Religious people have the a priori belief that God exists without any physical proof.

The jaded woman made a priori assumptions that all men were liars, but couldn't possibly know for sure because she has not dated all men.

Christopher Columbus had the a priori belief that the Earth was flat and his men could sail right off the edge because of what he knew about latitude, but without actual experience.

People make a priori assumptions that the sun will rise and set without needing actual proof of the events.

Lawyers use a priori arguments about their defendants earlier good behavior to try and counteract their current crime, despite evidence to the contrary.