But what was the a priori belief involved? I am trying to undersatand what you knew prior to being educated or to learning through experience about the world.
As used by philosophers, a priori is not the same as innate. For example, mathematical truth is considered a priori, since it is not truth about empirical reality. But there is no assumption that it was known innately.
Are you referring to things like the assumptions we make for plain geometry? Is that what you call "a priori"?
I don't claim to be an expert. I am just commenting on how philosophers seem to use the term "a priori". I am not asserting that it makes sense.
It is tied up with epistemology (theory of knowledge), where they use terminology such as:
a priori or a posteriori;
analytic or synthetic;
necessary or contingent. Kant complicated things by insisting that there could be a synthetic a priori, and Kant would have considered the truths of plane geometry to be synthetic a priori.