a priori
A priori knowledge is justified without appeal to experience, the way arithmetic is. A posteriori knowledge depends on experience, the way a claim about the weather does. The pair marks how a claim earns its warrant, not how confident anyone feels about it.
Also written: a posteriori
Read about a priori on Wikipedia
Sources
- A Priori Justification and Knowledge Stanford Encyclopedia of Philosophy
- The Analytic/Synthetic Distinction Stanford Encyclopedia of Philosophy