A priori is a philosophical term that refers to knowledge, judgments, and principles which are true without verification or testing. It is something that is considered to be universally valid by default. In other words, the information and assumptions that a person starts with do not need to be verified with experience, but are, instead true. A a priori deals with knowledge that does not need to be verified. An example would be "All bachelors are unmarried." This is true naturally and by definition.
A priori knowledge is considered by some to be a special kind of knowledge that is related more to intuition than fact. In other words, testing, experience, and logical verification are not needed. Knowledge is just known. For example
- Blue is a color.
- All triangles have three sides.
- A square cannot have five sides.
- Statements that contradict themselves are not true.