Third Passage From The Closing of The American Mind

I know that men are likely to bring what are only their prejudices to the judgment of alien peoples. Avoiding that is one of the main purposes of education. But trying to prevent it by removing the authority of men's reason is to render ineffective the instrument that can correct their prejudices. True openness is the accompaniment of the desire to know, hence of the awareness of ignorance. To deny the possibility of
knowing good and bad is to suppress true openness. A proper historical attitude would lead one to doubt the truth of historicism (the view that all thought is essentially related to and cannot transcend its own time) and treat it as a peculiarity of contemporary history. Historicism and cultural relativism actually are a means to avoid testing our own prejudices and asking, for example, whether men are really equal or whether that opinion is merely a democratic prejudice.