Of Bayesian Epistemology

Thomas Bayes (1702-1761) is a British Presbyterian minister in 18th century. Bayesian epistemology is a theory of knowledge that developed from Bayesian theorem (i.e. P(h|e) = P(e|h)P(h)/P(e)) and the Simple Rule (i.e. a person is justified in believing hypothesish, if and only if the probability of his very high). In a broad sense, Bayesian epistemology makes a general reference about all of the subjectivist theories concerning probable induction.According to traditional epistemology, our knowledge must be completely reliable. This is reflected in the standards of evaluation, according to which, what is evaluated is either confirmed or falsified. But in fact, all of our knowledge about the world, including perceptual judgments, consists of just hypotheses. Those hypotheses risk being falsified and even if they are defeated, they are still possibly to be restored. The most important thing is how to assess a hypothesis according to new evidence. On the other hand, in the wake of developments in the philosophy of science and in the probability theory, a kind of probable standard for knowledge evaluation, namely the probable induction, is gradually accepted by philosophers. Bayesian epistemology provides a computation method for assessing hypotheses when new evidence (may confirm or disconfirm a hypothesis) comes up. As a kind of decision theory, this method has obtained widespread application in various areas and has demonstrated the formidable vitality, though it has also caused a lot of controversy.This article attempts to clarify the long and short story of Bayesian epistemology as well as the argument involved, and to expound its significance on theory and reality. The foreword part of this article has expounded researching significance, domestic and foreign researching situation, researching method and innovation spots. First chapter introduces the theory background relating Bayesian epistemology emphatically. Second chapter introduces each kind of probability concept emphatically. And this is the foundation for understanding Bayesian epistemology. Third chapter is the core part of this article. It introduces each aspect of Bayesian epistemology specifically, including its core content, as well as the natural transition from core content (pure theory content) to Bayesian statistical inference and decision theory (application theory). The fourth chapter discusses the criticism to Bayesian epistemology as well as the possible responses. The conclusion is author's general attitude to Bayesian epistemology, and it explains its great significance from the theory to application.