Technology forecasters-soothsayers or scientists?

The techniques and pitfalls of trend extrapolation are examined by scrutinizing two elementary mathematical approaches that now enjoy acceptance in modeling innovation and projecting the growth of new sciences and technologies. The first of these approaches is continued exponential growth. The second approach is logistic growth, or growth that conforms to the ´S-shaped´ curve that traces the startup, midlife, and maturing of a technology. An introduction to each model is given, with examples that show how the models are used and sometimes misused. Thoughts from prominent futurists and philosophers of the credibility and intellectual legitimacy of forecasts are presented. It is concluded that the fundamental issues center on the correct use of inductive reasoning.<>