Suppose we want to know whether a person justifiably believes a certain claim. Further, suppose that our interest in this question is because we take such justification to be necessary for knowledge. To justifiably believe a claim requires more than there being a justification for that claim. Presumably, there is a justification for accepting all sorts of scientific theories of which I have no awareness; because of my lack of awareness, I do not justifiably believe those theories. Further, even if I, by chance, did believe one of those theories, I might not justifiably believe it; for I may be completely unaware of any justification for it. I then would not believe it..