In the wake of the publication of Forrester's World Dynamics and Meadow's The Limits to Growth-books which in The Netherlands may have received ex cessive attention from the public at large-the Netherlands Organization for Applied Scientific Research (TNO) established a commission under the chair manship of the late Professor R. Timman. The commission received the task of trying to find a sound philosophical basis for world modelling and to stimulate the building of models that incorporated those aspects of society which are usu ally left out of mathematical models because of technical...