Modeling of Vague Causal Relation in a Societal System by Multi-Foldld Multi-Stage Approximate Reasoning

Abstract

Most of causal relations in societal systems include inevitable vagueness. Systems Engineering provides several methods, for example, System Dynamics, for the quantitative modeling of the causal relations. System Dynamics is expressing the vague causality by using subjective supplementary variables and table functions. It, however, seems that approximate reasoning is just suitable for the modeling of such causality. In this paper, an approximate reasoning method is applied to the modeling of vague causal relations. Since the causal relations often have a chain structure, the approximate reasoning method must become a multi-stage type. Hence, multi-fold multi-stage approximate reasoning is introduced to the modeling of the vague causal relations in population growth.