We have serious difficulties when it comes to explaining what really defines an “expert” – a difficulty that goes beyond the explanatory range of defining experts by their individual performance. Take, for example, people who provide political advice or consult multinationals. What would qualify them as experts? How can we assess their performance? How can we disentangle their individual expert contribution and the success of the enterprise or party they work for? We cannot understand these cases if we don't consider what Hoffman, Feltovich, and Ford (1997) concluded: the “minimum unit of analysis” is the “expert-in-context” (p. 553)(see also Clancey, Chapter 8).

For the purpose of this chapter on social and sociological factors in the development of expertise, I assume that an expert has to be regarded as the connection between a person and a function. The function indicates the social context of the expert performance. In the following, I use a broad notion of function that includes both the pertinent duties and the effects of expert performance, such as the duties and work of a doctor, as well as the effect of music on its audience. In short: I understand function as defined by what an audience, patient, or customer would pay for. The function of medical therapy is to render a sick person healthy. The function of music is to please the audience (as entertainment) or peer professionals (as being excellent).