So, what is the difference between the terms a posteriori and a priori?
a posteriori: after experience.
a priori: independent of experience.
a posteriori knowledge depends on a justification of experience, to that which is contigent.
Example: a posteriori knowledge is that Canberra is the national capital city of Australia, or that your PC is on your desk.
a priori knowledge is that which is necessary and independent of experience.
Example: 2 + 2 = 4 or knowing that all bachelors are unmarried men.
Having said this, American philosopher Saul Kripke, argued that there are contigent truths that can be known a priori, as well as, necessary truths that are only discovered a posteriori.
