IFORS' Operational Research Hall of Fame Jay Wright Forrester

Abstract

Creator of the system dynamics modelling technique and a life-long practitioner and advocate of its use to promote long-term policy analysis, learning about complex organizations and the redesign of such organizations. Born: 14 July 1918, Climax, near Arnold, Nebraska, USA. Education: B.S. University of Nebraska (1939); S.M. Massachusetts Institute of Technology (MIT) (1945). Currently: Germeshausen Professor Emeritus and Senior Lecturer, MIT, USA. Key positions: Research Assistant, MIT Department of Electrical Engineering (1939–1944); Associate Director, MIT Servomechanism Laboratory (1940–1951); Director, Aircraft Stability and Control Analyzer project (1944–1946); Director, Whirlwind project (1946–1951); Head of Digital Computer Division, MIT Lincoln Laboratory (1951–1956); Professor of Management, MIT (1956–1972); Germeshausen Professor, MIT (1972–1989). Awards and Recognition: Fellow, Institute of Electrical and Electronic Engineers (1955); Academy of Management Award for Industrial Dynamics (1962); Member, National Academy of Engineering (1967); Inventor of the Year, George Washington University (1968); Fellow, American Academy of Arts and Sciences (1968); Fellow, Academy of Management (1969); Valdemar Poulsen Gold Medal, Danish Academy of Technical Sciences (1969); Organizational Development Council Publications Award for Urban Dynamics (1970); Member, Club of Rome (1970); Medal of Honour, Institute of Electrical and Electronics Engineers (1972); Benjamin Franklin Fellow of the Royal Society of Arts (London) (1972); Systems, Man, and Cybernetics Award for Outstanding Accomplishment, Institute of Electrical and Electronic Engineers (1972); New England Award, The Engineering Societies of New England (1972); Howard N. Potts Medal, The Franklin Institute (1974); Honorary Member, Society of Manufacturing Engineers (1976); Harry Goode Memorial Award, American Federation of Information Processing Societies (1977); National Inventors Hall of Fame (1979); The Common Wealth Award of Distinguished Service (1979); Fellow, American Association for the Advancement of Science (1980); Computer Pioneer Award, IEEE Computer Society (1982); Founding President, The System Dynamics Society (1983); James R. Killian Faculty Achievement Award, MIT (1987); Honorary Professor, Shanghai Institute of Technology (1987); Agricoltura 2000 Award, Italy (1987); Information Storage Award, IEEE Magnetics Society (1988); Lord Foundation Award (1988); US National Medal of Technology (1989); Pioneer Award, IEEE Aerospace and Electronic Systems Society (1990); Price Waterhouse Information Technology Leaders Award for Lifetime Achievement (1998); Honorary degrees from nine universities. Jay Wright Forrester's distinguished career at MIT led to his founding the field of system dynamics. By adapting servomechanistic ideas he created a new approach to simulating the behavior of social systems, to explaining that behavior and to crafting effective long-term policies. He established the subject as an academic discipline at MIT's Sloan School and led high-profile modeling studies himself. System dynamics is now one of the most widely used systems approaches in the world, with academics and practitioners on every continent, and interest, applications and publications all growing. Forrester's writings continue to inspire the field and he remains actively involved in its development. The induction of Forrester into the OR Hall of Fame might be seen at first as a curiosity. Here is a man who in 1979 became a member of the (USA) National Inventors' Hall of Fame for his invention of coincident-current magnetic core memory, patented in 1956 (Forrester, 1951, 1953). This might seem some considerable distance from OR. Furthermore, this is a man who surveyed the world of MS/OR in 1956 and, while acknowledging that it, “did pay its way”, concluded that it did not deal with, “major [problems] that made the difference between the companies that succeed and those that stagnate or fail” (Forrester, 1968b, p. 399). Although it is primarily his work after 1956 which merits Forrester's inclusion here, all of these achievements are the work of one man and can be seen to possess a unity. They constitute an outstanding contribution to the field of OR. The practical viewpoint and the intellectual basis of system dynamics both have their roots in the personal outlook and academic training of Forrester. Raised on a Nebraskan cattle ranch, he got his hands dirty finding practical solutions to real problems (Forrester, 1992). On the academic front, his time as a research assistant with Gordon Brown allowed him to work with this pioneer in servomechanism theory. During World War II, Forrester worked on feedback control systems and servo-control systems for radar. One of his most practical experiences resulted from his volunteering to repair an experimental device installed on the Lexington: with him aboard the aircraft carrier participated in the retaking of the Marshall Islands in 1943 and was torpedo bombed. Forrester's experiences from 1940–1951, as Associate Director of MIT's Servomechanism Laboratory and then Head of the Digital Computer Division in MIT's Lincoln Laboratory (1951–1956), were also immensely significant for his contribution to OR. He also directed the ASCA project, aimed at developing flight simulators to test new aircraft designs. This research led to the development of a high speed digital computer able to generate real-time simulations: in 1951, under Forrester's direction in the Digital Computer Laboratory, Whirlwind– then the world's only real-time digital computer – was designed and built. As a core element of SAGE (Semi-Automatic Ground Environment) Whirlwind became the first computer produced in volume. The vast SAGE system, developed under Forrester's responsibility, was built to defend North American airspace from attack and consisted of a network of digital computers and long-distance communication systems which sent target tracking information from radar stations to operators and allowed fighter aircraft and surface-to-air missiles to be deployed in response to threats. Forrester's achievements during this time were immense. They also have a strong flavor of OR to them: they gave Forrester experience in the management of complex, high-technology projects which also have interesting parallels with the earliest OR work on the air defence of the UK during World War II. In 1956, believing that he had already been practicing management via the large projects that he had run, Forrester took up a chair at MIT's Sloan School. He was given a year to contemplate what contribution he might make to the School. Serendipitously, Forrester then became involved in a project with the General Electric Corporation. Managers were puzzled by oscillations in their component inventories and workforce numbers. The working hypothesis was that the oscillations were caused by exogenous effects; business cycles and general “noise” imported from the market. These oscillations endured despite managers' best efforts to remove them: their existing policies did not produce the intended effect because their intuition had failed them. By talking to the managers Forrester elicited an account of how the system was put together, how it behaved over time and how they took actions intended to correct the oscillations. Forrester saw the situation as having many feedback loops, each made up from an inventory level, a manager's collecting information on that level, the decision he then took and the subsequent effects on the level. Forrester's servomechanism-based insight was that the combination of these numerous loops could result in the managers' actions producing the surprising, intuition-defeating effects. By representing the levels, actions and hence loops in a very broad brush way, and doing calculations of their values in a paper notebook, he was then able to confirm that the company's policies which tried to maintain constant inventories actually had the opposite effect: they amplified any oscillations that might arise. Furthermore they did this endogenously, no complex external explanation was needed. Using the precision and formality of his model Forrester was then able to design policies which the managers could use successfully to calm the oscillations. Forrester created computer simulations of this specific problem. His general conclusions concerned both the limitations of existing modeling approaches and the idea that servomechanism theory could be adapted to understand surprising, puzzling, counter-intuitive behavior in human systems (Forrester, 1956). Quite aggregated models could give an explanation of the source of the behavior. Moreover, they could then provide a rigorous basis for simulating the effects of different policies, building improved intuition about the consequences of those policies and helping managers choose policies which resulted in the long-term behavior that they actually wanted. Forrester called the approach “Industrial Dynamics” and the title of the resulting paper (1958) indicated that he had found what an engineer might achieve in the field of management. Forrester spent the next years developing these ideas via further applications (e.g. 1959) and an account of their basis and the contribution that they could make to management (Forrester, 1960). This latter, seminal paper presented “14 obvious truths” about existing modeling approaches which Forrester set out to disprove. Indeed, their rejection constitutes an intellectual agenda. These ideas – and further applications supported by computer simulations using the DYNAMO compiler – produced the magnum opus of system dynamics: Forrester's 1961Industrial Dynamics. The book opens with Forrester surveying the state of management studies. He saw merely a “very skilled art” generated by a mêlée of empirical observations. He therefore proposed that system dynamics could transform this state of affairs, creating a revolution in management science. His view was that feedback ideas were a solid theoretical analytical approach which would act as an integrating framework for diverse descriptions and explanations of the behavior of social systems. Companies, economies, all social systems, should be modeled as accumulations and rates of flow threaded together by information feedback loops involving delays and non-linear relationships. Computer simulation was then the means of deducing the time evolutionary dynamics endogenously created by such system structures. The purpose was first to learn about their modes of behavior and understand the underlying causal mechanisms. Beyond such explanation then came the true goal of system dynamics: organizational re-design. Using a computer simulation model it was possible to identify useful performance measures and key leverage points, promote individual and organizational learning, improve performance, and impart “a better intuitive feel [which] improves … judgement about the factors influencing company success” (p. 45). Industrial Dynamics makes this case using a range of examples as well as describing the approach to be used when building system dynamics models. In the chapter “Future of Industrial Dynamics” Forrester then underscores the breadth of system dynamics by outlining further applications and, in a reprise of his scene-setting introduction on the state of management studies, argues that organizational case studies can be brought to life using system dynamics models, these models acting as experimental laboratories both for research and in support of management education. It is worth identifying the three defining elements of system dynamics. The role of the first –“feedback loops”– has been described above. The second element is computer simulation. Although humans may be able to conceptualize complex causal relationships, they lack the cognitive capacity to infer their consequences over time; contrastingly, simulation rigorously deduces dynamic behavior. The third element is “engagement with mental models”. Managers have mental models, their assumptions about cause and effect, which are the basis for policy making, yet with social systems it is information that is not written down but which exists only in these mental models which is perhaps most important. Modeling must therefore stay close to managers, working to elicit their current mental models and express them in a computer model. Similarly, experimentation with such a model should yield learning, and help managers to improve their intuition and create a new, shared mental model which is the basis for improved future policy making. These three defining elements – feedback, simulation, engagement with mental models – allow Forrester's ideas to be put in context. Concentrating on those first two elements it is clear that Forrester's view was a systems one. He saw managers in different parts of an enterprise making decisions which had repercussions elsewhere in the organization. He saw those repercussions flowing round a feedback loop to return to the originator. (Although Forrester's ideas have various connections and antecedents – Wiener's control theories and Tustin's feedback study of economic systems – it is computer simulation which provides the vivifying power.) It is from this systems perspective that Forrester's dismissive remarks about OR should be seen. Indeed, though independent, his remarks are strikingly in tune with Russell Ackoff's contemporaneous concerns, including the view that OR was applied to problems of limited scope. The importance attached to engagement with mental models – elaborated in later publications (e.g. Forrester, 1971a) but clearly present in Industrial Dynamics– reveals further OR connections. The idea of shared mental models anticipates Mintzberg's work on “organizational memory” and the “organizational learning” work of the 1990s. The notion of creative play with computers echoes Papert's work on developing geometry skills in children using a programmable robot. However, it is the connection between Forrester's ideas and those of “problem structuring methods” (PSMs) that are of particular interest to operational researchers. In this regard, in both system dynamics and PSMs practice, models are seen as contingent entities, while both fields also emphasize group participation and the modeling process as learning experience and the value of the model being judged by a specific group dealing with a specific issue. Forrester's championing of these ideas significantly pre-dates its detailed handling within the OR community. Although one would hardly expect these ideas in Industrial Dynamics to be identical to today's PSMs thinking, the roots of modern system dynamics practice were clearly present in 1961. The form of group working practiced then was considerably limited by participants' ability to work easily with computer models. However, considering the software available until the late 1980s, it is a testament to the power of the system dynamics approach that any of Forrester's consulting assignments done directly with managers took place at all. That they did, and that he identified this as an important aspiration for system dynamics, speaks highly of his personality and imaginative intellectual vision. Subsequent research has linked system dynamics with more general work involving OR modeling in groups and with the literature on group decision support (Lane, 1992, 1994; Richmond, 1997; Vennix, 1996). Throughout the 1960s, Forrester developed the field of system dynamics via research projects, courses and improved software. He drew on the project experiences acquired by himself and his co-workers to publish Principles of Systems (1968d). This book introduces the basic ideas of system dynamics using a wide range of exercises and applications. His membership of the board of DEC also allowed him very clearly to deliver on the promise implicit in his rejection of OR. His “market growth model” provides powerful insights on why, “… companies often grow to a certain level and then stagnate or fail” (Forrester, 1990a, p. 6, 1968c). He summarized the achievements of his field after a decade of work while re-stating and extending “the task ahead” (Forrester, 1968b). He also responded to an intelligent critique of system dynamics from within the OR community with one of the best short treatments of the field (Forrester, 1968a). Towards the end of the decade the more general name “system dynamics” was adopted for the field. A further significant shift from corporate/industrial modeling came with an extension into public policy as a result of Forrester's work with ex-mayor of Boston John Collins. Urban Dynamics (1969) was a study of the mechanisms underlying the development, stagnation, decline and recovery of a city. Its audacity and courage are characteristically Forrestian. He has described elsewhere the strongly hostile reactions to this work but is also able to cite examples in which surprising “converts” were made. The key seemed to be spending sufficient time with the model to understand its assumptions and the source of its dynamics and policy insights. The account of Forrester's testimony to a US House of Representatives sub-committee on urban growth gives an idea of how he went about explaining his ideas (Forrester, 1970). In 1970 Forrester began working with the Club of Rome to understand the dynamics of aggregate global development. He used a system dynamics model to represent the links between population, natural resources, pollution, agricultural and industrial production, capital investment and quality of life. The resulting book, World Dynamics, was the object of worldwide discussion in popular and scholarly fora. The book asked sharp questions about the relationship between growth and quality of life. Only nine months later The Limits to Growth (Meadows et al., 1972), a further dispatch from this research frontier, outsold World Dynamics and created more debate. A subsequent long-term research program under Dennis Meadows deepened and extended this analysis, producing a series of publications (Meadows et al., 1974; Meadows and Meadows, 1973; Meadows, 1985). With this stream of work Forrester applied system dynamics to arguably the most important area of social policy and his work has been instrumental in shaping public thinking on environmentalism, development, pollution and resource restrictions. His insights on the aim of caring for the environment and the need to make trade-offs between long-term versus short-term effects have an important place in environmentalist thinking today, and his original model is the founding work of global modeling. Moving through the 1970s and into the 1980s one can see a weaving together of effects resulting in the institutionalization of Forrester's ideas. From the late 1970s onwards annual conferences were organized. The System Dynamics Society was created in 1983. A dedicated journal, The System Dynamics Review, appeared in 1985. The Fifth Discipline (Senge, 1990) explored the relationship between system dynamics and ideas of organizational learning and was a global best seller. Forrester himself remained active. Emerging from research on the US economy, the “National Model” produced significant structural insights into the causes of such phenomena as business cycles and “stagflation” from Forrester himself (1977a, b, 1978, 1979a, b, 1980a, 1981, 1985, 1987, 1989) and his co-researchers (e.g. Mass, 1975; Forrester et al., 1976; Sterman, 1985). The culmination of this project is another book by Forrester, tantalising chapters from which have been seen within the system dynamics community. Forrester retired from Sloan in 1989, an event which, as he once described to me in an email, “has had no effect whatsoever on my work”. Ever someone to identify the high leverage point in a system, he has taken his ideas on management education an

Cite this work

No public copy is stored for this record, so only the metadata is cited.

Stored only when both papers are in the corpus — 29 citations exist upstream.

Papers that cite the same references — the relational fallback while embeddings are still backfilling.