy Tweets⚡️ (@philosophytweet) April 30, 2013

All this staying indoors has really put a dent in my a posteriori knowledge but it's done wonders for my a priori knowledge

— Michael Bench-Capon (@MikeBenchCapon) June 3, 2020

 

 

Try using a posteriori!

True or False? 

A posteriori knowledge is thought to be self-evident.