System dynamics represents the study of complex systems’ behaviour over time, examining how feedback loops, delays, and non-linear relationships create patterns of change. At its core, this discipline reveals how systems generate their own behaviour through internal structure rather than external forces alone.
If systems thinking is the mindset - system dynamics is the math.
The field emerged from Jay Forrester’s work at MIT in the 1950s, originally applied to industrial dynamics before expanding to encompass urban planning, ecology, and social systems. System dynamics recognizes that causality in complex systems rarely flows in straight lines - instead, effects circle back to become causes through reinforcing and balancing feedback mechanisms. These circular causalities, combined with time delays between causes and effects, produce the counterintuitive behaviours that characterize everything from economic cycles to ecosystem collapse.
What distinguishes system dynamics from other analytical approaches is its emphasis on stocks and flows - the accumulations and rates of change that determine a system’s state at any moment. This framework reveals why systems exhibit resistance to change, why interventions often produce unintended consequences, and how small shifts in leverage points can transform entire system behaviors. The discipline connects directly to complexity science, cybernetics, and emergence, offering tools to understand phenomena from tipping points in climate systems to the spread of social contagion through networks.