a priori

A priori is a term applied to knowledge considered to be true without being based on previous experience or observation. In this sense, a priori describes knowledge that requires no evidence.

A priori comes from Latin and literally translates as “from the previous” or “from the one before.”

It’s often applied to things involving deductive reasoning, which uses general principles to arrive at specific facts or conclusions (from cause to effect).

It can be used as an adjective, as in a priori knowledge, or as an adverb, as in We shouldn’t assume a priori that this is true.

A priori contrasts with a posteriori, which literally translates as “from the latter” or “from the one behind” and is applied to things that are based on experience, observation, or existing data. A posteriori is applied to things that involve inductive reasoning, which uses specific instances to arrive at a general principle or law (from effect to cause).

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: Any proposition considered to be a priori knowledge should be carefully examined for bias. ​

The first records of the use of a priori in English come from the mid-1600s. The first part, a, means “from,” and priori means “previous” (the English words prior and priority are 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.

What are some other forms related to a priori?

• apriority (noun)

What are some synonyms for a priori?

• self-evident
• axiomatic

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

• apriorism
• prior
• priority

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

• knowledge
• reasoning
• epistemology 
• philosophy
• deduce
• argument
• experience

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

• a posteriori

A priori 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

The lesson (I think?): Different kids need different things in different areas right now. It’s not compassionate to a priori assume challenging them academically now is inherently harmful. Some intellectual fires may be lit during quarantine. Can schools still provide the sparks?

— Travis Pillow (@travispillow) March 29, 2020

“The day, the living day, the actual moment, the pang of real life, — to be faithful to this, one must always pay attention, one must never dismiss anything a priori as too trivial.”

Gorgeous forgotten gem: https://t.co/hNngIJ5LCe

— Maria Popova (@brainpicker) June 17, 2020

True or False? 

A priori knowledge is based on experience.