ABSTRACT
This chapter defines the conditions of safe prediction and distinguishes the areas where such conditions are in a greater or smaller measure wanting. A prediction is based on the law-determined behavior of the objects to which it applies; in consequence, it was long thought that scientific prediction held only for things, and not for man. The alchemist's mishap strikingly illustrates the necessity of minutely analyzing the initial conditions in experiments designed to establish a predictive and scientific proposition. Because of the importance of weather forecasts for the national economy, the Council of the American Meteorological Society issued the following statement for the express purpose of damping false hopes: Weather forecasts prepared in some detail are possible for two or three days in advance. If "legality" in the statistical sense was introduced into social science, A. Quetelet's observation that "illegality" in the juridical sense exhibited certain regularities had a great deal to do with it.
