Once scholars start to think about knowledge societies, at some point in their analyses they have to leave the realms of purely academic interactions among scientists in their sanitized production of knowledge. Conceptions of lay persons then come to the fore. Unfortunately, this realm of interaction traditionally has been far less subject to scholarly scrutiny. The focus of most studies is usually on knowledge, or to be more precise, scientific knowledge, with an odd confidence that this knowledge will faithfully migrate into a context of application once it has been accomplished. Lay persons are of interest for the social sciences as a public that needs and wants to be introduced to science proper. This is the approach that frames the traditional literature on Public Understanding of Science (PUS). Or, as a gesture in critique of PUS, the life world and thought processes of the lay persons themselves are put into focus. However, both of these views consider 'real' flesh and blood lay persons as the main objectives of their analyses. Let us begin our argument with an undemanding observation: in a knowledge society experts are to provide expertise (i.e. scientifically sound information about the facts), recommendations on feasible solutions, and guidance in a world that is ever more entangled with technologies. This observation implies a gradual shift from a scientific world to a shared world that people live in. Moreover, it entails that the experts have conceptions of the persons they should assist in their coping with the world. Conversely, between experts and lay persons there is a division of labour that is based on an epistemic asymmetry: the experts are supposed to be knowledgeable and the lay persons are ignorant. Our aim is to show how this observation about expertise, which seems so undemanding at first glance, turns out to be a thoroughly