Virtually everything we know depends in some way or other on the testimony of others. Thus, testimony is one of the most important sources of knowledge and epistemic justification. Despite the vital role that testimony occupies in our epistemic lives, traditional epistemological theories focused primarily on other sources, such as sense perception, introspection, reason, and memory, with relatively little attention devoted specifically to testimony. One reason for this neglect may lie in the traditional views, by such philosophers as Locke and Hume, about the status of testimony. Locke has particularly disparaging words to say abut the practice of relying on testimony. Hume has noticed the importance of testimony, but he has regarded testimony as simply one form of inductive evidence among others, which is in turn based on the perceptual evidence. According to Hume, testimony is the second-hand source of knowledge and justification. Therefore, we can say that Hume has proposed reductionist views on testimony.
Thomas Reid, a contemporary of Hume, suggests approach that is diametrically opposed to Hume's views. He argues that we should always accept someone's testimony unless we have good reason to suspect that a particular report is false. Unlike Hume, his default position is one of trust. For Reid, testimony has status of immediate, first-hand, and basic source of knowledge and justification. Thus, Reid has propounded non-reductionist views on testimony.
Reid introduces the two key principles of his theory of testimony in the Inquiry into the Human Mind. These principles are called the principles of veracity and credulity. They are the key elements in his non-reductionist account of how we successfully acquire justified belief or knowledge on the basis of testimony from others. This paper first aims to outline Reid's non-reductionist views on testimony, and examine them critically based on Van Cleve's view. Van Cleve point out that it is not always clear in Reid where psychology of testimony stops and epistemology begins. Very well, is his account of testimony just a piece of descriptive psychology, or is it meant as normative epistemology? Van Cleve believes his account of testimony is meant as both. Finally, I examine his non-reductionisit views of testimony critically under that interpretation.