What I was getting at, and on which I would welcome dialogue, is that Burton seems to be arguing that deficiencies within the feeling of certainty produce an epistemological relativism, whereby he implies that the sense of certainty about subjective states is equivalent to objective knowledge.
I think what Burton is really saying that the feeling of knowing is a defensive mechanism that prevents total uncertainty. It elicits the same type of response you would get from outracing an opponent, yet it is used to provide will. Without certainty a person would not be capable of anything, without the feeling of knowing there would be nothing telling the person that their impulse is correct and they should defend their conscious decision despite or in addition to the true nature of the input, and the reality of the situation.