Abstract
The paper questions the expert system paradigm, both in terms of its range of application, and as a significant contribution to the understanding of artificial intelligence. The viewpoint is that of the systems designer who must judge the applicability of these methods in imminent and future systems. The expert system paradigm, (ESP for short), is criticised not because it is ubiquitously wrong, but because its range of application appears to be very limited, and much promise is made of its application in areas where its success is likely to be little more than a matter of luck. The paper considers the success in both academic and commercial settings. It is suggested that the contribution of the ESP to the wider ambitions of AI is modest, and to the practical user is still a considerable and largely unquantifiable risk