Complex social systems are difficult to represent. Relationships between social forces demand feedback. For example, the causal connection between commodity price and consumer demand is a feedback system. Price increase tends to decrease demand for some commodities. On the other hand, an increased demand tends to elevate price. A stable system settles into equilibrium. A dynamic system is needed to model shifts in equilibrium brought about by changes in the causal environment. The knowledge-based expert system lacks the intrinsic structure for modeling these effects. Internally, all expert systems depend on these representations. Some attempt to simulate unrestricted graphs with virtual registers and loop counters. The result is a semantic gap between the internal representation of the social system and the social system itself. This article presents the Fuzzy Cognitive Map (FCM) alternative to the expert system. We first describe the FCM. We then diagram several social systems. Finally, we show a method for combining credibility-weighted FCMs to achieve a single global knowledge base. © 1991.
