Peripheral Vision

In this paper we describe a five-stage phenomenological model of skill acquisition, of which expertise is the highest stage. Contrary to the claims of knowledge engineers, we argue that expertise in general, and medical expertise in particular, cannot be captured in rule-based expert systems, since expertise is based on the making of immediate, unreflective situational responses; intuitive judgment is the hallmark of expertise. Deliberation is certainly used by experts, if time permits, but it is done for the purpose of improving intuition, not replacing it. The best way to avoid mistakes is to take responsibility for them when they occur, rather than try to prevent them by foolproof rules. In bureaucratic societies, however, there is the danger that expertise may be diminished through over-reliance on calculative rationality.