Abstract for: The Basics of System Dynamics: Discrete vs. Continuous Modelling of Time
System Dynamics deals with modelling processes over time. In this paper we discuss two ways to model changes over time: finite vs. infinitesimal. This leads to two different concepts of time: discrete time as a succession of time points and time intervals vs. continuous time. Although the System Dynamics concept of distinguishing between stocks and flows suggests a discrete modelling of time, SD is considered mostly a modelling technique based on continuous time. In the paper we argue to see SD modelling compatible with both the continuous and the discrete concept of time. We will show that this “hybrid” potential makes SD a superior technique for modelling time, which combines the advantages of continuous and discrete time concepts.