Does the accomplishment justify the investment in AI and expert systems?

The author briefly examines the trends in investment in artificial intelligence (AI) and expert systems. The author believes that AI has not lived up to the great expectations of the past three decades. However AI is a fundamentally important field, and in the years ahead expert systems which may be viewed as a part of AI will emerge as a key component of information science and technology. The author suggests that the failure of AI to achieve most of its stated goals is directly related to the almost total commitment of AI to classical predicate logic. Viewed in this perspective the author suggests that, to the extent that investment in AI has been channeled into the development of methods and techniques based on classical logic, it has not paid off. What is discernible, however, is a greater willingness on the part of the AI community to accept methods involving probabilistic reasoning, even though such reasoning is for the most part numerical rather than symbolic. Such reasoning, the author concludes, plays an essential role in expert systems, since it is unrealistic to assume that there is no uncertainty in the rule-base of a real-world system