To see the point of such a hierarchy, let us turn back to the concept of the evident. An evident proposition is one that is justified. But there are … - Roderick Chisholm

In making their assumptions, epistemologists presuppose that they are rational, beings. This means, in part, that they have certain properties which are such that, if they ask themselves, with respect to any one of these properties, whether or not they have that property, then it will be evident to them that they have it. It means further that they are able to know what they think and believe and that they can recognize inconsistencies.

You may have knowledge, then, without having any insight into the epistemic status of what you know. In other words, you may know a proposition h to be true without having any beliefs at all about the fact that h is evident or about what makes h evident for you. You will have some degree of insight into your knowledge of h if you have a true belief about what makes h evident for you. You will have a greater degree of insight if, moreover, you have no false belief to the effect that some other proposition makes h evident for you. And you will have an even greater degree of insight into the status of your knowledge of h, if you also know that e makes h evident for you. But our ordinary knowledge about such things as ships, trees, and houses does not require that we have any beliefs about our epistemic situation.

The objectivity principle tells us what kind of justification we can have for beliefs about justification:
(A5) If S knows that p, then, if S believes that he knows that p, then S knows that he knows that p