The book: "On Being Certain: Believing You Are Right Even When You're Not" by Robert A. Burton, M.D.
This book shook the foundation of my epistemological world. The crux is that the sense of knowing something is a feeling like anger or pride. Thus, the fact that you "know" something does not mean it's true.
He gives an example. Right after the Challenger exploded on take-off (back in 1986), a psychology researcher collected statements from a number of people about what they were doing when they heard the news. A few years later, he asked them again. They all remembered vividly. Except, their memories didn't necessarily match what they'd written. When shown their statements, some continued to insist that the statement was wrong, but their memory was right. It's a vivid demonstration of how utterly convincing the feeling of certainty is. But, it's just a feeling.
He goes further. We don't even have any way of knowing what unconscious mental processes went into a belief or conclusion. So introspection is of little use for determining which beliefs are true and which are false.
He gives examples involving medical doctors. One proclaims, "I believe in the necessity of research, but I know that personal experience is the 'proof of the pudding.' " Like many doctors, this one leans heavily on his own personal judgement based on experience. But how do we know that the judgement is tied tightly to reality?
Science is the best bet.
... we should know when we are basing our decisions on science and when they are based upon unsubstantiated experience, hunches, and gut feelings. But, as we've seen, we aren't reliable assessors of such arbitrary distinctions.
His suggestion is that we modulate the conviction of our beliefs by attempting to consider the probability that each is correct, and reflect that uncertainty when we express our beliefs to others.
Toward the end of the book, Dr. Burton seems to suggest that our brains are equipped with a sensory system for perceiving a representation of brain state. This is nothing short of a theory of consciousness, and nothing short of fascinating. Just like we have a sensory cortex for processing tactile and visual information, we might also have a sensory cortex for processing mental information. He doesn't say it point-blank, but launches the notion for the reader. It blew my mind. I'm not sure I agree with it, but then again, this book makes it abundantly clear that we should not let the feeling of believing fool us.