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Jay Wright Forrester – founder of our field, leader, mentor, guide, and friend – 1918-2016. Born on Bastille Day, “but to my knowledge,” he once said recently, “the French haven’t taken any notice of it yet.” The System Dynamics community has had him in its midst since the late 1950s. We’ve heard his exhortations (and occasional scoldings) over these almost-60 years, and have grown as individuals and as a field from the examples he set for us. In the early years he struck fear in our hearts as we tried to meet his demands. In the later years we realized the warmth that lay under his drive for our perfection, and we are grateful for all of it.

Jay’s quotes are endlessly instructive. He was always challenging: “The solutions to small problems yield small results. … The most important problems are but little more difficult to handle than the unimportant.” He startled us: “The most important decision of the CEO is how to limit growth.” He saw a similar phenomenon in global dynamics: “Relying on technology to solve the problems created by growth is to evade the question of how to slow growth.” He insisted on an endogenous view: “We cause our own problems.” He always sought wise generalizations from his own model-based work: “Even if we manage to find a high leverage point in a complex system, we’re very likely to push the lever in the wrong direction.” He sought to improve practice in management science: “It’s false to assume that accuracy must be achieved before precision is useful.” In his enthusiasm he occasionally overreached: “Only System Dynamics modelers can talk for an hour without contradicting themselves.” (Just recently he moderated that: “Well, maybe twenty minutes.”) He had unwavering, quiet confidence, and urged us to have it too: “Have courage…”

Many of us have memories we cherish and want to share about Jay. This page is for us all. Write what you want others to see and hear. We will all gain from our memories of Jay.


  • Ali N. Mashayekhi

    Jay Forrester was a genius, a great man of principles, a man with a briliiant mind. His clear systemic thinking was always amazing. He had a great impact directly on my life and the way that I look at the world and understand it and indirectly on many students that took system dynamics courses with me. Certaily our world lost one of his great thinker. I with many others will remember him with a great respect. I wish him to rest in peace.

  • Monte Kietpawpan

    I have never met Prof. Forrester in person, but had an e-mail communication with him on a new general theory he had created. To me, he is Father of Environmental Management, based on his work on World Dynamics and his concepts on global equilibrium, which has now become the Sustainable Development Goals (SDGs). When I was a Ph.D. student at Prince of Songkla University, Thailand, I enjoyed learning from his ideas and knowledge by reading his books/articles, which are good examples of plain, scholar, and insightful writing.

  • I was an undergraduate in electrical engineering at MIT from 1964-1968. My interest was to apply modern control theory to biology and I was infatuated with the power of differential equations. One of my roommates was in Course XV (Sloan School) and told me about DYNAMO. I studied what Dr. Forrester wrote and I built simple biological models in DYNAMO and CSMP. I assume most of the comments in this thread are from SD people, but Dr. Forrester’s influence (especially his equal fondness for Levels and Flows) has informed my entire career in physiology and cell and molecular biology. Biology is, in many ways, very different from SD, but for a few of us, Jay Forrester was every bit as important to biology as he was to System Dynamics.

  • George Papachristos

    I had the opportunity to briefly meet and chat with J.Forrester in Boston 2013. His humility and sharpness was enough to inspire not just as a system dynamicist but as a researcher. Such pivotal moments are rare and cherished.

  • The Millennium Institute would like to express our deepest condolences over the death of Jay Forrester.

    Jay was an inspiration to all of us at MI and the system dynamics community at large. Without his pioneering work, MI would not exist in its current form. We benefited immensely from his professional and excellent counsel, which we shall sorely miss.

    Please extend our sympathies to Jay’s family and loved ones.

    Sincerely, Hans R Herren, Matteo Pedercini, Weishuang Qu, Steve Arquitt, Gunda Zuellich, Assuad Carla Susana, Melak Mesfin, Max Kleemann, David Collste, Santiago Blanco

  • Theodore Economou

    It was Jay’s phrase “structure determines behavior” written on the back cover of “Principles of Systems” that literally stroke me, back in 1990. I then started to study his work in a way that people enjoy literature. But that was not enough for me. I started experimenting with Dynamo and PowerSim. I even requested and was kindly given by the U.S. Energy Department the full documentation of the Fossil II model, developed by the SD methodology, for studying purposes. Enthusiastic as I was with the SD methodology, I introduced it to the students of National School of Public Administration, where I was teaching by that time, to find out the great appeal of it to them.
    Jay’s work strongly influenced my way of thinking, my ability to gain insight and reasoning to mechanisms that produce events, not only in my professional life, but in personal one as well. His work is amazing and his contribution worldwide. His loss brought me great sadness, but this is only physical, for he will be forever present through his work for me, and I believe for all who had the opportunity to discover it.
    Theodore Economou,
    Athens, Greece

  • As almost everyone has mentioned regarding Jay’s influence on their lives, Jay was pivotal in changing the direction of my professional interest and energy. But it was the effect that I saw when my students built SD models and explained their thinking that solidified the direction of that change. It was as if building SD models served to unencumber their thinking. *Every* pre-college student *deserves* to have the opportunity to learn about the world this way. It is what gives me hope for the future. What I owe to Jay is a debt I can only pay forward.

  • Jeroen Struben

    Jay has fundamentally changed how one may think about problems of collective human behaviour, whether they affect our individual lives, our collective health, societal equity, or climate change. He provided the world with a perspective and with tools to understand those problems and improve the systems underlying them. He has inspired a community of researchers to learn and let others learn. He has deeply affected the lives of many of us, directly and indirectly. We will miss Jay tremendously but may only be grateful for his full life; and celebrate the life of this unique innovator, scholar, teacher, world changer, and not the least as a humble human being. Thank you Jay.

  • Thank you Prof Forrester for your enormous contribution to this field. It has been a great honor to meet you during the 2007 System Dynamics conference and to be part of the SD Society.

  • Jay Forrester is my first SD teacher, and best teacher all the time. Ten years ago, there was no online English bookstore, SD textbook or SD courses available. It was a photocopy of Jay Forrester’s Principles of Systems that I used as a wonderful introduction of SD. His amazing book gave me confidence to continue studying SD without a real teacher. He has always been my teacher, who I have never met, the best teacher.