The culturally-dominant view of the popularization of science rests on a two-stage model: first, scientists develop genuine knowledge; second, popularizers spread streamlined versions to the public. At best, popularization is seen as a low-status educational task of `appropriate simplification'. At worst, it is `pollution' — the distortion of science by outsiders. This paper shows that the dominant view suffers from conceptual problems, and greatly oversimplifies the process. But, despite these weaknesses, the dominant view serves scientists (and others who derive their authority from technical expertise) as a resource in public discourse, providing a repertoire of rhetorical devices for interpreting science for outsiders, and a powerful tool for sustaining the social hierarchy of expertise.