Knowledge through what others tell us not only forms a large part of the body of our knowledge but also originates the patterns of appraisal according to which we add beliefs to our present store of knowledge.1 I do not mean merely that what we add is often accepted from persons who have already contributed to our knowledge; beyond that, we have acquired habits of thought, tendencies to suspect and tendencies to approve both other-person-reports and purported perceptions, from our testimonial (...) relationships with others. For instance, who would not hesitate to say he saw a particular acquaintance (John Doe) at a visual distance of half a block, after he had just been told by someone he trusted and someone who ought to have known (e.g., John Doe’s wife) that John Doe had just telephoned from a store two hours travel time away? Yet apart from that report, one might have considered it evident that John Doe was half a block away, just because (ceteris paribus) it looked enough like John Doe; the evidence of our senses can be defeated by the authority we accord to the evidence of testimony. (shrink)