Jun 11, 2019
Published in: Social-Behavioral Modeling for Complex Systems, Chapter 25 (2019). doi: 10.1002/9781119485001.ch25
Posted on RAND.org on June 11, 2019
Fuzzy cognitive maps (FCMs) model feedback causal relations in interwoven webs of causality and policy variables. FCMs are fuzzy signed directed graphs that allow degrees of causal influence and event occurrence. Such causal models can simulate a wide range of policy scenarios and decision processes. Their directed loops or cycles directly model causal feedback. Their nonlinear dynamics permit forward-chaining inference from input causes and policy options to output effects. Users can add detailed dynamics and feedback links directly to the causal model or infer them with statistical learning laws. Users can fuse or combine FCMs from multiple experts by weighting and adding the underlying fuzzy edge matrices. The combined FCM tends to better represent domain knowledge as the expert sample size increases if the expert sample approximates a random sample. Many causal models use more restrictive directed acyclic graphs (DAGs) and Bayesian probabilities. DAGs do not model causal feedback because they do not contain closed loops. Combining DAGs also tends to produce cycles and thus tends not to produce a new DAG. Combining DAGs can produce an FCM. FCMs trade the numerical precision of Bayesian causal systems for pattern approximation, fast and scalable computation, and rich feedback representation. We show how FCMs can apply to the social scientific problem of public support for insurgency and terrorism and to US-China relations in Graham Allison's Thucydides' trap framework.