This paper suggests that library and information systems provide access to claims to knowledge rather than to knowledge or information and that such claims to knowledge are in fact claims to truth. The stated purpose of the paper is to explain why the library and information community should adhere to at least soft, if not hard, skepticism with regard to those claims to knowledge. The validity of claims to knowledge are assessed and claims to both everyday and academic knowledge are considered. The paper examines in turn each of four bases for claims to knowledge: (1) induction; (2) hypothecation; (3) definition (including knowledge claims rooted in logic and mathematics); and (4) access to inner states (either by direct report or by inference). The paper concludes that claims to truth cannot be affirmed and that most of what librarians and information workers call information, is in fact, opinion. (THC)