We all think we know much about the natural world. We hear, feel, see, taste, and smell parts of the world around us nearly continuously. Furthermore, we all accept that with knowledge of the present and the past coupled with induction, we could generate new knowledge about the future. Obviously, since the sun has risen in the east at least since the time of recorded history, the sun will most likely rise in the east tomorrow. But is this enough? How do we know when something is true? Must we prove something is true before we accept it as fact? What is the source of knowledge and can we develop a theory of human knowledge? The philosophical examination of human knowledge is referred to as epistemology ( Encyclopedia Americana 1994). As a division of philosophy, epistemology is the study of the origin of knowledge and attempts to develop a theory of the nature of knowledge (American Heritage Dictionary 1985).