Wednesday, May 7, 2008

Computer Models: " Misuse of Models" and "No model for policymaking"

I'm going to bring out the big guns.

I read a book last year, Useless Arithmetic: Why Environmental Scientists Can't Predict the Future, that, while a bit light on the 'whys', packs more understanding of computer modeling into230 pages than you are likely to find anywhere else.

The author, Orrin H. Pilkey is Emeritus Professor of Geology at Duke.
The first review I'm going to link to appeared in American Scientist. The reviewer is Carl Wunsch, Carl and Ida Green Professor of Physical Oceanography in the Department of Earth, Atmospheric and Planetary Sciences at the Massachusetts Institute of Technology.

What happens when an immature and incomplete science meets a societal demand for information and direction? The spectacle is not pretty, as we learn from Useless Arithmetic, a new book that describes a long list of incompetent and sometimes mindless uses of fragmentary scientific ideas in the realm of public policy. The troubling anecdotes that authors Orrin H. Pilkey and Linda Pilkey-Jarvis provide cross diverse fields, including fisheries management, nuclear-waste disposal, beach erosion, climate change, ore mining, seed dispersal and disease control. Their extended examples of the misuse of science are both convincing and depressing. The book is a welcome antidote to the blind use of supposedly quantitative models, which may well represent the best one can do, but which are not yet capable of producing useful information.

Unfortunately, the impression of the issues one gets from the book is sometimes misleading. The authors' target is "mathematical modeling" as practiced in science. Examples abound of theories being applied grossly beyond the limits of their demonstrable usefulness, leading to absurd results or producing "answers" to questions that are themselves absurd (What will be the hydrological cycle in Yucca Flat one million years in the future?).

But are fisheries management and nuclear-waste disposal scientific problems? The authors' examples are not really problems of science but of the application of science to a practical end (a definition of engineering); politics, economics, the legal system and even psychology are involved. When science is not ready to answer specific questions, but the political universe insists that policies must be put in place (How large a catch can the fishery sustain? Is malaria in Africa a greater problem than HIV? How rapidly will this beach erode?), the outcome is almost inevitable: Someone will rush forward claiming that the answer is at hand, and the political system, driven to cope with a public threat or desire, will likely implement some insupportable policy. When the science is incomplete, one enters the world of P. T. Barnum, medical nostrums and the carnival....

...Politicians must make and implement public policy even when science cannot provide truly skillful forecasts. Society has to make decisions in the face of major uncertainty about the outcome. More discussion of that necessity and how to cope with it would have been welcome in this book. As it is, the authors usefully raise the alarm about the misuse of poorly understood models and the illusion that because those models are complex, they must be meaningful. In the wrong hands, the best of models can be grossly misleading. To find many examples of that, read this book....SOURCE

The second reviewer, Stephen R Carpenter, is the S. A. Forbes Professor of Zoology and Halverson Professor of Limnology at the University of Wisconsin-Madison.

From Issues in Science and Technology via BNET:

...Many environmental problems, though, are beyond complicated: They are complex. Examples include global climate change; the sustainable mitigation of poverty; and managing tradeoffs among interacting ecosystem services such as food, fresh water, and wild living resources. Such problems selforganize from the interactions of trillions of organisms and decisions by millions of people in a changing world of turbulent atmosphere, ocean, and earth-surface dynamics. Successful solution in one place or time does not guarantee success elsewhere or in the future. Apparently successful solutions seem to sow the seeds of future failures. Prediction and control, the keys to solving complicated problems, fail in complex settings for several reasons, including lack of essential information, nonlinear dynamics, and human volition.

Complex problems must be faced with great humility because control is limited and predictions are unreliable. Yet predictions, however fraudulent, can have enormous economic and political influence if they are taken seriously by society. In this concise, powerful, and readable book, Orrin Pilkey and Linda Pilkey-Jarvis expose abuses of prediction in environmental decisionmaking. Their specific target is abstruse computer models used by private organizations or government agencies aiming to create spurious certainty, suppress alternative approaches, and influence public policy to reward narrow interest groups. Thus abuses that would be mere hubris if committed by an individual become sociopathic. The models are not designed to shed light on a problem but to create a politically advantageous shortcut to a selfinterested outcome....MORE