The levers of power are only loosely connected to operations.
9
Modelling can be controversial. World Dynamics was and still is a thought-provoking model, a potent catalyst for political debate and an instrument for serious policy making. It was also a focus of learned criticism about the nature and use of modelling and simulation in the social sciences. Quotations from the press and academic literature at the time convey the impact, both positive and negative, of the model on opinion leaders: ‘This is likely to be one of the most important documents of our age …’, New York Times; ‘There are too many assumptions that are not founded, and there is too high a level of aggregation in the model’, Science; ‘This year will not see the publication of a more important book than Forrester's World Dynamics, or a book more certain to arouse dislike’, Fortune; ‘This is a piece of irresponsible nonsense, a publicity stunt … extremely simplistic, given the current state of knowledge in the social sciences’, economists from Yale. Notice the sharp division of opinion on the scope, size, adequacy and usefulness of the model. The serious press thinks the work is important for its readers and worthy of policymakers' attention. Academics question the model's apparent simplicity. Not surprisingly judgements vary about the complexity and accuracy required of models (or even ideas and theories) for them to offer useful guidance to business and society. Modellers need to strike a careful balance.
10
Clover describes the poignant scene at Lowestoft in recent years: the unrepaired doorways and shabby 1930s office buildings on the seafront, symbols of economic collapse. This town was once among England's greatest fishing ports, famous the world over, with a history spanning 600 years.
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The diagram was created in the popular iThink language (isee systems, 2014). The symbols are pretty much standard for all system dynamics models, though there are differences of detail between the main alternative modelling software packages. Here, in Chapter 1, I briefly explain each symbol when I first refer to it in the text. Later, in Chapter 3, there is a more formal introduction to modelling symbols and equations, with a fully documented example.
12
Interestingly, some people dispute the existence of this circularity. They argue that the number of juveniles reaching fishable size each year has nothing to do with the number of parents in the sea because fish such as cod can produce upwards of seven million eggs in a season – most of which perish due to predation and environmental factors. However, the number of fish eggs is certainly related to the population of fish.
The levers of power are only loosely connected to operations.
