It's all about the deep questions.
Epistemology Essay #2: Sources of knowledge
This relatively short essay examines sources of knowledge, while trying to describe their fundamental properties. Historically, perception, memory, consciousness, and reason have been held to be the four sources of basic knowledge. For something to be classified as a basic source of knowledge, it must yield knowledge without positive dependence on other types of knowledge. For example, through reason I can know that if two people are first cousins, then they share a pair of grandparents. This knowledge was not gained by reference to any source of knowledge besides reason. The author of the essay, Paul Moser, then elaborates on each “basic source”. He considers the objection that perception really isn’t a basic source after all since to perceive something, one must (it has been said) be conscious of it. In response, he suggests that we change consciousness to “internal consciousness”, which would be a sort of consciousness of ones inner mental life, abstract objects, etc. Perception itself could be analyzed as a form of “external consciousness”, consciousness that is dependent on the outside world. With regard to memory, Paul denies that it is a basic source of knowledge. For to know something by memory, one must have known it previously by a non-memorial source, say testimony or perception. He does, however, emphasize the huge importance of memory in our daily lives. Without memory, we could only know what we hold in our consciousness at one particular instant in time, that is, not much. With regard to reason, Paul says that it is possible that reason give us justification for a certain belief without having knowledge of that belief, that is, reasons not infallible. To illustrate that prima face reasoning can lead to incorrect conclusions he considers the famous Russel’s paradox.
Russel’s Paradox- There is a class of philosophers, and there is a class of non-philosophers. Since the class of non-philosophers is itself not a philosopher, then it is a member of itself. Therefore, it seems plausible that there should be a class containing all classes that are not members of themselves, like the class of philosophers for example. Now, is this class a member of itself or not? If it is, then it cannot be a member of itself, and if it is not, then it must be a member of itself, a contradiction. Thus what may seem very plausible on the basis of reason can be seen to be false with further reflection.
Paul then considers the status of testimony as a source of knowledge. Now, there is no doubt that testimony is vastly important for what we know, perhaps even the majority of what we know is gained by testimony. However, Paul argues against the possibility of testimony being considered basic. One objection says that to believe p on the basis of testimony one must first perceptually believe that the person giving the testimony actually did give the testimony. A second objection says that there cannot be an infinite or circular chain of people believing p based on testimony, therefore there must be an initial source of p which was not derived from testimony. Memory and testimony are similar in this respect; they transmit knowledge rather than generating knowledge. Finally, towards the end of the essay, Paul explores the autonomy and grounding for knowledge. In particular, he maintains that every form of knowledge is defeasible by other sources of knowledge, and a big component of justification, says Paul, is coherence among one’s beliefs.