Uncertainty has been of concern to engineers, managers and . scientists
for many centuries. In management sciences there have existed
definitions of uncertainty in a rather narrow sense since the beginning
of this century. In engineering and uncertainty has for a long time been
considered as in sciences, however, synonymous with random, stochastic,
statistic, or probabilistic. Only since the early sixties views on
uncertainty have ecome more heterogeneous and more tools to model
uncertainty than statistics have been proposed by several scientists.
The problem of modeling uncertainty adequately has become more important
the more complex systems have become, the faster the scientific and
engineering world develops, and the more important, but also more
difficult, forecasting of future states of systems have become. The
first question one should probably ask is whether uncertainty is a
phenomenon, a feature of real world systems, a state of mind or a label
for a situation in which a human being wants to make statements about
phenomena, i. e., reality, models, and theories, respectively. One cart
also ask whether uncertainty is an objective fact or just a subjective
impression which is closely related to individual persons. Whether
uncertainty is an objective feature of physical real systems seems to be
a philosophical question. This shall not be answered in this volume.