The environments in which we live and operate—corporations, cities, even national economies—are far too complex in their structures and internal processes for any one individual to have a clear, coherent view of how they "work" as total systems—that is, of how particular actions can trigger a cascading series of ever-more indirect effects. At most, what we see and understand—often poorly, at that—are the workings of a tiny fraction of such systems. As a result, we regularly make decisions with little or no appreciation of their full range of consequences. And we also make decisions that, by virtue of their consequences, are not really ours to make. Indeed, lacking a systemic vision of causality, we have no way of knowing why policies—whether corporate or governmental, whether on low-cost housing or real-estate construction or production volumes or whatever—often produce results directly opposite to those intended. But we do know that this happens—all the time. The field of system dynamics provides an organizing framework for analyzing how such policies and decisions interact in complex and often unexpected ways. The field, originated in 1956 by Jay W. Forrester, Germeshausen Professor, Emeritus, at the Massachusetts Institute of Technology, makes it possible for senior managers...