MIT Sloan’s Jay Forrester, change-maker and inventor of system dynamics, dies at 98

Jay Forrester “standing on top of the fruits of his many careers. He’s standing on a device that integrates servomechanisms, digital controllers, and a sophisticated feedback control system.” MIT Sloan Professor John Sterman

“From the air traffic control system to 3-D printers, from the software that companies use to manage their supply chains to the simulations nations use to understand climate change, the world in which we live today was made possible by Jay’s work.” MIT Sloan Professor John Sterman is talking about legendary system dynamics pioneer Jay Forrester, who died November 16 at the age of 98. [Read the full tribute in MIT News.]

A mid-century invention, system dynamics (SD) is the analysis and redesign of any interdependent social, managerial, economic, or ecological system. SD has gained legions of adherents over the decades, and Forrester worked to develop new iterations almost up to the time of his death.

The dynamic Midwesterner arrived at MIT in 1939 with a degree in electrical engineering from the University of Nebraska and quickly grew to become a key actor in the development of digital computing and the national air defense system. He also led Project Whirlwind, a pivotal digital computing project, which led him to invent magnetic core memory, an early form of RAM. Forrester joined MIT Sloan in 1956 with the goal of applying his background in science and engineering to the essential issues that determine the success or failure of organizations.

“To me, Jay was MIT,” MIT Sloan Professor Nelson Repenning observed in a recent MIT Sloan tribute to Forrester. “He showed up to work on gunsights and radar mounts for the U.S. military, ended up playing a pioneering role in digital computing, and suddenly became a social scientist. I can’t imagine that happening anywhere else. It was the perfect match of a unique person [and institution].”

Forrester’s initial SD investigations were calculated by hand. He assembled a team of graduate students to interview employees in a company about how they made decisions at their individual operating points. “By tapping the wealth of information people possessed in their heads,” Forrester said, “we were able to build a model that revealed overall organization behaviors that resulted from the interconnected actions of many local decision-making individuals.”

In the late 50s and early 60s, Forrester and his students began building their simulation models with computers. By translating the policies, information flows, and interconnections of a company into computer instructions, they were able to create a model that could act out individual roles at each decision point. The computer would then feed the results of those actions into other connected decision points, allowing the model to generate the basis for its next round of simulated decision-making. The technology enabled the team to create a laboratory replica of a company that could be used to observe the behavioral consequences of company policies. “What we showed,” explained Forrester, “was that the policies believed to be the solution to the company’s problems were, instead, the cause of those problems.”

Continue reading