How Do We Know What We Don’t Know?

Even the most learned among us is ignorant. There is so much to know about our world that it is impossible to know it all. How, then, do we categorize what we don’t know? If we don’t know something, how do we realize that there is a gap in our knowledge? When we examine ourselves, how can we tell if there is a lack or some learning that needs to be done?

How do we know what we don’t know?

Related questions: How do we grow? What does it mean to learn? How do we organize knowledge?