Testimony and Memory

Abstract

The law distinguishes, among the things that a witness knows, those that he knows ‘of his own knowledge’, and allows him to testify only to them. This is in part because his confirmation of another witness’s testimony adds no weight to it if he derived his knowledge only from that other witness’s having told him. That is not the only reason, however. Only in special cases, such as a deathbed declaration, is second-hand evidence admitted at all. That is due both to the impossibility of testing it under cross-examination, that is, of probing its foundations, and to the well-known phenomenon of the corruption of information as it passes from its source along a chain of second-hand and third-hand transmitters. Historians, on the other hand, must perforce admit information given at second or later hand, since, very often, no other is available. The prejudice of the law against it has nevertheless often exerted a strong influence upon epistemologists; those subject to this influence consider that what a lawyer would deem me to know ‘of my own knowledge’ marks an upper bound to what I may genuinely be said to know at all.