Deciding whom to believe: testimony as evidence

Abstract

Testimony is our greatest source of belief. Most of the things we believe have been ac-quired from other people‘s words, not from evidence directly collected in the world through observation. Facts about the past or about remote places are obvious examples of testi-monial beliefs, but so are very personal facts such as the place and date of my birth, or the names of my great-grandparents. Scientific discoveries and theories are accepted by most of us on the basis of what others say. That smoking causes cancer or that the anomalies in observed galactic rotation can be explained by the theory of dark matter are claims which are impossible to verify by any one individual. In many cases I can neither imagine or understand the means by which my testimony-based beliefs could be directly verified, but I believe them nonetheless