Jay Forrester

Computer Pioneer & Founder of System Dynamics, MIT

About

Jay Wright Forrester (1918–2016) was an American engineer who built one of the first digital computers and then founded a field for understanding why human systems resist our intentions. At MIT he led Project Whirlwind, co-invented magnetic-core memory, the dominant computer memory from the mid-1950s to the mid-1970s, out of what he called 'necessity being the mother of invention,' and carried the work into the SAGE air-defense system. He then turned feedback engineering on firms, cities and the planet, founding system dynamics with 'Industrial Dynamics' (1961), 'Urban Dynamics' (1969) and 'World Dynamics' (1971), the model behind the Club of Rome's 'The Limits to Growth.' His recurring finding was that complex systems are counterintuitive: the few high-leverage policies are usually being pushed 'in the opposite direction.'

Key Contributions

Led MIT's Project Whirlwind, one of the first real-time digital computers
Co-invented magnetic-core memory, standard computer memory for two decades
Directed the computer work behind the SAGE air-defense system
Founded system dynamics with 'Industrial Dynamics' (1961)
Built 'World Dynamics' (1971), the basis of 'The Limits to Growth'; IEEE Medal of Honor (1972)

Videos & Interviews

Jay Forrester (Part 1)

Two hours of oral history for MIT's 150th anniversary, recorded in 2009. Forrester traces a single arc from feedback-control servomechanisms for Navy gun mounts, to Whirlwind and the magnetic-core memory he describes as "a clear case of necessity being the mother of invention," to the SAGE air-defense computers. Then he turns to system dynamics, which he built from what people know by experience rather than from numerical data alone, and to Urban Dynamics and World Dynamics, models that "caused quite a sensation." His sharpest claim comes near the end: in complex systems most policies are low-leverage, and anyone who has found a high-leverage one is very likely "pushing that policy in the opposite direction."

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Connections

Donella Meadows

Influenced

Environmental Scientist & Systems Thinker

Meadows learned system dynamics in Forrester's group at MIT, and The Limits to Growth (1972), which she led, grew out of his World Dynamics model built for the Club of Rome. Her most quoted essay, 'Leverage Points', opens with his observation that 'people know intuitively where leverage points are,' and that they almost always push them 'IN THE WRONG DIRECTION!' He gave her the method. What she added was the voice that let people outside MIT hear it.

donellameadows.org · en.wikipedia.org · youtube.com

Edward Lorenz

In contrast

Meteorologist & Founder of Chaos Theory, MIT

Two MIT men in the early 1960s, each running nonlinear feedback systems on early computers, drew opposite lessons from what they saw. Lorenz found that a deterministic system can be unpredictable in principle, so the forecast has a horizon no better model will pass. Forrester found that such systems are counterintuitive but can be modelled, so the right simulation could show a city or a planet where its levers really are. Read side by side, they bracket what anyone modelling a complex system today has to hold at once: how much can be known, and how much can still be steered.