What is "Knowledge"?
With knowledge, we can get something done. How do we describe or analyse what we seem to know as "knowledge"? Under what conditions that data, information and interpretation have become "knowledge"?
We justify "something is so" through our sensory and perceptual experience eg seeing or analyzing. With the evidential support, we believe that "something is so" and take it as true, due to consistency and coherence between a proposition and the reality. And if the truth is not absolute, we believe that our reasoning explains relations, maximizing truth and minimizing falsity at the same time.
Conflicting beliefs however are not uncommon. To determine what is true or false, we need justifying arguments. And those "valid" ones tend to have more probative value.