Philosophically, materialists and idealists understand the world differently. In materialist theory information directly represents the natural world, whereas idealism understands it to be the very structure of thought. Some of the problems arising between information theory and the actual practice of librarianship are due to mixing concepts from incompatible theories. The concept of information favored by materialist theories is not interchangeable with the concepts preferred by idealists and critical theorists. Materialism overemphasizes the empirical features of information, while giving short shrift to the possibility that information can be both factual and evaluative. Consequently, this leads to theories of information which are out of touch with the values, norms and purposes of ordinary people.