While this can't be defended from the aspect of empirical knowledge, it can be defended as an aspect of a priori knowledge. This would not be a priori knowledge that comes by reason, but rather by non intuitive immediate knowledge. In this case this would be an area of all content and no form. The fact that there is no form in this area would be the reason why the faculty of reason can't perceive it.
I admit there is a certain aspect of "faith in the wise" of this. But even the idea of faith in the wise can be defended. In general when you open a book on algebra, you have a certain amount of faith that the author knows something more than you about the subject. And you also depend on the implicit belief that there are no errors in the book. Even the knowledge that there is one single error in the book would immediately force you to put it down. So you do depend on faith in the wise for this.
This little essay gives an idea why I feel that the intuitionist school of philosophy missed a basic point about Kant.--that Reason can perceive universals. Once you get out of the area of universals you have to look for another source of knowledge. For instance the thing in itself. Once we are out of universals what reason do you have for thinking that reality should conform to what you think of it?
[Universals are explained by Michael Huemer: I have here two white pieces of paper. They are not the same piece of paper, but they have something in common: they are both white. What there are two of are called "particulars" - the pieces of paper are particulars. What is or can be common to multiple particulars are called "universals" - whiteness is a universal. A universal is capable of being present in multiple instances, as whiteness is present in many different pieces of paper. A particular doesn't have 'instances' and can only be present in one place at a time (distinct parts of it can be in different locations though), and particulars are not 'present in' things.]
Almost all ideas of the cult th Gra put into excommunication can be traced directly to Natan, the false prophet of Shabati Tzvi. The reason that most people are not aware of this is simply that they are usually not familiar with both sets of writings.
The area of non intuitive immediate knowledge is where the Intuitionists [like Prichard] are missing the point. They rightly see that reason perceives more than analytic propositions. But they do not see that still there is a limit to reason-the limit that it sees only universals.